[Abstract unavailable

The inhibitory effects of vitamin D on colitis have been previously documented. Global vitamin D receptor (VDR) deletion exaggerates colitis, but the relative anticolitic contribution of epithelial and nonepithelial VDR signaling is unknown. Here, we showed that colonic epithelial VDR expression was substantially reduced in patients with Crohn's disease or ulcerative colitis. Moreover, targeted expression of human VDR (hVDR) in intestinal epithelial cells (IECs) protected mice from developing colitis. In experimental colitis models induced by 2,4,6-trinitrobenzenesulfonic acid, dextran sulfate sodium, or CD4 + CD45RB hi T cell transfer, transgenic mice expressing hVDR in IECs were highly resistant to colitis, as manifested by marked reductions in clinical colitis scores, colonic histological damage, and colonic inflammation compared with WT mice. Reconstitution of Vdr-deficient IECs with the hVDR transgene completely rescued Vdr-null mice from severe colitis and death, even though the mice still maintained a hyperresponsive Vdr-deficient immune system. Mechanistically, VDR signaling attenuated PUMA induction in IECs by blocking NF-κB activation, leading to a reduction in IEC apoptosis. Together, these results demonstrate that gut epithelial VDR signaling inhibits colitis by protecting the mucosal epithelial barrier, and this anticolitic activity is independent of nonepithelial immune VDR actions.

Background: 1,25(OH) 2 D 3 inhibits NF-B activation by an undefined mechanism. Results: Vitamin D receptor protein binds to IKK␤ protein, blocking TNF␣-induced IKK complex formation and NF-B activity. Conclusion: The vitamin D receptor suppresses NF-B activation by directly interacting with IKK␤.Significance: This is a novel mechanism whereby 1,25(OH) 2 D 3 -VDR inhibits NF-B.

During angiogenesis, microvascular endothelial cells (ECs) secrete proteinases that permit penetration of the vascular basement membrane as well as the interstitial extracellular matrix. This study tested the hypothesis that cathepsin S (Cat S) contributes to angiogenesis. Treatment of cultured ECs with inflammatory cytokines or angiogenic factors stimulated the expression of Cat S, whereas inhibition of Cat S activity reduced microtubule formation by impairing cell invasion. ECs from Cat S-deficient mice showed reduced collagenolytic activity and impaired invasion of collagens type I and IV. Cat S-deficient mice displayed defective microvessel development during wound repair. This abnormal angiogenesis occurred despite normal vascular endothelial growth factor and basic fibroblast growth factor levels, implying an essential role for extracellular matrix degradation by Cat S during microvessel formation. These results demonstrate a novel function of endothelium-derived Cat S in angiogenesis.

Thoracic aortic dissection (TAD) is a catastrophic disease with high mortality and morbidity, characterized by fragmentation of elastin and loss of smooth muscle cells. However, the underlying pathological mechanisms of this disease remain elusive because there are no appropriate animal models, limiting discovery of effective therapeutic strategies. We treated mice on C57BL/6 and FVB genetic backgrounds with β-aminopropionitrile monofumarate (BAPN), an irreversible inhibitor of lysyl oxidase, for 4 wk, followed by angiotensin II (Ang II) infusion for 24 h. We found that the BAPN plus Ang II treatment induced formation of aortic dissections in 100% of mice on both genetic backgrounds. BAPN without Ang II caused dissections in few FVB mice, but caused 87% of C57BL/6 mice to develop TAD, with 37% dying from rupture of the aortic dissection. Moreover, a lower dose of BAPN induced TAD formation and rupture earlier with fewer effects on body weight. Therefore, we have generated a reliable and convenient TAD model in C57BL/6 mice for studying the pathological process and exploring therapeutic targets of TAD.