CD8+ T-cell exhaustion has been identified as a significant contributor to immunosuppression and immune escape in triple-negative breast cancer (TNBC). Dysfunction due to cell exhaustion is characterized by reduced effector capacity and sustained expression of inhibitory receptors (IRs). The factors contributing to CD8+ T-cell exhaustion are multifaceted, encompassing external influences such as the upregulation of IRs, reduction of effector cytokines, and internal changes within the immune cell, including transcriptomic alterations, epigenetic landscape remodeling, and metabolomic shifts. The impact of the altered TNBC tumor microenvironment (TME) on Tex is also a critical consideration. The production of exhausted CD8+ T-cells (CD8+ Tex) is positively correlated with poor prognosis and reduced response rates to immunotherapy in TNBC patients, underscoring the urgent need for the development of novel TNBC immunotherapeutic strategies that target the mechanisms of CD8+ T-cell exhaustion. This review delineates the dynamic trajectory of CD8+ T-cell exhaustion development in TNBC, provides an update on the latest research advancements in understanding its pathogenesis, and offers insights into potential immunotherapeutic strategies.

The current management of patients with stroke with intravenous thrombolysis and endovascular thrombectomy is effective only when it is timely performed on an appropriately selected but minor fraction of patients. The development of novel adjunctive therapy is highly desired to reduce morbidity and mortality with stroke. Since endothelial dysfunction is implicated in the pathogenesis of stroke and is featured with suppressed endothelial nitric oxide synthase (eNOS) with concomitant nitric oxide deficiency, restoring endothelial nitric oxide represents a promising approach to treating stroke injury.

This is a preclinical proof-of-concept study to determine the therapeutic effect of transcranial treatment with a low-power near-infrared laser in a mouse model of ischemic stroke. The laser treatment was performed before the middle cerebral artery occlusion with a filament. To determine the involvement of eNOS phosphorylation, unphosphorylatable eNOS S1176A knock-in mice were used. Each measurement was analyzed by a 2-way ANOVA to assess the effect of the treatment on cerebral blood flow with laser Doppler flowmetry, eNOS phosphorylation by immunoblot analysis, and stroke outcomes by infarct volumes and neurological deficits.

Pretreatment with a 1064-nm laser at an irradiance of 50 mW/cm2 improved cerebral blood flow, eNOS phosphorylation, and stroke outcomes.

Near-infrared II photobiomodulation could offer a noninvasive and low-risk adjunctive therapy for stroke injury. This new modality using a physical parameter merits further consideration to develop innovative therapies to prevent and treat a wide array of cardiovascular diseases.

The majority of vaccines have been delivered into the muscular tissue. Skin contains large amounts of antigen-presenting cells and has been recognized as a more immunogenic site for vaccine delivery. Intradermal delivery has been approved to improve influenza vaccine efficacy and spare influenza vaccine doses. In response to the recent monkeypox outbreak, intradermal delivery has been also approved to stretch the limited monkeypox vaccine doses to immunize more people at risk. Incorporation of vaccine adjuvants is promising to further increase intradermal vaccine efficacy and spare more vaccine doses. Yet, intradermal vaccination is associated with more significant local reactions than intramuscular vaccination. Thus, adjuvants suitable to boost intradermal vaccination need to have a good local safety without inducing overt local reactions. This review introduces currently approved adjuvants in licensed human vaccines and their relative reactogenicity for intradermal delivery and then introduces emerging chemical and physical adjuvants with a good local safety to boost intradermal vaccination. The rational to develop physical adjuvants, the types of physical adjuvants, and the unique advantages of physical adjuvants to boost intradermal vaccination are also introduced in this review.

Nitric oxide (NO) is a well-known gaseous mediator that maintains vascular homeostasis. Extensive evidence supports that a hallmark of endothelial dysfunction, which leads to cardiovascular diseases, is endothelial NO deficiency. Thus, restoring endothelial NO represents a promising approach to treating cardiovascular complications. Despite many therapeutic agents having been shown to augment NO bioavailability under various pathological conditions, success in resulting clinical trials has remained elusive. There is solid evidence of diverse beneficial effects of the treatment with low-power near-infrared (NIR) light, defined as photobiomodulation (PBM). Although the precise mechanisms of action of PBM are still elusive, recent studies consistently report that PBM improves endothelial dysfunction via increasing bioavailable NO in a dose-dependent manner and open a feasible path to the use of PBM for treating cardiovascular diseases via augmenting NO bioavailability. In particular, the use of NIR light in the NIR-II window (1000-1700 nm) for PBM, which has reduced scattering and minimal tissue absorption with the largest penetration depth, is emerging as a promising therapy. In this review, we update recent findings on PBM and NO.

Radiofrequency adjuvant (RFA) was recently developed to boost influenza vaccination without the safety concerns of chemical adjuvants due to their physical nature. Yet, the action mechanisms of RFA remain largely unknown. Omics techniques offer new opportunities to identify molecular mechanisms of RFA. This study utilized comparative tissue proteomics to explore molecular mechanisms of the physical RFA. Comparison of RFA and chemical adjuvant (Alum, AddaVax, MPL, MPL/Alum)-induced tissue proteome changes identified 14 exclusively induced proteins by RFA, among which heat shock protein (HSP) 70 was selected for further analysis due to its known immune-modulating functions. RFA showed much weakened ability to boost ovalbumin and pandemic influenza vaccination in HSP70 knockout than wild-type mice, hinting crucial roles of HSP70 in RFA effects. This study supports comparative tissue proteomics to be an effective tool to study molecular mechanisms of vaccine adjuvants.

Novel adjuvants are highly demanded to aid in development of improved or new vaccines against existing or emerging infectious diseases. Considering commonly used Alum and MF59 adjuvants induce tissue stress and release of endogenous danger signals to mediate their adjuvant effects, physical modalities may be used to induce tissue stress and endogenous danger signal release to enhance vaccine-induced immune responses. Furthermore, physical adjuvants are less likely to induce significant systemic adverse reactions due to their localized effects. Recently we found non-invasive radiofrequency (RF) pretreatment of the skin could significantly enhance intradermal vaccine-induced immune responses in murine models that included pandemic influenza vaccine, pre-pandemic vaccine, and influenza internal antigen vaccine. It remained to be explored whether the physical RF adjuvant (RFA) could be used to boost seasonal influenza vaccination, spare vaccine doses, and induce cross-protective immunity. This study found the physical RFA could significantly enhance seasonal influenza vaccine-induced immune responses against each viral strain and robustly enhance low-dose (nanograms) H3N2 vaccine-induced immune responses and protection in murine models. RFA also induced cross-protective immunity against heterologous and heterosubtypic influenza viruses. Further studies found heat shock protein 70 (inducible endogenous danger signal) and myeloid differentiation primary response 88 adaptor played a crucial role in dose-sparing effects of RFA. These data strongly support further development of the physical RFA to boost influenza vaccination.

With the development of laser technology in the 1960s, a technique was developed to inject intradermal vaccines immediately after irradiating the skin with laser light to elicit an adjuvant effect, referred to as "laser adjuvant." We have been investigating the mechanism of laser adjuvant in influenza mouse models using noninvasive continuous-wave (CW) near-infrared (NIR) light mainly at a wavelength of 1064 nm, and have shown that the production of reactive-oxygen-species (ROS) in the skin and mast cells in the skin tissue plays an important role in the laser adjuvant effect. The new wavelength of 1270 nm NIR light is characterized by its ability to elicit the same vaccine adjuvant effect as other wavelengths at a lower energy, and may be suitable for clinical applications. In this study, we investigated the physiological activity of CW1270 nm NIR light in mast cells, its biological activity on mouse skin, and the durability of the vaccine adjuvant effect in influenza vaccine mouse models. We show that irradiation of mast cells with 1270 nm NIR light produced ROS and ATP, and irradiation of isolated mitochondria also produced ATP. In mouse skin, the relative expression levels of chemokine mRNAs, such as Ccl2 and Ccl20, were increased by irradiation with 1270 and 1064 nm NIR light at minimum safe irradiance. However, the relative expression of Nfkb1 was increased at 1064 nm, but not at 1270 nm. Serum anti-influenza IgG antibody titers increased early after immunization with 1064 nm, whereas with 1270 nm, there was not only an early response of antibody production but also persistence of antibody titers over the medium- to long-term. Thus, to our knowledge, we show for the first time that 1270 nm NIR light induces ROS and ATP production in mitochondria as photoreceptors, initiating a cascade of laser adjuvant effects for intradermal vaccines. Additionally, we demonstrate that there are wavelength-specific variations in the mechanisms and effects of laser adjuvants. In conclusion, CW1270 nm NIR light is expected to be clinically applicable as a novel laser adjuvant that is equivalent or superior to 1064 nm NIR light, because it can be operated at low energy and has a wavelength-specific adjuvant effect with medium- to long-lasting antibody titer.

Immunotherapy, including immune checkpoint inhibitors, has revolutionized cancer treatment, but only a minor fraction of patients shows durable responses. A new approach to overcome this limitation is yet to be identified. Recently, we have shown that photobiomodulation (PBM) with near-infrared (NIR) light in the NIR-II window reduces oxidative stress and supports the proliferation of CD8+ T cells, suggesting that PBM with NIR-II light could augment anti-cancer immunity. Here, we report a novel approach to support tumor-infiltrating CD8+ T cells upon PBM with NIR-II laser with high tissue penetration depth. Brief treatments of a murine model of breast cancer with dual 1064 and 1270 nm lasers reduced the expression of the programmed cell death protein 1 (PD-1) in CD8+ T cells in a syngeneic mouse model of breast cancer. The direct effect of the NIR-II laser treatment on T cells was confirmed by the enhanced tumor growth delay by the adoptive transfer of laser-treated CD8+ T cells ex vivo against a model tumor antigen. We further demonstrated that specific NIR-II laser parameters augmented the effect of the immune checkpoint inhibitor on tumor growth. PBM with NIR-II light augments the efficacy of cancer immunotherapy by supporting CD8+ T cells. Unlike the current immunotherapy with risks of undesirable drug-drug interactions and severe adverse events, the laser is safe and low-cost. It can be broadly combined with other therapy without modification to achieve clinical significance. In addition, our study established a path to develop a novel laser-based therapy to treat cancer effectively.

There is solid evidence of the beneficial effect of photobiomodulation (PBM) with low-power near-infrared (NIR) light in the NIR-I window in increasing bioavailable nitric oxide (NO). However, it is not established whether this effect can be extended to NIR-II light, limiting broader applications of this therapeutic modality. Since we have demonstrated PBM with NIR laser in the NIR-II window, we determined the causal relationship between NIR-II irradiation and its specific biological effects on NO bioavailability. We analyzed the impact of NIR-II irradiation on NO release in cultured human endothelial cells using a NO-sensitive fluorescence probe and single-cell live imaging. Two distinct wavelengths of NIR-II laser (1064 and 1270 nm) and NIR-I (808 nm) at an irradiance of 10 mW/cm2 induced NO release from endothelial cells. These lasers also enhanced Akt phosphorylation at Ser 473, endothelial nitric oxide synthase (eNOS) phosphorylation at Ser 1177, and endothelial cell migration. Moreover, the NO release and phosphorylation of eNOS were abolished by inhibiting mitochondrial respiration, suggesting that Akt activation caused by NIR-II laser exposure involves mitochondrial retrograde signaling. Other inhibitors that inhibit known Akt activation pathways, including a specific inhibitor of PI3K, Src family PKC, did not affect this response. These two wavelengths of NIR-II laser induced no appreciable NO generation in cultured neuronal cells expressing neuronal NOS (nNOS). In short, NIR-II laser enhances bioavailable NO in endothelial cells. Since a hallmark of endothelial dysfunction is suppressed eNOS with concomitant NO deficiency, NIR-II laser technology could be broadly used to restore endothelial NO and treat or prevent cardiovascular diseases.

The development of vaccines against herpes simplex virus type 1 and type 2 (HSV1 and HSV-2) is an important goal for global health. In this review we reexamined (i) the status of ocular herpes vaccines in clinical trials; and (ii) discusses the recent scientific advances in the understanding of differential immune response between HSV infected asymptomatic and symptomatic individuals that form the basis for the new combinatorial vaccine strategies targeting HSV; and (iii) shed light on our novel "asymptomatic" herpes approach based on protective immune mechanisms in seropositive asymptomatic individuals who are "naturally" protected from recurrent herpetic diseases. We previously reported that phenotypically and functionally distinct HSV-specific memory CD8+ T cell subsets in asymptomatic and symptomatic HSV-infected individuals. Moreover, a better protection induced following a prime/pull vaccine approach that consists of first priming anti-viral effector memory T cells systemically and then pulling them to the sites of virus reactivation (e.g., sensory ganglia) and replication (e.g., eyes and vaginal mucosa), following mucosal administration of vectors expressing T cell-attracting chemokines. In addition, we reported that a combination of prime/pull vaccine approach with approaches to reverse T cell exhaustion led to even better protection against herpes infection and disease. Blocking PD-1, LAG-3, TIGIT and/or TIM-3 immune checkpoint pathways helped in restoring the function of antiviral HSV-specific CD8+ T cells in latently infected ganglia and increased efficacy and longevity of the prime/pull herpes vaccine. We discussed that a prime/pull vaccine strategy that use of asymptomatic epitopes, combined with immune checkpoint blockade would prove to be a successful herpes vaccine approach.

Adjuvants are essential for ensuring the efficacy of modern vaccines. Considering frequent local and systemic adverse reactions, research into the development of safer and more effective adjuvants is being actively conducted. In recent years, the novel concept of laser vaccine adjuvants, which use the physical energy of light, has been developed. For long, light has been known to affect the physiological functions in living organisms. Since the development of lasers as stable light sources, laser adjuvants have evolved explosively in multiple ways over recent decades. Future laser adjuvants would have the potential not only to enhance the efficacy of conventional vaccine preparations but also to salvage candidate vaccines abandoned during development because of insufficient immunogenicity or owing to their inability to be combined with conventional adjuvants. Furthermore, the safety and efficacy of non-invasive laser adjuvants make them advantageous for vaccine dose sparing, which would be favorable for the timely and equitable global distribution of vaccines. In this review, we first describe the basics of light-tissue interactions, and then summarize the classification of lasers, the history of laser adjuvants, and the mechanisms by which different lasers elicit an immune response.

Rapid establishment of herd immunity with vaccination is effective to combat emerging infectious diseases. Although the incorporation of adjuvant and intradermal (ID) injection could augment early responses to the vaccine, the current chemical or biological adjuvants are inappropriate for this purpose with their side effects and high reactogenicity in the skin. Recently, a near-infrared (NIR) laser has been shown to augment the immune response to ID vaccination and could be alternatively used for mass vaccination programs. Here, we determined the effect of NIR laser as well as licensed chemical adjuvants on the immunogenicity 1, 2, and 4 weeks after ID influenza vaccination in mice. The NIR laser adjuvant augmented early antibody responses, while the widely used alum adjuvant induced significantly delayed responses. In addition, the oil-in-water and alum adjuvants, but not the NIR laser, elicited escalated T_H2 responses with allergenic immunoglobulin E (IgE) responses. The effect of the NIR laser was significantly suppressed in the basic leucine zipper transcription factor ATF-like 3 (Batf3) knockout mice, suggesting a critical role of the cluster of differentiation 103⁺ (CD103)⁺ dendritic cells. The current preliminary study suggests that NIR laser adjuvant is an alternative strategy to chemical and biological agents to timely combat emerging infectious diseases. Moreover, its immunomodulatory property could be used to enhance the efficacy of immunotherapy for allergy and cancer.

Luteolin, a naturally found dietary flavonoid, has a wide range of beneficial biological effects, including effects against tumors and oxidants. Studies proved that luteolin can modulate immune responses. In this study, we investigated the function of luteolin as an antitumor vaccine adjuvant (to treat malignant melanoma) in vitro and in vivo. We found that Luteolin may activated the PI3K-Akt pathways in APCs (Antigen Presenting Cells), induced the activation of APCs, enhanced CTL (Cytotoxic T Lymphocyte) responses, and inhibited tolerogenic T cells. To prove the role of CD8+T cells in immune process, we sorted the CD8+T cells from the immunized mice and transferred them to the B16F10 tumor-bearing mice, the result showed that the survival rate was improved. We also observed that in the mice immunized with Luteolin as an adjuvant, the tumor growth was significantly reduced. Taken together, the result demonstrated that luteolin showed promising properties as a vaccine adjuvant for treating malignant melanoma.

Vaccine delivery via a microneedle (MN) system has been identified as a potential alternative to conventional vaccine delivery. MN can be self-administered, is pain-free and is capable of producing superior immunogenicity. Over the last few decades, significant research has been carried out in this area, and this review aims to provide a comprehensive picture on the progress of this delivery platform.

This review highlights the potential role of skin as a vaccine delivery route using a microneedle system, examines recent advancements in microneedle fabrication techniques, and provides an update on potential preclinical and clinical studies on vaccine delivery through microneedle systems against various infectious diseases. Articles for the review study were searched electronically in PubMed, Google, Google Scholar, and Science Direct using specific keywords to cover the scope of the article. The advanced search strategy was employed to identify the most relevant articles.

A significant number of MN mediated vaccine candidates have shown promising results in preclinical and clinical trials. The recent emergence of cleanroom free, 3D or additive manufacturing of MN systems and stability, together with the dose-sparing capacity of the Nanopatch® system, have made this platform, commercially, highly lucrative.

Near-infrared (NIR) light possesses many suitable optophysical properties for medical imaging including low autofluorescence, deep tissue penetration, and minimal light scattering, which together allow for high-resolution imaging of biological tissue. NIR imaging has proven to be a noninvasive and effective real-time imaging methodology that provides a high signal-to-background ratio compared to other potential optical imaging modalities. In response to this, the use of NIR imaging has been extensively explored in the field of immunotherapy. To date, NIR fluorescence imaging has successfully offered reliable monitoring of the localization, dynamics, and function of immune responses, which are vital in assessing not only the efficacy but also the safety of treatments to design immunotherapies optimally. This review aims to provide an overview of the current research on NIR imaging of the immune response. We expect that the use of NIR imaging will expand further in response to the recent success in cancer immunotherapy. We will also offer our insights on how this technology will meet rapidly growing expectations in the future.

The COVID-19 pandemic has taken the entire globe by storm. The pathogenesis of this virus has shown a cytokine storm release, which contributes to critical or severe multi-organ failure. Currently the ultimate treatment is palliative; however, many modalities have been introduced with effective or minimal outcomes. Meanwhile, enormous efforts are ongoing to produce safe vaccines and therapies. Phototherapy has a wide range of clinical applications against various maladies. This necessitates the exploration of the role of phototherapy, if any, for COVID-19. This critical review was conducted to understand COVID-19 disease and highlights the prevailing facts that link phototherapy utilisation as a potential treatment modality for SARS-CoV-2 viral infection. The results demonstrated phototherapy's efficacy in regulating cytokines and inflammatory mediators, increasing angiogenesis and enhancing healing in chronic pulmonary inflammatory diseases. In conclusion, this review answered the following research question. Which molecular and cellular mechanisms of action of phototherapy have demonstrated great potential in enhancing the immune response and reducing host-viral interaction in COVID-19 patients? Therefore, phototherapy is a promising treatment modality, which needs to be validated further for COVID-19 by robust and rigorous randomised, double blind, placebo-controlled, clinical trials to evaluate its impartial outcomes and safety.

Photobiomodulation is a well-established therapeutic modality. However, the mechanism of action is poorly understood, due to lack of research in the causal relationship between the near-infrared (NIR) light irradiation and its specific biological effects, hindering broader applications of this technology.

Since biological chromophores typically show several absorption peaks, we determined whether specific effects of photobiomodulation are induced with a combination of two wavelengths at a certain range of irradiance only, rather than a single wavelength of NIR light.

In order to analyze a wide array of combinations of multispectral NIR light at various irradiances efficiently, we developed a new optical platform equipped with two distinct wavelengths of NIR lasers by high-throughput multiple dosing for single-cell live imaging. Two wavelengths of 1064 and 1270 nm were selected based on their photobiomodulatory effects reported in the literature.

A specific combination of wavelengths at low irradiances (250 to 400  mW  /  cm2 for 1064 nm and 55 to 65  mW  /  cm2 for 1270 nm) modulates mitochondrial retrograde signaling, including intracellular calcium and reactive oxygen species in T cells. The time-dependent density functional theory computation of binding of nitric oxide (NO) to cytochrome c oxidase indicates that the illumination with NIR light could result in the NO release, which might be involved in these changes.

This optical platform is a powerful tool to study causal relationship between a specific parameter of NIR light and its biological effects. Such a platform is useful for a further mechanistic study on not only photobiomodulation but also other modalities in photomedicine.

The use of an immunologic adjuvant to augment the immune response is essential for modern vaccines which are relatively ineffective on their own. In the past decade, researchers have been consistently reporting that skin treatment with a physical parameter, namely laser light, augments the immune response to vaccine and functions as an immunologic adjuvant. This "laser adjuvant" has numerous advantages over the conventional chemical or biological agents; it is free from cold chain storage, hypodermic needles, biohazardous sharp waste, irreversible formulation with vaccine antigen, undesirable biodistribution in vital organs, or unknown long-term toxicity. Since vaccine formulations are given to healthy populations, these characteristics render the "laser adjuvant" significant advantages for clinical use and open a new developmental path for a safe and effective vaccine. In addition, laser technology has been used in the clinic for more than three decades and is therefore technically matured and has been proved to be safe. Currently, four classes of laser adjuvant have been reported; ultrashort pulsed, non-pulsed, non-ablative fractional, and ablative fractional lasers. Since each class of the laser adjuvant shows a distinct mechanism of action, a proper choice is necessary to craft an effective vaccine formulation toward a desired clinical benefit for a clinical vaccine to maximize protection. In addition, data also suggest that further improvement in the efficacy is possible when a laser adjuvant is combined with chemical or biological adjuvant(s). To realize these goals, further efforts to uncover the molecular mechanisms of action of the laser adjuvants is warranted. This review provides a summary and comments of the recent updates in the laser adjuvant technology.

Human papillomavirus (HPV) causes cervical carcinoma, which and is the third most common cancer, accounting for 275,000 deaths annually worldwide. Adjuvants have a key role in promotion of vaccine efficacy; therefore, using prophylactic and therapeutic vaccines combined with adjuvant could be of great benefit in prevention and treatment of cervical cancer. There are different types of adjuvants, including MF59^TM adjuvants, RNA-based, JY (interleukin2/chitosan), cholera toxin (CT), heat-labile enterotoxin (LT), Freund's adjuvant, alum, SA-4-1BBL, λ-carrageenan (λ-CGN), heat shock proteins (HSPs), juzen-taiho-to (JTT) and hochu-ekki-to (HET), ISCOM and ISCOMATRIX™, very small size proteoliposomes (VSSPs), granulocyte macrophage colony-stimulating factor (GM-CSF), and Toll-like receptors (TLRs). Adjuvants have various functions, especially in therapeutic vaccines, and they lead to an increase in cytotoxic T lymphocytes (CTLs), so they are important in the design of vaccines. Here, we review the currently used adjuvants and their combinations with HPV protein vaccines in order to introduce an appropriate adjuvant for HPV vaccines.

Many vaccines require adjuvants to enhance immunogenicity, but there are few safe and effective intradermal (i.d.) adjuvants. Murine studies have validated the potency of laser illumination of skin as an adjuvant for i.d. vaccination with advantages over traditional adjuvants. We report a pilot clinical trial of low-power, continuous-wave, near-infrared laser adjuvant treatment, representing the first human trial of the safety, tolerability, and cutaneous immune cell trafficking changes produced by the laser adjuvant. In this trial we demonstrated a maximum tolerable energy dose of 300 J/cm2 to a spot on the lower back. The irradiated spot was biopsied 4 h later, as was a control spot. Paired biopsies were submitted for histomorphologic and immunohistochemical evaluation in a blinded fashion as well as quantitative PCR analysis for chemokines and cytokines. Similar to prior murine studies, highly significant reductions in CD1a+ Langerhans cells in the dermis and CD11c+ dermal dendritic cells were observed, corresponding to the increased migratory activity of these cells; changes in the epidermis were not significant. There was no evidence of skin damage. The laser adjuvant is a safe, well-tolerated adjuvant for i.d. vaccination in humans and results in significant cutaneous immune cell trafficking.-Gelfand, J. A., Nazarian, R. M., Kashiwagi, S., Brauns, T., Martin, B., Kimizuka, Y., Korek, S., Botvinick, E., Elkins, K., Thomas, L., Locascio, J., Parry, B., Kelly, K. M., Poznansky, M. C. A pilot clinical trial of a near-infrared laser vaccine adjuvant: safety, tolerability, and cutaneous immune cell trafficking.

The treatment of skin with a low-power continuous-wave (CW) near-infrared (NIR) laser prior to vaccination is an emerging strategy to augment the immune response to intradermal vaccine, potentially substituting for chemical adjuvant, which has been linked to adverse effects of vaccines. This approach proved to be low cost, simple, small, and readily translatable compared with the previously explored pulsed-wave medical lasers. However, little is known on the mode of laser-tissue interaction eliciting the adjuvant effect. In this study, we sought to identify the pathways leading to the immunological events by examining the alteration of responses resulting from genetic ablation of innate subsets including mast cells and specific dendritic cell populations in an established model of intradermal vaccination and analyzing functional changes of skin microcirculation upon the CW NIR laser treatment in mice. We found that a CW NIR laser transiently stimulates mast cells via generation of reactive oxygen species, establishes an immunostimulatory milieu in the exposed tissue, and provides migration cues for dermal CD103+ dendritic cells without inducing prolonged inflammation, ultimately augmenting the adaptive immune response. These results indicate that use of an NIR laser with distinct wavelength and power is a safe and effective tool to reproducibly modulate innate programs in skin. These mechanistic findings would accelerate the clinical translation of this technology and warrant further explorations into the broader application of NIR lasers to the treatment of immune-related skin diseases.

Cancer immunotherapy, or the utilization of the body's immune system to attack tumor cells, has gained prominence over the past few decades as a viable cancer treatment strategy. Recently approved immunotherapeutics have conferred remission upon patients with previously bleak outcomes and have expanded the number of tools available to treat cancer. Nanoparticles -including polymeric, liposomal, and metallic formulations - naturally traffic to the spleen and lymph organs and the relevant immune cells therein, making them good candidates for delivery of immunotherapeutic agents. Metallic nanoparticle formulations in particular are advantageous because of their potential for dense surface functionalization and their capability for optical or heat based therapeutic methods. Many research groups have investigated the potential of nanoparticle-mediated delivery platforms to improve the efficacy of immunotherapies. Despite the significant preclinical successes demonstrated by many of these platforms over the last twenty years, few metallic nanoparticles have successfully entered clinical trials with none achieving FDA approval for cancer therapy. In this review, we will discuss preclinical research and clinical trials involving metallic nanoparticles (MNPs) for cancer immunotherapy applications and discuss the potential for clinical translation of MNPs.

There is an urgent need for chemical-free and biological-free safe adjuvants to enhance the immunogenicity of vaccines against widespread viral pathogens, such as herpes simplex virus 2 (HSV-2), that infect a large proportion of the world human population. In the present study, we investigated the safety, immunogenicity, and protective efficacy of a laser adjuvant-assisted peptide (LAP) vaccine in the B6 mouse model of genital herpes. This LAP vaccine and its laser-free peptide (LFP) vaccine analog contain the immunodominant HSV-2 glycoprotein B CD8⁺ T cell epitope (HSV-gB_498-505) covalently linked with the promiscuous glycoprotein D CD4⁺ T helper cell epitope (HSV-gD_49-89). Prior to intradermal delivery of the LAP vaccine, the lower-flank shaved skin of B6 or CD11c/eYFP transgenic mice received a topical skin treatment with 5% imiquimod cream and then was exposed for 60 s to a laser, using the FDA-approved nonablative diode. Compared to the LFP vaccine, the LAP vaccine (i) triggered mobilization of dendritic cells (DCs) in the skin, which formed small spots along the laser-treated areas, (ii) induced phenotypic and functional maturation of DCs, (iii) stimulated long-lasting HSV-specific effector memory CD8⁺ T cells (T_EM cells) and tissue-resident CD8⁺ T cells (T_RM cells) locally in the vaginal mucocutaneous tissues (VM), and (iv) induced protective immunity against genital herpes infection and disease. As an alternative to currently used conventional adjuvants, the chemical- and biological-free laser adjuvant offers a well-tolerated, simple-to-produce method to enhance mass vaccination for widespread viral infections.IMPORTANCE Herpes simplex viruses 1 and 2 (HSV-1 and HSV-2) infect a large proportion of the world population. There is an urgent need for chemical-free and biological-free safe adjuvants that would advance mass vaccination against the widespread herpes infections. The present study demonstrates that immunization with a laser-assisted herpes peptide vaccine triggered skin mobilization of dendritic cells (DCs) that stimulated strong and long-lasting HSV-specific effector memory CD8⁺ T cells (T_EM cells) and tissue-resident CD8⁺ T cells (T_RM cells) locally in the vaginal mucocutaneous tissues. The induced local CD8⁺ T cell response was associated with protection against genital herpes infection and disease. These results draw attention to chemical- and biological-free laser adjuvants as alternatives to currently used conventional adjuvants to enhance mass vaccination for widespread viral infections, such as those caused by HSV-1 and HSV-2.

Brief exposure of skin to near-infrared (NIR) laser light has been shown to augment the immune response to intradermal vaccination and thus act as an immunologic adjuvant. Although evidence indicates that the NIR laser adjuvant has the capacity to activate innate subsets including dendritic cells (DCs) in skin as conventional adjuvants do, the precise immunological mechanism by which the NIR laser adjuvant acts is largely unknown. In this study we sought to identify the cellular target of the NIR laser adjuvant by using an established mouse model of intradermal influenza vaccination and examining the alteration of responses resulting from genetic ablation of specific DC populations. We found that a continuous wave (CW) NIR laser adjuvant broadly modulates migratory DC (migDC) populations, specifically increasing and activating the Lang⁺ and CD11b^-Lang^- subsets in skin, and that the Ab responses augmented by the CW NIR laser are dependent on DC subsets expressing CCR2 and Langerin. In comparison, a pulsed wave NIR laser adjuvant showed limited effects on the migDC subsets. Our vaccination study demonstrated that the efficacy of the CW NIR laser is significantly better than that of the pulsed wave laser, indicating that the CW NIR laser offers a desirable immunostimulatory microenvironment for migDCs. These results demonstrate the unique ability of the NIR laser adjuvant to selectively target specific migDC populations in skin depending on its parameters, and highlight the importance of optimization of laser parameters for desirable immune protection induced by an NIR laser-adjuvanted vaccine.

A brief exposure of skin to a low-power, non-tissue damaging laser light has been demonstrated to augment immune responses to intradermal vaccination. Both preclinical and clinical studies show that this approach is simple, effective, safe and well tolerated compared to standard chemical or biological adjuvants. Until now, these laser exposures have been performed using a diode-pumped solid-state laser (DPSSL) devices, which are expensive and require labor-intensive maintenance and special training. Development of an inexpensive, easy-to-use and small device would form an important step in translating this technology toward clinical application. Here we report that we have established a handheld, near-infrared (NIR) laser device using semiconductor diodes emitting either 1061, 1258, or 1301nm light that costs less than $4000, and that this device replicates the adjuvant effect of a DPSSL system in a mouse model of influenza vaccination. Our results also indicate that a broader range of NIR laser wavelengths possess the ability to enhance vaccine immune responses, allowing engineering options for the device design. This small, low-cost device establishes the feasibility of using a laser adjuvant approach for mass-vaccination programs in a clinical setting, opens the door for broader testing of this technology with a variety of vaccines and forms the foundation for development of devices ready for use in the clinic.

Methods to deliver an antigen into the skin in a painless, defined, and reproducible manner are essential for transcutaneous immunization (TCI). Here, we employed an ablative fractional infrared laser (P.L.E.A.S.E. Professional) to introduce clinically relevant vaccines into the skin. To elicit the highest possible antibody titers with this system, we optimized different laser parameters, such as fluence and pore number per area, and tested various adjuvants.

BALB/c mice were immunized with Hepatitis B surface antigen (HBsAg) by laser-microporation. Adjuvants used were alum, CRM₁₉₇, monophosphoryl lipid A, heat-labile enterotoxin subunit B of E. coli (LT-B), and CpG ODN1826. The influence of different fluences (2.1 to 16.8J/cm²) and pore densities (5-15%) was investigated. Furthermore, immunogenicity of HBsAg and the commercially available conjugate vaccines ActHIB® and Menveo® applied via TCI was compared to standard i.m. injection. Antigen-specific antibody titers were assessed by luminometric ELISA.

Antibody titers against HBsAg were dependent on pore depth and peaked at a fluence of 8.4J/cm². Immunogenicity was independent of pore density. Adjuvantation with alum significantly reduced antibody titers after TCI, whereas other adjuvants only induced marginal changes in total IgG titers. LT-B and CpG shifted the polarization of the immune response as indicated by decreased IgG1/IgG2a ratios. HBsAg/LT-B applied via TCI induced similar antibody titers compared to i.m. injection of HBsAg/alum. In contrast to i.m. injection, we observed a dose response from 5 to 20μg after TCI. Both, ActHIB® and Menveo® induced high antibody titers after TCI, which were comparable to i.m. injection.

Alum, the most commonly used adjuvant, is contraindicated for transcutaneous vaccination via laser-generated micropores. TCI with optimized laser parameters induces high antibody titers, which cannot be significantly increased by the tested adjuvants. Commercially available vaccines formulated without alum have the potential for successful TCI via laser-generated micropores, without the need for reformulation.

Allergen-specific immunotherapy is the only curative approach for the treatment of allergies. There is an urgent need for improved therapies, which increase both, efficacy and patient compliance. Novel routes of immunization and the use of more advanced vaccine platforms have gained heightened interest in this field. Areas covered: The current status of allergen-specific immunotherapy is summarized and novel routes of immunization and their challenges in the clinics are critically discussed. The use of nanoparticles as novel delivery system for allergy vaccines is comprehensively reviewed. Specifically, the advantages of silica nanoparticles as vaccine carriers and adjuvants are summarized. Expert opinion: Future allergen-specific immunotherapy will combine engineered hypoallergenic vaccines with novel routes of administration, such as the skin. Due to their biodegradability, and the easiness to introduce surface modifications, silica nanoparticles are promising candidates for tailor-made vaccines. By covalently linking allergens and polysaccharides to silica nanoparticles, a versatile vaccination platform can be designed to specifically target antigen-presenting cells, render the formulation hypoallergenic, and introduce immunomodulatory functions. Combining potent skin vaccination methods, such as fractional laser ablation, with nanoparticle-based vaccines addresses all the requirements for safe and efficient therapy of allergic diseases.