CD8+ T cells and IFN-γ induce autoimmune myelofibrosis in mice.

Myelofibrosis usually occurs either as a part of a myelodysplastic syndrome or in conjunction with neoplasia. It is not commonly thought of an autoimmune disease. We reported that p40-/-IL-2Rα-/- (interleukin-12p40 and interleukin-2 receptor alpha double knockout) mice, a mouse model of human primary biliary cholangitis, exhibited features consistent with autoimmune myelofibrosis, including anemia associated with bone marrow fibrosis, and extramedullary hematopoiesis (EMH) including LSK (Lineage-c-Kit+Sca-1+) cells in spleen, liver and peripheral blood. There were also increased LSK cells in bone marrow but they demonstrated impaired hematopoiesis. Importantly effector memory T cells that infiltrated the bone marrow of p40-/-IL-2Rα-/- mice manifested a higher ability to produce IFN-γ. CD8+ T cells, already known to play a dominate role in portal inflammation, were also key for bone marrow dysregulation and EMH. IFN-γ was the key cytokine that induced bone marrow fibrosis, bone marrow failure and EMH. Finally anti-CD8α antibody therapy fully protected p40-/-IL-2Rα-/- mice from autoimmune myelofibrosis. In conclusion, our results demonstrate that CD8+ T cells and IFN-γ are associated with autoimmune myelofibrosis, a finding that may allow targeting of CD8+ T cells and IFN-γ as a therapeutic targets.

Block of both TGF-ß and IL-2 signaling impedes Neurophilin-1+ regulatory T cell and follicular regulatory T cell development.

Understanding the mechanisms that lead to autoimmunity is critical for defining potential therapeutic pathways. In this regard there have been considerable efforts in investigating the interacting roles of TGF-ß and IL-2 on the function regulatory T cells. We have taken advantage of dnTGF-ßRII Il2ra-/- (abbreviated as Il2ra-/-Tg) mouse model, which allows a direct mechanistic approach to define the relative roles of TGF-ß and IL-2 on Treg development. Il2ra-/-Tg mice spontaneously developed multi-organ autoimmune diseases with expansion of pathogenic T cells and enhanced germinal center response at 3-4 weeks of age. Importantly, peripheral Treg cells from Il2ra-/-Tg mice demonstrated an activated Th1-like stable phenotype and normal in vitro suppressive function, while thymus Treg increased but manifested decreased suppressive function. Interestingly, neither thymus nor peripheral Treg cells of Il2ra-/-Tg mice contained Neuropilin-1+ or PD-1hi phenotype, resulting in defective follicular regulatory T (Tfr) cell development. Such defective Tfr development led to elevated follicular T helper cells, enhanced germinal center responses and increased plasma cell infiltration. These data demonstrate an important synergetic role of TGF-ß and IL-2 in the generation, activation and stability of Treg cells, as well as their subsequent development into Tfr cells.

Forkhead Box O1 Regulates Macrophage Polarization Following Staphylococcus aureus Infection: Experimental Murine Data and Review of the Literature.

The functions of macrophages that lead to effective host responses are critical for protection against Staphylococcus aureus. Deep tissue-invading S. aureus initially countered by macrophages trigger macrophage accumulation and induce inflammatory responses through surface receptors, especially toll-like receptor 2 (TLR2). Here, we found that macrophages formed sporadic aggregates in the liver during infection. Within those aggregates, macrophages co-localized with T cells and were indispensable for their infiltration. In addition, we have focused on the mechanisms underlying the polarization of macrophages in Forkhead box transcription factor O1 (FoxO1) conditional knockout Lys Cre/+ FoxO1 fl/fl mice following S. aureus infection and report herein that macrophage M1-M2 polarization via TLR2 is intrinsically regulated by FoxO1. Indeed, for effective FoxO1 activity, stimulation of TLR2 is essential. However, following S. aureus challenge, there was a decrease in macrophage FoxO1, with increased phosphorylation of FoxO1 because of TLR2-mediated activation of PI3K/Akt and c-Raf/MEK/ERK pathway. Following infection in Lys Cre/+ FoxO1 fl/fl mice, mice became more susceptible to S. aureus with reduced macrophage aggregation in the liver and attenuated Th1 and Th17 responses. FoxO1 abrogation reduced M1 pro-inflammatory responses triggered by S. aureus and enhanced M2 polarization in macrophages. In contrast, overexpression of FoxO1 in macrophages increased pro-inflammatory mediators and functional surface molecule expression. In conclusion, macrophage FoxO1 is critical to promote M1 polarization and maintain a competent T cell immune response against S. aureus infection in the liver. FoxO1 regulates macrophage M1-M2 polarization downstream of TLR2 dynamically through phosphorylation.

Role of the heme oxygenase/carbon monoxide pathway in the pathogenesis and prevention of hepatic encephalopathy.

Hepatic encephalopathy (HE) is a severe complication of liver cirrhosis and its pathogenesis has yet to be fully elucidated. Previous studies have demonstrated that heme oxygenase-1 (HO-1) is important in the induction of liver cirrhosis. The present study aimed to investigate the role of HO-1 in the pathogenesis of HE. Rats were divided into 5 treatment groups; sham, bile duct ligation (BDL), HE, zinc protoporphyrin (ZnPP) and cobalt protoporphyrin (CoPP). The levels of HO-1 were examined by western blotting and quantitative real-time PCR (qRT-PCR). Serum levels of carboxyhemoglobin (COHb), ammonia levels in the plasma and brain, brain water content and portal vein pressure (PVP) were also quantified. Aquaporin-4 expression levels were measured by immunohistochemistry and qRT-PCR. The results demonstrated that the levels of HO-1 in the brain and the serum levels of COHb were significantly increased in the HE group compared with the BDL group. Brain water content, PVP and ammonia levels in the plasma and brain were increased in the HE and CoPP groups; however, these were reduced following the treatment with ZnPP. The levels of AQP-4 expression and oxidative stress in the brain were reduced following treatment with ZnPP and increased following treatment with CoPP. In conclusion, following the inhibition of HO-1 expression, treatment with ZnPP improved HE due to reducing the expression levels of AQP-4 and oxidative stress. Therefore, ZnPP treatment may represent a novel therapeutic approach for HE.