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Inhibition of dipeptidyl peptidase IV (DPP-IV) activity by NVP-DPP728, a DPP-IV inhibitor, improves the therapeutic efficacy of glucagon-like peptide-1 (GLP-1). CD26 is a membrane-associated glycoprotein with DPP-IV activity and is expressed on lymphocytes. We investigated the effect of NVP-DPP728 on reversing new-onset diabetes in nonobese diabetic (NOD) mice and modulating the inflammatory response and stimulating beta-cell regeneration. New-onset diabetic NOD mice were treated with NVP-DPP728 for 2, 4, and 6 wk. Blood glucose level was monitored. Regulatory T cells in thymus and secondary lymph nodes, TGF-beta1 and GLP-1 in plasma, and the insulin content in the pancreas were measured. Immunostaining for insulin and bromodeoxyuridine (BrdU) were performed. The correlation of beta-cell replication with inflammation was determined. In NVP-DPP728-treated NOD mice, diabetes could be reversed in 57, 74, and 73% of mice after 2, 4, and 6 wk treatment, respectively. Insulitis was reduced and the percentage of CD4(+)CD25(+)FoxP3(+) regulatory T cells was increased in treated NOD mice with remission. Plasma TGF-beta1 and GLP-1, the insulin content, and both insulin(+) and BrdU(+) beta-cells in pancreas were also significantly increased. No significant correlations were found between numbers of both insulin(+) and BrdU(+) beta-cells in islets and beta-cell area or islets with different insulitis score in NOD mice with remission of diabetes. In conclusion, NVP-DPP728 treatment can reverse new-onset diabetes in NOD mice by reducing insulitis, increasing CD4(+)CD25(+)FoxP3(+) regulatory T cells, and stimulating beta-cell replication. beta-Cell replication is not associated with the degree of inflammation in NVP-DPP728-treated NOD mice.

Sexual minorities have a higher prevalence of sleep deprivation as compared with their straight counterparts. Sleep deprivation varies by sexual identity and gender. Very short sleep duration is associated with some chronic health conditions among LGBT populations. Promotion of sleep health education and routine medical assessment of sleep disorders are critically needed for sexual minority adults.

BACKGROUND AND OBJECTIVE: Flavored electronic cigarettes (e-cigarettes) are not prohibited in the United States, and e-cigarette flavors proliferate on the market. This study sought to examine flavored e-cigarette use and its association with smoking among youth.

The immune privilege (IP) of hair follicles (HFs) has been well established in previous studies. However, whether cultured HF cells still exhibit IP properties, the individual factors involved in this process, and the detailed mechanisms that drive and maintain IP, are largely unidentified. We found preferential expression of IP-associated genes in cultured HF dermal papilla and dermal sheath cup cells (DSCCs) compared with non-follicular fibroblasts (FBs) at passage 4, suggesting a potential for functional IP. Notably, programmed cell death 1 ligand 1 (PD-L1) was significantly upregulated in DSCCs and dermal papilla cells relative to FBs. IFNγ secretion from peripheral blood mononuclear cells (PBMCs) co-cultured with histoincompatible DSCCs was significantly lower than with FB and higher percentages of early apoptotic, Annexin V+ cells were observed in PBMC co-cultured with DSCCs. Knockdown of PD-L1 translation by silencing interfering RNA in DSCCs enabled increased IFNγ secretion by PBMCs, whereas transfection of pCMV6-XL4/hPD-L1 in FB significantly reduced IFNγ secretion and increased apoptosis in co-cultured PBMCs. We also found that apoptosis in allogeneic T cells induced by DSCCs was largely dependent on the mitochondrial pathway. Our study suggests IP properties are exhibited in cultured DSCCs in part through expression of negative co-signaling molecule PD-L1.

B7-H4 is a newly identified B7 homolog that plays an important role in maintaining T-cell homeostasis by inhibiting T-cell proliferation and lymphokine-secretion. In this study, we investigated the signal transduction pathways inhibited by B7-H4 engagement in mouse T cells. We found that treatment of CD3+ T cells with a B7-H4.Ig fusion protein inhibits anti-CD3 elicited T-cell receptor (TCR)/CD28 signaling events, including phosphorylation of the MAP kinases, ERK, p38, and JNK. B7-H4.Ig treatment also inhibited the phosphorylation of AKT kinase and impaired its kinase activity as assessed by the phosphorylation of its endogenous substrate GSK-3. Expression of IL-2 is also reduced by B7-H4. In contrast, the phosphorylation state of the TCR proximal tyrosine kinases ZAP70 and lymphocyte-specific protein tyrosine kinase (LCK) are not affected by B7-H4 ligation. These results indicate that B7-H4 inhibits T-cell proliferation and IL-2 production through interfering with activation of ERK, JNK, and AKT, but not of ZAP70 or LCK.

Local expression of B7-H4 prolongs islet allograft survival in vivo, suggesting translational potential for beta-cell replacement with reduced immune injury.

OBJECTIVEAutoimmune diabetes is a T cell–mediated disease in which insulin-producing β-cells are destroyed. Autoreactive T cells play a central role in mediating β-cell destruction. B7-H4 is a negative cosignaling molecule that downregulates T-cell responses. In this study, we aim to determine the role of B7-H4 on regulation of β-cell–specific autoimmune responses.RESEARCH DESIGN AND METHODSPrediabetic (aged 3 weeks) female NOD mice (group 1, n = 21) were treated with intraperitoneal injections of B7-H4.Ig at 7.5 mg/kg, with the same amount of mouse IgG (group 2, n = 24), or with no protein injections (group 3, n = 24), every 3 days for 12 weeks.RESULTSB7-H4.Ig reduced the incidence of autoimmune diabetes, compared with the control groups (diabetic mice 28.6% of group 1, 66.7% of group 2 [P = 0.0081], and 70.8% of group 3 [group 1 vs. 3, P = 0.0035]). Histological analysis revealed that B7-H4 treatment did not block islet infiltration but rather suppressed further infiltrates after 9 weeks of treatment (group 1 vs. 2, P = 0.0003). B7-H4 treatment also reduced T-cell proliferation in response to GAD65 stimulation ex vivo. The reduction of diabetes is not due to inhibition of activated T cells in the periphery but rather to a transient increase of Foxp3+ CD4+ T-cell population at one week posttreatment (12.88 ± 1.29 vs. 11.58 ± 1.46%; n = 8; P = 0.03).CONCLUSIONSOur data demonstrate the protective role of B7-H4 in the development of autoimmune diabetes, suggesting a potential means of preventing type 1 diabetes by targeting the B7-H4 pathway.