Microbe-associated molecular patterns derived from fungi and bacteria promote IgG4 antibody production in patients with type 1 autoimmune pancreatitis.

Enhanced IgG4 antibody (Ab) response is a prominent feature of type 1 autoimmune pancreatitis (AIP). Innate immune responses associated with IgG4 Ab production are poorly defined. We have previously reported that peripheral blood mononuclear cells (PBMCs) isolated from patients with type 1 AIP produce large amounts of IgG4 Abs upon stimulation with bacterial cell wall components. In addition, we showed that activation of plasmacytoid dendritic cells producing interferon (IFN)-α, interleukin (IL)-33, and B cell-activating factor (BAFF) upon sensing intestinal bacteria mediates the development of experimental AIP. In this study, we attempted to clarify the role of innate immunity against fungi in inducing enhanced IgG4 Ab responses in type 1 AIP. PBMCs isolated from healthy controls and patients with type 1 AIP were stimulated with a broad range of bacterial and fungal cell wall components. The concentrations of IgG1, IgG4, and cytokines were measured using enzyme-linked immunosorbent assays. Cell wall components derived from bacteria and fungi induced IgG1 and IgG4 Ab production in patients with type 1 AIP. Various types of microbe-associated molecular pattern motifs enhanced IgG4 Ab production in patients with type 1 AIP compared with the limited motifs in healthy controls. The enhanced IgG1 and IgG4 Ab production that followed in response to bacterial and fungal cell wall components was parallel to that of IFN-α, IFN-γ, IL-10, IL-33, and BAFF. In conclusion, cell wall components derived from fungi as well as bacteria promote IgG4 Ab responses in patients with type 1 AIP.

A positive cytokine/chemokine feedback loop establishes plasmacytoid dendritic cell-driven autoimmune pancreatitis in IgG4-related disease.

The pathogenesis of the murine model of autoimmune pancreatitis associated with IgG4-related disease (AIP/IgG4-RD) induced by administration of polyinosinic-polycytidylic acid, is incompletely understood. While it is known that murine and human AIP/IgG4-RD is driven by plasmacytoid dendritic cells (pDCs) producing IFN-α, the origin of these cells and their relation to effector T cells is not known. Here we show that murine AIP was initiated by TLR3-bearing conventional DCs in the uninflamed pancreas whose activation by TLR3 ligand (polyinosinic-polycytidylic acid) caused IFN-α, CXCL9, and CXCL10 secretion. This, in turn, induced pancreatic recruitment of CXCR3+ T cells and these T cells, via their secretion of CCL25, facilitated migration of pDCs bearing CCR9 into the pancreas. This established a feedback loop anchored by the now dominant pDC production of IFN-α and the continued CXCR3+ T cell facilitation of pDC migration. Remarkably, the interaction between CXCR3+ T cells and pDCs also existed at the functional levels since this interaction enhanced the production of CCL25 and IFN-α by CXCR3+ T cells and pDCs, respectively. Evidence presented here that a similar disease mechanism was present in human AIP/IgG4-RD creates new avenues of disease treatment.

Transmesenteric internal hernia: an unexpected adverse event induced by colonoscopy.

Transmesenteric internal hernia is an uncommon cause of small bowel obstruction that occurs when small bowel loops protrude through a mesenteric defect into the abdominal cavity. Herein, we present an unexpected case of colonoscopy-induced transmesenteric internal hernia. An 81-year-old male patient presenting with intermittent hematochezia and constipation had undergone a laparoscopic left nephrectomy for ureteral cancer. A colonoscopy was performed to identify the etiology of his symptoms. He complained of severe abdominal pain 2 h after the examination despite uneventful endoscopic procedures, including cold snare polypectomy. Contrast-enhanced computed tomography revealed a strangulated small bowel obstruction with a closed-loop formation outside the descending colon. The small bowel loop was incarcerated into the left retroperitoneal space. Emergency laparotomy detected small bowel loops that prolapsed into the nephrectomy pedicle via a descending mesenteric defect, developed during the laparoscopic left nephrectomy. The incarcerated small bowel was detached from the hernia and returned to its normal position, and the mesenteric defect was closed. He demonstrated an uneventful postoperative course, with no internal hernia recurrence after discharge. This case indicates the risk of transmesenteric internal hernia through inadvertently created mesenteric defects should be borne in mind, especially when performing colonoscopies in patients who underwent laparoscopic nephrectomies.

Concurrent occurrence of ulcerative duodenitis and ulcerative colitis displaying unique responses to golimumab and ustekinumab.

Recent studies have reported the occurrence of upper gastrointestinal (UGI) inflammation in patients with ulcerative colitis (UC). However, whether UC-associated UGI and colorectal lesions share pathogenic cytokine profiles and responses to biologics remains unknown. Herein, we report a case of concurrent UC and ulcerative duodenitis (UD) that displayed unique responses to biologic treatment. Although treatment with prednisolone (PSL) failed to induce remission in both disorders, golimumab (GLM) and ustekinumab (UST) were effective against UD and UC, respectively, and remission of both disorders was achieved using UST. Immunofluorescence analyses revealed that numbers of immune cells expressing TNF-α were comparable in both duodenal and rectal mucosa before the treatment. GLM or UST treatment markedly decreased numbers of TNF-α-expressing duodenal immune cells, suggesting the presence of correlation between TNF-α expression and disease activity of UD. In contrast, TNF-α expression was not parallel to disease activity of UC because GLM or PSL failed to induce remission despite a marked reduction in TNF-α expression. Responsiveness to GLM or UST together with immunofluorescence studies suggests that TNF-α and IL-12/23p40 are pathogenic cytokines causing UD and UC, respectively, in the present case.

Reciprocal regulation of protein arginine deiminase 2 and 4 expression in the colonic mucosa of ulcerative colitis.

Neutrophils express protein arginine deiminase 2 and PAD4, both of which mediate the citrullination of target proteins to induce production of neutrophil extracellular traps. Although PAD-dependent NETs trigger inflammatory bowel disease, the mechanisms governing the expression of PAD2 and PAD4 are poorly understood. In this study, we tried to clarify expression mechanisms of PAD2 and PAD4 in the colonic mucosa of patients with ulcerative colitis and Crohn's disease. Administration of Cl-amidine, a pan PAD-inhibitor, attenuated the development of dextran sodium sulfate-induced colitis, the effects of which were accompanied by reduced IL-6 and TNF-α production by colonic lamina propria mononuclear cells upon exposure to Toll-like receptor ligands. The mRNA expression of colonic PAD2 and PAD4 was negatively and positively correlated with disease activity and pro-inflammatory cytokine responses in patients with UC, respectively. Reciprocal regulation of PAD2 and PAD4 mRNA expression was observed in the colonic mucosa of UC patients, but not in those of CD patients. PAD4 mRNA expression was correlated with disease activity and pro-inflammatory cytokine responses in patients with CD. Collectively, these data suggest that reciprocal regulation of PAD2 and PAD4 expression is associated with disease activity in UC patients.

Necrotizing Fasciitis of the Serratus Anterior in a Patient Treated With Infliximab and Prednisolone for Ulcerative Colitis and Rheumatoid Arthritis.

Necrotizing fasciitis (NF) is a rapidly progressive bacterial infection with high mortality. Invasive group A Streptococcus (GAS) infection is the leading cause of NF. Our understanding regarding clinicopathological features and pathogenesis of invasive GAS infection is expanding as the incidence of NF in healthy individuals increases. However, clinicopathological features of NF in the presence of autoimmune diseases have been poorly defined. We experienced NF in a patient treated with infliximab and prednisolone for ulcerative colitis and rheumatoid arthritis. Herein, we present time kinetics findings of clinical symptoms and laboratory data of GAS-associated NF in the presence of immunosuppressant-treated immune disorders.

Crosstalk between NOD2 and TLR2 suppresses the development of TLR2-mediated experimental colitis.

Nucleotide-binding oligomerization domain 2 (NOD2) is an intracellular sensor for muramyl dipeptide (MDP), a degradation product of bacterial cell wall peptidoglycan (PGN). PGN stimulates cell-surface Toll-like receptor 2 (TLR2) independently of NOD2, indicating the presence of crosstalk between extracellular TLR2 and intracellular NOD2 upon exposure to PGN. NOD2-deficient mice were sensitive, while TLR2-deficient mice were resistant to experimental colitis induced by intrarectal administration of PGN. Severe colitis in NOD2-deficient mice was accompanied by increased expression of nuclear factor-kappa B-dependent cytokines and decreased expression of autophagy-related 16-like 1 (ATG16L1). MDP activation of NOD2 enhanced autophagy mediated by TLR2 in human dendritic cells. mRNA expression of TLR2 tended to be higher in the colonic mucosa of patients with active ulcerative colitis compared to that of those in remission. Induction of remission was associated with increased mRNA expression of ATG16L1 in both ulcerative colitis and Crohn's disease patients. Conversely, mRNA expression of receptor-interacting serine/threonine-protein kinase 2 was higher in the inflammatory colonic mucosa of patients with active disease than in the non-inflamed mucosa of patients in remission, in both ulcerative colitis and Crohn's disease. These findings highlight the role of NOD2-TLR2 crosstalk in the immunopathogenesis of colitis.

Cytokine and chemokine profiles in ulcerative colitis relapse after coronavirus disease 2019 vaccination.

Coronavirus disease 2019 (COVID-19) vaccines are highly effective; however, vaccine-related adverse events, including autoimmunity, have been reported. Case reports describing relapse or new-onset of ulcerative colitis (UC) after COVID-19 mRNA vaccination are available. However, the molecular mechanisms underlying the development of colonic inflammation associated with COVID-19 mRNA vaccination are poorly understood. Furthermore, it is unclear whether the relapse of UC after COVID-19 vaccination is driven by unique cytokine responses that differ from those of UC not associated with vaccination. mRNAs derived from COVID-19 vaccines are potent inducers of type I IFN response. We encountered three cases of UC relapse after COVID-19 vaccination. mRNA expressions of IFN-α, IFN-ß, IL-1ß, and IL-12/23p40 showed higher tendency in the colonic mucosa of patients with UC associated with vaccination compared with those not associated with vaccination. In contrast, the expressions of C-X-C motif chemokine ligand 9 (CXCL9) and CXCL10 were comparable. Immunofluorescence analyses also showed higher expression of IFN-α in the colonic mucosa of patients with UC associated with COVID-19 vaccination than in those not associated with vaccination. Taken together, these data suggest that the colonic mucosa of patients with UC who relapsed after COVID-19 vaccination was characterized by enhanced type I IFN responses.

Role of leucine-rich repeat kinase 2 in severe acute pancreatitis.

Introduction: Intrapancreatic activation of trypsinogen caused by alcohol or high-fat intake and the subsequent autodigestion of the pancreas tissues by trypsin are indispensable events in the development of acute pancreatitis. In addition to this trypsin-centered paradigm, recent studies provide evidence that innate immune responses triggered by translocation of intestinal bacteria to the pancreas due to intestinal barrier dysfunction underlie the immunopathogenesis of acute pancreatitis. Although severe acute pancreatitis is often associated with pancreatic colonization by fungi, the molecular mechanisms linking fungus-induced immune responses to the development of severe acute pancreatitis are poorly understood. Leucine-rich repeat kinase 2 (LRRK2) is a multifunctional protein that mediates innate immune responses to fungi and bacteria. Mutations in Lrrk2 is a risk factor for Parkinson's disease and Crohn's disease, both of which are driven by innate immune responses to gut organisms. Discussion: In this Minireview article, we discuss how activation of LRRK2 by the recognition of fungi induces severe acute pancreatitis.

Circumferential Stenosis of the Second Part of the Duodenum Caused by Eosinophilic Gastroenteritis.

Isolated eosinophilic gastroenteritis (EGE) of the second part of the duodenum is rare. We herein report a case of EGE limited to the second part of the duodenum that caused circumferential stenosis due to massive wall thickening. A boring biopsy was useful to verify the accumulation of eosinophils. Induction of remission by prednisolone was accompanied by a marked reduction in the mRNA expression of interleukin-6, C-C motif chemokine ligand 17 (CCL17), and CCL26 without any reduction in prototypical EGE-associated T helper type 2 cytokines (IL-5, IL-13). Thus, the enhanced expression of IL-6, CCL17, and CCL26 might be involved in the development of EGE in this case.

Leucine-rich repeat kinase 2 promotes the development of experimental severe acute pancreatitis.

Translocation of gut bacteria into the pancreas promotes the development of severe acute pancreatitis (SAP). Recent clinical studies have also highlighted the association between fungal infections and SAP. The sensing of gut bacteria by pattern recognition receptors promotes the development of SAP via the production of proinflammatory cytokines; however, the mechanism by which gut fungi mediate SAP remains largely unknown. Leucine-rich repeat kinase 2 (LRRK2) is a multifunctional protein that regulates innate immunity against fungi via Dectin-1 activation. Here, we investigated the role of LRRK2 in SAP development and observed that administration of LRRK2 inhibitors attenuated SAP development. The degree of SAP was greater in Lrrk2 transgenic (Tg) mice than in control mice and was accompanied by an increased production of nuclear factor-kappaB-dependent proinflammatory cytokines. Ablation of the fungal mycobiome by anti-fungal drugs inhibited SAP development in Lrrk2 Tg mice, whereas the degree of SAP was comparable in Lrrk2 Tg mice with or without gut sterilization by a broad range of antibiotics. Pancreatic mononuclear cells from Lrrk2 Tg mice produced large amounts of IL-6 and TNF-α upon stimulation with Dectin-1 ligands, and inhibition of the Dectin-1 pathway by a spleen tyrosine kinase inhibitor protected Lrrk2 Tg mice from SAP. These data indicate that LRRK2 activation is involved in the development of SAP through proinflammatory cytokine responses upon fungal exposure.

Regulation of type I IFN responses by deubiquitinating enzyme A in inflammatory bowel diseases.

The development of Inflammatory bowel disease (IBD) is driven by excessive production of pro-inflammatory cytokines including TNF-α, IL-12, and IL-23. This notion is supported by the remarkable clinical success of biologics targeting these cytokines. Recognition of cell wall components derived from intestinal bacteria by Toll-like receptors (TLRs) induces the production of these pro-inflammatory cytokines by macrophages and dendritic cells in human IBD and experimental colitis model. Although sensing of bacterial nucleic acids by endosomal TLRs, specifically TLR3, TLR7, and TLR9 leads to robust production of type I IFNs, it remains debatable whether TLR-mediated type I IFN responses are pathogenic or protective in IBD patients. Additionally, recent studies identified deubiquitinating enzyme A (DUBA) as a novel negative regulator of TLR-mediated type I IFN responses. In light of these observations and their potential applications, in this review, we summarize recent findings on the roles of type I IFN responses and DUBA-mediated negative regulation of these responses in human IBD and experimental colitis model.

A review of contrast-enhanced harmonic endoscopic ultrasonography for pancreatic solid tumors.

Endoscopic ultrasonography (EUS) is superior to other imaging modalities in the detection of pancreatic masses, although differentiating the types of pancreatic masses detected on EUS remains challenging. However, the value of contrast-enhanced harmonic EUS (CH-EUS) using ultrasound contrast agents for this differentiation has been reported. CH-EUS plays a pivotal role in analysis of small lesions that can only be detected with EUS. Recently, CH-EUS was used for staging and/or determining the resectability of pancreatic cancer in several clinical trials. In addition, it is used to estimate the response of pancreatic cancer to chemotherapy and to determine the prognosis in cases of pancreatic cancer and pancreatic neuroendocrine neoplasms. It is also postulated that CH-EUS improves the diagnostic performance of endoscopic ultrasound-guided fine-needle aspiration biopsy (EUS-FNAB) through complementary diagnoses using CH-EUS and EUS-FNAB, or CH-EUS-guided EUS-FNAB. Thus, CH-EUS has been employed for various qualitative diagnoses, including differentiation of pancreatic masses. Second-generation contrast agents such as Sonazoid are used clinically for ultrasound diagnostic imaging of liver and breast disease. The positioning of CH-EUS with Sonazoid as a test for the diagnosis of solid pancreatic tumors is an issue for further studies.

Impact of Smad4 and p53 mutations on the prognosis of patients with pancreatic ductal adenocarcinoma undergoing chemotherapy.

BACKGROUND: This prospective cohort study evaluated the feasibility of using endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB) samples for comprehensive mutational analysis of cancer-related genes using microtissues. METHODS: Fifty patients with suspected pancreatic cancer presenting consecutively at the Kindai University Hospital between January 2018 and January 2019 were enrolled. Cancerous tissues from EUS-FNB were obtained from each tumor and subjected to histological examination and mutational analysis. The primary endpoint was the collection rate of EUS-FNB specimens suitable for comprehensive cancer panels using deep sequencing. Clinical history and genetic variations between the disease control and progressive disease groups of patients on chemotherapy were evaluated as secondary endpoints. RESULTS: The collection rate of EUS-FNB specimens suitable for comprehensive cancer panels using deep sequencing was 93.6%. The cancer panel was sequenced for 25 patients with pancreatic cancer treated initially with systemic chemotherapy. Mutation in p53 and Smad4 were positively and negatively associated, respectively, with disease control at the initial evaluation. The median time to progression in 15 patients with p53 and without Smad4 mutations was 182.0 days; whereas, it was 92.5 days in other 10 patients; this difference was significant (p = 0.020). CONCLUSIONS: Tissue samples from EUS-FNB were suitable for mutational analysis. Pancreatic cancers with p53 and without Smad4 mutations responded better to chemotherapy and had a better prognosis than those others.