Fasting-Refeeding Impacts Immune Cell Dynamics and Mucosal Immune Responses.

Nutritional status potentially influences immune responses; however, how nutritional signals regulate cellular dynamics and functionality remains obscure. Herein, we report that temporary fasting drastically reduces the number of lymphocytes by ∼50% in Peyer's patches (PPs), the inductive site of the gut immune response. Subsequent refeeding seemingly restored the number of lymphocytes, but whose cellular composition was conspicuously altered. A large portion of germinal center and IgA+ B cells were lost via apoptosis during fasting. Meanwhile, naive B cells migrated from PPs to the bone marrow during fasting and then back to PPs during refeeding when stromal cells sensed nutritional signals and upregulated CXCL13 expression to recruit naive B cells. Furthermore, temporal fasting before oral immunization with ovalbumin abolished the induction of antigen-specific IgA, failed to induce oral tolerance, and eventually exacerbated food antigen-induced diarrhea. Thus, nutritional signals are critical in maintaining gut immune homeostasis.

The epigenetic regulator Uhrf1 facilitates the proliferation and maturation of colonic regulatory T cells.

Intestinal regulatory T cells (Treg cells) are necessary for the suppression of excessive immune responses to commensal bacteria. However, the molecular machinery that controls the homeostasis of intestinal Treg cells has remained largely unknown. Here we report that colonization of germ-free mice with gut microbiota upregulated expression of the DNA-methylation adaptor Uhrf1 in Treg cells. Mice with T cell-specific deficiency in Uhrf1 (Uhrf1(fl/fl)Cd4-Cre mice) showed defective proliferation and functional maturation of colonic Treg cells. Uhrf1 deficiency resulted in derepression of the gene (Cdkn1a) that encodes the cyclin-dependent kinase inhibitor p21 due to hypomethylation of its promoter region, which resulted in cell-cycle arrest of Treg cells. As a consequence, Uhrf1(fl/fl)Cd4-Cre mice spontaneously developed severe colitis. Thus, Uhrf1-dependent epigenetic silencing of Cdkn1a was required for the maintenance of gut immunological homeostasis. This mechanism enforces symbiotic host-microbe interactions without an inflammatory response.

Composition of fatty acids in a high-fat diet affects adipose tissue inflammation by inducing calreticulin on adipocytes and activating group 1 innate lymphoid cells.

Obesity-induced adipose tissue inflammation plays a critical role in the development of metabolic diseases. For example, NK1.1+ group 1 innate lymphoid cells (G1-ILCs) in adipose tissues are activated in the early stages of inflammation in response to a high-fat diet (HFD). In this study, we examined whether the composition of fatty acids affected adipose inflammatory responses induced by an HFD. Mice were fed a stearic acid (C18:0)-rich HFD (HFD-S) or a linoleic acid (C18:2)-rich HFD (HFD-L). HFD-L-fed mice showed significant obesity compared with HFD-S-fed mice. Visceral and subcutaneous fat pads were enlarged and contained more NK1.1+KLRG1+ cells, indicating that G1-ILCs were activated in HFD-L-fed mice. We examined early changes in adipose tissues during the first week of HFD intake, and found that mice fed HFD-L showed increased levels of NK1.1+CD11b+KLRG1+ cells in adipose tissues. In adipose tissue culture, addition of 4-hydroxynonenal, the most frequent product of lipid peroxidation derived from unsaturated fatty acids, induced NK1.1+CD11b+CD27- cells. We found that calreticulin, a ligand for the NK activating receptor, was induced on the surface of adipocytes after exposure to 4-hydroxynonenal or a 1-week feeding with HFD-L. Thus, excess fatty acid intake and the activation of G1-ILCs initiate and/or modify adipose inflammation.

A purified diet affects intestinal epithelial proliferation and barrier functions through gut microbial alterations.

The gut microbiota plays a crucial role in maintaining epithelial barrier function. Although multiple studies have demonstrated the significance of dietary factors on the gut microbiota and mucosal barrier function, the impact of a purified diet, which has long been used in various animal experiments, on intestinal homeostasis remains to be elucidated. Here, we compared the impact of two different types of diets, a crude diet and an AIN-93G-formula purified diet, on epithelial integrity and the gut microbiota. Purified diet-fed mice exhibited shorter villi and crypt lengths and slower epithelial turnover, particularly in the ileum. In addition, antimicrobial products, including REG3γ, were substantially decreased in purified diet-fed mice. Purified diet feeding also suppressed α1,2-fucosylation on the epithelial surface. Furthermore, the purified diet induced metabolic rewiring to fatty acid oxidation and ketogenesis. 16S ribosomal RNA gene sequencing of the ileal contents and mucus layer revealed distinct gut microbiota compositions between the purified and crude diet-fed mice. Purified diet feeding reduced the abundance of segmented filamentous bacteria (SFB), which potently upregulate REG3γ and fucosyltransferase 2 (Fut2) by stimulating group 3 innate lymphoid cells (ILC3s) to produce IL-22. These observations illustrate that the intake of a crude diet secures epithelial barrier function by facilitating SFB colonization, whereas a purified diet insufficiently establishes the epithelial barrier, at least partly owing to the loss of SFB. Our data suggest that the influence of purified diets on the epithelial barrier integrity should be considered in experiments using purified diets.

Induction of Kallikrein-Related Peptidase 13 and TET2/3 by Anticancer Drugs and Poor Prognosis of Patients with Esophageal Squamous Cell Carcinoma After Preoperative Treatment.

BACKGROUND: Preoperative chemotherapy/chemoradiotherapy has been generally considered for the treatment of esophageal squamous cell carcinoma (ESCC) to improve prognosis. We examined the effects of anticancer drugs on the expression of kallikrein-related peptidase 13 (KLK13), a potential ESCC prognostic marker, and its clinical relevance in patients who received chemotherapy/chemoradiotherapy for ESCC. METHODS: Overall, 105 patients with ESCC who received chemotherapy or chemoradiotherapy before esophagectomy were enrolled. The expression of KLK13 in biopsy samples obtained before chemotherapy/chemoradiotherapy and resected ESCC tumors was assessed by immunohistochemical staining. The effects of 5-fluorouracil (5-FU) and/or cisplatin (CDDP) exposure on the expressions of KLK13 and ten-eleven translocation dioxygenases (TET) in ESCC cells were examined by reverse transcription-polymerase chain reaction. RESULTS: Immunohistochemical staining of paired ESCC specimens before (biopsy samples) and after (resected specimens) chemotherapy/chemoradiotherapy demonstrated a change in KLK13 expression. KLK13 and TET2/3 transcriptions were induced when human ESCC cell lines were treated with 5-FU and/or CDDP. Among patients with KLK13-negative status before chemotherapy/chemoradiotherapy, those with KLK13-positive resected tumors had a significantly poorer prognosis than those with KLK13-negative resected tumors (p = 0.0477). By using tumor cells isolated from ESCC biopsy tissues obtained before chemotherapy/chemoradiotherapy, we established a primary culture system and detected the induction of KLK13 expression by anticancer drugs. CONCLUSIONS: Preoperative treatments alter KLK13 expression in ESCC. The conversion of KLK13 expression from a negative status in biopsy samples to a positive status in resected tumor samples is a predictor of poor prognosis. KLK13 status is a potential marker for decision making to avoid harmful chemotherapy/chemoradiotherapy in patients with ESCC.

Loss of GSTO2 contributes to cell growth and mitochondria function via the p38 signaling in lung squamous cell carcinoma.

Glutathione S-transferase omega 2 (GSTO2) lacks any appreciable GST activity, but it exhibits thioltransferase activity. The significance of GSTO2 in lung function has been reported; however, the precise expression and molecular function of GSTO2 in the lungs remain unclear. In the present study, we found that GSTO2 is expressed in airway basal cells, non-ciliated, columnar Clara cells, and type II alveolar cells, which have self-renewal capacity in the lungs. Contrastingly, no GSTO2 expression was observed in 94 lung squamous cell carcinoma (LSCC) samples. When human LSCC cell lines were treated with 5-aza-2'-deoxycytidine, a DNA-methyltransferase inhibitor, GSTO2 transcription was induced, suggesting that aberrant GSTO2 hypermethylation in LSCC is the cause of its downregulation. Forced GSTO2 expression in LSCC cell lines inhibited cell growth and colony formation in vitro. In a subcutaneous xenograft model, GSTO2-transfected cells formed smaller tumors in nude mice than mock-transfected cells. Upon intravenous injection into nude mice, the incidence of liver metastasis was lower in mice injected with GSTO2-transfected cells than in those injected with mock-transfected cells. In addition, GSTO2 induction suppressed the expression of ß-catenin and the oxygen consumption rate, but it did not affect the extracellular acidification rate. Furthermore, GSTO2-transfected cells displayed lower mitochondrial membrane potential than mock-transfected cells. When GSTO2-transfected cells were treated with a p38 inhibitor, ß-catenin expression and mitochondrial membrane potential were recovered. Our study indicated that the loss of GSTO2 via DNA hypermethylation contributes to the growth and progression of LSCC, probably by modulating cancer metabolism via the p38/ß-catenin signaling pathway.

Expression Status of Serine Protease 27: A Prognostic Marker for Esophageal Squamous Cell Carcinoma Treated with Preoperative Chemotherapy/Chemoradiotherapy.

BACKGROUND: A previous study conducted a transcriptome analysis of paired normal and esophageal squamous cell carcinoma (ESCC) tissue samples. The results showed that the expression of serine protease 27 (PRSS27) was perturbed in tumor samples. Hence, this retrospective study aimed to validate the prognostic significance of PRSS27 in patients with preoperative treatment for ESCC. METHODS: We enrolled 86 patients who received preoperative treatment before esophagectomy for ESCC. The expression of PRSS27 in resected ESCC and biopsy tissue samples obtained before preoperative treatment was evaluated via immunostaining, and its relationship with clinicopathological features and prognosis was analyzed. RESULTS: In normal esophageal mucosa tissue samples, PRSS27 was expressed in the cytoplasm of spinous cells in the suprabasal layer and basal cells in the basal layer. Of 64 resected ESCC tissue samples, 35 (54.7%) expressed PRSS27 and 29 (45.3%) did not. Moreover, ectopic nuclear expression of PRSS27 was observed. Based on multivariate analysis, PRSS27 expression in resected tumor samples was a predictor of poor prognosis. In cases in which PRSS27 expression was observed in biopsy samples, patients with PRSS27-negative resected tumors had a better postoperative prognosis than those with PRSS27-positive resected tumors. CONCLUSIONS: PRSS27 expression in resected ESCC tissue samples is a poor prognostic factor in ESCC patients with preoperative treatment. Furthermore, conversion of PRSS27 expression from positive in biopsy samples to negative in resected tumor samples is a predictor of good prognosis in these patients. Hence, PRSS27 status is an effective tool for decision making regarding adjuvant treatment in ESCC patients.

Glutathione S-transferase omega 2 regulates cell growth and the expression of E-cadherin via post-transcriptional down-regulation of ß-catenin in human esophageal squamous cells.

Glutathione S-transferase omega 2 (GSTO2), which belongs to the superfamily of GST omega class, lacks any appreciable GST activity. Although GSTO2 exhibits thioltransferase and glutathione dehydrogenase activities, its precise expression and physiological functions are still unclear. In the present study, we found that GSTO2 is exclusively expressed in the basal cell layer in Ki67-negative non-proliferative cells in the human esophageal mucosa. GSTO2 overexpression in esophageal squamous cell carcinoma (ESCC) cell lines inhibited cell growth and colony formation, and GSTO2-transfected cells formed smaller tumors in nude mice compared with mock-transfected cells. Interestingly, GSTO2 induction suppressed the expressions of E-cadherin and ß-catenin at the cell-cell contact site. We quantified the phosphorylation levels of key proteins of MAPK signaling pathway and identified phosphorylation of p38. Additionally, HSP27, a downstream molecule of p38, was accelerated in GSTO2-transfected cells, unlike in mock-transfected cells. When GSTO2-transfected cells were treated with a p38 inhibitor, the expression of ß-catenin and the membrane localization of E-cadherin was recovered. We next examined GSTO2 expression in 61 ESCC tissues using quantitative reverse transcription polymerase chain reaction and immunostaining. The results showed that GSTO2 mRNA and protein were significantly reduced in ESCC compared with normal tissues. When human ESCC cell lines were treated with 5-aza-2'-deoxycytidine, a DNA-methyltransferase inhibitor, GSTO2 transcription was induced, suggesting that aberrant hypermethylation is the cause of the down-regulated expression. Our results indicate that GSTO2 expression inhibits the membrane localization of E-cadherin, probably by modulation of the p38 signaling pathway. Down-regulation of GSTO2 by DNA hypermethylation contributes to the growth and progression of ESCC.

Induction of IFN-λ3 as an additional effect of nucleotide, not nucleoside, analogues: a new potential target for HBV infection.

OBJECTIVE: The clinical significance of polymorphisms in the interleukin-28B gene encoding interferon (IFN)-λ3, which has antiviral effects, is known in chronic HCV but not in HBV infection. Thus, we measured IFN-λ3 levels in patients with HBV and investigated its clinical significance and association with nucleos(t)ide (NUC) analogue administration. DESIGN: Serum IFN-λ3 level was measured in 254 patients with HBV with varying clinical conditions using our own high sensitivity method. The resulting values were compared with various clinical variables. In addition, cell lines originating from various organs were cultured with NUCs, and the production of IFN-λ3 was evaluated. RESULTS: Higher serum IFN-λ3 levels were detected in the patients treated with nucleotide analogues (adefovir or tenofovir) compared with those treated with nucleoside analogues (lamivudine or entecavir). There were no other differences in the clinical background between the two groups. A rise in the serum IFN-λ3 levels was observed during additional administration of the nucleotide analogues. In vitro experiments showed that the nucleotide analogues directly and dose-dependently induced IFN-λ3 production only in colon cancer cells. Furthermore, the supernatant from cultured adefovir-treated colon cancer cells significantly induced IFN-stimulated genes (ISGs) and inhibited hepatitis B surface antigen (HBsAg) production in hepatoma cells, as compared with the supernatant from entecavir-treated cells. CONCLUSIONS: We discovered that the nucleotide analogues show an additional pharmacological effect by inducing IFN-λ3 production, which further induces ISGs and results in a reduction of HBsAg production. These findings provide novel insights for HBV treatment and suggest IFN-λ3 induction as a possible target.

A Histone Methyltransferase ESET Is Critical for T Cell Development.

ESET/SETDB1, one of the major histone methyltransferases, catalyzes histone 3 lysine 9 (H3K9) trimethylation. ESET is critical for suppressing expression of retroviral elements in embryonic stem cells; however, its role in the immune system is not known. We found that thymocyte-specific deletion of ESET caused impaired T cell development, with CD8 lineage cells being most severely affected. Increased apoptosis of CD8 single-positive cells was observed, and TCR-induced ERK activation was severely inhibited in ESET(-/-) thymocytes. Genome-wide comprehensive analysis of mRNA expression and H3K9 trimethylation revealed that ESET regulates expression of numerous genes in thymocytes. Among them, FcγRIIB, whose signaling can inhibit ERK activation, was strongly and ectopically expressed in ESET(-/-) thymocytes. Indeed, genetic depletion of FcγRIIB in ESET(-/-) thymocytes rescued impaired ERK activation and partially restored defective positive selection in ESET(-/-) mice. Therefore, impaired T cell development in ESET(-/-) mice is partly due to the aberrant expression of FcγRIIB. Collectively, to our knowledge, we identify ESET as the first trimethylated H3K9 histone methyltransferase playing a crucial role in T cell development.

Intermittent fasting prompted recovery from dextran sulfate sodium-induced colitis in mice.

Fasting-refeeding in mice induces transient hyperproliferation of colonic epithelial cells, which is dependent on the lactate produced as a metabolite of commensal bacteria. We attempted to manipulate colonic epithelial cell turnover with intermittent fasting to prompt recovery from acute colitis. Acute colitis was induced in C57BL/6 mice by administration of dextran sulfate sodium in the drinking water for 5 days. From day 6, mice were fasted for 36 h and refed normal bait, glucose powder, or lactylated high-amylose starch. On day 9, colon tissues were subjected to analysis of histology and cytokine expression. The effect of lactate on the proliferation of colonocytes was assessed by enema in vivo and primary culture in vitro. Intermittent fasting resulted in restored colonic crypts and less expression of interleukin-1ß and interleukin-17 in the colon than in mice fed ad libitum. Administration of lactate in the colon at refeeding time by enema or by feeding lactylated high-amylose starch increased the number of regenerating crypts. Addition of lactate but not butyrate or acetate supported colony formation of colonocytes in vitro. In conclusion, intermittent fasting in the resolution phase of acute colitis resulted in better recovery of epithelial cells and reduced inflammation.

Interferon-γ constrains cytokine production of group 2 innate lymphoid cells.

Group 2 innate lymphoid cells (ILC2s) produce a significant amount of interleukin-5 (IL-5), which supports eosinophil responses in various tissues; they also produce IL-13, which induces mucus production and contributes to tissue repair or fibrosis. The ILC2s are activated by alarmins, such as IL-33 released from epithelia, macrophages and natural killer T (NKT) cells in response to infection and allergen exposure, leading to epithelial injury. We examined gene expression in lung ILC2s and found that ILC2s expressed Ifngr1, the receptor for interferon-γ (IFN-γ). Interferon-γ severely inhibited IL-5 and IL-13 production by lung and kidney ILC2s. To evaluate the effects in vivo, we used α-galactosylceramide (α-GalCer) to induce NKT cells to produce IL-33 and IFN-γ. Intraperitoneal injection of α-GalCer in mice induced NKT cell activation resulting in IL-5 and IL-13 production by ILC2s. Administration of anti-IFN-γ together with α-GalCer significantly enhanced the production of IL-5 and IL-13 by ILC2s in lung and kidney. Conversely, cytokine production from ILC2s was markedly suppressed after injection of exogenous IL-33 in Il33(-/-) mice pre-treated with α-GalCer. Hence, IFN-γ induced or already present in tissues can impact downstream pleiotropic functions mediated by ILC2s, such as inflammation and tissue repair.

Pathological activation of canonical nuclear-factor κB by synergy of tumor necrosis factor α and TNF-like weak inducer of apoptosis in mouse acute colitis.

Tumor necrosis factor (TNF)-α is a major effector in various inflammatory conditions. TNF-like weak inducer of apoptosis (TWEAK) is a member of the TNF superfamily that promotes inflammatory tissue damage through its receptor, FGF-inducible molecule 14 (Fn14). Since both TWEAK and TNF-α have been shown to mediate pathological responses through inter-dependent or independent pathways by in vitro, the potential interplay of these pathways was investigated in a mouse colitis model. Acute colitis was induced by rectal injection of trinitrobenzene sulfonic acid (TNBS), with administration of control IgG, TNF receptor (TNFR)-Ig chimeric protein, anti-TWEAK monoclonal antibody, or the combination of TNFR-Ig and anti-TWEAK antibody. On day 4, disease severity was evaluated and gene expression profiling was analyzed using whole colon tissue. NF-κB activation was investigated with Western blot. Levels of transcript of TWEAK, Fn14 and NF-κB-related molecules were measured in purified colon epithelial cells (ECs). As a result, activation of the canonical (p50/RelA), but not noncanonical (p100/RelB)-mediated pathway was the hallmark of inflammatory responses in this model. Inflammation induced upregulation of Fn14 only in ECs but not in other cell types. Combination treatment of TNFR-Ig and anti-TWEAK antibody synergistically reduced disease severity in comparison with the control antibody or single agent treatment. Gene expression profile of the colon indicated downregulation of canonical NF-κB pathway with combination treatment. In conclusion, synergistic activation of canonical NF-κB by TWEAK and TNF-α is critical for the induction of inflammatory tissue damage in acute inflammation.

Colonic epithelial cells express specific ligands for mucosal macrophage immunosuppressive receptors siglec-7 and -9.

Immune cells are known to express specific recognition molecules for cell surface glycans. However, mechanisms involved in glycan-mediated cell-cell interactions in mucosal immunity have largely been left unaccounted for. We found that several glycans preferentially expressed in nonmalignant colonic epithelial cells serve as ligands for sialic acid-binding Ig-like lectins (siglecs), the immunosuppressive carbohydrate-recognition receptors carried by immune cells. The siglec ligand glycans in normal colonic epithelial cells included disialyl Lewis(a), which was found to have binding activity to both siglec-7 and -9, and sialyl 6-sulfo Lewis(x), which exhibited significant binding to siglec-7. Expression of these siglec-7/-9 ligands was impaired upon carcinogenesis, and they were replaced by cancer-associated glycans sialyl Lewis(a) and sialyl Lewis(x), which have no siglec ligand activity. When we characterized immune cells expressing siglecs in colonic lamina propriae by flow cytometry and confocal microscopy, the majority of colonic stromal immune cells expressing siglec-7/-9 turned out to be resident macrophages characterized by low expression of CD14/CD89 and high expression of CD68/CD163. A minor subpopulation of CD8(+) T lymphocytes also expressed siglec-7/-9. Siglec-7/-9 ligation suppressed LPS-induced cyclooxygenase-2 expression and PGE(2) production by macrophages. These results suggest that normal glycans of epithelial cells exert a suppressive effect on cyclooxygenase-2 expression by resident macrophages, thus maintaining immunological homeostasis in colonic mucosal membranes. Our results also imply that loss of immunosuppressive glycans by impaired glycosylation during colonic carcinogenesis enhances inflammatory mediator production.

Sugar and arginine facilitate oral tolerance by ensuring the functionality of tolerogenic immune cell subsets in the intestine.

Although oral tolerance is a critical system in regulating allergic disorders, the mechanisms by which dietary factors regulate the induction and maintenance of oral tolerance remain unclear. To address this, we explored the differentiation and function of various immune cells in the intestinal immune system under fasting and ad libitum-fed conditions before oral ovalbumin (OVA) administration. Fasting mitigated OVA-specific Treg expansion, which is essential for oral tolerance induction. This abnormality mainly resulted from functional defects in the CX3CR1+ cells responsible for the uptake of luminal OVA and reduction of tolerogenic CD103+ dendritic cells. Eventually, fasting impaired the preventive effect of oral OVA administration on asthma and allergic rhinitis development. Specific food ingredients, namely carbohydrates and arginine, were indispensable for oral tolerance induction by activating glycolysis and mTOR signaling. Overall, prior food intake and nutritional signals are critical for maintaining immune homeostasis by inducing tolerance to ingested food antigens.

Viral protein R of human immunodeficiency virus type-1 induces retrotransposition of long interspersed element-1.

BACKGROUND: Viral protein R (Vpr), a protein of human immunodeficiency virus type-1 (HIV-1) with various biological functions, was shown to be present in the blood of HIV-1-positive patients. However, it remained unclear whether circulating Vpr in patients' blood is biologically active. Here, we examined the activity of blood Vpr using an assay system by which retrotransposition of long interspersed element-1 (L1-RTP) was detected. We also investigated the in vivo effects of recombinant Vpr (rVpr) by administrating it to transgenic mice harboring human L1 as a transgene (hL1-Tg mice). Based on our data, we discuss the involvement of blood Vpr in the clinical symptoms of acquired immunodeficiency syndrome (AIDS). RESULTS: We first discovered that rVpr was active in induction of L1-RTP. Biochemical analyses revealed that rVpr-induced L1-RTP depended on the aryl hydrocarbon receptor, mitogen-activated protein kinases, and CCAAT/enhancer-binding protein ß. By using a sensitive L1-RTP assay system, we showed that 6 of the 15 blood samples from HIV-1 patients examined were positive for induction of L1-RTP. Of note, the L1-RTP-inducing activity was blocked by a monoclonal antibody specific for Vpr. Moreover, L1-RTP was reproducibly induced in various organs, including the kidney, when rVpr was administered to hL1-Tg mice. CONCLUSIONS: Blood Vpr is biologically active, suggesting that its monitoring is worthwhile for clarification of the roles of Vpr in the pathogenesis of AIDS. This is the first report to demonstrate a soluble factor in patients' blood active for L1-RTP activity, and implies the involvement of L1-RTP in the development of human diseases.

Kallikrein-related peptidase 13 expression and clinicopathological features in lung squamous cell carcinoma.

Lung squamous cell carcinoma (LSCC) is associated with poor prognosis. Molecular targeting drugs have been demonstrated to be effective for lung adenocarcinoma; however, they are often not effective for LSCC. Kallikrein-related peptidase 13 (KLK13) expression enhances the malignancy of lung adenocarcinoma; however, its expression and crucial role in LSCC remain largely unknown. The present study examined the relationship between the KLK13 expression and clinicopathological features of LSCC. A total of 94 patients diagnosed with LSCC who underwent lobectomy, segmentectomy or wedge resection were selected. KLK13 expression was evaluated through immunostaining of formalin-fixed paraffin-embedded sections of surgical specimens. Of the 94 LSCC samples, 70 exhibited no KLK13 expression, while the remaining 24 exhibited ectopic expression. KLK13 expression in tumors was focal and restricted to the cytoplasm of keratinized cells. LSCC cases were classified into KLK13-negative and KLK13-positive groups, and KLK13 expression was positively associated with E-cadherin expression (P=0.0143). Associations between KLK13 expression and keratinization (P=0.0052) or absence of lymphatic vessel invasion (P=0.0603) were observed; however, these trends did not reach statistical significance. The present findings indicated that KLK13 expression in keratinized LSCC may have a protective role in lymphatic vessel invasion of LSCC, which suggests its significance for therapeutic applications against LSCC.

The epithelia-specific membrane trafficking factor AP-1B controls gut immune homeostasis in mice.

BACKGROUND & AIMS: Epithelial cells that cover the intestinal mucosal surface maintain immune homeostasis and tolerance in the gastrointestinal tract. However, little is known about the molecular mechanisms that regulate epithelial immune functions. Epithelial cells are distinct in that they are highly polarized; this polarity is, at least in part, established by the epithelium-specific polarized sorting factor adaptor protein (AP)-1B. We investigated the role of AP-1B-mediated protein sorting in the maintenance of gastrointestinal immune homeostasis. METHODS: The role of AP-1B in intestinal immunity was examined in AP-1B-deficient mice (Ap1m2(-/-)) by monitoring their phenotypes, intestinal morphology, and epithelial barrier functions. AP-1B-mediated protein sorting was examined in polarized epithelial cells from AP-1B knockdown and Ap1m2(-/-) mice. RESULTS: Ap1m2(-/-) mice developed spontaneous chronic colitis, characterized by accumulation of interleukin-17A-producing, T-helper 17 cells. Deficiency of AP-1B caused epithelial immune dysfunction, such as reduced expression of antimicrobial proteins and impaired secretion of immunoglobulin A. These defects promoted intestinal dysbiosis and increased bacterial translocation within the mucosa. Importantly, AP-1B deficiency led to mistargeting of a subset of basolateral cytokine receptors to the apical plasma membrane in a polarized epithelial cell line and in colonic epithelial cells from mice. AP1M2 expression was reduced significantly in colonic epithelium samples from patients with Crohn's disease. CONCLUSIONS: AP-1B is required for proper localization of a subset of cytokine receptors in polarized epithelial cells, which allows them to respond to cytokine signals from underlying lamina propria cells. The AP-1B-mediated protein sorting machinery is required for maintenance of immune homeostasis and prevention of excessive inflammation.