No abstract

The IL-33-type 2 innate lymphoid cell (ILC2) axis has an important role in tissue homeostasis, inflammation, and wound healing. However, the relative importance of this innate immune pathway for immunotherapy against inflammation and tissue damage remains unclear. Here, we show that treatment with recombinant mouse IL-33 prevented renal structural and functional injury and reduced mortality in mice subjected to ischemia-reperfusion injury (IRI). Compared with control-treated IRI mice, IL-33-treated IRI mice had increased levels of IL-4 and IL-13 in serum and kidney and more ILC2, regulatory T cells (Tregs), and anti-inflammatory (M2) macrophages. Depletion of ILC2, but not Tregs, substantially abolished the protective effect of IL-33 on renal IRI. Adoptive transfer of -expanded ILC2 prevented renal injury in mice subjected to IRI. This protective effect associated with induction of M2 macrophages in kidney and required ILC2 production of amphiregulin. Treatment of mice with IL-33 or ILC2 after IRI was also renoprotective. Furthermore, in a humanized mouse model of renal IRI, treatment with human IL-33 or transfer of-expanded human ILC2 ameliorated renal IRI. This study has uncovered a major protective role of the IL-33-ILC2 axis in renal IRI that could be potentiated as a therapeutic strategy.

Mitochondrial dysfunction is a key feature of injury to numerous tissues and stem cell aging. Although the tissue regenerative role of mesenchymal stem cell (MSC)derived extracellular vesicles (MSC-EVs) is well known, their specific role in regulating mitochondrial function in target cells remains elusive. Here, we report that MSC-EVs attenuated mtDNA damage and inflammation after acute kidney injury (AKI) and that this effect was at least partially dependent on the mitochondrial transcription factor A (TFAM) pathway. In detail, TFAM and mtDNA were depleted by oxidative stress in MSCs from aged or diabetic donors. Higher levels of TFAM mRNA and mtDNA were detected in normal control (NC) MSC-EVs than in TFAM-knockdown (TFAM-KD) and aged EVs. EV-mediated TFAM mRNA transfer in recipient cells was unaffected by transcriptional inhibition. Accordingly, the application of MSC-EVs restored TFAM protein and TFAM-mtDNA complex (nucleoid) stability, thereby reversing mtDNA deletion and mitochondrial oxidative phosphorylation (OXPHOS) defects in injured renal tubular cells. Loss of TFAM also led to downregulation of multiple anti-inflammatory miRNAs and proteins in MSC-EVs. In vivo, intravenously injected EVs primarily accumulated in the liver, kidney, spleen, and lung. MSC-EVs attenuated renal lesion formation, mitochondrial damage, and inflammation in mice with AKI, whereas EVs from TFAM-KD or aged MSCs resulted in poor therapeutic outcomes. Moreover, TFAM overexpression (TFAM-OE) improved the rescue effect of MSC-EVs on mitochondrial damage and inflammation to some extent. This study suggests that MSC-EVs are promising nanotherapeutics for diseases characterized by mitochondrial damage, and TFAM signaling is essential for maintaining their regenerative capacity.

TGF- is a key profibrotic factor, but targeting TGF- to prevent fibrosis also abolishes its protective anti-inflammatory effects. Here, we investigated the hypothesis that we can redirect TGF- signaling by preventing downstream profibrotic interaction of -catenin with T cell factor (TCF), thereby enhancing the interaction of-catenin with Foxo, a transcription factor that controls differentiation of TGF- induced regulatory T cells (iTregs), and thus, enhance anti-inflammatory effects of TGF- In iTregs derived from EL4 T cells treated with recombinant human TGF-1 (rhTGF-1) , inhibition of-catenin/TCF transcription with ICG-001 increased Foxp3 expression, interaction of -catenin and Foxo1, binding of Foxo1 to the Foxp3 promoter, and Foxo transcriptional activity. Moreover, the level of-catenin expression positively correlated with the level of Foxo1 binding to the Foxp3 promoter and Foxo transcriptional activity. T cell fate mapping in Foxp3 Ly5.1/5.2 mice revealed that coadministration of rhTGF-1 and ICG-001 further enhanced the expansion of iTregs and natural Tregs observed with rhTGF-1 treatment alone. Coadministration of rhTGF-1 with ICG-001 also increased the number of Tregs and reduced inflammation and fibrosis in the kidney fibrosis models of unilateral ureteric obstruction and ischemia-reperfusion injury. Notably, ICG-001 prevented the fibrosis in distant organs (lung and liver) caused by rhTGF-1. Together, our results show that diversion of -catenin from TCF- to Foxo-mediated transcription inhibits the-catenin/TCF-mediated profibrotic effects of TGF- while enhancing the -catenin/Foxo-mediated anti-inflammatory effects. Targeting-catenin/Foxo may be a novel therapeutic strategy in the treatment of fibrotic diseases that lead to organ failure.