C5a stimulation induces caspase-1 activation and mature IL-1ß production in human peripheral blood mononuclear cells.

The complement component C5a contributes to the recruitment of immune cells to inflamed tissues and local inflammation. The proinflammatory cytokine interleukin (IL)-1ß is also related to inflammatory disorders through inflammasome activation. However, the association between inflammasome activation and C5a is unclear. Human peripheral blood mononuclear cells (PBMCs) were stimulated with C5a and measured for IL-1ß secretion by enzyme-linked immunosorbent assay (ELISA). The pro-IL-1ß expression in cell lysates was also examined by Western blot analysis. Similarly, magnetic bead-isolated CD14+ monocyte-depleted and lymphocyte-depleted PBMCs were stimulated with C5a, and immunoblot analysis was performed using an anti-cleaved-IL-1ß (p17) antibody. FACS was performed to detect caspase-1-activated cells. C5a-stimulated PBMCs produced IL-1ß in C5a concentration-dependent manner. The protein levels of pro-IL-1ß in the cell lysates were significantly increased. Furthermore, the cleaved-IL-1ß (p17) was faintly detected in the same lysates. Active caspase-1 was demonstrated in C5a-simulated CD14+ monocytes by FACS. Cleaved-IL-1ß (p17) was demonstrated in the supernatant of C5a-stimulated PBMCs. Lymphocyte-depleted PBMCs stimulated with C5a but monocyte-depleted PBMCs produced cleaved-IL-1ß (p17). C5a induced the production of mature IL-1ß in PBMCs. The IL-1ß production is mediated mainly by caspase-1 activation in CD14+ monocytes. These results suggest that C5a alone potentiates mature IL-1ß production mainly in monocytes.

Apelin expression is downregulated in T cells in a murine model of chronic colitis.

Apelin (APL), an endogenous ligand for APJ, has been reported to be upregulated in a murine model of acute colitis induced by sodium dextran sulfate, as well as inflammatory bowel diseases (IBD) in humans. However, the mechanisms and functions of APL/APJ axis in the pathogenesis of IBD are unclear. We herein analyzed CD4+ T cells to determine the functions of APL in a murine model of chronic colitis induced in Rag deficient mice (Rag-/-). In colonic tissues of wild-type mice (WT), we found that APL was expressed especially in the lamina propria lymphocytes, where CD4+ T cells are dominant, rather than the epithelial cells. Unexpectedly, the APL expression was rather downregulated in the colonic tissue of the chronic colitis group compared to the control groups (Rag-/- before colitis induction and WT). The APL expression was downregulated when naïve T cells were differentiated into effecter T cells. A lack of APL resulted in decreased naïve T cells and increased effecter T cells in secondary lymphoid organs. A synthetic APL peptide, [Pyr1]-APL-13, increased IL-10 and decreased IFN-γ productions by effecter T cells. Administration of [Pyr1]-APL-13 improved survival rate in association with lessened colitis severity and decreased pro-inflammatory cytokine production. This is the first report showing immunological function of APL specifically on T cells, and these results indicate that APL/APJ axis may be a novel therapeutic target for IBD.

Endoscopic submucosal dissection with the combination of a scissor-type knife and novel traction method for colonic neoplasm involving a diverticulum.

Video 1A 35-mm laterally spreading tumor partially infiltrated the interior portion of the diverticular orifice in the ascending colon. Glycerol and hyaluronate solution were injected into the submucosa to maintain adequate mucosal elevation. Mucosal incision and submucosal dissection were performed using a DualKnife and insulation-tipped knife from the anal side; however, safe submucosal dissection was challenging with these knives because of severe fibrosis and abundant blood vessels in the diverticulum. Therefore, to improve the visibility of the submucosa, a scissor-type knife and a multiloop traction device was used to facilitate the submucosal dissection. Finally, en bloc resection was achieved in 117 minutes without adverse events. A part of the diverticular defect after endoscopic submucosal dissection was clipped to prevent delayed perforation.

Colonic Endoscopic Submucosal Dissection for a Granular Cell Tumor with Insufficient Endoscopic Manipulation in the Hepatic Flexure.

This report describes a granular cell tumor (GCT) with insufficient endoscopic manipulation in the hepatic flexure (HF) of the colon, which was treated by endoscopic submucosal dissection (ESD) using a splinting tube and the spring S-O clip traction method. A 44-year-old man presented with a 10 mm subepithelial tumor in the HF near the ascending colon on colonoscopy. The lesion had a smooth surface without erosion. The histology of biopsied specimen from the lesion was suspected as a GCT. Most GCTs are considered low-grade malignant, but ESD was chosen to treat the lesion due to the patient's insistence on endoscopic treatment. Because the lesion was located in the HF, it was assumed that the scope manipulation during ESD would be difficult. During ESD, a splinting tube was utilized to stabilize endoscopic manipulation and the spring S-O clip traction method to keep clear visualization of the submucosa, and the procedure was completed without adverse events. An 8 × 7 mm lesion with negative margins was removed by ESD. Hematoxylin and eosin staining showed atypical cells with round-to-oval nuclei and acidophilic vesicles, and immunohistochemical staining for S-100 protein was strongly positive with a Ki-67 labeling index of 5%. The lesion was pathologically confirmed as a GCT. This case showed the usefulness and safety of ESD for GCT with insufficient endoscopic manipulation in the HF.

Evaluation of the relationship between the spleen volume and the disease activity in ulcerative colitis and Crohn disease.

ABSTRACT: Inflammatory bowel disease (IBD) is caused by the activation of an abnormal immune response in the intestinal mucosa; the spleen is involved in the main immune response. Ulcerative colitis (UC) and Crohn disease (CD) have different inflammatory mechanisms; this study aimed to quantitatively measure and compare the spleen volumes between patients with UC and CD and examine the relationship between spleen volume and disease activity in both.We retrospectively analyzed 44 patients with IBD aged 30-60 years (UC group, n = 24; CD group, n = 20). The control group comprised 19 patients with pancreatic cysts that did not affect the spleen volume. All patients underwent computed tomography (CT) between April 2014 and March 2019. Using the Image J software, spleen volumes in the UC, CD, and control groups were measured accurately from the CT images and adjusted for the body weight.No significant differences in the sex, age, or body weight were noted between the UC and CD groups and the control group. The spleen volumes, adjusted for the body weight, were 2.2 ±â€Š1.0 cm3/kg, 2.0 ±â€Š1.0 cm3/kg, and 3.6 ±â€Š1.7 cm3/kg in the control, UC, and CD groups, respectively. The volumes differed significantly between the CD and control groups (P = .01), but not between the UC and control groups (P = .43). Furthermore, a significant strong correlation was found between the disease activity and the body weight-adjusted spleen volume in patients with CD (P < .01).The spleen volume, adjusted for the body weight, was significantly larger in patients with CD than in the controls and was also strongly correlated with the CD activity. These results suggest that the immune response in CD may affect the spleen volume.

Increased CEACAM1 expression on peripheral blood neutrophils in patients with rheumatoid arthritis.

Altered expression of adhesion molecules in immune cells has been demonstrated in rheumatoid arthritis (RA). Carcinoembryonic-antigen-related cell-adhesion molecule 1 (CEACAM1) is an adhesion molecule that acts as a coinhibitory receptor in the immune system. We investigated the role of CEACAM1 in immune cell subsets of patients with RA. Peripheral blood was obtained from 37 patients with RA and 20 healthy controls (HC). The expression of CEACAM1 and T-cell immunoglobulin mucin domain molecule (TIM) -3 on peripheral blood mononuclear cells and neutrophils was analyzed by flow cytometry. Intracellular TIM-3 expression was analyzed using cellular lysates by Western blot analysis. Serum levels of soluble CEACAM1 (sCEACAM1) were estimated by an enzyme-linked immunosorbent assay. CEACAM1 expression was not detected in peripheral blood mononuclear cells, including in CD14(+) monocytes and CD3(+) lymphocytes isolated from patients with RA or HC. However, substantial cell-surface expression of CEACAM1 was detected in peripheral blood neutrophils, and it was significantly elevated in samples from patients with RA without remission compared to those in remission. There was no significant difference in serum levels of sCEACAM1 between patients with RA and HC. Cell-surface expression of TIM-3 was not detected in peripheral blood neutrophils from patients with RA or HC but was seen in CD14(+) monocytes. However, there was no significant difference in TIM-3 expression on monocytes between patients with RA and HC. Our data indicate that cell-surface expression of CEACAM1 on peripheral blood neutrophils are higher in patients with RA and that it is associated with rheumatoid inflammation. Further studies are needed to explore the potential role of CEACAM1 in rheumatoid inflammatory pathways.

Trichuris trichiura Incidentally Detected by Colonoscopy and Identified by a Genetic Analysis.

Although trichuriasis, a zoonotic disease, has recently become rare in Japan due to improved environmental hygiene, we herein report a 79-year-old man in whom a worm was incidentally found in the ascending colon during colonoscopy for positive fecal occult blood and was endoscopically removed. A genetic analysis identified the worm as Trichuris trichiura possessing mixed sequences from non-human primate and human origins. Despite controversy regarding Trichuris trichiura infection originating from Japanese macaques, according to some studies, it originates primarily from humans. This report suggests the efficacy of a genetic analysis for identifying infection sources.

A potent endocytosis inhibitor Ikarugamycin up-regulates TNF production.

Ikarugamycin (IK) is an antibiotic which has been reported to have a variety of functions, such as inhibition of clathrin-mediated endocytosis (CME), anti-tumor effects and regulation of the immune system. Whether IK influences cytokine production is poorly understood. We have investigated the relationship between IK and production of tumor necrosis factor-α (TNF). TNF plays a pivotal role in pathogenesis of many diseases. Although the dynamics of soluble TNF (sTNF) has been widely explored so far, the functions of the membrane form of TNF (mTNF) have not been fully elucidated. We demonstrated that IK increases the amount of mTNF and prolongs the duration of TNF expression. This effect is unrelated to the shedding activity of disintegrin and metalloproteinase domain-containing protein 17 (ADAM 17). Our results revealed that there is a mechanism to terminate inflammation at the cellular level which IK dysregulates. Furthermore, IK can be a tool to study TNF signaling due to its effect of increasing mTNF expression.

Oral administration of D-serine prevents the onset and progression of colitis in mice.

BACKGROUND: L-amino acids are the predominant forms of organic molecules on the planet, but recent studies have revealed that various foods contain D-amino acids, the enantiomers of L-amino acids. Though diet plays important roles in both the development and progression of inflammatory bowel disease (IBD), to our best knowledge, there has been no report on any potential interactions between D-amino acids and IBD. In this report, we aim to assess the effects of D-serine in a murine model of IBD. MATERIALS AND METHODS: To induce chronic colitis, naïve CD4 T cells (CD4+ CD62+ CD44low) from wild-type mice were adoptively transferred into Rag2-/- mice, after or before the mice were orally administered with D-serine. In vitro proliferation assays were performed to assess naïve CD4 T cell activation under the Th-skewing conditions in the presence of D-serine. RESULTS: Mice treated with D-serine prior to the induction of colitis exhibited a reduction in T-cell infiltration into the lamina propria and colonic inflammation that were not seen in mice fed with water alone or L-serine. Moreover, D-serine suppressed the progression of chronic colitis when administered after the disease induction. Under in vitro conditions, D-serine suppressed the proliferation of activated CD4 T cells and limited their ability to differentiate to Th1 and Th17 cells. CONCLUSION: Our results suggest that D-serine not only can prevent, but also has efficacious effects as a treatment for IBD.

Nickel ions attenuate autophagy flux and induce transglutaminase 2 (TG2) mediated post-translational modification of SQSTM1/p62.

Nickel, the most frequent contact allergy cause, is widely used for various metallic materials and medical devices. Autophagy is an intracellular protein degradation system and contributes to metal recycling. However, it is unclear the functions of nickel in autophagy. We here demonstrated that NiCl2 induced microtubule-associated protein 1 light chain 3 (LC3)-II and LC3 puncta, markers of autophagosomes. Bafilomycin A1 (BafA1) treatment did not enhance LC3 puncta under NiCl2 stimulation, suggesting that NiCl2 did not induce autophagic flux. In addition, NiCl2 promotes the accumulation of SQSTM1/p62 and increased SQSTM1/p62 colocalization with lysosomal-associated membrane protein 1 (LAMP1). These data indicated that NiCl2 attenuates autophagic flux. Interestingly, NiCl2 induced the expression of the high-molecular-weight (MW) form of SQSTM1/p62. Inhibition of NiCl2-induced reactive oxygen species (ROS) reduced the high-MW SQSTM1/p62. We also showed that NiCl2-induced ROS activate transglutaminase (TG) activity. We found that transglutaminase 2 (TG2) inhibition reduced high-MW SQSTM1/p62 and SQSTM1/p62 puncta under NiCl2 stimulation, indicating that TG2 regulates SQSTM1/p62 protein homeostasis under NiCl2 stimulation. Our study demonstrated that nickel ion regulates autophagy flux and TG2 restricted nickel-dependent proteostasis.

CEACAM1 specifically suppresses B cell receptor signaling-mediated activation.

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) expressed in T cells may regulate immune responses in the gut. In addition to T cells, B cells are also an important population in the gut-associated lymphoid tissues that orchestrate mucosal homeostasis. However, the role of CEACAM1 in B cells has not been elucidated. We herein analyzed mature B cells to determine the functions of CEACAM1. Flow cytometry revealed high expression of CEACAM1 on B cells in secondary lymphoid tissues. Cytokine production induced by activation of B cell receptor (BCR) signaling was suppressed by CEACAM1 signaling in contrast to that associated with either Toll-like receptor 4 or CD40 signaling. Confocal microscopy revealed co-localization of CEACAM1 and BCR when activated with anti-Igµ F(ab')2 fragment. Overexpression of CEACAM1 in a murine B cell line, A20, resulted in reduced expressions of activation surface markers with decreased Ca2+ influx after BCR signal activation. Overexpression of CEACAM1 suppressed BCR signal cascade in A20 cells in association with decreased spontaneous proliferation. Our results suggest that CEACAM1 can regulate BCR-mediated mature B cell activation in lymphoid tissues. Therefore, further studies of this molecule may lead to greater insights into the mechanisms of immune responses within peripheral tissues and the potential treatment of inflammatory diseases.

Upregulation of complement C1q reflects mucosal regeneration in a mouse model of colitis.

Confirming mucosal healing is important in inflammatory bowel disease treatment. Complement C1q-mediated Wnt signaling activation has recently been suggested to mediate tissue repair and mucosal regeneration. We investigated the involvement of complement C1q and Wnt signaling in intestinal mucosal regeneration using a murine colitis model. The colitis model was established by providing C57BL/6J mice with 4% dextran sodium sulfate (DSS) for 1 week (inflammation phase) followed by regular water for 2 weeks (recovery phase). After 3 weeks, we investigated the relationship between C1q in serum and colonic tissue during the inflammation and recovery phases. We assessed Wnt signaling activity by evaluating ß-catenin expression in mouse intestinal tissue. Serum C1q levels were elevated during the recovery phase. C1q-specific staining indicated high C1q expression in pathological intestinal tissue during the inflammation and recovery phases. C1q mRNA and protein expression was increased during both phases. Interestingly, C1q-expressing cells were consistent with macrophages (F4/80-positive cells). Moreover, the expression of ß-catenin increased in the colonic tissues during the recovery phase of DSS-induced colitis but decreased during the inflammation phase of DSS-induced colitis. C1q expression may mediate Wnt signaling activity and intestinal epithelial regeneration.

Receptor-Interacting Protein Kinase 3 (RIPK3) inhibits autophagic flux during necroptosis in intestinal epithelial cells.

Autophagy is an intracellular process that regulates the degradation of cytosolic proteins and organelles. Dying cells often accumulate autophagosomes. However, the mechanisms by which necroptotic stimulation induces autophagosomes are not defined. Here, we demonstrate that the activation of necroptosis with TNF-α plus the cell-permeable pan-caspase inhibitor Z-VAD induces LC3-II and LC3 puncta, markers of autophagosomes, via the receptor-interacting protein kinase 3 (RIPK3) in intestinal epithelial cells. Surprisingly, necroptotic stimulation reduces autophagic activity, as evidenced by enlarged puncta of the autophagic substrate SQSTM1/p62 and its increased colocalization with LC3. However, necroptotic stimulation does not induce the lysosomal-associated membrane protein 1 (LAMP1) nor syntaxin 17, which mediates autophagosome-lysosome fusion, to colocalize with LC3. These data indicate that necroptosis attenuates autophagic flux before the lysosome fusion step. Our findings may provide insights into human diseases involving necroptosis.

A20 and ABIN-1 synergistically preserve intestinal epithelial cell survival.

A20 (TNFAIP3) and ABIN-1 (TNIP1) are candidate susceptibility genes for inflammatory bowel disease and other autoimmune or inflammatory diseases, but it is unclear how these proteins interact in vivo to prevent disease. Here we show that intestinal epithelial cell (IEC)-specific deletion of either A20 or ABIN-1 alone leads to negligible IEC loss, whereas simultaneous deletion of both A20 and ABIN-1 leads to rapid IEC death and mouse lethality. Deletion of both A20 and ABIN-1 from enteroids causes spontaneous cell death in the absence of microbes or hematopoietic cells. Studies with enteroids reveal that A20 and ABIN-1 synergistically restrict death by inhibiting TNF-induced caspase 8 activation and RIPK1 kinase activity. Inhibition of RIPK1 kinase activity alone, or caspase inhibition combined with RIPK3 deletion, abrogates IEC death by blocking both apoptosis and necroptosis in A20 and ABIN-1 double-deficient cells. These data show that the disease susceptibility proteins A20 and ABIN-1 synergistically prevent intestinal inflammation by restricting IEC death and preserving tissue integrity.

B cell activation in the cecal patches during the development of an experimental colitis model.

Although previous studies have suggested that appendix seems to be involved in the colitis, the role of this in the pathogenesis remains unclear. In this study, we assessed the importance of appendiceal lymphoid follicles, specifically the cecal patches (CP) in mice, using an experimental colitis model. Treatment with oxazolone resulted in ulcerations particularly at CP with follicular expansion as well as colitis. The colitis was attenuated by either appendectomy or the absence of mature B cells. We therefore established an intravital imaging system accompanied by the fluorescence resonance energy transfer technology to analyze the dynamic immune response of CP B cells. Our observation revealed frequent Ca2+ signaling in CP B cells during the early phase of colitis development. These findings suggested that the CP B cells may be involved in the pathogenesis of colitis including inflammatory bowel diseases in humans.