Bone marrow progenitor cells do not contribute to liver fibrogenic cells

AIM:To investigate the contribution of bone marrow(BM) cells to hepatic fibrosis.METHODS:To establish a model of chimerism,C57Bl/6 female mice were subjected to full-body irradiation(7 Gy) resulting in BM myeloablation.BM mononuclear cells obtained from male transgenic mice expressing enhanced green fluorescent protein(GFP) were used for reconstitution.Engraftment was confirmed by flow cytometry.To induce liver injury,chimeric animals received carbon tetrachloride(CCl4) 0.5 mL/kg intraperitoneally twice a week for 30 d(CCl4 30 d) and age-matched controls received saline(Saline 30 d).At the end of this period,animals were sacrificed for post mortem analysis.Liver samples were stained with hematoxylin and eosin to observe liver architectural changes and with Sirius red for collagen quantification by morphometric analysis.α-smooth muscle actin(α-SMA) was analyzed by confocal microscopy to identify GFP+ cells with myofibroblast(MF) characteristics.Liver tissue,BM and peripheral blood were collected and prepared for flow cytometric analysis using specific markers for detection of hepatic stellate cells(HSCs) and precursors from the BM.RESULTS:Injury to the liver induced changes in the hepatic parenchymal architecture,as reflected by the presence of inflammatory infiltrate and an increase in collagen deposition(Saline 30 d = 11.10% ± 1.12% vs CCl4 30 d = 12.60% ± 0.73%,P = 0.0329).Confocal microscopy revealed increased reactivity against α-SMA in CCl4 30 d compared to Saline 30 d,but there was no co-localization with GFP+ cells,suggesting that cells from BM do not differentiate to MFs.Liver flow cytometric analysis showed a significant increase of CD45+/GFP+ cells in liver tissue(Saline 30 d = 3.2% ± 2.2% vs CCl4 30 d = 5.8% ± 1.3%,P = 0.0458),suggesting that this increase was due to inflammatory cell infiltration(neutrophils and monocytes).There was also a significant increase of common myeloid progenitor cells(CD117+/CD45+) in the livers of CCl4-treated animals(Saline 30 d = 2.16% ± 1.80% vs CCl4 30 d = 5.60% ± 1.30%,P = 0.0142).In addition the GFP-/CD38+/CD45-subpopulation was significantly increased in the CCl4 30 d group compared to the Saline 30 d group(17.5% ± 3.9% vs 9.3% ± 2.4%,P = 0.004),indicating that the increase in the activated HSC subpopulation was not of BM origin.CONCLUSION:BM progenitor cells do not contribute to fibrosis,but there is a high recruitment of inflammatory cells that stimulates HSCs and MFs of liver origin.? 2012 Baishideng.All rights reserved.

Brain scarring in infants:immunological insights from a neonatal hypoxic-ischemic encephalopathy model

Neonatal hypoxic-ischemic encephalopathy(HIE)is a significant cause of disability in children.Improving brain function and accelerating neurological recovery may require a combination of neuroprotective and pro-regenerative treatments at different stages of HIE.While the first hours after the neonatal insult are the most critical period for neuroprotection,the existence of secondary and tertiary mechanisms of brain injury offers the possibility of preventing delayed neurodegeneration in the subsequent days,weeks,or months(Levison et al.,2022).

Distinct T helper cell-mediated antitumor immunity:T helper 2 cells in focus

The adaptive arm of the immune system is crucial for appropriate antitumor immune responses.It is generally accepted that clusters of differentiation 4^(+)(CD4^(+))T cells,which mediate T helper(Th)1 immunity(type 1 immunity),are the primary Th cell subtype associated with tumor elimination.In this review,we discuss evidence showing that antitumor immunity and better prognosis can be associated with distinct Th cell subtypes in experimental mouse models and humans,with a focus on Th2 cells.The aim of this review is to provide an overview and understanding of the mechanisms associated with different tumor outcomes in the face of immune responses by focusing on the(1)site of tumor development,(2)tumor properties(i.e.,tumor metabolism and cytokine receptor expression),and(3)type of immune response that the tumor initially escaped.Therefore,we discuss how low-tolerance organs,such as lungs and brains,might benefit from a less tissue-destructive immune response mediated by Th2 cells.In addition,Th2 cells antitumor effects can be independent of CD8^(+)T cells,which would circumvent some of the immune escape mechanisms that tumor cells possess,like low expression of major histocompatibility-I(MHC-I).Finally,this review aims to stimulate further studies on the role of Th2 cells in antitumor immunity and briefly discusses emerging treatment options.

Monocytes in neonatal stroke and hypoxic-ischemic encephalopathy:Pathophysiological mechanisms and therapeutic possibilities

Neonatal arterial ischemic stroke(NAIS)and neonatal hypoxic-ischemic encephalopathy(HIE)are common causes of neurological impairments in infants,for which treatment options are very limited.NAIS and HIE induce an innate immune response that involves the recruitment of peripheral immune cells,including monocytes,into the brain.Monocytes and monocyte-derived cells have the potential to contribute to both harmful and beneficial pathophysiological processes,such as neuroinflammation and brain repair,but their roles in NAIS and HIE remain poorly understood.Furthermore,recent evidence indicates that monocyte-derived macrophages can persist in the brain for several months following NAIS and HIE in mice,with possible long-lasting consequences that are still unknown.This review provides a comprehensive overview of the mechanisms of monocyte infiltration and their potential functions in the ischemic brain,focusing on HIE and NAIS.Therapeutic strategies targeting monocytes and the possibility of using monocytes for cell-based therapies are also discussed.