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BACKGROUND AND OBJECTIVE While pro-inflammatory monocyte trafficking to the intestine has been partially characterised,the molecules required for migration of tolerogenic mononuclear phagocytes (dendritic cells (DC) and macrophages) are unknown. We hypothesised that the gut-homing receptor integrin α4β7 is required for this process. METHODS We used a T cell-mediated colitis model to study the role of α4β7 in the innate immune compartment. We then performed competitive bone marrow (BM) reconstitution experiments to assess the requirement of α4β7 in the generation of intestinal retinoic acid (RA)-producing CD11c(hi) DC (ALDE(+)DC) and CD64 macrophages. Using mixed BM chimeras we also asked whether α4β7 is required to give rise to tolerogenic mononuclear phagocytes. RESULTS Lack of β7 integrins in the innate immune compartment (β7(-/-)RAG2(-/-) mice) markedly accelerated T cell-mediated colitis,which was correlated with lower numbers and frequencies of ALDE(+)DC in mesenteric lymph nodes. Consistent with a role of α4β7 in the generation of intestinal mononuclear phagocytes,BM cells from β7(-/-) mice poorly reconstituted small intestine ALDE(+)DC and Mφ when compared to their wild type counterparts. In addition,mice lacking β7 integrins in the CD11c(hi) compartment showed decreased ability to induce Foxp3(+) T(REG) and IL-10-producing T cells. CONCLUSIONS Mice lacking β7 integrins in the innate immune compartment are more susceptible to intestinal inflammation,which is correlated with a requirement of β7 integrins to reconstitute gut mononuclear phagocytes with tolerogenic potential. View Publication

The shortage of human organs and tissues for transplant has led to significant interest in xenotransplantation of pig tissues for human patients. However,transplantation of pig organs results in an acute immune rejection,leading to death of the organ within minutes. The $\$-1,3-galactosyltransferase (GALT) gene has been knocked out in pigs to reduce rejection,yet additional genes need to be modified to ultimately make pig tissue immunocompatible with humans. The development of pig induced pluripotent stem cells (piPSCs) from GALT knockout (GALT-KO) tissue would provide an excellent cell source for complex genetic manipulations (e.g.,gene targeting) that often require highly robust and proliferative cells. In this report,we generated GALT-KO piPSCs by the overexpression of POU5F1,SOX2,NANOG,LIN28,KLF-4,and C-MYC reprogramming genes. piPSCs showed classical stem cell morphology and characteristics,expressing integrated reprogramming genes in addition to the pluripotent markers AP,SSEA1,and SSEA4. GALT-KO piPSCs were highly proliferative and possessed doubling times and telomerase activity similar to human embryonic stem cells. These results demonstrated successful reprogramming of GALT-KO fibroblasts into GALT-KO piPSCs. GALT-KO piPSCs are potentially an excellent immortal cell source for the generation of pigs with complex genetic modifications for xenotransplantation,somatic cell nuclear transfer,or chimera formation. View Publication

Substrate composition significantly impacts human pluripotent stem cell (hPSC) self-renewal and differentiation,but relatively little is known about the role of endogenously produced extracellular matrix (ECM) components in regulating hPSC fates. Here we identify $\$-5 laminin as a signature ECM component endogenously synthesized by undifferentiated hPSCs cultured on defined substrates. Inducible shRNA knockdown and Cas9-mediated disruption of the LAMA5 gene dramatically reduced hPSC self-renewal and increased apoptosis without affecting the expression of pluripotency markers. Increased self-renewal and survival was restored to wild-type levels by culturing the LAMA5-deficient cells on exogenous laminin-521. Furthermore,treatment of LAMA5-deficient cells with blebbistatin or a ROCK inhibitor partially restored self-renewal and diminished apoptosis. These results demonstrate that endogenous $\$-5 laminin promotes hPSC self-renewal in an autocrine and paracrine manner. This finding has implications for understanding how stem cells dynamically regulate their microenvironment to promote self-renewal and provides guidance for efforts to design substrates for stem cell bioprocessing. View Publication

BACKGROUND Epidemiological surveys have revealed that low serum vitamin D level was correlated with increased risk of tumors. Dysfunctional T cells in patients with tumor are characterized as exhausted with high levels of immune checkpoint receptors (ICRs). However,whether the reduced level of vitamin D in patients with cancer correlates with cytotoxic T-cell exhaustion is unknown. METHODS Periphery blood samples from 172 patients with non-small cell lung cancer (NSCLC) were prospectively collected. Patients with NSCLC received one course of intravenous docetaxel (75 mg/m2) followed by treatment with or without rocaltrol at a dose of 0.5-2.0 µg/day for total of 3 weeks. We performed phenotypical and functional analysis of T-cell through flow cytometry. Vitamin D receptor (VDR) knockout and overexpression CD8+ and V$\delta$2+ T cells were constructed using Cas9-gRNA targeted and overexpressing approaches to identify 1$\alpha$,25(OH)2D3/VDR-mediated transcription regulation for ICRs or antitumor activity in T cells. RESULTS We show that serum level of vitamin D is negatively correlated with expression of programmed cell death-1 (PD-1),T-cell immunoreceptor with Ig and ITIM domains (TIGIT),and T-cell immunoglobulin and mucin-domain containing-3 (Tim-3),but positively correlated with CD28 expression on CD8+ and V$\gamma$9V$\delta$2+ T cells in patients with NSCLC. 1$\alpha$,25(OH)2D3,the active form of vitamin D,promotes the nuclear translocation of VDR,which binds to the promoter region of Pdcd1,Tim3,and Tigit genes and inhibits their expression. Besides,1$\alpha$,25(OH)2D3 pretreatment also promotes the methylation of CpG island in the promoter region of the Pdcd1 gene and increases H3K27 acetylation at the promoter region of the Cd28 gene,which leads to surface PD-1 downregulation and CD28 upregulation,respectively. We further reveal that VDR-mediated Ca2+ influx enhanced expression of Th1 cytokines via T-cell receptor activation. Functionally,1$\alpha$,25(OH)2D3 pretreated CD8+ T cells or V$\gamma$9V$\delta$2+ T cells showed increased Th1 cytokine production and enhanced antitumor immunity. Finally,oral 1$\alpha$,25(OH)2D3 could also decrease expression of PD-1,Tim-3,TIGIT and increase expression of CD28,resulting in cytokine production (associated with antitumor immunity) by cytotoxic T cells of patients with NSCLC. CONCLUSIONS Our findings uncover the pleiotropic effects of 1$\alpha$,25(OH)2D3 in rescuing the exhausted phenotype of human cytotoxic T cells in patients with tumor and in promoting their antitumor immunity. TRIAL REGISTRATION NUMBER ChiCTR2100051135. View Publication

The active form of vitamin D,1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)),has potent immunomodulatory properties that have promoted its potential use in the prevention and treatment of infectious disease and autoimmune conditions. A variety of immune cells,including macrophages,dendritic cells,and activated T cells express the intracellular vitamin D receptor and are responsive to 1,25(OH)(2)D(3.) Despite this,how 1,25(OH)(2)D(3) regulates adaptive immunity remains unclear and may involve both direct and indirect effects on the proliferation and function of T cells. To further clarify this issue,we have assessed the effects of 1,25(OH)(2)D(3) on human CD4(+)CD25(-) T cells. We observed that stimulation of CD4(+)CD25(-) T cells in the presence of 1,25(OH)(2)D(3) inhibited production of proinflammatory cytokines including IFN- gamma,IL-17,and IL-21 but did not substantially affect T cell division. In contrast to its inhibitory effects on inflammatory cytokines,1,25(OH)(2)D(3) stimulated expression of high levels of CTLA-4 as well as FoxP3,the latter requiring the presence of IL-2. T cells treated with 1,25(OH)(2)D(3) could suppress proliferation of normally responsive T cells,indicating that they possessed characteristics of adaptive regulatory T cells. Our results suggest that 1,25(OH)(2)D(3) and IL-2 have direct synergistic effects on activated T cells,acting as potent anti-inflammatory agents and physiologic inducers of adaptive regulatory T cells. View Publication

Vitamin D has been known to be important for skeletal development and growth but the mechanism whereby it affects these processes is not well understood. We report now that the hormonal metabolite of vitamin D3,namely 1,25-dihydroxyvitamin D3,stimulates chondrogenesis in cultures of stage 24 chick embryo limb bud mesenchymal cells,as evidenced by morphologic changes as well as by increased transcription of collagen type II and core protein genes. This effect appears to be specific to 1,25(OH)2D3 since 24,25(OH)2D3 or D3 does not influence chondrogenesis in this system,and is probably mediated via the specific 1,25(OH)2D3 receptor protein which is undetectable in untreated cells but appears following exposure to the hormone. View Publication