Mayuko Yamamoto

Essential Roles of IL-6 Trans-Signaling in Colonic Epithelial Cells, Induced by the IL-6/Soluble–IL-6 Receptor Derived from Lamina Propria Macrophages, on the Development of Colitis-Associated Premalignant Cancer in a Murine Model

Activation of the IL-6/Stat3 via IL-6 trans-signaling plays an important role in the pathogenesis of inflammatory bowel disease. Colitis-associated cancer (CAC) is a large bowel cancer and occurs with long-standing inflammatory bowel disease. The role of the IL-6/Stat3 in the development of CAC has not been fully understood. We investigate whether IL-6 trans-signaling contributes to the development of CAC using a mouse colitis-associated premalignant cancer (CApC) model. Chronic colitis (CC) was induced in BALB/c mice using dextran sodium sulfate. CApC was induced by dextran sodium sulfate treatment to CC-affected mice. IL-6 expression was determined by quantitative RT-PCR and immunofluorescence staining in colon. Phospho-Stat3 expression was examined by Western blotting and immunofluorescence analysis. The expression of IL-6 receptors (i.e., the IL-6R α-chain and gp130) and tumor necrosis factor-α converting enzyme in the colon was examined by laser-capture microdissection and immunofluorescence staining. Soluble IL-6Rα (sIL-6Rα) was examined by Western blotting of epithelial cell-depleted colonic tissues. We also investigated whether a soluble gp130-Fc fusion protein could prevent CApC. IL-6 expression was increased in the colon of CC- and CApC-affected mice and was restricted to lamina propria-macrophages. The expression of IL-6Rα and tumor necrosis factor-α converting enzyme was increased in the lamina propria CD11b-macrophages of CC-affected mice. sIL-6Rα expression was also increased in these tissues. Reduced levels of IL-6Rα generation were observed in the colonic epithelial cells of CC- and CApC-affected mice and were associated with the increased expression of gp130 and phospho-Stat3. Treatment with soluble gp130Fc significantly reduced the CApC. IL-6 trans-signaling in epithelial cells induced by macrophage-derived IL-6/sIL-6Rα plays a crucial role in the development of CAC.

The Production of IL-10 by Human Regulatory T Cells Is Enhanced by IL-2 through a STAT5-Responsive Intronic Enhancer in the IL-10 Locus

STAT5 molecules are key components of the IL-2 signaling pathway, the deficiency of which often results in autoimmune pathology due to a reduced number of CD4+CD25+ naturally occurring regulatory T (Treg) cells. One of the consequences of the IL-2-STAT5 signaling axis is up-regulation of FOXP3, a master control gene for naturally occurring Treg cells. However, the roles of STAT5 in other Treg subsets have not yet been elucidated. We recently demonstrated that IL-2 enhanced IL-10 production through STAT5 activation. This occurred in two types of human Treg cells: a novel type of umbilical cord blood-derived Treg cell, termed HOZOT, and Tr1-like Treg cells, IL-10-Treg. In this study, we examined the regulatory mechanisms of IL-10 production in these Treg cells, focusing specifically on the roles of STAT5. By performing bioinformatic analysis on the IL-10 locus, we identified one STAT-responsive element within intron 4, designated I-SRE-4, as an interspecies-conserved sequence. We found that I-SRE-4 acted as an enhancer element, and clustered CpGs around the I-SRE-4 were hypomethylated in IL-10-producing Treg cells, but not in other T cells. A gel-shift analysis using a nuclear extract from IL-2-stimulated HOZOT confirmed that CpG DNA methylation around I-SRE-4 reduced STAT5 binding to the element. Chromatin immunoprecipitation analysis revealed the in situ binding of IL-2-activated STAT5 to I-SRE-4. Thus, we provide molecular evidence for the involvement of an IL-2-STAT5 signaling axis in the expression of IL-10 by human Treg cells, an axis that is regulated by the intronic enhancer, I-SRE-4, and epigenetic modification of this element.

A component of polysaccharide peptidoglycan complex on Lactobacillus induced an improvement of murine model of inflammatory bowel disease and colitis-associated cancer

Interleukin‐6 (IL‐6)/signal transducer and activator of transcription 3 (STAT3) signals play key roles in the pathogenesis of inflammatory bowel disease (IBD). We previously described that both intact cells and a cell wall‐derived polysaccharide–peptidoglycan complex (PSPG) in a strain of lactobacillus [Lactobacillus casei Shirota (LcS)] inhibited IL‐6 production in lipopolysaccharide (LPS)‐stimulated lamina propria mononuclear cells (LPMCs) isolated from murine IBD. Diets with LcS improve murine IBD by suppression of IL‐6 synthesis in LPMCs. Moreover, LcS supplementation with fermented milk ameliorates disease activity in patients with active ulcerative colitis. Here, we focused on the specific roles of PSPG in LcS concerning their anti‐inflammatory actions. PSPG derived from LcS, and no other strain of lactobacilli, inhibited IL‐6 production in LPS‐stimulated murine IBD LPMCs. Purified PSPG‐I from LcS inhibited IL‐6 synthesis in LPS‐stimulated murine IBD LPMCs through the inhibition of nuclear factor‐κB. The anti‐IL‐6 action of LcS PSPG was abrogated by masking with monoclonal anti‐PSPG‐I. Furthermore, PSPG‐I‐negative L. casei strains (PSPG‐I‐negative mutant LcS: LCΔPSPG‐I, L. casei ATCC 334) did not inhibit IL‐6 production. Finally, we confirmed the effects of PSPG‐I on LcS in the models of both IBD and colitis‐associated cancer (CAC). In the IBD model, ingestion of LcS improved ileitis and inhibited activation of IL‐6/STAT3 signaling, while ingestion of the LCΔPSPG‐I strain did not. In the CAC model, treatment with LcS, but not the LCΔPSPG‐I strain, showed tumour‐suppressive effects with an inhibition of IL‐6 production in the colonic mucosa. These results suggested that a specific polysaccharide component in an L. casei strain plays a crucial role in its anti‐inflammatory actions in chronic intestinal inflammatory disorders.

Psoriatic Inflammation Facilitates the Onset of Arthritis in a Mouse Model

Psoriatic arthritis (PsA) is a seronegative, inflammatory joint disease associated with psoriasis. In most patients with PsA, skin lesions precede arthritis; however, the causality of skin inflammation for the development of arthritis remains unclear. Gp130F759/F759 knock-in (F759) mice develop autoimmune arthritis after 1 year of age through persistent signal transducer and activator of transcription 3 (Stat3) activation due to impairment in SOCS3-dependent negative regulation. Here, we crossed F759 mice with K5.Stat3C transgenic mice, in which keratinocytes express constitutive active Stat3 (Stat3C), leading to generation of psoriasis-like skin change. F759 mice harboring the K5.Stat3C transgene not only had aggravated skin lesions but also spontaneously developed arthritis with high penetrance in adjacent paws as early as 3 weeks of age. The joint lesions included swelling of the peripheral paws and nail deformities contiguous with the skin lesions, closely resembling PsA. Histopathologic study revealed enthesitis and bone erosions, with mononuclear cell infiltrates. Quantitative reverse transcriptase-PCR (RT-PCR), immunohistochemical analyses, and flow cytometry showed upregulation of the IL-23/T helper type 17 (Th17) pathway in affected joints. Furthermore, enforced generation of psoriasis-like skin inflammation by topical treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) in F759 mice induced swelling of the underlying joints. This animal model renders psoriatic inflammation as the driver of arthritis and helps to further understand the pathogenesis of PsA.

Gut microbiota and colorectal cancer

The mucosal immune system is unique to the gastrointestinal mucosa, in which a large number of immune cells are located and exert multiple functions. Meanwhile, ~100 trillion microorganisms are thought to co-inhabit in the gastrointestinal tract. Furthermore, immune cells and gut microbiota have a mutual influence and the maintenance of this symbiotic relationship results in gut homeostasis. A recent study suggested that a disturbance of gut microbiota—so called “dysbiosis”—is related to various diseases, such as inflammatory bowel disease (IBD) and colitis-associated cancer (CAC). In this review, we discuss the relationship between gut microbiota and the mucosal immune system with regard to the development of IBD and CAC. In addition, we elucidate the possibility of probiotics in treatment against these diseases.

Cathepsin K Is Involved in Development of Psoriasis-like Skin Lesions through TLR-Dependent Th17 Activation

Cathepsins (CTSs) are lysosomal cysteine proteases that play an important role in the turnover of intracellular proteins and extracellular proteins, such as the degradation of extracellular matrices and the processing of antigenic proteins. A CTS inhibitor, NC-2300, not only suppresses bone erosion by inhibition of cathepsin K (CTSK), but also ameliorates paw swelling at inflamed joints in adjuvant-induced arthritis in rats. It has been demonstrated that the amelioration of joint inflammation by NC-2300 is mediated by the downregulation of cytokine expression in dendritic cells, which are essential for Th17 activation. In this work, we studied the role for CTSs in the pathogenesis of psoriasis-like lesion in K5.Stat3C mice, a mouse model of psoriasis, in which Th17 contributes to lesion development similar to psoriasis. Psoriatic lesions expressed increased levels of Ctsk and Ctss mRNA compared with uninvolved skin and normal control skin. Similarly, the epidermis and dermis in K5.Stat3C mice demonstrated increased CTSK activities, which were sensitive to NC-2300. Topical treatment with NC-2300 significantly ameliorated 12-O-tetradecanoylphorbol-13-acetate–induced psoriasis-like lesions in K5.Stat3C mice, and downregulated the expression of IL-12, IL-23, and Th17 cytokines. In vitro experiments revealed that TLR7 activation of bone marrow–derived myeloid dendritic cells led to increase in IL-23 at mRNA and protein levels, which were downregulated by NC-2300. These results suggest that CTSK plays a role in development of psoriatic lesions through TLR7-dependent Th17 polarization.

Epidermal triglyceride levels are correlated with severity of ichthyosis in Dorfman–Chanarin syndrome

BACKGROUND Dorfman-Chanarin syndrome (DCS), also referred to as neutral lipid storage disease with ichthyosis, is a rare autosomal recessive form of nonbullous congenital ichthyosiform erythroderma, characterized by the presence of intracellular lipid droplets in multiorgans. DCS patients often have mutations in CGI-58, which is an activator of adipose triglyceride lipase (ATGL), leading to accumulation of triglycerides (TG). OBJECTIVE To study whether a patient with DCS demonstrates TG accumulation in the epidermis and to analyze whether TG levels are correlated with skin disease activity. METHODS Skin specimen from a 62-year-old man with DCS was stained with oil red O, and analyzed on electromicrographs. Sequencing analysis of CGI-58 was performed using the patients blood cells. The scales from the lesion were subject to lipid analysis by high-performance thin-layer chromatography (HPTLC). RESULTS The patient demonstrated ichthyoform erythroderma with a distinct seasonal fluctuation: his skin lesions were aggravated in summer but resolved during winter. Epidermis of the lesion showed intracellular lipid droplets. Sequencing analysis revealed a novel missense mutation in the exon 3 of CGI-58 gene. Lipid analysis of the scales from his lesions, compared with those from normal human control, revealed increased levels of triglycerides (TG) but, in turn, decreased levels of free fatty acids, suggesting dysfunction of adipose TG lipase. Notably, the TG levels in the scales from the patient were positively correlated with the severity of ichthyosis. CONCLUSION These results suggest that TG accumulation by epidermal keratinocytes directly contributes to ichthyosiform phenotype of DCS.

Novel mechanisms of suppressor activity exhibited by cytotoxic regulatory T cell lines, HOZOT

OBJECTIVE Regulatory T (Treg) cells, which play a central role in maintaining immune tolerance, can be grouped into different subtypes, such as naturally occurring Treg, type-1 T regulatory, and Th3. The suppressor activities of Treg cells are mediated through several molecular mechanisms, including immunosuppressive cytokines, cell surface molecules, and cytolytic molecules. In a previous report, we described a novel regulatory human T-cell line (termed HOZOT). The line was established by cocultivating human umbilical cord blood cells with mouse stromal cells in the absence of exogenous cytokines. In this study, we investigated the mechanism of HOZOTs suppressor activity. MATERIALS AND METHODS Suppressor activity of HOZOT was evaluated in vitro by assessing their inhibition of allogeneic mixed lymphocyte reaction, in which CD4+CD25(-) responder T cells were stimulated by dendritic cells (DCs). Responder T cells as well as DCs were prepared from umbilical cord blood using magnetic-activated cell sorting separation system. DNA microarray analysis was performed to search for specific molecules involved in HOZOTs suppressor mechanisms. RESULTS We confirmed that suppressing effects were observed in all three subpopulations of CD4/CD8 phenotype. We ruled out possible involvement of HOZOTs cytotoxic activity as well as participation of surface molecules, including cytotoxic T-lymphocyte-associated protein-4, programmed death-1, and glucocorticoid-inducible tumor necrosis factor receptor in suppressor. The supernatant obtained from HOZOT and DC coculture revealed mixed lymphocyte reaction inhibitory activity, indicating the presence of a soluble factor, which mediates suppressor function. Blocking experiments demonstrated that interleukin-10 and transforming growth factor-beta were not responsible factors. CONCLUSIONS HOZOT exerted suppressor activity in the absence of cell contact mechanisms, which are distinct from those of naturally occurring Treg, type-1 T regulatory, and Th3.

Transition of psoriasiform drug eruption to psoriasis de novo evidenced by histopathology

Drug reaction can be one of the triggering factors either for exacerbation of pre‐existing psoriasis or precipitation of psoriasis de novo. Herein, we report a case with psoriasiform drug eruption due to pravastatin, but it relapsed after discontinuance of the drug. Serial investigation of the histopathology and immunohistochemistry with anti‐signal transducer and activator of transcription 3 (STAT3) revealed drug reaction‐associated lesions intermingled with psoriasiform changes, which later predominated, suggesting a conversion into psoriasis de novo.

Interleukin-8 and RANTES are signature cytokines made by HOZOT, a new type of regulatory T cells

Distinct cytokine production profiles define the effector functions of both helper and regulatory T cells. Recently, we established novel cytotoxic regulatory T (Treg) cell lines, HOZOT, which have been characterized as IL-10-producing T cells. In this study, we further characterized HOZOT by performing comprehensive analyses of cytokines produced by HOZOTs in order to identify a signature cytokine profile. Using DNA microarrays, we compared the gene expression profiles of HOZOT-4, a representative HOZOT cell line, under three different conditions. Seven genes, including IL-8, IL-10, IL-13, MIP-1alpha, and MIP-1beta, were identified as inducible cytokines when stimulated with stromal cells or anti-CD3/CD28 antibodies. Twelve genes, including IL-2, IL-3, IL-4, IL-22, CCL1, and lymphotactin, were categorized as antibody stimulation-responsive but stromal cell-non-responsive. Three genes, IL-32, RANTES, and CCL23, were constitutively expressed irrespective of stimulation condition. Among these cytokines, we focused on two chemokines, IL-8 and RANTES for further studies, and found that only HOZOT produced both of them at considerable levels whereas other T cell subsets, including Tregs and helper T cells, did not. Kinetic and inhibition experiments revealed contrasting properties for the two chemokines. IL-8 was induced only after stimulation, whereas RANTES mRNA and protein accumulated to high levels even before stimulation. Interestingly, IL-8 mRNA was induced by cycloheximide treatment and RANTES showed reduced mRNA but increased protein expression by antibody stimulation. As a whole, the unique cytokine signature profile consisting of Th1, Th2, and cytolytic T cell cytokines as well as Treg cytokines reflect the multifunctional nature of HOZOT. In particular, the dual production of IL-8 and RANTES by distinct mechanisms is a hallmark of HOZOT.