Mesenchymal Stem Cell-Derived Exosomes Ameliorate Diabetic Kidney Disease Through the NLRP3 Signaling Pathway.

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease worldwide. Exosomes (Exo) derived from human umbilical cord mesenchymal stem cells (HUC-MSCs) have been demonstrated to be an effective therapy for DKD, but the underlying mechanisms of this action remain poorly defined. We investigated the association of DKD with inflammasome activation and the pathophysiological relevance of Exo-mediated inflammation relief as well as damage repair in this progression. We co-cultured podocytes and HUC-MSCs derived Exo (MSCs-Exo) under high glucose (HG) and injected MSCs-Exo into diabetic mice, then we detected the NLRP3 inflammasome both in vitro and in vivo. We found that HG reduced the viability of podocytes, activated the NLRP3 signaling pathway and increased inflammation in podocytes and diabetic mice. MSCs-Exo attenuated the inflammation, including the expression of IL-6, IL-1β, IL-18, TNF-α; depressed the activation of NLRP3 signaling pathway in podocytes under HG and diabetic mice, ameliorated kidney injury. Furthermore, miR-22-3p, which is relatively highly expressed miRNAs in exosomes of MSCs, may be the key point in this progress, by suppressing the expression of its known target, NLRP3. Knocking down miR-22-3p from MSCs-Exo abolished their anti-inflammation activity and beneficial function both in vitro and in vivo. Collectively, our results have demonstrated that exosomes transferring miR-22-3p protected the podocytes and diabetic mice from inflammation by mediating NLRP3 inflammasome, indicating that MSC-derived exosomes may be a promising therapeutic cell-free strategy for DKD.