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Immunoglobulin A (IgA) nephropathy is an important cause of end-stage kidney disease (ESKD). Tubulointerstitial inflammation and subsequent fibrosis appear to be a major contributor of the disease progression to ESKD; however, the underlying mechanism is poorly understood. Herein, we report that a unique feature of CYLD expression in kidneys of patients with IgA nephropathy and a CYLD-mediated negative regulation of inflammatory responses in human tubular epithelial cells. Immunochemical staining revealed that CYLD was predominantly expressed in renal tubular epithelial cells in 81% of the patients (37 cases) with proteinuric IgA nephropathy. Patients with positive CYLD had significantly less tubulointerstitial lesions and higher estimated glomerular filtration rate (eGFR) levels when compared with those negative. Logistic regression analysis indicated that eGFR was a predictor for the CYLD expression. In cultured human tubular epithelial HK-2 cells, tumor necrosis factor-alpha (TNFalpha) up-regulated CYLD expression. Adenoviral knockdown of CYLD did not affect albumin-, hydrogen peroxide (H(2)O(2))-, tunicamycin- or thapsigargin-induced cell death; however, it enhanced TNFalpha-induced expression of intracellular adhesion molecule (ICAM)-1 as well as activation of c-Jun N-terminal kinase (JNK). Moreover, monocyte adhesion to the TNFalpha-inflamed HK-2 cells was significantly increased by the CYLD shRNA approach. Taken together, our results suggest that CYLD negatively regulates tubulointertitial inflammatory responses via suppressing activation of JNK in tubular epithelial cells, putatively attenuating the progressive tubulointerstitial lesions in IgA nephropathy.

Growth of new blood vessels (angiogenesis), required for all tumor growth, is stimulated by the expression of vascular endothelial growth factor (VEGF). VEGF is up-regulated in all known solid tumors but also in atherosclerosis, diabetic retinopathy, arthritis, and many other conditions. Conventional VEGF isoforms have been universally described as proangiogenic cytokines. Here, we show that an endogenous splice variant, VEGF165b, is expressed as protein in normal cells and tissues and is circulating in human plasma. We also present evidence for a sister family of presumably inhibitory splice variants. Moreover, these isoforms are down-regulated in prostate cancer. We also show that VEGF165b binds VEGF receptor 2 with the same affinity as VEGF165 but does not activate it or stimulate downstream signaling pathways. Moreover, it prevents VEGF165-mediated VEGF receptor 2 phosphorylation and signaling in cultured cells. Furthermore, we show, with two different in vivo angiogenesis models, that VEGF165b is not angiogenic and that it inhibits VEGF165-mediated angiogenesis in rabbit cornea and rat mesentery. Finally, we show that VEGF165b expressing tumors grow significantly more slowly than VEGF165-expressing tumors, indicating that a switch in splicing from VEGF165 to VEGF165b can inhibit tumor growth. These results suggest that regulation of VEGF splicing may be a critical switch from an antiangiogenic to a proangiogenic phenotype.

Objective To evaluate the safety and efficacy of inserting a straight-tip Tenckhoff catheter configured with a subcutaneous artificial swan neck. Design Clinical outcomes of conventional swan-neck straight-tip catheters and Tenckhoff straight-tip catheters implanted with an artificial subcutaneous swan neck were compared in a prospective randomized controlled trial in a single-center setting. Patients and Methods Patients undergoing peritoneal dialysis catheter insertion were randomized to receive either a double-cuff straight-tip Tenckhoff catheter with an artificial subcutaneous swan-neck (TC) or a conventional double-cuff straight-tip swan-neck catheter (SN). The primary outcome was catheter exit-site infection rate; the secondary outcomes were catheter-related mechanical events and surgery-related bleeding. Results A total of 39 consecutive patients were enrolled: 20 into the TC group and 19 into the SN group. More exit-site infections were observed in the SN group than in the TC group, although the difference was not statistically significant (0.97 vs 0.51 episodes per patient-year, p = 0.0657). However, there were more peritonitis episodes in the TC group than in the SN group (0.35 vs 0.15 episodes per patient-year, p = 0.0256). Exit-site and main wound bleeding post surgery were generally mild and similar in the 2 groups. No events of dialysate leakage, catheter tip migration, or subcutaneous cuff protrusion were observed in patients of either group. Outflow failure due to mechanical causes occurred in 2 patients in the TC group and in 1 patient in the SN group during the intermittent peritoneal dialysis period; all were corrected successfully by laparoscopic omentectomy. Conclusions Placement of the double-cuff straight-tip Tenckhoff catheter configured with an artificial subcutaneous swan neck appears to be an effective and safe procedure. It may be a good alternative to the conventional swan-neck catheter.

Despite production by podocytes of the proangiogenic molecule vascular endothelial growth factor-A (VEGF), the glomeruli are not sites of angiogenesis. We recently described mRNA expression of an inhibitory splice variant of VEGF (VEGF165b) in normal kidney (Bates DO, Cui TG, Doughty JM, Winkler M, Sugiono M, Shields JD, Peat D, Gillatt D, and Harper SJ. Cancer Res 62: 4123–4131, 2002). Available anti-VEGF antibodies do not distinguish stimulatory from inhibitory VEGF families. To assess the production of VEGF165(stimulatory) and VEGF165b (inhibitory) isoforms by human podocytes, we examined both primary cultured and conditionally immortalized human podocytes using family- and isoform-specific RT-PCR. In addition, VEGF protein production was analyzed in podocytes, using isoform-specific double-strand small-interference RNAs (siRNA). RT-PCR demonstrated the production of VEGF189mRNA by podocytes of both phenotypes. In contrast, on differentiation there was a splicing change from VEGF165to VEGF165b mRNA. In addition, VEGF protein in the supernatant of conditionally immortalized, differentiated podocytes was reduced by VEGF165b siRNA to 20 ± 11% of the level of mock-transfected cells ( P < 0.01). No reduction was seen with mismatch siRNA. Moreover, there was no reduction in VEGF protein concentration in the supernatant of primary cultured, dedifferentiated human podocytes (109 ± 8% of mismatch siRNA, P > 0.1). In conclusion, differentiated but not dedifferentiated human podocytes secrete significant amounts of VEGF165b protein. It is possible that this may explain the paradox of high VEGF production in the glomerulus but no angiogenesis. Furthermore, the existence of this splicing switch in relation to podocyte phenotype suggests that alternative splicing of the VEGF pre-RNA is a regulated process that is open to manipulation and therefore could be a target for novel cancer therapies.