Temporal clinical, proteomic, histological and cellular immune responses of dextran sulfate sodium-induced acute colitis

AIM To investigate the temporal clinical, proteomic, histological and cellular immune profiles of dextran sulfate sodium(DSS)-induced acute colitis.METHODS Acute colitis was induced in C57 BL/6 female mice by administration of 1%, 2% or 3% DSS in drinking water for 7 d. Animals were monitored daily for weight loss, stool consistency and blood in the stool, while spleens and colons were harvested on day 8. A time course analysis was performed in mice ingesting 3% DSS, which included colon proteomics through multiplex assay, colon histological scoring by a blinded investigator, and immune response through flow cytometry or immunohistochemistry of the spleen, mesenteric lymph node and colon.RESULTS Progressive worsening of clinical colitis was observed with increasing DSS from 1% to 3%. In mice ingesting 3% DSS, colon shortening and increase in proinflammatory factors starting at day 3 was observed, with increased spleen weights at day 6 and day 8. This coincided with cellular infiltration in the colon from day 2 to day 8, with progressive accumulation of macrophages F4/80^+, T helper CD4^+(Th), T cytotoxic CD8^+(Tcyt) and T regulatory CD25^+(Treg) cells, and progressive changes in colonic pathology including destruction of crypts, loss of goblet cells and depletion of the epithelial barrier. Starting on day 4, mesenteric lymph node and/or spleen presented with lower levels of Treg, Th and Tcyt cells, suggesting an immune cell tropism to the gut. CONCLUSION These results demonstrate that the severity of experimental colitis is dependent on DSS concentration, correlated with clinical, proteomic, histological and cellular immune response on 3% DSS.

Intravenous vs intraperitoneal mesenchymal stem cells administration:What is the best route for treating experimental colitis?

AIM:To investigate the therapeutic effects of mesenchymal stem cells(MSCs)transplanted intraperitoneally andintravenously in a murine model of colitis.METHODS:MSCs were isolated from C57BL/6 mouse adipose tissue.MSC cultures were analyzed according to morphology,cellular differentiation potential,and surface molecular markers.Experimental acute colitis was induced in C57BL/6 mice by oral administration of2%dextran sulfate sodium(DSS)in drinking water ad libitum from days 0 to 7.Colitis mice were treated with1×106 MSCs via intraperitoneal or intravenous injection on days 2 and 5.The disease activity index was determined daily based on the following parameters:weight loss,stool consistency and presence of blood in the feces and anus.To compare morphological and functional differences in tissue regeneration between different MSC injection modalities,mice were euthanized on day 8,and their colons were examined for length,weight,and histopathological changes.Inflammatory responses were determined by measuring the levels of different serum cytokines using a CBA Th1/Th2/Th17 kit.Apoptotic rates were evaluated by terminal deoxynucleotidyl transferase-mediated d UDPbiotin nick end labeling assay.RESULTS:Intravenous infusion of MSCs was more effective than intraperitoneal treatment(P<0.001)in reducing the clinical and histopathologic severity of colitis,which includes weight loss,diarrhea and inflammation.An histological evaluation demonstrated decreased colonic inflammation based on reduced crypt loss and reduced infiltration of inflammatory cells.This therapeutic effect was most likely mediated by the down-regulation of pro-inflammatory cytokines[interleukin(IL)-6 and tumor necrosis factor(TNF)];and by the up-regulation of anti-inflammatory cytokines(IL-10 and IL-4).Intravenous transplantation alsoinduced high levels of IFN that lead to activation of the immunosuppressive activity of the MSCs,which did not occur with intraperitoneal transplantation(P=0.006).An increase in apoptotic T cells was observed after intravenous,but not intraperitoneal,MSC infusion,suggesting that MSCs can induce apoptosis in resistant T cells in colonic inflammation(P=0.027).CONCLUSION:Our results demonstrate that intravenous treatment is a superior method for reducing colon inflammation compared with intraperitoneal therapy.

Cell membrane and bioactive factors derived from mesenchymal stromal cells: Cell-free based therapy for inflammatory bowel diseases

Inflammatory bowel diseases(IBD)are chronic inflammatory disorders of the gastrointestinal tract associated with multifactorial conditions such as ulcerative colitis and Crohn’s disease.Although the underlying mechanisms of IBD remain unclear,growing evidence has shown that dysregulated immune system reactions in genetically susceptible individuals contribute to mucosal inflammation.However,conventional treatments have been effective in inducing remission of IBD but not in preventing the relapse of them.In this way,mesenchymal stromal cells(MSC)therapy has been recognized as a promising treatment for IBD due to their immunomodulatory properties,ability to differentiate into several tissues,and homing to inflammatory sites.Even so,literature is conflicted regarding the location and persistence of MSC in the body after transplantation.For this reason,recent studies have focused on the paracrine effect of the biofactors secreted by MSC,especially in relation to the immunomodulatory potential of soluble factors(cytokines,chemokines,and growth factors)and extracellular vehicles that are involved in cell communication and in the transfer of cellular material,such as proteins,lipids,and nucleic acids.Moreover,treatment with interferon-γ,tumor necrosis factor-α,and interleukin-1βcauses MSC to express immunomodulatory molecules that mediate the suppression via cell-contact dependent mechanisms.Taken together,we present an overview of the role of bioactive factors and cell membrane proteins derived from MSC as a cell-free therapy that can improve IBD treatment.

Effects of living and metabolically inactive mesenchymal stromal cells and their derivatives on monocytes and macrophages

Mesenchymal stromal cells (MSCs) are multipotent and self-renewing stem cellsthat have great potential as cell therapy for autoimmune and inflammatorydisorders, as well as for other clinical conditions, due to their immunoregulatoryand regenerative properties. MSCs modulate the inflammatory milieu by releasingsoluble factors and acting through cell-to-cell mechanisms. MSCs switch theclassical inflammatory status of monocytes and macrophages towards a nonclassicaland anti-inflammatory phenotype. This is characterized by an increasedsecretion of anti-inflammatory cytokines, a decreased release of pro-inflammatorycytokines, and changes in the expression of cell membrane molecules and inmetabolic pathways. The MSC modulation of monocyte and macrophage phenotypesseems to be critical for therapy effectiveness in several disease models, sincewhen these cells are depleted, no immunoregulatory effects are observed. Here,we review the effects of living MSCs (metabolically active cells) and metabolicallyinactive MSCs (dead cells that lost metabolic activity by induced inactivation) andtheir derivatives (extracellular vesicles, soluble factors, extracts, and microparticles)on the profile of macrophages and monocytes and the implications forimmunoregulatory and reparative processes. This review includes mechanisms ofaction exhibited in these different therapeutic appro-aches, which induce the antiinflammatoryproperties of monocytes and macrophages. Finally, we overviewseveral possibilities of therapeutic applications of these cells and their derivatives,with results regarding monocytes and macrophages in animal model studies andsome clinical trials.