1,25(OH)(2)D(3) has antiproliferative effects and promotes cell differentiation. This consideration has provided the rationale for studies in subtotally nephrectomized rats showing that 1,25(OH)(2)D(3) interfered with glomerulosclerosis. The cellular mechanisms involved have remained obscure, however. It was the purpose of the present study to assess glomerular structure and cellular composition in subtotally nephrectomized (SNX) rats treated with nonpharmacological doses of 1,25(OH)(2)D(3). Male Sprague-Dawley rats were sham operated (sham) or underwent SNX under general anesthesia and received either solvent or 1,25(OH)(2)D(3) (3 ng.100 g body wt(-1).day(-1) sc). Blood pressure (BP) and albuminuria were measured. After 16 wk, the remnant renal tissue was perfusion fixed and morphometric and stereological measurements were carried out. The expression of proliferating cellular antigen (PCNA), cyclin-dependent kinase inhibitor p27, Wilms tumor gene (WT1), and desmin, a marker of early podocyte damage, was investigated by immunohistology. BP, serum creatinine, and urinary albumin excretion were significantly higher in SNX than in sham rats. Albuminuria was significantly lower in SNX+1,25(OH)(2)D(3) compared with SNX+solvent rats. Mean glomerular tuft volume was significantly higher in SNX+solvent (2.69 +/- 0.21 gx 10(6) microm(3)) than in sham rats (1.44 +/- 0.17 and 1.28 +/- 0.14 x 10(6) microm(3)); it was significantly (P < 0.05) lower in SNX+1,25(OH)(2)D(3) rats (1.81 +/- 0.16 x 10(6) microm(3)). The main finding was a significantly higher number of podocytes in SNX+1,25(OH)(2)D(3) (88 +/- 9) and sham (98 +/- 17) compared with SNX+solvent rats (81 +/- 8.7). In parallel, the increase in podocyte volume in SNX+solvent rats was abrogated by treatment with 1,25(OH)(2)D(3), and immunohistochemistry revealed less expression of desmin, PCNA, and p27, suggesting less podocyte injury and activation of the cyclin cascade. This study identifies the podocyte as an important target cell for the renoprotective action of 1,25(OH)(2)D(3). This notion is suggested by less evidence of podocyte injury, decreased podocytes loss, and abrogation of podocyte hypertrophy, findings that may also explain less pronounced albuminuria and glomerulosclerosis.

Objective. Rheumatoid arthritis (RA) is characterized by profound mononuclear cell (MNC) recruitment into synovial tissue (ST), thought to be due in part to tumor necrosis factor ␣ (TNF␣), a therapeutic target for RA. Although chemokines may also be involved, the mechanisms remain unclear. We undertook this study to examine the participation of CXCL16, a novel chemokine, in recruitment of MNCs to RA ST in vivo and to determine the signal transduction pathways mediating this process. Conclusion. Taken together, these results point to a unique role for CXCL16 as a premier MNC recruiter in RA and suggest additional therapeutic possibilities, targeting CXCL16, its receptor, or its signaling pathways.

IntroductionMigration inhibitory factor (MIF) is a pleotropic cytokine which plays a pivotal role in inflammatory and immune-mediated diseases such as rheumatoid arthritis (RA) and atherosclerosis. MIF is secreted by T lymphocytes and macrophages on lipopolysaccharide (LPS) exposure and induces secretion of tumor necrosis factor-␣ (TNF-␣) by mouse macrophages. 1,2 In RA, MIF is highly expressed in macrophages, endothelial cells, synovial tissue (ST) fibroblasts, serum, and synovial fluids. 1,2 MIF stimulates macrophage release of proinflammatory cytokines such as TNF-␣, interleukin 1 ␤ (IL-1␤), 4 MIF up-regulates IL-1␤, matrix metalloproteinases (MMPs) MMP-1, MMP-3, MMP-9, and MMP-13 in RA ST fibroblasts. 5,6 In rodent arthritis models, administration of anti-MIF antibody ameliorates arthritis with profound inhibition of clinical and histologic features of disease. [7][8][9] Anti-MIF treatment ameliorates acute encephalomyelitis and experimental autoimmune myocarditis in mice. 10,11 These studies show a key role of MIF in the pathogenesis of immunologic and inflammatory diseases.We have shown that MIF is a potent angiogenic factor. 12 Anti-MIF inhibits tumor growth and tumor-associated angiogenesis, and MIF is a required factor for tumor-initiated endothelial cell proliferation and tumor neovascularization. 13,14 Vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) in soluble forms (sVCAM-1 and sICAM-1, respectively) are potent angiogenic mediators, and RA synovial fluid-induced angiogenesis is blocked by anti-VCAM-1. 15,16 MIF is found in human vascular endothelial cells, which have been considered to play a pivotal role in systemic inflammatory and immunologic diseases by producing cytokines and growth factors. 17 Adhesion of inflammatory cells to vascular endothelium is the initial step in leukocyte recruitment and is mediated by a number of cell adhesion molecules such as ICAM-1, VCAM-1, E-, P-, and L-selectin, as well as integrins. MIF up-regulates ICAM-1 on endothelial cells. 18 Rat kidney VCAM-1 and ICAM-1 expression are decreased by anti-MIF treatment, blocking the development of glomerulonephritis. 19 Similarly, anti-MIF prevents VCAM-1 up-regulation on endothelial cells and improves acute encephalomyelitis in mice. 11 Cell adhesion molecules mediate and amplify the inflammatory response by allowing the ingress of leukocytes into diseased tissues. 20-22 VCAM-1 and ICAM-1 may be used as a reliable measure of the extent of atherosclerotic progression, and focal expression of adhesion molecules is consistently found in atherosclerotic plaques in humans. [22][23][24] The most compelling data for the necessity of adhesion molecules in the development of atherosclerotic plaques came from a report indicating that mice deficient in adhesion molecules are protected against atherosclerosis when fed an atherogenic diet. 25 Those studies support the role of adhesion molecules in immune-mediated diseases. For personal use only. on May 11, 2018. by guest www.bloodjournal.org From ...

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