Enhancement of T Follicular Helper Cell-Mediated Humoral Immunity Reponses During Development of Experimental Autoimmune Myasthenia Gravis.

Myasthenia gravis (MG) is a prototypical antibody-mediated neurological autoimmune disease with the involvement of humoral immune responses in its pathogenesis. T follicular helper (Tfh) cells have been implicated in many autoimmune diseases. However, whether and how Tfh cells are involved in MG remain unclear. Here, we established and studied a widely-used and approved animal model of human MG, the rat model with acetylcholine receptor alpha (AChRα) subunit (R-AChR97-116)-induced experimental autoimmune myasthenia gravis (EAMG). This model presented mild body-weight loss 10 days after the first immunization (representing the early stage of disease) and more obvious clinical manifestations and body-weight loss 7 days after the second immunization (representing the late stage of disease). AChR-specific pre-Tfh cells and mature Tfh cells were detected in these two stages, respectively. In co-cultures of Tfh cells and B cells, the number of IgG2b-secreting B cells and the level of anti-AChR antibodies in the supernatant were higher in the cultures containing EAMG-derived Tfh cells. In immunohistochemistry and immunofluorescence assays, a substantial number of CD4+/Bcl-6+ T cells and a greater number of larger germinal centers were observed in lymph node tissues resected from EAMG rats. Based on these results, we hypothesize that an AChR-specific Tfh cell-mediated humoral immune response contributes to the development of EAMG.

MicroRNA 182 inhibits CD4+CD25+Foxp3+ Treg differentiation in experimental autoimmune encephalomyelitis.

MicroRNA 182 has been found to have a distinct contribution in the clonal expansion of activated- and functioning of specialized-helper T cells. In this study we knocked down microRNA 182 in vivo and induced experimental autoimmune encephalomyelitis (EAE) to determine the influences of microRNA 182 in the Treg cells functional specialization through Foxo1 dependent pathway in the peripheral lymphoid organs. Down-regulation of microRNA 182 significantly increased the proportions of Foxp3+ T cells in the peripheral lymph nodes and spleen. In vivo study verified a positive correlation between microRNA 182 levels and symptom severity of EAE, and a negative correlation between microRNA 182 and the transcriptional factor Foxp3. In vitro polarization study also confirmed the contribution of Foxo1 in microRNA 182 mediated down-regulation of Foxp3+ T cells. Together, our results provide evidence that during the development of EAE, microRNA 182 repressed Treg cells differentiation through the Foxo1 dependent pathway.

Effect of ginkgolide B on brain metabolism and tissue oxygenation in severe haemorrhagic stroke.

Ginkgolide B, a diterpene, is an herbal constituent isolated from the leaves of Ginkgo biloba tree. The present study demonstrates the effect of ginkgolide B in osmotherapy on brain metabolism and tissue oxygenation. Multimodality monitoring including intracranial pressure (ICP), cerebral perfusion pressure (CPP), partial pressure of brain tissue oxygen (PbtO2), lactate/pyruvate ratio (LPR) and microdialysis were employed to study the effect of ginkgolide B osmotherapy. The results demonstrated that administration of 15% solution of ginkgolide B to the comatose patients with raised ICP (> 20 mm Hg) and resistant to standard therapy led to a significant decrease in ICP. The cerebral microdialysis was used to compare mean arterial blood pressure (MAP), ICP, CPP, PbtO2, brain lactate, pyruvate and glucose level after hourly intervals starting 3 h before and up to 4 h after hyperosmolar therapy. There was a decrease in ICP in 45 min from 23 ± 14 mm Hg (P < 0.001) to 18 ± 24 mm Hg and increase in CPP after 1 h of gingkolide B infusion from 74 ± 18 to 85 ± 22 mm Hg (P < 0.002). However there was no significant effect on MAP but PbtO2 was maintained in the range of 22-26. The peak lactate/pyruvate ratio was recorded at the time of initiation of osmotherapy (44 ± 20) with an 18% decrease over 2 h following gingkolide B therapy. Also the brain glucose remained unaffected.

Human mesenchymal stem cells increases expression of α-tubulin and angiopoietin 1 and 2 in focal cerebral ischemia and reperfusion.

Angiogenesis is associated with improved neurologic recovery after cerebral ischemia. Human bone marrow mesenchymal stem cells (hMSCs) have been successfully used to treat ischemic stroke and were shown to induce the expression of a number of neurotrophic factors including VEGF, epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) in a rat middle cerebral artery occlusion (MCAO) ischemia model. In this study, we aimed to understand the mechanism underlying the improvement of neurological function following hMSCs transplantation into MCAO rats. We established a rat MCAO model and used immunofluorescence to evaluate α-tubulin expression in the hippocampus. We used RT-PCR to determine the expression of Ang-1 and Ang-2 mRNAs after transplantation of hMSCs into MCAO rats. We showed a significant decrease in α-tubulin expression in rats with cerebral ischemia, suggesting that α-tubulin is a protective protein in cerebral ischemia Transplantation of hMSCs significantly upregulated α-tubulin levels in the hippocampus. Transplantation of hMSCs also resulted in a significant upregulation of Ang-1 and Ang-2 mRNAs in MCAO rats. Ang-2 expression was upregulated earlier than Ang-1, suggesting that (1) transplantation of hMSCs promotes angiogenesis and that (2) Ang-2 may be an initiator of angiogenesis. Our results provide a theoretical basis for the therapeutic use of hMSCs in cerebral ischemia.

All-trans-retinoic acid ameliorates experimental allergic encephalomyelitis by affecting dendritic cell and monocyte development.

Experimental allergic encephalomyelitis (EAE) can be induced in animal models by injecting the MOG35-55 peptide subcutaneously. Dendritic cells (DCs) that are located at the immunization site phagocytose the MOG35-55 peptide. These DCs mature and migrate into the nearest draining lymph nodes (dLNs), then present antigen, resulting in the activation of naive T cells. T helper type 1 (Th1) and Th17 cells are the primary cells involved in EAE progression. All-trans-retinoic acid (AT-RA) has been shown to have beneficial effects on EAE progression; however, whether AT-RA influences DC maturation or mediates other functions is unclear. In the present study, we showed that AT-RA led to the down-regulation of MHC class II, CD80 (B7-1) and CD86 (B7-2) expressed on the surface of DCs that were isolated from dLNs or spleen 3 days post-immunization in an EAE model. Changes to DC function influenced Th1/Th17 subset polarization. Furthermore, the number of CD44(+) monocytes (which might trigger EAE progression) was also significantly decreased in dLNs, spleen, subarachnoid space and the spinal cord parenchyma after AT-RA treatment. These findings are the first to demonstrate that AT-RA impairs the antigen-presenting capacity of DCs, leading to down-regulation of pathogenic Th1 and Th17 inflammatory cell responses and reducing EAE severity.

Effects of IL-17A on the occurrence of lung adenocarcinoma.

The relationship between IL-17A and cancer, whether beneficial or antagonistic, continues to be a controversial issue. In this study, effects of IL-17A on lung adenocarcinoma were investigated using lung cancer cell lines, 95D and 95C. In the presence or absence of IL-17A, cell proliferation and VEGF secretion were detected. Effects of IL-17A on capillary networks and process of angiogenesis were also evaluated. In vivo, the level of IL-17A was assayed in the serum of lung adenocarcinoma patients. At the same time, slices of adenocarcinoma tissue were analyzed for expression of IL-17A, its receptor (IL-17RA), VEGF, CD4(+)-IL-17A+ cells and CD8(+)-IL-17A+ cells by immunohistochemistry and immunofluorescence assays. IL-17A did not have effect on the proliferation of 95D or 95C cells, however, the elevated expression of VEGF in supernatant of 95D or 95C cells was found to be IL-17A concentration-dependent. Supernatants from 95D or 95C cells treated with IL-17A could obviously facilitate angiogenesis, compared with IL-17A absence group (P < 0.01). Higher levels of IL-17A were detected in serum of patients with lung adenocarcinoma than healthy controls (P < 0.001). Higher positive expressions of IL-17A, IL-17RA and VEGF were confirmed in lung adenocarcinoma lesion tissues compared to pericancerous normal tissues (P < 0.001). Tnc17 cells, as well as Th17 cells were found in adenocarcinoma tissue, indicating a potential role of these cells in disease. In summary, IL-17A might affect lung adenocarcinoma by promoting angiogenesis, while the role of Tnc17 cells or Th17 cells remains to be elucidated.

Therapeutic effect of co-transplantation of neuregulin-1-transfected Schwann cells and bone marrow stromal cells on spinal cord hemisection syndrome.

The aim of this present study is to evaluate the therapeutic effect of co-transplantation of neuregulin-1-transfected Schwann cells (SCs) and bone marrow stromal cells (BMSCs) on a rat model of spinal cord hemi-section injuries (Brown-Séquard syndrome), which is relevant to human clinical spinal cord injury. Both in vivo and in vitro data we received demonstrated that co-transplantation BMSCs with NRG1-transfected SCs reduced the size of cystic cavities, promoted axonal regeneration and hind limb functional recovery in comparison with SCs or BMSCs transplantation alone or together, and this treatment could provide important insights into potential therapies of spinal cord hemi-section injuries.

Calcium-sensing receptors regulate cardiomyocyte Ca2+ signaling via the sarcoplasmic reticulum-mitochondrion interface during hypoxia/reoxygenation.

Communication between the SR (sarcoplasmic reticulum, SR) and mitochondria is important for cell survival and apoptosis. The SR supplies Ca2+ directly to mitochondria via inositol 1,4,5-trisphosphate receptors (IP3Rs) at close contacts between the two organelles referred to as mitochondrion-associated ER membrane (MAM). Although it has been demonstrated that CaR (calcium sensing receptor) activation is involved in intracellular calcium overload during hypoxia/reoxygenation (H/Re), the role of CaR activation in the cardiomyocyte apoptotic pathway remains unclear. We postulated that CaR activation plays a role in the regulation of SR-mitochondrial inter-organelle Ca2+ signaling, causing apoptosis during H/Re. To investigate the above hypothesis, cultured cardiomyocytes were subjected to H/Re. We examined the distribution of IP3Rs in cardiomyocytes via immunofluorescence and Western blotting and found that type 3 IP3Rs were located in the SR. [Ca2+]i, [Ca2+]m and [Ca2+]SR were determined using Fluo-4, x-rhod-1 and Fluo 5N, respectively, and the mitochondrial membrane potential was detected with JC-1 during reoxygenation using laser confocal microscopy. We found that activation of CaR reduced [Ca2+]SR, increased [Ca2+]i and [Ca2+]m and decreased the mitochondrial membrane potential during reoxygenation. We found that the activation of CaR caused the cleavage of BAP31, thus generating the pro-apoptotic p20 fragment, which induced the release of cytochrome c from mitochondria and the translocation of bak/bax to mitochondria. Taken together, these results reveal that CaR activation causes Ca2+ release from the SR into the mitochondria through IP3Rs and induces cardiomyocyte apoptosis during hypoxia/reoxygenation.

The effect of electroacupuncture on T cell responses in rats with experimental autoimmune encephalitis.

Successive electroacupuncture (EA) stimulation on Zusanli ST36 acupoints of rats with experimental autoimmune encephalitis (EAE), which is an inflammatory disease mediated by autoreactive T cells, relieved disease severity, inhibited specific T cell proliferation and rebuilt the CD4+ T cell subset balance. In addition, EA-treated rats had significantly higher ACTH concentrations in vivo compared to untreated EAE rats. These results indicated that EA stimulation could relieve the severity of EAE by restoring balance to the Th1/Th2/Th17/Treg Th cell subset responses by stimulating the hypothalamus to increase ACTH secretion.

MMP-mediated cleavage of beta-dystroglycan in myelin sheath is involved in autoimmune neuritis.

Alpha-/beta-dystroglycans (DG) located at the outmost layer of myelin sheath play a critical role in its formation and stability in the peripheral nerve system. The demyelination of nerve fibers is present in autoimmune neuritis, however, it is not known about the molecular mechanisms underlying this pathological process. In an animal model of experimental autoimmune neuritis, we observed that beta-DG cleavage was associated with the demyelination of peripheral nerves. The neuritis and beta-DG cleavage were accompanied by matrix metalloproteinase (MMP)-2/-9 over-expressions and attenuated by captopril, a MMP inhibitor. The blockade of MMPs also improves clinical signs. Our results reveal a crucial role of MMP-mediated beta-DG cleavage in autoimmune neuritis, such as Guillain-Barre' syndrome, and bring insights into therapeutic strategies for autoimmune diseases.

IL-17 potentiates neuronal injury induced by oxygen-glucose deprivation and affects neuronal IL-17 receptor expression.

Interleukin-17 (IL-17) is active in a variety of brain injuries, including ischemia. The objective of this study was to test the hypothesis that IL-17 potentiates neuronal injury after stroke. Increased expression of IL-17 and IL-17 receptor (IL-17R) in serum and cortex was evaluated by ELISA, RT-PCR and immunohistochemistry. In the in vitro model of oxygen-glucose deprivation (OGD), IL-17 showed a dose-dependent effect in promoting neuronal injury through IL-17-IL-17R combination which can be blocked by IL-17R/Fc chimera. Our results demonstrated the up-regulation of IL-17 and IL-17R following permanent middle cerebral artery occlusion and suggested that they contributed to stroke outcome.

A role for the parafascicular thalamic nucleus in the development of morphine dependence and withdrawal.

The parafascicular thalamic nucleus (nPf) is a critical relay in the ascending system that mediates motor control in the central nervous system (CNS). Yet, little is known about whether or not the nPf is involved in the development of morphine dependence and withdrawal. In the present study, kainic acid was used to chemically destroy the nPf in Wistar rats, and morphine dependence and withdrawal models were established. Morphine withdrawal symptoms score was evaluated in each group. An electrophysiological method was used to measure the changes in spontaneous discharge of nPf neurons. mu-Opioid receptor (MOR) mRNA level in nPf was detected using semi-quantitative RT-PCR. The ultrastructural alterations were examined by transmission electron microscopy. Results showed that the bilateral lesion of nPf had a marked influence on the development of morphine dependence and withdrawal. In order to address the mechanisms underlying, we found: (1) the average frequency and sum of nPf neurons that exhibited spontaneous discharge were increased in the morphine withdrawal group in comparison with the sham model group (P<0.05); (2) MOR mRNA level in the nPf of the morphine dependence group was decreased in comparison with that of the sham model group (1.45+/-0.38 vs. 5.37+/-0.94, P<0.01). In the morphine withdrawal group, which underwent 40 h withdrawal, the MOR mRNA level was higher than that in the morphine dependence group (2.97+/-0.73 vs. 1.45+/-0.38, P<0.05) but still lower than that in the sham model group (P<0.05); (3) the ultrastructural injuries of nPf neurons, which were in the nucleus, organelles and neuropil, were marked in the morphine dependent and withdrawal groups. Our study indicated that nPf played an important role in the development of morphine dependence and withdrawal. The results suggest that nPf may become a therapeutic target for treating morphine withdrawal syndrome.

BM stromal cells ameliorate experimental autoimmune myasthenia gravis by altering the balance of Th cells through the secretion of IDO.

In addition to their capacity to differentiate, BM stromal cells (BMSC) have immunosuppressive qualities that make them strong candidates for use in cell therapy against human autoimmune diseases. We studied the immunoregulatory activities of BMSC on experimental autoimmune myasthenia gravis (EAMG) in vitro and in vivo. Intravenous administration of syngenic BMSC to EAMG-model rats on the day of their second immunization was effective in ameliorating the pathological features of the disease. In vitro, the proliferative ability of T cells or B cells from EAMG rats was inhibited when they were cocultured with BMSC at proper ratios. This inhibitory effect was at least partially dependent on the secretion of IDO. We also determined that the development of EAMG is accompanied by an imbalance among the Th1, Th2, Th17, and Treg cell subsets, and that this can be corrected by the administration of BMSC, which leads to an increase of Th2 (IL-4) and Treg (Foxp3) cells, and a reduction of Th1 (IFN-gamma) and Th17 (IL-17) cells, through an IDO-dependent mechanism. These results provide further insights into the pathogenesis of MG, EAMG, and other immune-mediated diseases, and support a potential role for BMSC in their treatment.

Administration of bone marrow stromal cells ameliorates experimental autoimmune myasthenia gravis by altering the balance of Th1/Th2/Th17/Treg cell subsets through the secretion of TGF-beta.

Bone marrow stromal cells (BMSCs) are strong candidates for cell therapy against human autoimmune diseases. Intravenous administration of syngenic BMSCs to EAMG-model rats effectively ameliorated the disease, partially through a TGF-beta-dependent mechanism. The proliferative ability of T or B cells from EAMG rats was inhibited by BMSCs at proper cocultured ratios. And the imbalance of Th1, Th2, Th17 and Treg cell subsets accompanied with the development of EAMG was corrected by the administration of BMSCs. These results provide further insights into the pathogenesis of MG, EAMG, and other immune-mediated diseases, and support a potential role for BMSCs in their treatment.

RAGE expression is up-regulated in human cerebral ischemia and pMCAO rats.

To determine whether the receptor for advanced glycation endproducts (RAGE) contributes to cerebral ischemia, we evaluated RAGE expression in human cerebral ischemia and a model of permanent middle cerebral artery occlusion (pMCAO) in rats. Biopsy specimens were obtained from 12 patients with unilateral cerebral infarction. For the pMCAO model, the middle cerebral artery (MCA) of Sprague-Dawley (SD) rats was permanently occluded. Immunohistochemistry and Western blotting were used to measure RAGE expression in the ischemic hemisphere relative to the normal hemisphere. PC12 cells subjected to oxygen and glucose deprivation (OGD) were used to evaluate the role of RAGE in cell injury. As expected, cerebral ischemia patients expressed elevated levels of RAGE in the ischemic hemisphere. In 1 and 2 days pMCAO rats, levels of RAGE were higher in the ischemic hemisphere relative to the non-ischemic hemisphere, and expression was primarily located in the penumbra of the ischemic hemisphere. In PC12 cells, levels of RAGE increased after 7h of OGD culture. Notably, blockade of RAGE with a selective RAGE antibody in vitro reduced the cytotoxicity caused by OGD. The present data suggest that RAGE is up-regulated in human cerebral ischemia and pMCAO rats, suggesting a role for RAGE in brain ischemia.

Voriconazole into PLGA nanoparticles: improving agglomeration and antifungal efficacy.

This study is concerned with preparing PLGA nanoparticles loaded with voriconazole (PNLV), investigating the burst release and agglomeration of PNLV, and also evaluating antifungal efficacy of PNLV compared with voriconazole (VRC). The emulsion-solvent evaporation technique for nanoparticles and tests against fungi were completed. The amount of VRC in PNLV with sodium hexametaphosphate was 2.01+/-0.27%, and burst release of PNLV was reduced by about 33% using 20% ethanol solution (n=3). The mean D(50) of PNLV with or without this salt was 132.8 nm and 6.3 microm, respectively (n=5). In vitro; the fungal numbers treated with PNLV (3.5 mg/ml, equal amount calculated by VRC) and VRC (70 microg/ml) in tubes at the day 7 were 5.74 log(10) and 6.72 log(10), respectively (P<0.05). In vivo; the fungal burden treated with PNLV and VRC in tissue from mice kidneys at day 7 after administration was 0.64 log(10) and 2.61 log(10), respectively (5 mg/kg, P<0.001). The hematoxylin-eosin stain in mice kidney showed that the pathological lesions treated with PNLV were relieved in contrast with those with VRC. These results suggest that the emulsion-solvent evaporation process is feasible in preparing PNLV. Moreover, ethanol solution decreased burst release and Na-HMP inhibited agglomeration. PNLV could improve the VRC antifungal efficacy.

[Effects of bone marrow mesenchymal stem cells on the proliferation of hepatocytes and cirrhotic fat-storing cells in vitro].

OBJECTIVE: To investigate the differentiation of bone marrow mesenchymal stem cells (BMSCs) and the effects of BMSCs on the proliferation of cirrhotic fat-storing cells (CFSC) and hepatocytes in vitro. METHODS: BMSCs and hepatocytes were isolated and harvested from the bone marrow and livers of rats. A co-culture system was set up by transwell inserts in which the two chambers were separated by a semipermeable membrane. BMSCs labeled with PKH26 were cultured with hepatocytes/CFSC in the co-culture system and also in a cell-cell direct contact culture system. Anti-albumin and anti-smooth muscle alpha-actin (alpha-SMA) antibodies were tested by using fluorescence immunocytochemistry. BMSCs and hepatocytes/CFSC cultured alone served as controls. The proliferation level of hepatocytes in the co-culture system was measured. CFSC were cultured with the conditional medium of BMSCs, and their quantities were measured microscopically. RESULTS: Expression of albumin was observed in the hepatocytes of the two culture systems after they were cultured for 72 h but the albumin levels were higher in the cell-cell direct contact culture system (P<0.01). As compared to the controls, the number of hepatocytes was larger in the co-culture system (P<0.01). No expression of alpha-SMA in CFSC was observed in either culture system. The proliferation of CFSC was inhibited by the conditional medium of BMSCs. The longer the time of the co-culturing the more significant was the CFSC growth suppression (P<0.01). CONCLUSIONS: BMSCs can be induced into hepatocytes by a local micro-environment formed by hepatocytes. BMSCs may promote proliferation of hepatocytes and inhibit proliferation of CFSC.

[Immunoregulative effect of NK1.1+ cells on the development of experimental autoimmune myasthenia gravis].

AIM: To investigate the effect and immuoregulative mechanisms of NK1.1(+) cells on the development of experimental autoimmune myasthenia gravis (EAMG). METHODS: The NK1.1(+) cells were depleted by intraperitoneal (i.p.) administration of anti-mouse NK1.1 mAb to C57BL/6 mice. Mice were immunized subcutaneously with AChR in CFA. The incidence and severity of EAMG was determined according to the Lennon disease symptoms grading. IFN-gamma and IL-4 in MNCs culture medium were measured by ELISA. AChR IgG of serum was measured by radioimmunoassay. In some experiments, the anti-IFN-gamma mAb was injected (i.p.) to neutralize IFN-gamma. RESULTS: The onset of EAMG was delayed and the severity was decreased obviously in NK1.1(+) cell-depleted mice. However, depletion of NK1.1(+) cells after immunization had no impact on the development of EAMG. Depletion of NK1.1(+) cells could significantly reduce the expression of AChR-specific antibody as well as the production of IFN-gamma. The development of EAMG and production of AChR specific Ab in NK1.1(+) cell-depleted mice were decreased obviously after treating with anti-IFN-gamma antibody. CONCLUSION: NK1.1(+) cells are involved in the early EAMG, and NK1.1(+) cells could enhance the production of IFN-gamma released by AChR-specific T cells as well as the AChR-specific antibodies, which may enhance the outcome of EAMG.

[Inhibiton of experimental autoimmune encephalomyelitis in Lewis rats by nasal administration of encephalitogenic MBP peptides: synergistic effects of MBP 68-86 and 87-99].

AIM: To explore the synergistic effect of MBP 68-86 and 87-99, on the inhibition of experimental autoimmune encephalomyelitis (EAE) in Lewis rat by nasal administration. METHODS: Three different MBP peptides(MBP 68-86, 87-99, and the non-encephalitogenic peptide 110-128) were synthesized and administrated nasally to Lewis rat on day-11, -10, -9, -8 and -7 prior to immunization with the guinea pig MBP (gp-MBP)+CFA, which was used to induce EAE. The protective effect on Lewis rat from EAE by the MBP peptides was evaluated. RESULTS: Protection was achieved with the encephalitogenic peptides MBP 68-86 and 87-99, MBP 68-86 being more potent, but not with MBP 110-128. Neither MBP 68-86 nor 87-99 used alone conferred complete protection to gp-MBP-induced EAE. In contrast, nasal administration of a mixture of MBP 68-86 and 87-99 completely blocked gp-MBP-induced EAE even at lower dosage than being used alone. Rats tolerized with MBP 68-86+87-99 nasally showed decreased T cell responses to MBP, reflected by lymphocyte proliferation and IFN-gamma ELISPOT assays. Rats tolerized with MBP 68-86+87-99 also had abrogated MBP-reactive IFN-gamma and TNF-alpha mRNA expression in lymph node cells compared to rats receiving MBP 110-128 nasally, while similar low levels of MBP-reactive TGF-beta and IL-4 mRNA expressing cells were observed in the two groups. CONCLUSION: Nasal administration of encephalitogenic MBP peptides can induce antigen-specific T cell tolerance and confer incomplete protection to gp-MBP-induced EAE, and MBP 68-86 and 87-99 have synergistic effects. Non-regulatory mechanisms are proposed to be responsible for tolerance development after nasal peptide administration.

[Study on therapy of experimental autoimmune neuritis by bone marrow stromal cells].

AIM: To investigate the therapeutic effect of bone marrow stromal cells (BMSCs) transplantation on experimental autoimmune neuritis (EAN) and study the possible mechanism. METHODS: EAN model was established by immunizing Lewis rats with P(0)180-199 peptide and complete Freund's adjuvant (CFA). In the therapy group, BMSCs (2x10(6) cells/rat) were marked with fluorochrome PKH26 and injected into the rats' caudal vein 10 d after immunization. The therapeutic effect of BMSC transplantation on EAN rats was investigated by clinical assessment, immunohistochemical staining, and ELISA, respectively. RESULTS: The injected BMSCs could migrate to the demyelinated nerve tissues, and the demyelination and inflammatory infiltration was relieved. The infiltration of CD4(+) and CD8(+) T cells and the sera level of IFN-gamma and TNF-alpha were decreased significantly (P<0.05), whereas IL-4 level in the supernatant of cultured lymphocytes was increased (P<0.05). CONCLUSION: Certain therapeutic effect of BMSC transplantation on EAN was observed. BMSCs could reverse the disbalance of Th1/Th2 cells by regulating the cytokine expression and could inhibit the activation and proliferation of T cells.