Mesenchymal stem cell-derived conditioned medium attenuate angiotensin II-induced aortic aneurysm growth by modulating macrophage polarization.

Mesenchymal stem cells (MSCs) exhibit therapeutic benefits on aortic aneurysm (AA); however, the molecular mechanisms are not fully understood. The current study aimed to investigate the therapeutic effects and potential mechanisms of murine bone marrow MSC (BM-MSCs)-derived conditioned medium (MSCs-CM) on angiotensin II (AngII)-induced AA in apolipoprotein E-deficient (apoE-/- ) mice. Murine BM-MSCs, MSCs-CM or control medium were intravenously administrated into AngII-induced AA in apoE-/- mice. Mice were sacrificed at 2 weeks after injection. BM-MSCs and MSCs-CM significantly attenuated matrix metalloproteinase (MMP)-2 and MMP-9 expression, aortic elastin degradation and AA growth at the site of AA. These treatments with BM-MSCs and MSCs-CM also decreased Ly6chigh monocytes in peripheral blood on day 7 and M1 macrophage infiltration in AA tissues on day 14, whereas they increased M2 macrophages. In addition, BM-MSCs and MSCs-CM reduced MCP-1, IL-1Ra and IL-6 expression and increased IL-10 expression in AA tissues. In vitro, peritoneal macrophages were co-cultured with BM-MSCs or fibroblasts as control in a transwell system. The mRNA and protein expression of M2 macrophage markers were evaluated. IL-6 and IL-1ß were reduced, while IL-10 was increased in the BM-MSC systems. The mRNA and protein expression of M2 markers were up-regulated in the BM-MSC systems. Furthermore, high concentration of IGF1, VEGF and TGF-ß1 was detected in MSCs-CM. Our results suggest that MSCs-CM could prevent AA growth potentially through regulating macrophage polarization. These results may provide a new insight into the mechanisms of BM-MSCs in the therapy of AA.

Diverse roles of macrophage polarization in aortic aneurysm: destruction and repair.

Aortic aneurysm (AA) is defined as an enlargement of the aorta greater than 1.5 times its normal size. Early diagnosis of AA is challenging and mortality of AA is high. Curative pharmacological treatments for AA are still lacking, highlighting the need for better understanding of the underlying mechanisms of AA progression. Accumulating studies have proven that the polarization state of circulating monocyte-derived macrophages plays a crucial role in regulating the development of AA. Distinct macrophage subtypes display different functions. Several studies targeting macrophage polarization during AA formation and progression showed potential treatment effects. In this review, we focus on the recent advances of research on macrophage polarization in the progression of AA and propose that targeting macrophage polarization could hold great promise for preventing and treating AA.

Biofunction and clinical potential of extracellular vesicles from methicillin-resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA), a globally widespread pathogen that is highly resistant to antibiotics, can lead to serious infection, and has fairly limited treatment options. Over decades, extracellular vesicles (EVs) from MRSA have received increasing attention, and their roles in the pathogenesis of MRSA have been well studied. The secretion process of MRSA EVs is complex and regulated by various factors. During this process, EVs carry a variety of bioactive molecules including enzymes, lipoproteins, toxins, DNA, and RNA, which play important roles in antibiotic resistance, cytotoxicity, and immune escape. Biological enzymes and drug resistance genes are important factors for MRSA EVs to promote drug resistance. As the components of EVs are derived from MRSA, these compounds can trigger the immune response of the host, and thus have great potential as a vaccine. These lipid-coated vesicles secreted by MRSA contain a variety of bioactive factors, which are considered as the critical factors affecting the pathogenesis, drug resistance, and colonization of MRSA, and thus have the potential to treat these patients infected with MRSA. However, the clinical application of MRSA EVs as the acellular vaccines is still a long way off, and further research should be encouraged to bridge the gap between theoretical study and practical application.

A novel STAT3 inhibitor attenuates angiotensin II-induced abdominal aortic aneurysm progression in mice through modulating vascular inflammation and autophagy.

Abdominal Aortic aneurysm (AAA) is associated with chronic inflammation, cells apoptosis, and impairment of autophagy. BP-1-102, a novel potent STAT3 inhibitor, has been recently reported to significantly block inflammation-related signaling pathways of JAK2/STAT3 and NF-κB, as well as regulate autophagy. However, its role in vascular inflammation and AAA progression remains to be elucidated. In the present study, the effect and potential mechanisms of BP-1-102 on angiotensin II (AngII) induced AAA in ApoE-/- mice were investigated. AAA was induced in ApoE-/- mice with infusion of AngII for 28 days. BP-1-102 was administrated orally to mice every other day. Mice were sacrificed on day 7, day 14, and day 28 to evaluate the treatment effects. BP-1-102 markedly decreased AAA incidence and aortic diameter, maintained elastin structure and volume, reduced the expression of pro-inflammatory cytokines and MMPs, and inhibited inflammatory cells infiltration. Moreover, BP-1-102 dramatically reduced the expression of JAK2, p-STAT3, p-NF-κB, and Bcl-xL but maintained the expression of LC3B and Beclin in AAA tissues. In vitro, vascular smooth muscle cells (VSMCs) were treated with AngII and/or BP-1-102 at indicated time and concentration. BP-1-102 inhibited AngII-induced JAK2/STAT3 and NF-κB signaling activation and maintained autophagy-related proteins expression in VSMCs. Taken together, our findings suggest that BP-1-102 inhibits vascular inflammation and AAA progression through decreasing JAK2/STAT3 and NF-κB activation and maintaining autophagy.