We describe a protocol to study inflammatory responses triggered by the mRNA-lipid nanoparticle (LNP) vaccine formulations in skin, muscle, and lung and the adaptive immune responses induced in the draining lymph nodes. Here, we will present how to deliver these reagents through intradermal, intramuscular, and intranasal routes, generating single-cell suspensions from the inoculated and target organs for downstream analyses. For complete details on the use and execution of this protocol, please refer to Ndeupen et al. (2021) and (2022).

Rhynchosia nulubilis (black soybean) has many applications in oriental medicine. It is traditionally used to treat disease related with high blood pressure, diabetes, inflammation, and osteoporosis. Furthermore, fermented soybean foods have traditionally been used for immunity enhancement in East Asia. However, the anti-inflammatory effects of germinated R. nulubilis (GR) against delayed-type hypersensitivity (DTH) are not fully understood.

This study aimed to investigate the anti-inflammatory effects of germinated Rhynchosia nulubilis (GR) fermented with the lactic acid bacterium Lactobacillus pentosus SC65 (GR-SC65) isolated from pickled burdock.

We investigated the effects of GR-SC65 (300 mg/kg/day) on ear thickness and immune cell infiltration in DNFB-induced DTH in mice. We used dexamethasone (3 mg/kg) as a reference drug. Changes in infiltration of CD4+ and CD8+ T cells and NK cells were examined by immunohistochemistry. In addition, we investigated cytokine and chemokine production related to DTH using reverse transcription-polymerase chain reaction. We also investigated DTH-related cytokine production using lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells.

Two lactic acid bacterial strains (Lactobacillus pentosus SC65 and Pediococcus pentosaceus ON81A) were selected for fermenting GR due to their high 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity. The total polyphenol contents (TPCs) in GR-SC65 and GR-ON81A were higher than that in unfermented GR (∗∗∗P < 0.001 vs. GR). Content of daidzein, glycitein, and genistein, the deglycosylated form of isoflavonoids, was higher in GR-SC65 than in unfermented GR. The ethanol extracts of GR-SC65 exerted a stronger anti-inflammatory activity than GR by inhibiting pro-inflammatory cytokines, such as tumor necrosis factor (TNF), interleukin-6 (IL-6), and interleukin-1β (IL-1β) in LPS-induced RAW264.7 macrophages. GR-SC65 reduced 1-fluoro-2,4-dinitrofluorobenzene (DNFB)-induced ear swelling and hyperplasia as well as vascular permeability. Fewer infiltrated CD4+ and CD8+ T cells were observed in the ear tissue of the GR-SC65-treated mice than those of the unfermented GR-treated mice. Furthermore, fewer infiltrated NK cells were observed in the GR-SC65 treated mice, than in the GR-treated mice. GR-SC65 significantly diminished the levels of CCL5 and COX-2 mRNAs and increased the level of IL-10 mRNA.

These data suggest that GR-SC65 can be used as a health supplement or a prophylactic against delayed-type hypersensitive inflammatory disease.

Conventional dendritic cells expressing the XCR1 chemokine receptor (cDC1s) excel at cross-presentation. Here, we developed and used a mouse model in which a Cre recombinase is expressed under the control of the Xcr1 gene while preserving XCR1 expression. We used it to generate mice with conditional deletion of MHC class II (MHCII) molecules on cDC1s. By preventing cDC1s to receive suppressive regulatory T cell inputs via MHCII-restricted interactions, the objective of the present study was to gauge whether MHCII-deficient cDC1s lose their capacity of tolerizing autoreactive CD8⁺ T cells. Whereas MHCII⁺ cDC1 readily cross-tolerized strongly autoreactive CD8⁺ T cells specific for a keratinocyte-derived self-antigen, MHCII-deficient cDC1s converted them into potent effectors capable of triggering a fast-onset lethal autoimmunity associated with severe skin histopathological manifestations. Preventing egress of such pathogenic self-reactive CD8⁺ T cell effectors from the cutaneous draining lymph nodes abrogated the autoimmune condition. Therefore, our results revealed that the cross-tolerizing capacity of cDC1s is not a property fully acquired at the time they undergo homeostatic maturation but needs to be enforced via MHCII-restricted, suppressive interactions with regulatory T cells.

Here we describe a new mouse model that exploits the pattern of expression of the high-affinity IgG receptor (CD64) and allows diphtheria toxin (DT)-mediated ablation of tissue-resident macrophages and monocyte-derived cells. We found that the myeloid cells of the ear skin dermis are dominated by DT-sensitive, melanin-laden cells that have been missed in previous studies and correspond to macrophages that have ingested melanosomes from neighboring melanocytes. Those cells have been referred to as melanophages in humans. We also identified melanophages in melanocytic melanoma. Benefiting of our knowledge on melanophage dynamics, we determined the identity, origin, and dynamics of the skin myeloid cells that capture and retain tattoo pigment particles. We showed that they are exclusively made of dermal macrophages. Using the possibility to delete them, we further demonstrated that tattoo pigment particles can undergo successive cycles of capture-release-recapture without any tattoo vanishing. Therefore, congruent with dermal macrophage dynamics, long-term tattoo persistence likely relies on macrophage renewal rather than on macrophage longevity.