Pouchitis is defined as inflammation of the ileal pouch created during a restorative proctocolectomy with ileal pouch-anal anastomosis. Although the incidence of this inflammatory condition is high, the exact etiology often remains unclear and the management challenging. In this review, we summarize the clinical presentation, pathogenesis, diagnosis, and management of this common complication.

The newly discovered zoonotic coronavirus swine acute diarrhea syndrome coronavirus (SADS-CoV) causes acute diarrhea, vomiting, dehydration, and high mortality rates in newborn piglets. Although SADS-CoV uses different strategies to evade the host's innate immune system, the specific mechanism(s) by which it blocks the interferon (IFN) response remains unidentified. In this study, the potential of SADS-CoV nonstructural proteins (nsp) to inhibit the IFN response was detected. The results determined that nsp1 was a potent antagonist of IFN response. SADS-CoV nsp1 efficiently inhibited signal transducer and activator of transcription 1 (STAT1) phosphorylation by inducing Janus kinase 1 (JAK1) degradation. Subsequent research revealed that nsp1 induced JAK1 polyubiquitination through K11 and K48 linkages, leading to JAK1 degradation via the ubiquitin-proteasome pathway. Furthermore, SADS-CoV nsp1 induced CREB-binding protein degradation to inhibit IFN-stimulated gene production and STAT1 acetylation, thereby inhibiting STAT1 dephosphorylation and blocking STAT1 transport out of the nucleus to receive antiviral signaling. In summary, the results revealed the novel mechanisms by which SADS-CoV nsp1 blocks the JAK-STAT signaling pathway via the ubiquitin-proteasome pathway. This study yielded valuable findings on the specific mechanism of coronavirus nsp1 in inhibiting the JAK-STAT signaling pathway and the strategies of SADS-CoV in evading the host's innate immune system.

Ulcerative colitis (UC) is a chronic intestinal inflammatory disease and familial adenomatous polyposis (FAP) is an autosomal dominant inherited disease. Both diseases, despite being different, may require the same surgical procedure: proctocolectomy with ileal pouch-anal anastomosis (IPAA). The main complication after this procedure is pouch inflammation (pouchitis). This inflammatory complication can affect up to 60 percent of patients who receive IPAA for UC, and a very small percentage of the FAP patients. The purpose of this review was to determine the current molecular mechanisms in its pathogenesis and detail the risk factors involved in pouchitis, its diagnosis, and treatment.

Although the etiology of pouchitis remains unknown, inflammatory cytokines are significantly associated with the pathogenesis of pouchitis. The cytokine responses that characterize inflammatory bowel diseases (IBD) are key pathogenic components of the disease. Although cytokine profiles in the colonic mucosa have been investigated in experimental colitis models or IBD patients, cytokine profiles in the ileal mucosa at colectomy have been rarely assessed.

To assess the relationship between pouchitis and T helper (Th) cytokines in the ileal mucosa collected at the time of colectomy and pouch construction.

This retrospective study involved 68 consecutive patients from January 2004 to May 2011 who underwent ileal pouch-anal anastomosis for ulcerative colitis. Samples were obtained from the terminal ileum of resected specimens at time of total colectomy or subtotal colectomy. mRNA expression levels of Th cytokines (IFN-γ, IL-23A, IL-5, IL-13 and IL-17A) were determined.

Forty of 68 patients (58.8%) developed pouchitis. There was no association between IL-23A expression levels and incidence of pouchitis (p = 0.301). Patients with elevated IFN-γ had a significantly higher incidence of pouchitis compared with low IFN-γ patients (p = 0.043). Univariate analysis demonstrated a total dose of prednisolone > 7000 mg administered before colectomy (p = 0.04) and high IFN-γ expression (p = 0.02) were significant risk factors for pouchitis onset. In multivariate analysis, elevated IFN-γ messenger(m)RNA levels were significantly associated with pouchitis onset (p = 0.03).

IFN-γ expression in the normal ileal mucosa at the time of colectomy may be an important factor in the pathophysiology of pouchitis.

In recent years, researchers have devoted much attention to the diverse roles of macrophages and their contributions to tissue development, wound healing, and angiogenesis. What should not be lost in the discussions regarding the diverse biology of these cells is that when perturbed, macrophages are the primary contributors to potentially pathological inflammatory processes. Macrophages stand poised to rapidly produce large amounts of inflammatory cytokines in response to danger signals. The production of these cytokines can initiate a cascade of inflammatory mediator release that can lead to wholesale tissue destruction. The destructive inflammatory capability of macrophages is amplified by exposure to exogenous interferon-γ, which prolongs and heightens inflammatory responses. In simple terms, macrophages can thus be viewed as incendiary devices with hair triggers waiting to detonate. We have begun to ask questions about how these cells can be regulated to mitigate the collateral destruction associated with macrophage activation.

Interferons (IFN) are subdivided into type I IFN (IFN-I, here synonymous with IFN-α/β), type II (IFN-γ) and type III IFN (IFN-III/IFN-λ) that reprogram nuclear gene expression through STATs 1 and 2 by forming STAT1 dimers (mainly IFN-γ) or the ISGF3 complex, a STAT1-STAT2-IRF9 heterotrimer (IFN-I and IFN-III). Dominant IFN activities in the immune system are to protect cells from viral replication and to activate macrophages for enhanced effector function. However, the impact of IFN and their STATs on the immune system stretches far beyond these activities and includes the control of inflammation. The goal of this review is to give an overview of the different facets of the inflammatory process that show regulatory input by IFN/STAT.

Ileal pouch-anal anastomosis (IPAA) is the preferred surgical procedure for patients with refractory ulcerative colitis (UC) and familial adenomatous polyposis (FAP). However, pouchitis is the most common complication after IPAA in UC patients and only occurs after ileostomy closure. Therefore, it is important to get more information about the role of the ileal pouch microbiota and mucosa susceptibility to inflammation in UC patients. Therefore, we evaluated Toll-like receptors (TLRs) expression in normal endoscopic and histological mucosa of the ileal pouch in patients with UC and FAP, in order to find any abnormality in this pathway in asymptomatic patients, which may contribute to pouchitis.

Twelve patients (six with UC and six with FAP) with "J" pouch reconstruction, after total rectocolectomy, were studied. Biopsies were obtained from the mucosa of the pouch. Normal ileum biopsies were obtained from six patients submitted to ileocolonoscopy with no abnormalities. The specimens were snap-frozen and the expressions of TLR2, TLR4 and JNK (nuclear signalization factor) were determined by immunoblot protein extract.

Patients with UC had significantly higher protein levels of TLR4 than controls and FAP. The expressions of TLR2 and JNK were similar in the groups.

Patients with UC had higher levels of TLR4, even in the absence of clinical, endoscopic and histological pouchitis. These findings may explain a tendency towards the up-regulation of intracellular pathways activated by bacterial antigens in UC patients, which could contribute to the production of proinflammatory mediators and pouchitis development.

Pouchitis after total rectocolectomy is the most common complication of ulcerative colitis (UC). The immunological mechanisms involved in the genesis of pouchitis are unclear. Therefore, we evaluated the inflammatory activity in normal ileal pouch mucosa by determining signal transducers and activators of transcription (STAT-1) activation and cytokine expression in patients operated for UC and familial adenomatous polyposis (FAP). Eighteen asymptomatic patients, who underwent total rectocolectomy and J pouch, were evaluated: nine with UC and nine with FAP. The activation of STAT-1 and cytokine expression were determined by immunoblot of total protein extracts from pouch mucosal biopsies. The absence of pouchitis was assessed by clinical, histological and endoscopic parameters, according to the Pouchitis Disease Activity Index. The patients were not receiving any medication. Analysis of variance (anova) and Tukey-Kramer's test were applied. The local ethical committee approved the study and informed consent was signed by all participants. STAT-1 activation was increased in UC when compared to FAP and controls (P < 0.05). Higher levels of interferon (IFN)-gamma expression were observed in UC patients when compared to the control group (P < 0.05), but were similar to FAP. In contrast, cytokine signalling (SOCS-3) and interleukin (IL)-10 expression were similar in all groups (P > 0.05). These findings could explain the higher susceptibility to this inflammatory complication in UC when compared to FAP. A tendency towards increased levels of IFN-gamma and STAT-1 in patients with UC, even without clinical and endoscopic evidence of pouchitis, was observed; studying inflammatory activity in asymptomatic ileal pouches may help understanding of the pathogenesis of pouchitis.

Ileal pouch-anal anastomosis is the procedure of choice in the surgical management of refractory ulcerative colitis. Pouchitis affects up to 60% of patients following ileal pouch-anal anastomosis for ulcerative colitis. It overlaps significantly with ulcerative colitis such that improvements in our understanding of one will impact considerably on the other. The symptoms are distressing and impinge significantly on patients' quality of life. Despite 30 years of scientific and clinical investigation, the pathogenesis of pouchitis is unknown; however, recent advances in molecular and cell biology make a synergistic hypothesis possible. This hypothesis links interaction between epithelial metaplasia, changes in luminal bacteria (in particular sulfate-reducing bacteria), and altered mucosal immunity. Specifically, colonic metaplasia supports colonization by sulfate-reducing bacteria that produce hydrogen sulfide. This causes mucosal depletion and subsequent inflammation. Although in most cases antibiotics lead to bacterial clearance and symptom resolution, immunogenetic subpopulations can develop a chronic refractory variant of pouchitis. The aims of this paper are to discuss proposed pathogenic mechanisms and to describe a novel mechanism that combines many hypotheses and explains several aspects of pouchitis. The implications for the management of both pouchitis and ulcerative colitis are discussed.

Pouchitis is a major long-term complication of ileal pouch-anal anastomosis for ulcerative colitis. The aim of this study is to investigate the efficacy of leukocytapheresis for the treatment of active pouchitis.

Eight patients with active pouchitis received leukocytapheresis weekly for 5 weeks in an open-label treatment protocol together with baseline therapy.

Patients showed significant improvement in their pouchitis disease activity index scores, from 9.5 (range, 8-10) to 4.0 (range, 2-8) (P < 0.05). Six (75%) of the 8 treated patients achieved remission. No adverse events were observed.

Leukocytapheresis therapy could be a new therapeutic strategy for patients with pouchitis after ileal pouch-anal anastomosis for ulcerative colitis. These encouraging results lead us to propose a randomized controlled trial.

Difuse proliferative lupus nephritis (DPLN) is the most common and severe form of lupus nephritis. A predominance of IFN-gamma-producing T cells in both peripheral and renal tissues of patients with DPLN has been identified which suggests an important role for cell-mediated immunity in the pathogenesis of this complication in SLE. The biological effects of IFN-gamma rely mainly on the activity of the transcription factor called signal transducer and activator of transcription (STAT)-1. To assess the IFN-gamma/STAT-1 pathway in DPLN, we examined the expression of STAT-1 in renal biopsies from 15 DPLN patients by immunohistochemical staining with an anti-STAT-1 antibody. The expression of STAT-1 in renal tissues was correlated with several clinical and laboratory findings in these DNPN patients.STAT-1 was activated in the tubular cells in all DPLN patients. Seven of 15 DPLN biopsies (46.7%) showed positive cells in glomeruli. Five of these seven DPLN biopsies (71.4%) with positive glomerular cells showed a serum creatinine >1.5 mg/mL at the time the biopsy was carried out whereas only one of eight DPLN biopsy specimens (12.5%) without positive glomerular cells, showed a serum creatinine >1.5 mg/mL (P = 0.041). Moreover, the percentage of DPLN patients with a worse renal outcome in those who showed expression of STAT-1 in glomerulari were higher in comparison to those without STAT-1 expression (P = 0.041). Our results show that STAT-1 is activated in DPLN suggesting that biological effects of IFN-gamma in renal tissues depend, at least in part, on the activation of STAT-1.

The suppressor of cytokine signaling-1 (SOCS1) is a potent negative regulator of various cytokines and it has been implicated in the regulation of immune responses. However, the role of SOCS1 in inflammatory bowel diseases (IBDs) has not been clarified. To determine the role of SOCS1 in colitis, we generated SOCS1/T-cell receptor alpha (TCRalpha) double knockout (DKO) mice.

The depletion of interferon gamma (IFNgamma) and IL-4 was achieved by crossing the DKO mice with IFNgamma knockout (KO) mice and by the administration of anti-IL-4 antibody, respectively. The activation of cytokine-induced transcription factors was determined by Western blotting with phosphorylation-specific antibodies, and the induction of inflammatory factors was measured by reverse-transcription polymerase chain reaction.

Much more severe colitis developed in 100% of the DKO mice within 9 weeks of age than in TCRalpha-KO mice. Although the proportion and the activation status of CD4(+) TCRalpha(-)beta(+) T cells in DKO mice were similar to those in TCRalpha-KO mice, signal transducer and activator of transcription 1, nuclear factor kappaB, and their target genes were hyperactivated in infiltrated mononuclear cells and colonic epithelial cells in DKO mice. Cytokine-depletion experiments showed that exacerbated colitis in the DKO mice was dependent on both IFNgamma and IL-4. SOCS1-deficient cells were hypersensitive to IFNgamma, IL-4, and lipopolysaccharides, depending on the target genes.

SOCS1 plays an important role in preventing murine colitis by restricting the cytokine signals. SOCS1/TCRalpha DKO mice could be a useful model for investigating human IBD.

STAT1 is a transcription factor that plays a crucial role in signaling by interferons (IFNs). In this study we demonstrated that inhibitors of histone deacetylase (HDAC) activity, butyrate, trichostatin A, and suberoylanilide hydroxamic acid, prevented IFNgamma-induced JAK1 activation, STAT1 phosphorylation, its nuclear translocation, and STAT1-dependent gene activation. Furthermore, we showed that silencing of HDAC1, HDAC2, and HDAC3 through RNA interference markedly decreased IFNgamma-driven gene activation and that overexpression of HDAC1, HDAC2, and HDAC3 enhanced STAT1-dependent transcriptional activity. Our data therefore established the essential role of deacetylase activity in STAT1 signaling. Induction of IRF-1 by IFNgamma requires functional STAT1 signaling and was abrogated by butyrate, trichostatin A, suberoylanilide hydroxamic acid, and STAT1 small interfering RNA. In contrast, silencing of STAT1 did not interfere with IFNgamma-induced expression of STAT2 and caspase-7, and HDAC inhibitors did not preclude IFNgamma-induced expression of STAT1, STAT2, and caspase-7, suggesting that HDAC inhibitors impede the expression of IFNgamma target genes whose expression depends on STAT1 but do not interfere with STAT1-independent signaling by IFNgamma. Finally, we showed that inhibitors of deacetylase activity sensitized colon cancer cells to IFNgamma-induced apoptosis through cooperative negative regulation of Bcl-x expression, demonstrating that interruption of the balance between STAT1-dependent and STAT1-independent signaling significantly alters the biological activity of IFNgamma.

Pouchitis is one of the commonest and most debilitating complications of a restorative proctocolectomy. The cause remains elusive, though a number of approaches have been shown to alleviate the condition. This review outlines current evidence relating to pouchitis, obtained from randomised and nonrandomised studies. Medline, the Bath Information Data Service (BIDS) and PubMed were searched using the keywords 'pouchitis' and 'inflammatory bowel disease'. In addition, articles were cross-referenced, and the abstracts of recent colorectal meetings studied.

Pouchitis is the major long-term complication after ileal pouch-anal anastomosis (IPAA) in patients operated on for ulcerative colitis. The cause is unknown, but both the history of ulcerative colitis and increased bacterial concentration are important factors. Chemokines are mediators for the recruitment of inflammatory cells to the site of inflammation. This study examined the tissue expression of a panel of specific chemokines and the corresponding recruitment of inflammatory cells in IPAA tissue with and without inflammation and after antibiotic treatment.

Biopsy specimens postoperatively from ulcerative colitis patients with IPAA were obtained by endoscopy. Biopsies were taken from 8 patients with noninflamed IPAA and from 14 patients with an episode of acute pouchitis, before and after antibiotic treatment. Biopsies were stained for CD68, CD3, elastase, eotaxin, IP-10, MCP-1, MCP-3, and IL-8 and analyzed by NIH Image analyzer.

Expression of IL-8, MCP-1, MCP-3, and IP-10 was significantly higher in pouchitis than normal pouch. The expression of MCP-1, MCP-3 and IP-10 were significantly lower after antibiotic treatment.

These data support the importance of chemokines for the leukocyte recruitment in pouch tissue during acute pouchitis.

Human tropomyosin isoform 5 (hTM5) is a cytoskeletal protein expressed in normal epithelial cells, predominantly in the colon. An autoimmune response toward hTM5 has been reported in ulcerative colitis (UC). Whether hTM5 expression in the ileum is involved in pouchitis is unknown. We assessed hTM5 expression on ileal epithelial cells at surgery and subsequently on development of pouchitis in UC.

In a prospective longitudinal study, 28 UC patients undergoing ileal pouch procedures were included. Biopsy samples were taken from the rectum at surgery, as well as from the ileal pouch at surgery and at 6 months. The specimens were stained by immunoperoxidase using the anti-hTM5 monoclonal antibody CG3. Pouchitis was assessed by the Pouchitis Disease Activity Index and hTM5 expression on a scale of 0-3.

At surgery, in rectal samples, hTM5 expression was strong in all epithelial cells including the luminal surface, whereas in ileal samples hTM5 was not expressed or focally expressed only in the goblet cells. At 6 months, the ileum was found to have undergone morphological changes, becoming similar to the colon and showing shortening or reduced number of villi. These changes were associated with a diffuse hTM5 staining in the goblet cells and in the nongoblet epithelial cells lining the crypts and the lumen. The hTM5 score was related to the Pouchitis Disease Activity Index at 6 months (r = 0.82; p = 0.01).

Expression of hTM5 shows a different pattern in the ileal pouch in UC after surgery. This event is associated with morphological changes of the ileum toward colonic epithelium, related to the development of pouchitis.

Celiac disease (CD) is an enteropathy characterized by a Th1-type immune response to the dietary gluten. The transcriptional mechanisms or factors that control Th1 cell development in this condition remain to be elucidated. The aim of this study was to analyze in CD the expression of interferon (IFN) regulatory factor (IRF)-1, a transcription factor that regulates the differentiation and function of Th1 cells. Duodenal biopsies were taken from children with untreated CD and control children, and analyzed for IRF-1 by Southern blotting of reverse-transcriptase PCR products and Western blotting. IRF-1 DNA-binding activity was assessed by electrophoretic shift mobility assay. The effect of gliadin stimulation on IRF-1 induction was investigated in an ex vivo organ culture of treated CD biopsies. Enhanced IRF-1 was seen in untreated CD in comparison with controls. This was evident at both the RNA and protein level. Furthermore, untreated CD samples exhibited stronger nuclear accumulation and DNA-binding activity of IRF-1 than controls. In contrast, IRF-2, a transcriptional repressor that binds the same DNA element and competes with IRF-1, was expressed at the same level in nuclear proteins extracted from both untreated CD and control patients. In explant cultures of treated CD biopsies, gliadin enhanced both IRF-1 RNA and protein. This effect was prevented by a neutralizing IFN-gamma antibody. Furthermore, stimulation of normal duodenal biopsies with IFN-gamma enhanced IRF-1. These data indicate that IRF-1 is a hallmark of the gliadin-mediated inflammation in CD and suggest that IFN-gamma/IRF-1 signaling pathway can play a key role in maintaining and expanding the local Th1 inflammatory response in this disease.

The biological effects of interferon (IFN)-gamma rely mainly on the activity of the transcription factor signal transducer and activator of transcription (STAT) 1 and the intracellular levels of suppressor of cytokine signaling (SOCS)-1, a negative regulator that controls the amplitude and duration of STAT-1 activation. IFN-gamma is a key mediator of the immunopathology in celiac disease (CD, gluten-sensitive enteropathy). Thus we have investigated STAT-1 signaling and SOCS-1 expression in this condition. As expected, high local concentrations of IFN-gamma were invariably seen in duodenal biopsies from CD patients in comparison to controls. On the basis of immunohistochemistry, STAT-1 phosphorylation, nuclear localization, and DNA-binding activity, STAT-1 activation was consistently more pronounced in CD compared with controls. Despite samples from CD patients containing abundant SOCS-1 mRNA, SOCS-1 protein was expressed at the same level in CD patients and controls. In explant cultures of CD biopsies, gliadin induced the activation of STAT-1 but not SOCS-1. Furthermore, inhibition of STAT-1 prevented the gliadin-mediated induction of ICAM-1 and B7-2. These data suggest that persistent STAT-1 activation can contribute to maintaining and expanding the local inflammatory response in CD.

To determine the efficacy of infliximab in the treatment of chronic refractory pouchitis complicated by fistulae following ileal pouch-anal anastomosis for ulcerative colitis.

This open study included seven patients (four females, three males) with chronic refractory pouchitis complicated by fistulae. Pouchitis was diagnosed by clinical, endoscopic and histological criteria. The sites of the fistulae were as follows: pouch-bladder in one, vaginal in three, perianal in two, and both vaginal and perianal in one. Extra-intestinal manifestations (erythema nodosum, arthralgia) were present in four patients. Crohn's disease was carefully excluded in all patients after re-evaluation of the history, re-examination of the original proctocolectomy specimen and examination of the proximal small bowel. All patients had been treated with antibiotics and three with steroids. Patients received infliximab, 5 mg/kg, at 0, 2 and 6 weeks. Azathioprine (2.5 mg/kg) was also started for all patients as bridge therapy. Clinical response was classified as complete, partial or no response. Fistulae closure was classified as complete (cessation of fistulae drainage and total closure of all fistulae), partial (a reduction in the number, size, drainage or discomfort associated with fistulae) or no closure. The pouchitis disease activity index and quality of life were also used as outcome measures.

Clinically, all patients improved. At the 10-week follow-up, six of the seven patients had a complete clinical response, and five had complete fistulae closure. At the 10-week follow-up, the median pouchitis disease activity index decreased from 12 (baseline) (range, 10-15) to 5 (range, 3-8); the median quality of life decreased from 37 points (range, 33-40) to 14 (range, 9-18). Erythema nodosum and arthralgia showed complete remission soon after the first infusion of infliximab.

These preliminary results indicate that infliximab may be recommended for the treatment of refractory pouchitis complicated by fistulae following ileal pouch-anal anastomosis for ulcerative colitis.