Junctional Adhesion Molecules (JAMs) are components and regulators of the well-characterized epithelial and endothelial tight junction. Since the molecular components of native fibroblast adherens-like junctions remain poorly described we determined JAM expression profiles in fibroblasts. We found JAM-C on human dermal, lung, and corneal primary fibroblast cultures. Within murine lines, JAM-A was found in L-cells, JAM-C in 3T3 L1 cells, and both JAM-A and JAM-C were co-expressed in NIH 3T3 fibroblasts. In primary dermal fibroblasts, JAM-C concentrated at zipper-like junctions that formed between apposing cells. Dual immunostaining showed JAM-C co-localization with the ZO-1 intracellular scaffolding molecule at cell contacts that ranged from 7 microm to over 25 microm in length. JAM-C also labeled similar zipper-like junctions detected with N-Cadherin and Cadherin-11 antibodies. We conclude that endogenous JAM-C is an integral component of the dermal fibroblast adherens-like junction, and our data extend the expression and potential function of JAMs into mesenchymal tissues.

Diets high in cholesterol and cholate such as the Paigen diet have been used to study atherogenesis, lithogenesis, and proinflammatory microvascular changes induced by nutritional hypercholesterolemia. Although these diets lead to chronic hepatic inflammation and fibrosis, the early inflammatory changes have been poorly characterized. TLR4, a known receptor for LPS, is also a receptor for a variety of endogenous ligands and has been implicated in atheroma formation. Here, we specifically examined the early inflammatory response of the liver to the atherogenic (ATH) diet and the possible contribution of TLR4. Animals fed the high-cholesterol/cholate diet for 3 weeks developed a significant, predominantly mononuclear leukocyte infiltration in the liver, hepatic steatosis, elevated hepatic expression of MCP-1, RANTES, and MIP-2, and increased serum levels of liver enzymes. In TLR4-deleted animals, there was a 30% attenuation in the serum alanine transaminase levels and a 50% reduction in the leukocyte infiltration with a fourfold reduction in chemokine expression. In contrast, hepatic steatosis did not differ from wild-type controls. TLR2 deletion had no effect on diet-induced hepatitis but increased the amount of steatosis. We conclude that the early inflammatory liver injury but not hepatic lipid loading induced by the ATH diet in mice is mediated in part by TLR4.

Interstitial fibrosis plays a major role in progression of renal diseases. Oncostatin M (OSM) is a cytokine that regulates cell survival, differentiation, and proliferation. Renal tissue from patients with chronic obstructive nephropathy was examined for OSM expression. The elevated levels in diseased human kidneys suggested possible correlation between OSM level and kidney tissue fibrosis. Indeed, unilateral ureteral obstruction (UUO), a model of renal fibrosis, increased OSM and OSM receptor (OSM-R) expression in a time-dependent manner within hours following UUO. In vitro, OSM overexpression in tubular epithelial cells (TECs) resulted in epithelial-myofibroblast transdifferentiation. cDNA microarray technology identified up-regulated expression of immune modulators in obstructed compared with sham-operated kidneys. In vitro, OSM treatment up-regulated CC chemokine ligand CCL7, and CXC chemokine ligand (CXCL)-14 mRNA in kidney fibroblasts. In vivo, treatment of UUO mice with neutralizing anti-OSM antibody decreased renal chemokines expression. In conclusion, OSM is up-regulated in kidney tissue early after urinary obstruction. Therefore, OSM might play an important role in initiation of renal fibrogenesis, possibly by inducing myofibroblast transdifferentiation of TECs as well as leukocyte infiltration. This process may, in turn, contribute in part to progression of obstructive nephropathy and makes OSM a promising therapeutic target in renal fibrosis.

We found that γδ T cells migrate into murine corneal epithelium in response to epithelial wounding, and wound healing and inflammation are significantly reduced in TCRδ −/− mice (Am. J. Pathol 171:838–845, 2007). The current work is to define mechanisms for migration of γδ T cells into corneal epithelium. Limbal and paralimbal corneal epithelium was collected at 0 and 3 hrs after central abrasion in female C57BL/6 mice for qrtPCR, and immunocytology. Results: ICAM‐1 mRNA was increased 26 fold at 3 hrs. Anti‐ICAM‐1 staining was negative at 0 hr, but strongly positive over the limbal and paralimbal epithelium at 3 hrs. γ/δ T cells increased at 3 hrs after injury, but ICAM‐1−/− mice failed to show an increase. Of 11 chemokine receptors probed, only CCR3 and CCR5 were significantly increased in wildtype mice at 3 hrs. mRNA for chemokines recognized by these receptors was significantly increased: CCL3 (MIP‐1α), CCL4 (MIP‐1β), CCL5 (RANTES) and CCL7 (MCP‐3). Further, CXCL10 (IP‐10) mRNA was also significantly increased. CXCL10 is known to attract some γδ T cells, but its receptor (CXCR3) was not evident here. Conclusion: The migration of γδ T cells into murine corneal epithelium in response to epithelial abrasion appears to depend on ICAM‐1 expression, and since CCR5 is reported on some γδ T cells, our observations suggest a mechanism for attraction into corneal epithelium.Source of research support: General Clinical Research Centers