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.

Background & Aim: Prolonged inflammatory bowel diseases (IBD) such as ulcerative colitis and Crohn's disease may promote carcinogenesis in the epithelia. It has been reported that activation of NF-κB pathway in both intestinal epithelial cells and myeloid cells are significant for the development of colitis-associated cancer (CAC). We previously reported that specific up-regulation of the type 2 receptor for tumor necrosis factor (TNFR2) rather than TNFR1 expression was observed in the inflamed colonic epithelia and further in the CAC. It is known that TNFR2 signaling may induce NF-κB activation, but the role of its expression in the setting of CAC has not been elucidated. Here we analyzed TNFR2 signaling in the colonic epithelial cells. Methods & Results: As previously observed in animal models of colitis and CAC, the expression of TNFR2 was up-regulated in an epithelial cell line, MOC1, which was derived from murine colonic ‘non-cancer' tissue, when stimulated with recombinant (r) IFN-γ. MOC1 cells incubated with both rIFN-γ and rTNF showed that NFκB pathway was activated rather than apoptosis pathway. Furthermore, the activated NFκB in MOC1 cells was associated with the expression of myosin light chain kinase (MLCK) as well as disrupted tight junction (TJ) in a rTNF dose-dependent manner. Such MLCK upregulation and TJ disruption in MOC1 cells were abrogated by either anti-TNF mAb (MP6XT22), TNFR2-specific siRNA or even MLCK inhibitor (ML-7). Using an animal model of CAC involving azoxymethane (AOM) and dextran sodium sulfate (DSS), the colonic lamina propria was found to have pro-tumorigenic cytokine production such as IL-1β, IL-6 and MIP-2 in association with epithelial NF-κB activation, TNFR2 and MLCK up-regulations and epithelial TJ disruption. AOM and DSS-administered mice with either MP6-XT22 or ML7 treatment failed to show significant abrogation of colitis severity, however such treatments revealed the restored epithelial TJ and decreased pro-tumorigenic cytokine production in the colonic tissues in association with the reduced CAC development. Conclusions: Our studies showed that epithelial NF-κB activation via TNFR2 signaling in the context of IBD may be involved in the epithelial permeabilization and pro-tumorigenic cytokine production that result in the induction of CAC development.

It has been suggested that prolonged inflammatory bowel diseases (IBD) may lead to colitis-associated carcinogenesis (CAC). We previously observed that the NF-κB activation in colonic epithelial cells is associated with increased tumor necrosis factor receptor 2 (TNFR2) expression in CAC development. However, the mechanism by which epithelial NF-κB activation leading to CAC is still unclear. Myosin light chain kinase (MLCK) has been reported to be responsible for the epithelial permeability associated with TNF signaling. Therefore we focused on the role of MLCK expression via TNFR2 signaling on CAC development. Pro-tumorigenic cytokines such as IL-1β, IL-6 and MIP-2 production as well as INF-γ and TNF production at the lamina propria were increased in the setting of colitis, and further in tumor tissues in associations with up-regulated TNFR2 and MLCK expressions in the epithelial cells of a CAC model. The up-regulated MLCK expression was observed in TNF-stimulated colonic epithelial cells in a dose-dependent fashion in association with up-regulation of TNFR2. Silencing TNFR2, but not TNFR1, resulted in restoration of epithelial tight junction (TJ) associated with decreased MLCK expression. Antibody-mediated blockade of TNF signaling also resulted in restoration of TJ in association with suppressed MLCK expression, and interestingly, similar results were observed with suppressing TNFR2 and MLCK expressions by inhibiting MLCK in the epithelial cells. Silencing of MLCK also resulted in suppressed TNFR2, but not TNFR1, expression, suggesting that the restored TJ leads to reduced TNFR2 signaling. Such suppression of MLCK as well as blockade of TNFR2 signaling resulted in restored TJ, decreased pro-tumorigenic cytokines and reduced CAC development. These results suggest that MLCK may be a potential target for the prevention of IBD-associated tumor development.

We previously reported that IL-7(-/-)RAG(-/-) mice receiving naive T cells failed to induce colitis. Such abrogation of colitis may be associated with not only incomplete T cell maintenance due to the lack of IL-7, but also with the induction of colitogenic CD4(+) T cell apoptosis at an early stage of colitis development. Moreover, NK cells may be associated with the suppression of pathogenic T cells in vivo, and they may induce apoptosis of CD4(+) T cells. To further investigate these roles of NK cells, RAG(-/-) and IL-7(-/-)RAG(-/-) mice that had received naive T cells were depleted of NK cells using anti-asialo GM1 and anti-NK1.1 Abs. NK cell depletion at an early stage, but not at a later stage during colitogenic effector memory T cell (T(EM)) development, resulted in exacerbated colitis in recipient mice even in the absence of IL-7. Increased CD44(+)CD62L(-) T(EM) and unique CD44(-)CD62L(-) T cell subsets were observed in the T cell-reconstituted RAG(-/-) recipients when NK cells were depleted, although Fas, DR5, and IL-7R expressions in this subset differed from those in the CD44(+)CD62L(-) T(EM) subset. NK cell characteristics were the same in the presence or absence of IL-7 in vitro and in vivo. These results suggest that NK cells suppress colitis severity in T cell-reconstituted RAG(-/-) and IL-7(-/-)RAG(-/-) recipient mice through targeting of colitogenic CD4(+)CD44(+)CD62L(-) T(EM) and, possibly, of the newly observed CD4(+)CD44(-)CD62L(-) subset present at the early stage of T cell development.

[Background and Aim] Natural killer (NK) cells are associated with regulation of acquired immune responses related to inflammatory diseases such as experimental autoimmune encephalomyelitis and colitis. However, the detail mechanism of NK cell-regulation of pathogenic T cell in inflammation remains unclear. We therefore examine the role of NK cells in a murine model of chronic colitis. [Methods and Results] Anti-asialo GM1 (ASGM1) Ab was injected into RAG deficient (RAG-/-) mice in order to deplete NK cells, followed by adoptive transfer of CD62L+ CD44(naive) T cells. The NK cell depletion interestingly resulted in an increase of CD62LCD44T cells in the spleen and the mesenteric lymph nodes 5 days after T cell reconstitution despite slight exacerbation of colitis compared to mice without NK cell depletion. Flow cytometric analysis showed the CD62Land CD44T cell subset to be Qa-1DR5Lo IL-7R+, while the CD62LCD44+ effecter/memory T cells (TEM) expressed Qa-1+ DR5Hi IL-7R+, suggesting that CD62LCD44T cells are regulated by NK cells in a different mechanism from that of TEM by NK cells via apoptosis. Neither the cytotoxic activity nor the surface markers of NK cells, such as NKG2A/C/E, NKG2D, Ly49, CD94, KLRG1, CD11b and CD27, were affected in the presence or absence of IL-7. Our interest in IL-7 stems from our previous report that IL-7 deficiency completely abrogates colitis in RAG-/mice receiving naive T cells. It had been suggested that such abrogation of colitis may be associated with not only the lack of IL-7 but also another mechanism by which the development of colitis is suppressed at the early stage. Therefore, anti-ASGM1 Ab was injected into RAG-/IL-7-/(DKO) mice receiving naive T cells. The NK cell depletion at the early stage during the induction of colitis resulted in severe colitis in the DKO mice with associated increase in the production of proinflammatory cytokines such as IFN-γ. [Conclusions]Our study suggests that the development of TEM, which induces chronic inflammation, through CD62LCD44T cell subset may be affected by both the presence of NK cells and IL-7, and regulating these mechanisms could be a potential therapeutic target for IBD.

BACKGROUND: Mast cells play a key role in the pathophysiology of inflammatory bowel disease (IBD).Tranilast, N-(3,4-dimethoxycinnamoyl) anthranilic acid, a mast cell stabilizer, has been empirically used for IBD in Japan.The mechanism of tranilast in the improvement of IBD, however, has not yet been clearly delineated, and requires further investigation.Recently, heme oxygenase (HO)-1 has attracted attention in the pro-inflammation mechanism of tranilast.Aim: To investigate the role of tranilast for the treatment of IBD, and elucidated the mechanism and involvement of HO-1 in this effect, we administered tranilast intrarectally to dextran sulfate sodium (DSS)-induced colitis in mice.METHODS: Colitis was induced in C57BL/6(B6) mice by adding 3% DSS in drinking water ad libium for 5 days.Tranilast was administered by enema on day 0, day 2, and day 4 after induction of colitis.The disease activity index (DAI) and degree of colon injury were determined to know the clinical course of colitis.Toluidine blue staining was carried out to identify the mast cell.Staining for HO-1 with immunofluorescence to evaluate the expression of HO-1 in the colon.Total RNA was extracted from colon specimens with quantitative reverse transcription-polymerase chain reaction (RT-PCR).RESULTS: Tranilast ameliorated DSS colitis clinically and pathologically with decreased number and degranulation of mast cells in the colon of DSS colitis.mRNA expression was increased for tumor necrosis factor(TNF)-α, interferon(IFN)-γ, interleukin (IL)-6, and decreased that for IL-10 in the colon of DSS colitis.In contrast, tranilast markedly decreased expression of mRNAs for the proinflammatory cytokines, and increased that of the anti-inflammatory cytokines.Moreover, tranilast increased HO-1 expression on colonic epithelial cells as well as on colon infiltrating cells of DSS colitis.CONCLUSION: Tranilast ameliorated DSS colitis by regulating mast cell degranulation, decreasing inflammatory cytokines and increasing anti-inflammatory cytokines.Tranilast might exert these effects partly through enhanced HO-1 expression in the colon, suggesting a potential adjunctive therapy for IBD.

BACKGROUND: Mast cells play a key role in the pathophysiology of inflammatory bowel disease (IBD). Tranilast, N-(3,4-dimethoxycinnamoyl) anthranilic acid, a mast cell stabilizer, has been empirically used for IBD in Japan. The mechanism of tranilast in the improvement of IBD, however, has not yet been clearly delineated, and requires further investigation. Recently, heme oxygenase (HO)-1 has attracted attention in the pro-inflammationmechanism of tranilast. Aim: To investigate the role of tranilast for the treatment of IBD, and elucidated the mechanism and involvement of HO-1 in this effect, we administered tranilast intrarectally to dextran sulfate sodium (DSS)-induced colitis in mice. METHODS: Colitis was induced in C57BL/6(B6) mice by adding 3% DSS in drinking water ad libium for 5 days. Tranilast was administered by enema on day 0, day 2, and day 4 after induction of colitis. The disease activity index (DAI) and degree of colon injury were determined to know the clinical course of colitis. Toluidine blue staining was carried out to identify the mast cell. Staining for HO1 with immunofluorescence to evaluate the expression of HO-1 in the colon. Total RNA was extracted from colon specimens with quantitative reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Tranilast ameliorated DSS colitis clinically and pathologically with decreased number and degranulation of mast cells in the colon of DSS colitis. mRNA expression was increased for tumor necrosis factor(TNF)-α, interferon(IFN)-γ, interleukin (IL)-6, and decreased that for IL-10 in the colon of DSS colitis. In contrast, tranilast markedly decreased expression of mRNAs for the proinflammatory cytokines, and increased that of the anti-inflammatory cytokines. Moreover, tranilast increased HO-1 expression on colonic epithelial cells as well as on colon infiltrating cells of DSS colitis. CONCLUSION: Tranilast ameliorated DSS colitis by regulating mast cell degranulation, decreasing inflammatory cytokines and increasing anti-inflammatory cytokines. Tranilast might exert these effects partly through enhanced HO-1 expression in the colon, suggesting a potential adjunctive therapy for IBD.

In recent times, considerable attention has been paid to the nutritional impact of the sharp hikes in the international food prices which took place in 2007–8 and 2010–11. While understandable, this growing focus has perhaps obscured the impact of other variables affecting malnutrition in Sub-Saharan Africa, i.e. the long-term impact of agricultural policies on food supply and prices, large and persistent seasonal variations in food prices, and the impact of famines which still affect parts of the continent. This paper focuses on the relative impact of these factors on child malnutrition (measured by the number of child admissions to feeding centres) in Malawi and Niger, two countries which closely represent the situation of other small, landlocked, subsistence agricultural economies facing severe food security problems. Our analysis shows that in these countries the drivers of changes in domestic staple prices and child malnutrition are related not only – or not primarily – to variations of international food prices but also to the impact of agricultural policies on food production and prices, in a persistent food price seasonality, and in recurrent and poorly managed famines. These factors can exert a strong upward pressure on food prices and child malnutrition even during years of falling international prices.