TNFR2 interposes the proliferative and NF-κB-mediated inflammatory response by podocytes to TNF-α

The development of proliferative podocytopathies has been linked to ligation of TNFR2 expressed on the renal parenchyma; however, the TNFR2 positive cells within the kidney responsible for podocyte injury are unknown. We detected de novo expression of TNFR2 on podocytes prior to hyperplastic injury in crescentic glomerulonephritis of mice with nephrotoxic nephritis, and in collapsing glomerulopathy of Tg26 HIV/nl mice, kd/kd mice, and humans. We further found that serum levels of soluble TNF-α and TNFR2 correlated significantly with renal injury in Tg26 HIV/nl mice. Thus, we asked whether ligand binding of TNFR2 on podocytes ex vivo precipitates the characteristic proliferative and pro-inflammatory diseased podocyte phenotypes. Soluble TNF-α activated NF-κB and dose-dependently induced podocyte proliferation, marked by expression of the podocyte G 1 cyclin and NF-κB target gene, cyclin D1. Microarray gene and chemokine protein expression profiling showed a marked pro-inflammatory NF-κB signature, and activated podocytes secreting CCL2 and CCL5 induced macrophage migration in transwell assays. Neutralization of TNFR2 on podocytes with blocking antibodies abrogated NF-κB activation and the induction of cyclin D1 by TNF-α, and identified TNFR2 as the primary receptor that induced IκBα degradation, the initiating event in NF-κB activation. These results suggest that TNFR2 expressed on podocytes and its canonical NF-κB signaling may directly interpose the compound pathogenic responses by podocytes to TNF-α, absent other TNFR2 positive renal cell-types in proliferative podocytopathies

Non‐viral delivery of nuclear factor‐κB decoy ameliorates murine inflammatory bowel disease and restores tissue homeostasis

BACKGROUND: Nuclear factor‐κB (NF‐κB) is a key transcriptional regulator of inflammatory bowel disease (IBD). AIM: To investigate the therapeutic potential of a locally administered “non‐viral” nuclear factor‐κB decoy (NFκBD) in multiple experimental models of IBD. METHODS: A fully phosphorothioated decoy oligonucleotide with improved stability that specifically binds NF‐κB and blocks inflammatory mediators regulated by this transcription factor without the help of viral envelope‐assisted delivery was developed. The therapeutic effects of NFκBD were studied in the trinitrobenzene sulphonic acid, oxazolone and dextran sodium sulphate induced colitis models. RESULTS: Intracolonic administration of NFκBD results in the delivery of NFκBD to inflammatory cells and a reduction of NF‐κB heterodimers. In the T helper cell 1‐driven trinitrobenzene sulphonic acid‐induced colitis model, mice receiving NFκBD treatment exhibit a dose‐dependent reduction in disease severity and a more rapid recovery to normal body weight, similar to a clinically relevant dose of budesonide. Clinical efficacy was corroborated by considerable reductions in colitis pathology and tissue levels of several pro‐inflammatory markers, including tumour necrosis factor α, interleukin 6, interleukin 1β and monocyte chemotactic protein 1. NFκBD also mitigates disease activity in the T helper cell 2‐like oxazolone colitis and epithelial injury‐related acute dextran sodium sulphate colitis models. Interestingly, restoration of tissue homeostasis is observed in NFκBD‐treated animals with the rapid re‐emergence of functional goblet cells and a return to normal patterns of cell proliferation in the mucosal epithelium and smooth muscle cell layers. CONCLUSIONS: These data support the potential use of “naked” NFκBD as a cross‐functional therapeutic in IBD, and show for the first time that it can facilitate the restoration of colon homeostasis and function