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Aims: The role of kidney infiltrating T cells in the pathology of lupus nephritis is unclear. This study was undertaken to investigate whether CD4+ T cell responses to a surrogate mesangial antigen can initiate glomerulonephritis. Methods: Ovalbumin (OVA) was deposited in the glomerular mesangium of C57BL/6 (B6) mice using anti-α8-integrin immunoliposomes (α8ILs). This was followed by injection of activated OVA-reactive CD4+ transgenic OT2 T cells. Trafficking of antigen-specific OT2 T cells to kidneys and lymph nodes was studied by flow cytometry. Glomerular pathology and immune cell infiltration was characterized by immunostaining. Role of CCR2 deficiency on T cell-mediated glomerulonephritis was investigated using B6.ccr2–/– mice. Results: α8ILs delivered OVA specifically to the renal glomeruli. Adoptively transferred OT2 T cells preferentially accumulated in renal lymph nodes and in the renal cortex. Kidneys showed glomerular inflammation with recruitment of endogenous T cells, dendritic cells and macrophages. T cell-mediated inflammation induced mesangial cell activation and an increase in glomerular MCP1 and fibronectin. The formation of inflammatory foci was driven by Ly6C monocytes and was CCR2 dependent. Conclusions: The findings from this study show that T cells reactive with antigens in the mesangium are sufficient to initiate glomerular pathology. Antigen-specific CD4 T cells act by inducing glomerular MCP1 production which mediates recruitment of inflammatory monocytes resulting in glomerulonephritis. Thus, downmodulation of T cell responses within the kidneys of lupus patients will be a beneficial therapeutic approach.

Sphingosine 1-phosphate (S1P), a pleiotropic lipid mediator, binds to five related G-protein-coupled receptors to exert its effects. As S1P1 receptor (S1P1R) activation blocks kidney inflammation in acute renal injury, we tested whether activation of S1P1Rs ameliorates renal injury in early-stage diabetic nephropathy (DN) in rats. Urinary albumin excretion increased in vehicle-treated diabetic rats (single injection of streptozotocin), compared with controls, and was associated with tubule injury and increased urinary tumor necrosis factor-α (TNF-α) at 9 weeks. These effects were significantly reduced by FTY720, a non-selective, or SEW2871, a selective S1P1R agonist. Interestingly, only FTY720 was associated with reduced total lymphocyte levels. Albuminuria was reduced by SEW2871 in both Rag-1 (T- and B-cell deficient) and wild-type diabetic mice after 6 weeks, suggesting that the effect was independent of lymphocytes. Another receptor, S1P3R, did not contribute to the FTY720-mediated protection, as albuminuria was also reduced in diabetic S1P3R knockout mice. Further, both agonists restored WT-1 staining along with podocin and nephrin mRNA expression, suggesting podocyte protection. This was corroborated in vitro, as SEW2871 reduced TNF-α and vascular endothelial growth factor mRNA expression in immortalized podocytes grown in media containing high glucose. Whether targeting kidney S1P1Rs will be a useful therapeutic measure in DN will need direct testing.

Renal TGF-β regulation in spontaneously diabetic NOD mice with correlations in mesangial cells. Diabetic nephropathy is characterized by excessive glomerular matrix accumulation, basement membrane thickening and sclerosis. Although it is clear that systemic metabolic disturbances precipitate such renal changes, the signals and pathways involved in this process are not fully elucidated. Recent evidence suggests that growth factors/cytokines are intimately involved in the pathogenesis of diabetic nephropathy. Because of its prosclerotic properties, transforming growth factor-β (TGF-β) is a prime candidate mediator of diabetic nephrosclerosis. We examined perfused kidney tissues isolated from spontaneously diabetic, non-obese diabetic mice (NOD) for TGF-β content. By using murine isotype specific TGF-β probes, we demonstrate that within 5 to 10 days of hyperglycuria renal TGF-β2 mRNA and protein content increases. By immunohistochemical analysis, de novo TGF-β immunoreactivity was detected within both glomeruli and the interstitium. In order to determine the signals involved in promoting kidney TGF-β content in vivo , TGF-β regulation was examined in renal mesangial cells in vitro . Murine mesangial cells stimulated with glycosylated protein secrete bioactive TGF-β and demonstrate a disproportionate increase in the steady state levels of TGF-β2 mRNA. These data suggest that a major early renal response in NOD mice to hyperglycemia or to glycosylated proteins is characterized by increases in TGF-β2.

Effect of hemodialysis and peritoneal dialysis on aztreonam pharmacokinetics. Aztreonam, a new monobactam, will be widely used because of its broad aerobic gram-negative bacterial coverage and its apparent low risk of allergic phenomena in penicillin/cephalosporin-sensitive patients. We examined aztreonam kinetics in patients during hemodialysis and in the interdialytic period and in patients on continuous ambulatory peritoneal dialysis (CAPD), and related aztreonam to urea clearance (CL). In hemodialysis patients, aztreonam serum half-life was 7.9 hr between and 2.7 hr during dialysis sessions. CLserum, CLrenal, and CLother were 24.4, 0.5, and 23.9 ml/min, respectively, during the interdialytic period. Four hours of dialysis removed 38.2% (range, 27 to 58%) of antibiotic. CL of aztreonam by hemodialysis was 36.6 to 43.2 ml/min, 50 to 77% greater than interdialytic CL. CL of urea by hemodialysis was 112.4 to 155.6 ml/min; CLaztreonam/CLurea ratio was 0.28 to 0.33 during the hemodialysis sessions. During CAPD, aztreonam serum half-life after intravenous dosing was 7.1 hr; dialysate recovery, 9.7% of the dose; CLserum, CLrenal, CLperitoneal dialysis, and CLother were 23.8, 0.5, 2.1, and 21.3 ml/min, respectively. CLurea by CAPD was 6.5 ml/min. Thus, CLaztreonam during CAPD was 32% of CLurea. Aztreonam was detectable in dialysate at 48 hr (eight exchanges) after peritoneal administration in the first exchange. Hemodialysis and CAPD patients given aztreonam treatment should receive the standard dose of aztreonam as a loading dose, followed by one-fourth the loading dose at standard dose intervals. Hemodialysis patients should receive a supplemental dose equal to half their usual maintenance dose immediately after each dialysis session. For CAPD patients with peritonitis due to susceptible organisms, a 1-g i.v. loading dose followed by a 0.5-g i.p. dose every 6 hr is suggested. In any individual patient undergoing hemodialysis or CAPD, the relationship between CLurea and CLaztreonam should allow appropriate antibiotic dose adjustment.Effet de l'hémodialyse et de la dialyse péritonéale sur la pharmacocinétique de l'aztréonam. L'aztréonam, une nouvelle monobactame, sera largement employée en raison de son vaste spectre bactérien gramnégatif aérobie et de son faible risque apparent de phénomènes allergiques chez les malades sensibles à la pénicilline/céphalosporine. Nous avons examiné la cinétique de l'aztréonam chez des malades pendant l'hémodialyse et durant la période interdialytique, et chez des malades en dialyse péritonéale continue ambulatoire (CAPD) et nous avons relié la clearance de l'aztréonam à celle de l'urée (CL). Chez les hémodialysés, la demi-vie sérique de l'aztréonam était de 7,9 hr entre et 2,7 hr pendant les séances de dialyse. CLsérum, CLrénale, et CLautres étaient de 24,4, 0,5, et 23,9 ml/min, respectivement pendant la période interdialytique. Quatre heures de dialyse épuraient 38,2% (de 27 à 58%) de l'antibiotique. CL de l'aztréonam par l'hémodialyse était de 36,6 à 43,2 ml/min, 50 à 77% plus élevée que CL interdialytique. CL de l'urée par hémodialyse était de 112,4 à 155,6 ml/min; le rapport CLaztréonam/CLurée était de 0,28 à 0,33 pendant les séances d'hémodialyse. Au cours de la CAPD, la demi-vie sérique de l'aztréonam après administration i.v. était de 7,1 hr; la récupération dans le dialysat de 9,7% de la dose; CLsérum, CLrénale, CLdialyse péritonéale, et CLautres étaient de 23,8, 0,5, 2,1, et 21,3 ml/min respectivement. CLurée par CAPD était de 6,5 ml/min. Ainsi, CLaztréonam pendant la CAPD était de 32% de CLurée. L'aztréonam etait détectable dans le dialysat 48 hr (nuit échanges) après administration péritonéale lors du premier échange. Les malades en hémodialyse ou CAPD traités par l'aztréonam devraient recevoir la dose standard d'aztréonam comme dose de charge suivie par un quart de la dose de charge aux intervalles de la dose standard. Les hémodialysés devraient recevoir une dose supplémentaire égale à la moitié de leur dose d'entretien habituelle immédiatement après chaque séance de dialyse. Chez les malades en CAPD atteints de péritonite par des organismes sensibles, il est suggéré une dose de charge de 1-g i.v., suivie de 0,5-g par voie intrapéritonéale toutes les 6 hr. Chez tout malade en hémodialyse ou CAPD individuellement, la relation entre CLurée et CLaztréonam devrait permettre l'ajustement posologique approprié de l'antibiotique.

T-cells and macrophages in rapidly progressive glomerulonephritis: Clinicopathologic correlations. We phenotyped with monoclonal antibodies (MAb) the cellular infiltrates in kidneys of patients with rapidly progressive glomerulonephritis (RPGN) responsive (R) or nonresponsive (NR) to pulse methylprednisolone therapy (PM)-eight anti-GBM, six no immune deposits, three immune complex, two vasculitis, and one proliferative GN. There were glomerular, periglomerular, crescentic, and interstitial T and T-cell subsets. Few interstitial and no glomerular B and NK cells were observed. TH cells were much more common than TS. Phenotypes were quantitatively evaluated in 221 nephritic and 32 control glomeruli.T and/or TH cells were positively correlated with MΦ, r = 0.30 to 0.74,P < 0.05 to 0.0005. Although differences in phenotypes were observed, these differences were insufficient to distinguish between subtypes. Analysis of R and NR revealed no relationship to percent crescents, entry serum creatinine, oliguria, or need for dialysis. NR was related to presence of anti-GBM disease,P = 0.001, as was ability to stop dialysis, 0 of 7 GBM versus 9 of 10 other,P < 0.001. Mild infiltrates of lymphocytes and MΦ correlated with R,P ≤ 0.02. R had fewer numbers of TH and MΦ in glomeruli,P = 0.0001, in crescents,P < 0.02, and total TH and MΦ compared to NR, P < 0.001. Crescentic and total TH/S ratios were lower in NR than R, P < 0.05. These findings demonstrate that components of the cell-mediated immune (CMI) system are present by MAb analysis, that subtypes cannot be differentiated by CMI constitution, and R to PM is related to intensity and composition of CMI involvement. Independence of the CMI system relative to anti-GBM disease remains to be clarified.