A1 astrocytes contribute to murine depression-like behavior and cognitive dysfunction, which can be alleviated by IL-10 or fluorocitrate treatment.

BACKGROUND: Astrocytes are crucial regulators in the central nervous system. Abnormal activation of astrocytes contributes to some behavior deficits. However, mechanisms underlying the effects remain unclear. Here, we studied the activation of A1 astrocytes and their contribution to murine behavior deficits. METHODS: A1 astrocytes were induced by treatment with lipopolysaccharide (LPS) in vitro. The functional phenotype of astrocytes was determined by quantitative RT-PCR, ELISA, and immunohistochemistry. To assess the role of A1 astrocytes in vivo, mice were injected intraperitoneally with LPS. Then, murine behaviors were tested, and the hippocampus and cortex were analyzed by quantitative RT-PCR, ELISA, and immunohistochemistry. The function of IL-10 and fluorocitrate on A1 astrocyte activation was also examined. RESULTS: Our results show that astrocytes isolated from B6.129S6-Il10tm1Flv/J homozygotes (IL-10tm1/tm1) were prone to characteristics of A1 reactive astrocytes. Compared with their wild-type counterparts, IL-10tm1/tm1 astrocytes exhibited higher expression of glial fibrillary acidic protein (GFAP). Whether or not they were stimulated with LPS, IL-10tm1/tm1 astrocytes exhibited enhanced expression of A1-specific transcripts and proinflammatory factors IL-1ß, IL-6, and TNFα. In addition, IL-10tm1/tm1 astrocytes demonstrated hyperphosphorylation of STAT3. Moreover, astrocytes from IL-10tm1/tm1 mice showed attenuated phagocytic ability and were neurotoxic. IL-10tm1/tm1 mice demonstrated increased immobility time in the forced swim test and defective learning and memory behavior in the Morris water maze test. Moreover, enhanced neuroinflammation was found in the hippocampus and cortex of IL-10tm1/tm1 mice, accompanying with more GFAP-positive astrocytes and severe neuron loss in the hippocampus. Pretreatment IL-10tm1/tm1 mice with IL-10 or fluorocitrate decreased the expression of proinflammatory factors and A1-specific transcripts in the hippocampus and cortex, and then alleviated LPS-induced depressive-like behavior. CONCLUSION: These results demonstrate that astrocytes isolated from B6.129S6-Il10tm1Flv/J homozygotes are prone to A1 phenotype and contribute to the depression-like behavior and memory deficits. Inhibiting A1 astrocyte activation may be an attractive therapeutic strategy in some neurodegenerative diseases.

SOCS1 Regulates the Immunomodulatory Roles of MSCs on B Cells.

BACKGROUND AND OBJECTIVES: The effective use of MSCs for the treatment of some B cell-mediated immune diseases is quite limited. The main reason is that the immunomodulatory effects of mesenchymal stem cells (MSCs) on B cells are unclear, and their underlying mechanisms have not been fully explored. METHODS AND RESULTS: By co-culturing B cells with MSCs without (MSC/CTLsh) or with suppressor of cytokine signaling 1 (SOCS1) knockdown (MSC/SOCS1sh), we found that MSCs inhibited B cell proliferation, activation and terminal differentiation. Remarkably, the highest inhibition of B cell proliferation was observed in MSC/SOCS1sh co-culture. Besides, MSC/SOCS1sh reversed the inhibitory effect of MSCs in the last stage of B cell differentiation. However, MSC/SOCS1sh had no effect on inhibiting B cell activation by MSCs. We also showed that IgA+ B cell production was significantly higher in MSC/SOCS1sh than in MSC/CTLsh, although no difference was observed when both MSCs co-cultures were compared to isolated B cells. In addition, MSCs increased PGE2 production after TNF-α/IFN-γ stimulation, with the highest increase observed in MSC/SOCS1sh co-culture. CONCLUSIONS: Our results highlighted the role of SOCS1 as an important new mediator in the regulation of B cell function by MSCs. Therefore, these data may help to develop new treatments for B cell-mediated immune diseases.

Vitamin C Treatment Rescues Prelamin A-Induced Premature Senescence of Subchondral Bone Mesenchymal Stem Cells.

Aging is a predominant risk factor for many chronic conditions. Stem cell dysfunction plays a pivotal role in the aging process. Prelamin A, an abnormal processed form of the nuclear lamina protein lamin A, has been reported to trigger premature senescence. However, the mechanism driving stem cell dysfunction is still unclear. In this study, we found that while passaging subchondral bone mesenchymal stem cells (SCB-MSCs) in vitro, prelamin A accumulation occurred concomitantly with an increase in senescence-associated ß-galactosidase (SA-ß-Gal) expression. Unlike their counterparts, SCB-MSCs with prelamin A overexpression (MSC/PLA) demonstrated decreased proliferation, osteogenesis, and adipogenesis but increased production of inflammatory factors. In a hind-limb ischemia model, MSC/PLA also exhibited compromised therapy effect. Further investigation showed that exogenous prelamin A triggered abnormal nuclear morphology, DNA and shelterin complex damage, cell cycle retardation, and eventually cell senescence. Changes in gene expression profile were also verified by microarray assay. Interestingly, we found that ascorbic acid or vitamin C (VC) treatment could inhibit prelamin A expression in MSC/PLA and partially reverse the premature aging in MSC/PLA, with reduced secretion of inflammatory factors and cell cycle arrest and resistance to apoptosis. Importantly, after VC treatment, MSC/PLA showed enhanced therapy effect in the hind-limb ischemia model. In conclusion, prelamin A can accelerate SCB-MSC premature senescence by inducing DNA damage. VC can be a potential therapeutic reagent for prelamin A-induced aging defects in MSCs.

miR-129-5p Regulates the Immunomodulatory Functions of Adipose-Derived Stem Cells via Targeting Stat1 Signaling.

Adipose-derived stem cells (ASCs) have become one of the most promising stem cell populations for cell-based therapies in regenerative medicine and for autoimmune disorders owing to their multilineage differentiation and immunomodulatory capacities, respectively. One advantage of ASC-based therapy lies in their immunosuppressive potential. However, how to get ASCs to provide consistent immunosuppression remains unclear. In the current study, we found that miR-129-5p was induced in ASCs treated with inflammatory factors. ASCs with miR-129-5p knockdown exhibited enhanced immunosuppressive capacity, as evidenced by reduced expression of proinflammatory factors, with concurrent increased expression of inducible nitric oxide synthases (iNOS) and nitric oxide (NO) production. These cells also had an increased capacity to inhibit T cell proliferation in vitro. ASCs with miR-129-5p knockdown alleviated inflammatory bowel diseases and promoted tumor growth in vivo. Consistently, ASCs that overexpressed miR-129-5p exhibited reduced iNOS expression. Furthermore, we show that miR-129-5p knockdown in ASCs results in hyperphosphorylation of signal transducer and activator of transcription 1 (Stat1). When fludarabine, an inhibitor of Stat1 activation, was added to ASCs with miR-129-5p knockdown, iNOS mRNA and protein levels were significantly reduced. Collectively, these results reveal a new role for miR-129-5p in regulating the immunomodulatory activities of ASCs by targeting Stat1 activation. These novel insights into the mechanisms of ASC immunoregulation may lead to the consistent production of ASCs with strong immunosuppressive functions and thus better clinical utility of these cells.