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Objective@#To investigate the effect of human umbilical cord mesenchymal stem cells derived exosomes (hUC-MSC-exo) on the phenotype of peripheral blood macrophages from rabbit autoimmune dry eye and the expression of related cytokines.@*Methods@#The hUC-MSCs were isolated and characterized.Exosomes derived from hUC-MSCs were extracted by ultracentrifugation and observed directly using electronic microscopy.Specific markers of exosomes were analyzed by Western blot.Six rabbits were randomly divided into the normal control group and the dry eye group by using the random number table method, 3 rabbits for each group.Rabbit model of autoimmune dry eye was established in the dry eye group, and the lacrimal glands were collected for quantitative real-time PCR (qRT-PCR) at the 8th week.In vitro, activated peripheral blood mononuclear cells (PBMCs) from rabbit autoimmune dry eye model were incubated with hUC-MSC-exo or phosphate buffered saline (PBS). After 48 hours, cells from the hUC-MSC-exo group and the PBS control group were collected.The mRNA expression levels of related cytokine genes and subpopulation-related marker genes in macrophages were quantified by qRT-PCR.The use and care of the animals complied with Regulations for the Administration of Affair Concerning Experimental Animals by State Science and Technology Commission.This study protocol was approved by Ethic Committee of Tianjin Medical University Eye Hospital (No.TJYY20181217001). Written informed consent was obtained from each family before obtaining umbilical cord.@*Results@#Exosomes derived from hUC-MSCs had typical morphology and specific markers.qRT-PCR results showed that, the relative expression quantity of M1 macrophages phenotypic molecular nitric oxide synthase 2 (NOS2) mRNA and inflammatory factor tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) mRNA in the lachrymal organization in the dry eye model group was significantly higher than those in the normal control group (3.06±1.00 vs. 1.00±0.03, 2.77±0.72 vs. 1.01±0.02 and 1.30±0.08 vs. 1.01±0.01, respectively), the relative expression quantity of M2 macrophages phenotypic molecular arginase 1 (Arg1), CD206 and IL-10 mRNA in the lachrymal organization in the dry eye model group was significantly lower than those in the normal control group (0.55±0.07 vs. 1.00±0.00, 0.60±0.13 vs.1.00±0.00, 0.65±0.14 vs. 1.01±0.01, respectively), with significant differences between them (all at P<0.05). In vitro, the relative expression quantity of M1 macrophages phenotypic molecular NOS2 mRNA and inflammatory factor TNF-α, IL-1β mRNA in PBMCs in the hUC-MSC-exo group was significantly lower than those in the PBS control group (0.59±0.08 vs.0.98±0.03, 0.56±0.07 vs. 1.03±0.11, 0.47±0.04 vs.1.00±0.08)(all at P<0.05); the relative expression quantity of M2 macrophages phenotypic molecular Arg1, CD206 mRNA and anti-inflammatory cytokine TGF-β, IL-10 and IL-4 mRNA in PBMCs in the hUC-MSC-exo group was significantly higher than those in the PBS control group (2.13±0.28 vs. 1.10±0.17, 1.32±0.03 vs. 1.01±0.06, 1.53±0.20 vs. 1.05±0.10, 1.47±0.08 vs.0.98±0.03, 1.51±0.16 vs. 1.01±0.03), with significant differences between them (all at P<0.05).@*Conclusions@#hUC-MSC-exo can polarize peripheral blood macrophages toward immune-suppressive M2-like phenotype, inhibit the production of pro-inflammatory cytokines TNF-α and IL-1β, and meanwhile increase the expression of anti-inflammatory factors IL-10 and TGF-β.
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Objective To establish the model of autoimmune dry eye and analyze the level of cytokines and the pathological changes of autoimmune dry eye rabbits treated with human umbilical cord mesenchymal stem cells (MSCs).Methods Twentyfour female New Zealand rabbits were randomly divided into three groups:Normal control group,dry eye group and MSCs treatment group,8 cases in each group.After treated with MSCs for six weeks,the pathological changes were observed,and the expression of Th1 and Th17 cell differentiation related cytokines mRNA in lacrimal gland tissue was detected by real-time quantitative PCR.The percentage of regulatory T cells (CD4 +Foxp3 + cells) in the lacrimal gland and spleen tissues of the dry eye model group and MSCs treatment group was measured by flow cytometry.Results After treatment with MSCs for 6 weeks,HE staining from each rabbit lacrimal gland showed that,the normal control group showed no or only a few lymphocytes;The lacrimal gland cells were atrophied in the dry eye group,the distribution of lymphocyte scattered around the gland and small blood vessels;Compared with dry eye group,the lacrimal gland lymphocyte infiltration reduced in MSCs treatment group,and the cell morphology were better.Compared with dry eye group,lymphocyte infiltration and aggregation in the conjunctival conjunctiva in MSCs treatment group were significantly reduced,the epithelial structure was intact,and the degeneration and atrophy cells were rare.The expression of inflammatory factors including interferon-γ(IFN-γ),Interleukin-17 (IL-17) and transcription factor T-bet mRNA were decreased in MSCs treatment group,there were significant difference compared with dry eye group (all P ＜ 0.05);Thl7 cell associated cytokines IL-17 expression levels were decreased,but no significant difference was found between two groups (P ＞ 0.05);The expression of transcription factor RORrt mRNA in dry eye group was significantly decreased,the difference was statistically significant (P ＜ 0.05).The expression of inflammatory factors TNF-α in the lacrimal gland tissue of MSCs treatment group was significantly lower than that in the dry eye model group,while the expression of the anti-inflammatory factor TGF-β was significantly higher than that in the dry eye model group,and the differences were statistically significant (all P＜0.05).The regulatory T cells (CD4 + Foxp3 + cells) in the lacrimal gland of dry eye model group accounted for 10％ of lymphocytes was,while the treatment group accounted for 27.8％,MSCs group was significantly higher than dry eye group,the difference was statistically significant (P ＜ 0.05).Conclusion MSCs can reduce the histopathological changes of the immune dry eye,and they may have immunoregulatory effects on autoimmune dry eye.The mechanisms of immunomodulatory effects may be related to the balance of inflammatory cytokines and anti-inflammatory cytokines.
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Mesenchymal stem cells (MSCs) have good immune regulatory function,can inhibit many immune cell proliferation,direct effects on activation and proliferation of T cell,play a role in immune regulation by Treg cells or by the secretion of soluble factors regulating Thl/Th2 secretion and reaction equilibrium,inhibit the inflammation through the anti-inflammatory,regulation of cytokines expression at the same time,so reduce the expression levels of matrix metalloproteinase-2 and-9,which may promote lacrimal gland tissue damage,and thus play a role in immune regulation.MSCs can reduce the autoimmune dry eye clinical index,recovery secretion function of part lacrimal gland.This article reviews the research advances in inmmmne regulation of MSCs on autoimmune dry eye.