Inhibition of allogeneic islet graft rejection by VISTA-conjugated liposome.

The Ig superfamily member V-domain Ig-containing suppressor of T-cell activation (VISTA) is a negative regulator with broad-spectrum activities and has reported that blockade of VISTA or combination with other negative checkpoint receptors sufficiently break tumor tolerance. However, it remains unclear whether VISTA could induce allogeneic T-cell hyporesponsiveness and inhibit allograft rejection. Here we found VISTA treatment significantly inhibited lymphocyte proliferation and activation in allogeneic MLR assay through impairing SYK-VAV pathway. Interestingly, though neither VISTA protein nor VISTA-Fc fusion protein administration exerted satisfactory immunosuppressive effect on allograft survival due to their short half-life in circulation, this problem was solved by conjugating VISTA protein on liposome by biotin-streptavidin system, which markedly prolonged its circulating half-life to 60 h. With islet transplant model, administration of VISTA-conjugated liposome could markedly prolong allograft survival by inhibition of SYK-VAV pathway, thus maintained the normal blood glucose level of recipients during treatment period. The results indicate VISTA is a promising therapeutic target to treat allograft rejection of islet transplantation.

Tanshinone IIA activates autophagy to reduce liver ischemia-reperfusion injury by MEK/ERK/mTOR pathway.

Autophagy is a highly conserved cell program in eukaryotic cells, which plays an important role for cells to deal with adverse external stimuli such as ischemia-reperfusion. Tanshinone IIA (TanIIA) is well known for its protective effect on myocardial disease, and it is know that it also could regulate autophagy in different cells. As this has not yet been shown for hepatocytes, using a mice liver ischemia-reperfusion model, we detected the role of TanIIA in regulating autophagy and the subsequent protective effects on hepatocytes. Our data showed that TanIIA pretreatment could significantly enhance autophagy by the MEK/ERK/mTOR pathway in hepatocytes after liver ischemia-reperfusion, and the enhanced autophagy decreased ROS generation by clearing damaged mitochondria, providing a protective effect on liver ischemia-reperfusion. This protective effect is manifested as reduced serum enzyme levels, reduced liver tissue damage, decreased inflammatory cell infiltration, decreased inflammatory cytokines and reduced hepatocyte apoptosis. In brief, moderate TanIIA utilization might be a potential treatment approach for clinically liver ischemia-reperfusion.

Rb selectively inhibits innate IFN-ß production by enhancing deacetylation of IFN-ß promoter through HDAC1 and HDAC8.

Type I IFN production is tightly controlled by host to generate efficient viral clearance without harmful immunopathology or induction of autoimmune disorders. Epigenetic regulation of type I IFN production in innate immunity and inflammatory disorders remains to be fully understood. Several tumor suppressors have been shown to regulate immune response and inflammation. However, the non-classical functions of tumor suppressors in innate immunity and inflammatory diseases need further identification. Here we report retinoblastoma protein (Rb) deficiency selectively enhanced TLR- and virus-triggered production of IFN-ß which thus induced more IFN-α generation in the later phase of innate stimuli, but had no effect on the production of TNF, IL-6 and early phase IFN-α in macrophages. Rb1(fl/fl)Lyz2cre(+) Rb-deficient mice exhibited more resistant to lethal virus infection and more effective clearance of influenza virus. Rb selectively bound Ifnb1 enhancer region, but not the promoter of Ifna4, Tnf and Il6, by interacting with c-Jun, the component of IFN-ß enhanceosome. Then Rb recruited HDAC1 and HDAC8 to attenuate acetylation of Histone H3/H4 in Ifnb1 promoter, resulting in suppression of Ifnb1 transcription. Therefore, Rb selectively inhibits innate IFN-ß production by enhancing deacetylation of Ifnb1 promoter, exhibiting a previous unknown non-classical role in innate immunity, which also suggests a role of Rb in the regulation of type I IFN production in inflammatory or autoimmune diseases.

Pioglitazone inhibits angiotensin II-induced atrial fibroblasts proliferation via NF-κB/TGF-ß1/TRIF/TRAF6 pathway.

The exact mechanisms underlying inhibitory effects of pioglitazone (Pio) on Angiotensin II (AngII)-induced atrial fibrosis are complex and remain largely unknown. In the present study, we examined the effect of Pio on AngII-induced mice atrial fibrosis in vivo and atrial fibroblasts proliferation in vitro. In vivo study showed that AngII infusion induced atrial fibrosis and increased expressions of Toll/IL-1 receptor domain-containing adaptor inducing IFN-ß (TRIF) and tumor necrosis factor receptor associated factor 6 (TRAF6) in mice models. However, those effects could be attenuated by Pio (P<0.01). As for in vitro experiment, Pio suppressed AngII-induced atrial fibroblasts proliferation via nuclear factor-κB/transforming growth factor-ß1/TRIF/TRAF6 signaling pathway in primary cultured mice atrial fibroblasts (P<0.01). In conclusion, suppression of Pio on AngII-induced atrial fibrosis might be related to its inhibitory effects on above signaling pathway.

Tri-iodothyronine preconditioning protects against liver ischemia reperfusion injury through the regulation of autophagy by the MEK/ERK/mTORC1 axis.

BACKGROUND AND OBJECTIVES: The autophagy pathway has previously been suggested as an important protective factor in liver injury. The purpose of this study is to demonstrate the protective, autophagy-modulating effect of tri-iodothyronine (T3) on liver ischemia reperfusion injury. METHODS: Liver ischemia reperfusion was induced in male C57BL/6 mice after T3 administration. Liver function, histological damage, inflammatory infiltration, cytokine production, oxidative stress, antioxidant capacity, autophagy changing, and autophagy-associated intracellular signaling pathway were assessed to evaluate the impact of antecedent T3 treatment on ischemia reperfusion induced liver injury. RESULTS: After 70% liver ischemia reperfusion injury, mice that were preconditioned with appropriate T3 displayed significantly preserved liver function, less histological damage, less apoptosis, and enhanced antioxidant capacity. Further studies revealed that mice which were preconditioned with T3 before IR induction exhibited an increased level of autophagy mediated by MEK/ERK/mTORC1. CONCLUSIONS: Our results provide the first line of evidence indicating that antecedent T3 injection can provide protection for the liver against ischemia reperfusion induced injury by enhancing autophagy. Therefore, T3 preconditioning could be a potential therapeutic approach to prevent liver IR injury related to various clinical conditions.

TRIF promotes angiotensin II-induced cross-talk between fibroblasts and macrophages in atrial fibrosis.

AIMS: Atrial fibroblasts and macrophages have long been thought to participate in atrial fibrillation (AF). However, which specific mediator may regulate the interaction between them remains unclear. METHODS AND RESULTS: We provided the evidence for the involvement of Toll/IL-1 receptor domain-containing adaptor inducing IFN-ß (TRIF), an important inflammation-related molecule, in the pathophysiology of AF. Patients with AF showed higher levels of angiotensin II (AngII) and TRIF expression and larger number of macrophages infiltration in left atria appendage than individuals with sinus rhythm (SR). In the cell study, AngII induced chemokines expressions in mouse atrial fibroblasts and AngII-stimulated atrial fibroblasts induced the chemotaxis of macrophages, which were reduced by losartan and TRIF siRNA. Meanwhile, AngII-stimulated atrial fibroblasts proliferation was enhanced by macrophages. CONCLUSIONS: Our data demonstrated that TRIF may be a crucial factor promoting the interaction between atrial fibroblasts and macrophages, leading to atrial fibrosis.

Inhibition of glycogen synthase kinase 3 ameliorates liver ischemia/reperfusion injury via an energy-dependent mitochondrial mechanism.

BACKGROUND & AIMS: The mechanisms of glycogen synthase kinase-3 (GSK-3)-mediated cytoprotection during liver ischemia/reperfusion (I/R) remain controversial, particularly in older organs. This study explores the role and potential mechanisms of GSK-3 in young and aging livers. METHODS: A rodent partial warm I/R model was used to evaluate the therapeutic potential of GSK-3 modulation during hepatic I/R in young and aging Sprague-Dawley rats. RESULTS: GSK-3 inhibition through IPC or SB216763 (SB21) preconditioning protected young rats from I/R-induced liver injury. This protection was absent in old animals but could be restored by glucose infusion prior to the I/R insult. The protection conferred by GSK-3 inhibition depended on mitochondrial metabolism regulation. Indeed, the inhibition of GSK-3 suppressed mitochondrial permeability transition pore (MPTP) opening, triggering mitohormesis in young animals, whereas insufficient fuel suppressed mitochondrial metabolism and inactivated the GSK-3-related protection in old animals. SB21 and glucose reactivated the mitochondrial F0F1-ATPase and subsequent protective cascades in the senescent liver. These effects were antagonized by an ATPase inhibitor and by an MPTP opener. CONCLUSIONS: The protection conferred by GSK-3 inhibition during hepatic I/R insult is energy dependent, particularly in senescent livers. These findings demonstrate a key role for GSK-3-related mitochondrial energy homeostasis, which may shed new light on the clinical use of GSK-3 inhibitors to protect liver function in surgical settings, particularly for older patients.

Causal relationship between circulating cytokines and follicular lymphoma: a two-sample Mendelian randomization study.

Follicular lymphoma (FL), derived from germinal centre (GC) B cells, is a kind of systemic neoplasm. Even though FL is indolent, it remains an incurable haematology Neoplasm. Accumulating evidence has suggested that the circulating cytokine is associated with the development of FL, yet the causal relationship between FL and circulating cytokines remains undetermined. Therefore, we conducted a two-sample Mendelian randomization (MR) to confirm the causal link between FL and levels of circulating cytokines with the use of summary data on circulating cytokines and FL. All these data from genome-wide association study were derived from the Genome-wide pQTL mapping which contains 14,824 individuals. FL data were acquired exclusively from FinnGen, where 218,792 individuals (522 cases vs. 218,270 controls) were involved. Various statistical methods, including the inverse variance weighted method (IVW), weighted median (WME), simple model, weighted model (WM) and MR-Egger, were used to evaluate the potential causal connection between circulating cytokines and FL. Sensitivity analysis, which involves the examination of the heterogeneity, pleiotropy, and leave-one-out method, was also performed to ensure more trustworthy results. A bidirectional MR test was performed to evaluate the direction of causal association between circulating cytokines and FL. Combining all the steps of MR analysis, we revealed four causal cytokines: C-X-C motif chemokine ligand 5 (CXCL5), interleukin-15 receptor A (IL15RA), interleukin-20 (IL20), and neurotrophin-3 (NT-3). The risk of FL may be inversely linked to CXCL5 (OR=0.73, CI: 0.545-0.979, P=0.036), IL-15RA (OR=0.669, CI: 0.451-0.993, P=0.046), and IL-20 (OR=0.565, CI: 0.325-0.981, P=0.043) but positively linked to NT-3 (OR=1.872, CI: 1.063-3.297, P=0.03). In addition, in our study, no causal effect of FL on cytokines was demonstrated and no significant heterogeneity and pleiotropy were found. Our research revealed the causal relationship between cytokines and FL, along with both the anti-protective effect of CXCL5, IL-15RA, and IL-20 and the protective effect of neurotrophin-3 on FL. These findings aim to provide new clues regarding the pathogenesis of FL and to extend the potential of circulating cytokines to therapeutic interventions.

Beneficial effects of pioglitazone on atrial structural and electrical remodeling in vitro cellular models.

It has been demonstrated that atrial remodeling contributes toward atrial fibrillation (AF) maintenance and angiotensin II (AngII) is involved in the pathogenesis of atrial remodeling. Peroxisome proliferator-activated receptor-γ (PPAR-γ) agonists have been shown to inhibit atrial remodeling. However, the underlying mechanisms are poorly understood. In the present study we investigated the regulating effects of PPAR-γ agonist on AngII-induced atrial structural and electrical remodeling in vitro cellular models. The effects of pioglitazone on AngII-induced connective tissue growth factor (CTGF) expression and cell proliferation were assessed in primary-cultured mouse atrial fibroblasts. The influences of pioglitazone on AngII-induced L-type calcium channel (ICa-L) α1c expression and current density were evaluated in atrial myocytes (HL-1). Pioglitazone attenuated AngII-induced CTGF expression and proliferation in atrial fibroblasts, and pioglitazone also inhibited the expression or phosphorylation of AngII-induced transforming growth factor-ß1 (TGF-ß1), tumor necrosis factor receptor associated factor 6 (TRAF6), TGF-ß-associated kinase 1 (TAK1) and Smad2/3. In HL-1 cells, pioglitazone suppressed AngII-induced ICa-L α1c expression and current density as well as CAMP responsive element binding protein (CREB) phosphorylation. Besides, pioglitazone inhibited AngII-induced production of AngII type I receptor (AT1R) and downregulation of PPAR-γ in both atrial fibroblasts and HL-1 cells. In conclusion, Pioglitazone suppresses AngII-induced CTGF expression and proliferation in atrial fibroblasts, which might be at least in part related with its inhibitory effects on TGF-ß1/Smad2/3 and TGF-ß1/TRAF6/TAK1 signaling pathways. Moreover, pioglitazone also attenuates AngII-induced ICa-L remodeling in HL-1 cells, which might be at least in part associated with its inhibitory effect on CREB phosphorylation. It is suggested that PPAR-γ agonist may have potential applications in preventing atrial remodeling.

MicroRNA-185 suppresses proliferation, invasion, migration, and tumorigenicity of human prostate cancer cells through targeting androgen receptor.

Previous studies have shown that androgen receptor (AR) is involved in the progression of prostate cancer (CaP) by several mechanisms. However, how AR is regulated has not been fully understood. In this study, miR-185 was found to be down-regulated in clinical CaP samples. Targets prediction revealed that AR had putative complementary sequences to miR-185, which was confirmed by the following dual luciferase reporter assay. Overexpression of miR-185 could reduce the expression of AR protein but not mRNA in LNCaP cells. The proliferation of LNCaP cells was inhibited by overexpression of miR-185. Cell cycle analysis revealed cell cycle arrest at G0/G1 phase. The invasive and migration abilities of cells could also be suppressed by miR-185. Furthermore, miR-185 inhibited tumorigenicity in a CaP xenografts model. CDC6, one target of AR and an important regulatory molecule for cell cycle, was found to be down-regulated by overexpression of miR-185. Our findings suggest that miR-185 could function as a tumor-suppressor gene in CaP by directly targeting AR, and act as a potential therapeutic target for CaP.

Angiotensin II increases CTGF expression via MAPKs/TGF-ß1/TRAF6 pathway in atrial fibroblasts.

The activation of transforming growth factor-ß1(TGF-ß1)/Smad signaling pathway and increased expression of connective tissue growth factor (CTGF) induced by angiotensin II (AngII) have been proposed as a mechanism for atrial fibrosis. However, whether TGFß1/non-Smad signaling pathways involved in AngII-induced fibrogenetic factor expression remained unknown. Recently tumor necrosis factor receptor associated factor 6 (TRAF6)/TGFß-associated kinase 1 (TAK1) has been shown to be crucial for the activation of TGF-ß1/non-Smad signaling pathways. In the present study, we explored the role of TGF-ß1/TRAF6 pathway in AngII-induced CTGF expression in cultured adult atrial fibroblasts. AngII (1 µM) provoked the activation of P38 mitogen activated protein kinase (P38 MAPK), extracellular signal-regulated kinase 1/2(ERK1/2) and c-Jun NH(2)-terminal kinase (JNK). AngII (1 µM) also promoted TGFß1, TRAF6, CTGF expression and TAK1 phosphorylation, which were suppressed by angiotensin type I receptor antagonist (Losartan) as well as p38 MAPK inhibitor (SB202190), ERK1/2 inhibitor (PD98059) and JNK inhibitor (SP600125). Meanwhile, both TGFß1 antibody and TRAF6 siRNA decreased the stimulatory effect of AngII on TRAF6, CTGF expression and TAK1 phosphorylation, which also attenuated AngII-induced atrial fibroblasts proliferation. In summary, the MAPKs/TGFß1/TRAF6 pathway is an important signaling pathway in AngII-induced CTGF expression, and inhibition of TRAF6 may therefore represent a new target for reversing Ang II-induced atrial fibrosis.

Flurbiprofen, a cyclooxygenase inhibitor, protects mice from hepatic ischemia/reperfusion injury by inhibiting GSK-3ß signaling and mitochondrial permeability transition.

Flurbiprofen acts as a nonselective inhibitor for cyclooxygenases (COX-1 and COX-2), but its impact on hepatic ischemia/reperfusion (I/R) injury remains unclear. Mice were randomized into sham, I/R and flurbiprofen (Flurb) groups. The hepatic artery and portal vein to the left and median liver lobes were occluded for 90 min and unclamped for reperfusion to establish a model of segmental (70%) warm hepatic ischemia. Pretreatment of animals with flurbiprofen prior to I/R insult significantly decreased serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH), and prevented hepatocytes from I/R-induced apoptosis/necrosis. Moreover, flurbiprofen dramatically inhibited mitochondrial permeability transition (MPT) pore opening, and thus prevented mitochondrial-related cell death and apoptosis. Mechanistic studies revealed that flurbiprofen markedly inhibited glycogen synthase kinase (GSK)-3ß activity and increased phosphorylation of GSK-3ß at Ser9, which, consequently, could modulate the adenine nucleotide translocase (ANT)-cyclophilin D (CyP-D) complex and the susceptibility to MPT induction. Therefore, administration of flurbiprofen prior to hepatic I/R ameliorates mitochondrial and hepatocellular damage through inhibition of MPT and inactivation of GSK-3ß, and provides experimental evidence for clinical use of flurbiprofen to protect liver function in surgical settings in addition to its conventional use for pain relief.

Hepatic microenvironment programs hematopoietic progenitor differentiation into regulatory dendritic cells, maintaining liver tolerance.

The liver has been generally considered an organ prone to tolerance induction and maintenance. However, whether and how the unique liver microenvironment contributes to tolerance maintenance is largely unknown. Here, we used liver fibroblastic stromal cells to mimic the liver microenvironment and found that liver stroma could induce Lin(-)CD117(+) progenitors to differentiate into dendritic cells (DCs) with low CD11c, MHC II but high CD11b expression, high IL-10, but low IL-12 secretion. Such regulatory DCs could inhibit T-cell proliferation in vitro and in vivo, induce apoptosis of the activated T cells, and alleviate the damage of autoimmune hepatitis. Furthermore, liver stroma-derived macrophage colony-stimulating factor (M-CSF) was found to contribute to the generation of such regulatory DCs. Regulatory DC-derived PGE2 and T cell-derived IFN-gamma were responsible for the regulatory function. The natural counterpart of regulatory DCs was phenotypically and functionally identified in the liver. Importantly, Lin(-)CD117(+) progenitors could be differentiated into regulatory DCs in the liver once transferred into the liver. Infusion with liver regulatory DCs alleviated experimental autoimmune hepatitis. Therefore, we demonstrate that the liver microenvironment is highly important to program progenitors to differentiate into regulatory DCs in situ, which contributes to the maintenance of liver tolerance.

[Effects of astilbin on the expression of TNF alpha and IL-10 in liver warm ischemia-reperfusion injury].

OBJECTIVES: To investigate the effects of astilbin on the expressions of TNF alpha and IL-10 during liver warm ischemia-reperfusion injury. METHODS: C57BL/ 6 mice were randomly divided into 4 groups (n = 8): sham-operated group (Sham), model control group(I/R), low dosage of astilbin treatment group (10 mg/kg) and high dosage of astilbin (40 mg/kg) treatment group. The treatment group mice were intraperitoneally injected with 10 or 40 mg/kg astilbin 24 hours and one hour before Ischemia, the hepatic ischemia-reperfusion model were thus established. After jn90 of min ischemia and 6 h reperfusion of the partial hepatic lobe, the expressions of TNF alpha and IL-10 in liver tissues collected from the experimental groups were detected by Western blot and semiquantitative RT-PCR. RESULTS: The expression of TNF alpha protein in liver tissues gradually decreased in treatment groups (low and high dosages of astilbin treatment groups) as compared to the I/R model control group. Similar results were observed in the mRNA expressions of these genes as determined by semiquantitative RT-PCR (P less than 0.05 for low dosage group; P less than 0.01 for high dosage group). Compared with the I/R model control group, the expression of IL-10 was increased in both treatment groups (low dosage group P less than 0.05; large dosage group P less than 0.01). CONCLUSION: Treatment with astilbin decreases TNF alpha expression but induces IL-10 expression in liver during warm ischemia-reperfusion injury.

Inhibition of miR-93 promotes interferon effector signaling to suppress influenza A infection by upregulating JAK1.

Type I interferons play a critical role in host defense against influenza virus infection. Interferon cascade induces the expression of interferon-stimulated genes then subsequently promotes antiviral immune responses. The microRNAs are important regulators of innate immunity, but microRNAs-mediated regulation of interferon cascade during influenza infection remains to be fully identified. Here we found influenza A virus (IAV) infection significantly inhibited miR-93 expression in alveolar epithelial type II cells through RIG-I/JNK pathway. IAV-induced downregulation of miR-93 was found to upregulate JAK1, the target of miR-93, and then feedback promote antiviral innate response by facilitating IFN effector signaling. Importantly, in vivo administration of miR-93 antagomiR markedly suppressed IAV infection, protecting mice form IAVs -associated death. Hence, the inducible downregulation of miR-93 feedback suppress IAV infection by strengthening IFN-JAK-STAT pathway via JAK1 upregulation, and in vivo inhibition of miR-93 bears considerable therapeutic potential for suppressing IAV infection.

Blocking activity of the HPV18 virus in cervical cancer cells using the CRISPR/Cas9 system.

OBJECTIVE: Specific sgRNA-sequences targeting oncogenes E6 and E7 in HPV18 were designed using the CRISPR/Cas9 system. These sgRNAs knocked out E6 and E7 expressions and were used to study their effects on the proliferation and cell cycle of the cervical cancer HeLa cell line. METHODS: Lentivirus vectors targeting E6 and E7 oncogenes were constructed and transfected into HeLa cells. mRNA and protein expression levels of E6 and E7 were measured by RT-PCR and Western blot, respectively. The cell cycle was detected by flow cytometry. A colony formation assay was applied to evaluate the proliferation capacity of the HeLa cells. RESULTS: Three E6 Cas9-sgRNA vectors targeting E6 and three E7 Cas9-sgRNA vectors targeting E7 genes were constructed and transfected into HeLa cells, respectively. RT-PCR results showed that all three E6 and E7 sgRNAs inhibited the expressions of E6 or E7 mRNA, respectively, when compared with the control groups. The inhibition ratios of the three groups of E6-sgRNAs were 28%, 85%, and 19%; the E7-sgRNAs were 86%, 25%, and 27%, respectively (P<0.05), with E6-sgRNA2 and E7-sgRNA1 having the greatest inhibitory effects. Western blot results showed that, compared with the control group, the protein expressions of E6 and E7 in the sgRNAs transfected group were also decreased, and E6-sgRNA2 and E7-sgRNA1 had the most inhibitory effects on E6 and E7 proteins. Flow cytometry results showed that the number of cells in G1/G0 was increased by 14.2% in the E6-sgRNA2 transfection group, and by 7.1% in the E7-sgRNA1 transfection group. Colony formation assay results showed that after transfection of E6 or E7 sgRNA plasmids, the HeLa cell colony was reduced significantly compared with the control group. CONCLUSIONS: The CRISPR/Cas9 system targeting HPV18 E6 or E7 genes effectively blocked the transcription and expression of oncogenes E6 or E7 in HeLa cells, which resulted in cell cycle arrest and reduced cell proliferation.

Involvement of the programmed death-1/programmed death-1 ligand pathway in CD4+CD25+ regulatory T-cell activity to suppress alloimmune responses.

BACKGROUND: Immune regulatory CD4+CD25+ T (regulatory T; Treg) cells play a vital role in the induction and maintenance of self-tolerance. They are essential for the homeostasis of T cells, the prevention of autoimmunity, and the induction of tolerance to allogeneic donor grafts. However, the underlying mechanism of their functions remains mostly elusive. Therefore, we investigated here a crucial role of Treg cells in their response to alloantigen via the programmed death (PD)-1/PD-1 ligand (PD-L1) pathway. METHODS: In vitro mixed lymphocyte reaction (MLR) assay, graft-versus-host disease (GvHD) and a skin transplantation model were used to evaluate the mechanisms of PD-1/PD-L1 pathway. RESULTS: Blockade of the PD-1/PD-L1 pathway using anti-PD-L1 monoclonal antibodies (mAb) is found to inhibit Treg cell's ability to suppress and restore CD4+CD25-T-cell proliferation in vitro. GvHD was lethal after adoptive transfer of allogeneic C57BL/6 (H-2K) spleen cells to NOD/SCID (H-2K) mice unless CD25+ T cells were also included. Strikingly, the suppression of GvHD by CD25+ cells was abrogated by anti-PD-L1 mAb administration. The abrogation of Treg-cell-mediated suppression could also be demonstrated in a Balb/c (H-2K) to B6/Rag-2KO (H-2K) skin-allograft model. CONCLUSIONS: The blockade of the PD-1/PD-L1 pathway abrogates Treg-mediated immunoregulation, thus suggesting that the PD-1/PD-L1 pathway is required for Treg suppression of the alloreactive responses of CD4+CD25-T cells. This finding has important implications for clarifying the mechanisms of allograft rejection and GvHD.

Sirtinol regulates the balance of Th17/Treg to prevent allograft rejection.

BACKGROUND: Current immunosuppressive medications used after transplantation induce significant toxicity , and a new medication regimen is needed. Based on recent research, Sirt1 exerts a proinflammatory effect on the immune response. Sirtinol is a Sirt1 inhibitor, but its impact on allograft rejection and its molecular mechanisms of action have not yet been reported. RESLUTS: In this study, we examined the effect of sirtinol on prolonging allograft survival in a mouse cervical heterotopic heart transplantation model. Based on an examination of the allograft, allografts from sirtinol-treated recipients show significantly lower levels of IL-17A expression and higher levels of Foxp3 expression. In vivo, sirtinol reduces the proportion of Th17 cells and increases the proportion of Treg cells in splenocytes from recipients. In vitro, sirtinol reduces the proportion of Th17 cells and decreases the expression of IL-17A and RORγt in an isolated CD4+ T cell population. Moreover, we identified synergistic effects of sirtinol and FK506 on prolonging allograft survival, and sirtinol synergizes with FK506 to promote Foxp3 expression. CONCLUSION: Sirtinol, a Sirt1 inhibitor, may be a promising immunosuppressive drug to prevent the rejection reaction in combination with FK506.