Background: MicroRNA-29b (miR-29b) has been suggested to possess pro-inflammatory activity, which can partially be explained by the repression of tumor necrosis factor alpha protein three antibody (TNFAIP3). Meanwhile, it also promotes thyroid cell proliferation via Smad signaling pathways. The present study aimed to elucidate the role of miR-29b in Henoch Schonlein purpura nephritis (HSPN) and its underlying molecular mechanism in angiotensin II (Ang II)-induced human glomerular mesangial cell (HGMC) activation.

Methods: We evaluated miR-29b expression in 35 HSPN renal tissues based on crescent formation, glomerular sclerosis, interstitial fibrosis, thrombosis formation and capillary loop necrosis. Meanwhile, HGMCs were cultured, treated with Ang II and then transfected with LV-hsa-miR-29b-1 to induce miR-29b overexpression or LV-hsa-miR-29b-3p-inhibition to inhibit miR-29b expression. Finally, we examined the effects of miR-29b on cell proliferation and release of inflammatory mediators.

Results: We observed that miR-29b expression was significantly higher in the crescent group than in the no crescent group. MiR-29b overexpression induced the release of intercellular adhesion molecule-1, interleukin-1β (IL-1β), IL-6, IL-8, the increase of CyclinA2, CyclinD1, and cell proliferation. It also could inhibit the expressions of TNFAIP3 and NF-kappa-B-repressing factor (NKRF). Correspondingly, miR-29b inhibition produced the opposite effects and increased the expression of TNFAIP3 and NKRF.