Selective Targeting of α4ß7/MAdCAM-1 Axis Suppresses Fibrosis Progression by Reducing Proinflammatory T Cell Recruitment to the Liver.

Integrin α4ß7+ T cells perpetuate tissue injury in chronic inflammatory diseases, yet their role in hepatic fibrosis progression remains poorly understood. Here, we report increased accumulation of α4ß7+ T cells in the liver of people with cirrhosis relative to disease controls. Similarly, hepatic fibrosis in the established mouse model of CCl4-induced liver fibrosis was associated with enrichment of intrahepatic α4ß7+ CD4 and CD8 T cells. Monoclonal antibody (mAb)-mediated blockade of α4ß7 or its ligand mucosal addressin cell adhesion molecule (MAdCAM)-1 attenuated hepatic inflammation and prevented fibrosis progression in CCl4-treated mice. Improvement in liver fibrosis was associated with a significant decrease in the infiltration of α4ß7+ CD4 and CD8 T cells, suggesting that α4ß7/MAdCAM-1 axis regulates both CD4 and CD8 T cell recruitment to the fibrotic liver, and α4ß7+ T cells promote hepatic fibrosis progression. Analysis of hepatic α4ß7+ and α4ß7- CD4 T cells revealed that α4ß7+ CD4 T cells were enriched for markers of activation and proliferation, demonstrating an effector phenotype. The findings suggest that α4ß7+ T cells play a critical role in promoting hepatic fibrosis progression, and mAb-mediated blockade of α4ß7 or MAdCAM-1 represents a promising therapeutic strategy for slowing hepatic fibrosis progression in chronic liver diseases.

Chronic SIV-Induced neuroinflammation disrupts CCR7+ CD4+ T cell immunosurveillance in the rhesus macaque brain.

CD4+ T cells survey and maintain immune homeostasis in the brain, yet their differentiation states and functional capabilities remain unclear. Our approach, combining single-cell transcriptomic analysis, ATAC-Seq, spatial transcriptomics, and flow cytometry, revealed a distinct subset of CCR7+ CD4+ T cells resembling lymph node central memory (TCM) cells. We observed chromatin accessibility at the CCR7, CD28, and BCL-6 loci, defining molecular features of TCM. Brain CCR7+ CD4+ T cells exhibited recall proliferation and interleukin-2 production ex vivo, showcasing their functional competence. We identified the skull bone marrow as a local niche for these cells alongside CNS border tissues. Sequestering TCM cells in lymph nodes using FTY720 led to reduced CCR7+ CD4+ T cell frequencies in the cerebrospinal fluid, accompanied by increased monocyte levels and soluble markers indicating immune activation. In macaques chronically infected with SIVCL757 and experiencing viral rebound due to cessation of antiretroviral therapy, a decrease in brain CCR7+ CD4+ T cells was observed, along with increased microglial activation and initiation of neurodegenerative pathways. Our findings highlight a role for CCR7+ CD4+ T cells in CNS immune surveillance, and their decline during chronic SIV highlights their responsiveness to neuroinflammation.

Western diet dampens T regulatory cell function to fuel hepatic inflammation in nonalcoholic fatty liver disease.

Background and aims: The immunosuppressive T regulatory cells (Tregs) regulate immune responses and maintain immune homeostasis, yet their functions in nonalcoholic fatty liver disease (NAFLD) pathogenesis remains controversial. Methods: Mice were fed a normal diet (ND) or a western diet (WD) for 16 weeks to induce NAFLD. Diphtheria toxin injection to deplete Tregs in Foxp3 DTR mice or Treg induction therapy in WT mice to augment Treg numbers was initiated at twelve and eight weeks, respectively. Liver tissues from mice and NASH human subjects were analyzed by histology, confocal imaging, and qRT-PCR. Results: WD triggered accumulation of adaptive immune cells, including Tregs and effector T cells, within the liver parenchyma. This pattern was also observed in NASH patients, where an increase in intrahepatic Tregs was noted. In the absence of adaptive immune cells in Rag1 KO mice, WD promoted accumulation of intrahepatic neutrophils and macrophages and exacerbated hepatic inflammation and fibrosis. Similarly, targeted Treg depletion exacerbated WD-induced hepatic inflammation and fibrosis. In Treg-depleted mice, hepatic injury was associated with increased accumulation of neutrophils, macrophages, and activated T cells within the liver. Conversely, induction of Tregs using recombinant IL2/αIL2 mAb cocktail reduced hepatic steatosis, inflammation, and fibrosis in WD-fed mice. Analysis of intrahepatic Tregs from WD-fed mice revealed a phenotypic signature of impaired Treg function in NAFLD. Ex vivo functional studies showed that glucose and palmitate, but not fructose, impaired the immunosuppressive ability of Treg cells. Conclusions: Our findings indicate that the liver microenvironment in NAFLD impairs ability of Tregs to suppress effector immune cell activation, thus perpetuating chronic inflammation and driving NAFLD progression. These data suggest that targeted approaches aimed at restoring Treg function may represent a potential therapeutic strategy for treating NAFLD. Lay summary: In this study, we elucidate the mechanisms contributing to the perpetuation of chronic hepatic inflammation in nonalcoholic fatty liver disease (NAFLD). We show that dietary sugar and fatty acids promote chronic hepatic inflammation in NAFLD by impairing immunosuppressive function of regulatory T cells. Finally, our preclinical data suggest that targeted approaches aimed at restoring T regulatory cell function have the potential to treat NAFLD.

Selective targeting of α 4 ß 7 /MAdCAM-1 axis suppresses liver fibrosis by reducing proinflammatory T cell recruitment to the liver.

Integrin α 4 ß 7 + T cells perpetuate tissue injury in chronic inflammatory diseases, yet their role in hepatic fibrosis progression remains poorly understood. Here we report increased accumulation of α 4 ß 7 + T cells in the liver of people with cirrhosis relative to disease controls. Similarly, hepatic fibrosis in the established mouse model of CCl 4 -induced liver fibrosis was associated with enrichment of intrahepatic α 4 ß 7 + CD4 and CD8 T cells. Monoclonal antibody (mAb)-mediated blockade of α 4 ß 7 or its ligand mucosal addressin cell adhesion molecule (MAdCAM)-1 attenuated hepatic inflammation and prevented fibrosis progression in CCl 4 treated mice. Improvement in liver fibrosis was associated with a significant decrease in the infiltration of α 4 ß 7 + CD4 and CD8 T cells suggesting that α 4 ß 7 /MAdCAM-1 axis regulates both CD4 and CD8 T cell recruitment to the fibrotic liver, and α 4 ß 7 + T cells promote hepatic fibrosis progression. Analysis of hepatic α 4 ß 7 + and α 4 ß 7 -CD4 T cells revealed that α 4 ß 7 + CD4 T cells enriched for markers of activation and proliferation demonstrating an effector phenotype. Notably, blockade of α 4 ß 7 or MAdCAM-1 did not affect the recruitment of Foxp3+ regulatory T cells, demonstrating the specificity of α 4 ß 7 /MAdCAM-1 axis in regulating effector T cell recruitment to the liver. The findings suggest that α 4 ß 7 + T cells play a critical role in promoting hepatic fibrosis progression, and mAb-mediated blockade of α 4 ß 7 or MAdCAM-1 represents a promising therapeutic strategy for slowing hepatic fibrosis progression in chronic liver diseases.

Aldose reductase regulates hyperglycemia-induced HUVEC death via SIRT1/AMPK-α1/mTOR pathway.

Although hyperglycemia-mediated death and dysfunction of endothelial cells have been reported to be a major cause of diabetes associated vascular complications, the mechanisms through which hyperglycemia cause endothelial dysfunction is not well understood. We have recently demonstrated that aldose reductase (AR, AKR1B1) is an obligatory mediator of oxidative and inflammatory signals induced by growth factors, cytokines and hyperglycemia. However, the molecular mechanisms by which AR regulates hyperglycemia-induced endothelial dysfunction is not well known. In this study, we have investigated the mechanism(s) by which AR regulates hyperglycemia-induced endothelial dysfunction. Incubation of human umbilical vein endothelial cells (HUVECs) with high glucose (HG) decreased the cell viability and inhibition of AR prevented it. Further, AR inhibition prevented the HG-induced ROS generation and expression of BCL-2, BAX and activation of Caspase-3 in HUVECs. AR inhibition also prevented the adhesion of THP-1 monocytes on HUVECs, expression of iNOS and eNOS and adhesion molecules ICAM-1 and VCAM-1 in HG-treated HUVECs. Further, AR inhibition restored the HG-induced depletion of SIRT1 in HUVECs and increased the phosphorylation of AMPKα1 along-with a decrease in phosphorylation of mTOR in HG-treated HUVECs. Fidarestat decreased SIRT1 expression in HUVECs pre-treated with specific SIRT1 inhibitor but not with the AMPKα1 inhibitor. Similarly, knockdown of AR in HUVECs by siRNA prevented the HG-induced HUVECs cell death, THP-1 monocyte adhesion and SIRT1 depletion. Furthermore, fidarestat regulated the phosphorylation of AMPKα1 and mTOR, and expression of SIRT1 in STZ-induced diabetic mice heart and aorta tissues. Collectively, our data suggest that AR regulates hyperglycemia-induced endothelial death and dysfunction by altering the ROS/SIRT1/AMPKα1/mTOR pathway.

Aspalatone Prevents VEGF-Induced Lipid Peroxidation, Migration, Tube Formation, and Dysfunction of Human Aortic Endothelial Cells.

Although aspalatone (acetylsalicylic acid maltol ester) is recognized as an antithrombotic agent with antioxidative and antiplatelet potential; its efficacy in preventing endothelial dysfunction is not known. In this study, we examined the antiangiogenic, antioxidative, and anti-inflammatory effect of aspalatone in human aortic endothelial cells (HAECs). Specifically, the effect of aspalatone on VEGF-induced HAECs growth, migration, tube formation, and levels of lipid peroxidation-derived malondialdehyde (MDA) was examined. Our results indicate that the treatment of HAECs with aspalatone decreased VEGF-induced cell migration, tube formation, and levels of MDA. Aspalatone also inhibited VEGF-induced decrease in the expression of eNOS and increase in the expression of iNOS, ICAM-1, and VCAM-1. Aspalatone also prevented the VEGF-induced adhesion of monocytes to endothelial cells. Furthermore, aspalatone also prevented VEGF-induced release of inflammatory markers such as Angiopoietin-2, Leptin, EGF, G-CSF, HB-EGF, and HGF in HAECs. Thus, our results suggest that aspalatone could be used to prevent endothelial dysfunction, an important process in the pathophysiology of cardiovascular diseases.

Aldose reductase inhibitor increases doxorubicin-sensitivity of colon cancer cells and decreases cardiotoxicity.

Anthracycline drugs such as doxorubicin (DOX) and daunorubicin remain some of the most active wide-spectrum and cost-effective drugs in cancer therapy. However, colorectal cancer (CRC) cells are inherently resistant to anthracyclines which at higher doses cause cardiotoxicity. Our recent studies indicate that aldose reductase (AR) inhibitors such as fidarestat inhibit CRC growth in vitro and in vivo. Here, we show that treatment of CRC cells with fidarestat increases the efficacy of DOX-induced death in HT-29 and SW480 cells and in nude mice xenografts. AR inhibition also results in higher intracellular accumulation of DOX and decreases the expression of drug transporter proteins MDR1, MRP1, and ABCG2. Further, fidarestat also inhibits DOX-induced increase in troponin-I and various inflammatory markers in the serum and heart and restores cardiac function in mice. These results suggest that fidarestat could be used as adjuvant therapy to enhance DOX sensitivity of CRC cells and to reduce DOX-associated cardiotoxicity.

Aldose Reductase Mediates NLRP3 Inflammasome-Initiated Innate Immune Response in Hyperglycemia-Induced Thp1 Monocytes and Male Mice.

Despite recent studies that show oxidative stress-generated reactive oxygen species (ROS) regulate NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome-mediated innate immune response in various diabetic complications, the mechanism by which ROS activate innate immune response is not well understood. We have shown previously that aldose reductase (AR), besides reducing glucose, reduces lipid aldehydes and their glutathione conjugates and participates in various oxidative stress-induced inflammatory pathways. To understand the role of AR in ROS-induced innate immune response, we have investigated the mechanism(s) by which AR activates hyperglycemia-induced NLRP3 inflammsome-initiated innate immune response in Thp1 monocytes and in streptozotocin (STZ)-induced diabetic mice. In Thp1 monocytes, inhibition or ablation of AR prevented high-glucose-induced activation of NLRP3 inflammasome and caspase-1 and release of the innate immune cytokines interleukin (IL)-1ß and IL-18. AR inhibition in Thp1 cells also prevented the high-glucose-induced generation of ROS, influx of Ca2+, efflux of K+, and activation of Lyn, Syk, and PI3K. Furthermore, the AR inhibitor fidarestat prevented the expression of NLRP inflammasome components in STZ-induced diabetic mouse heart and aorta, and also prevented the release of various cytokines in the serum. Collectively, our data suggest that AR regulates hyperglycemia-induced NLRP3 inflammasome-mediated innate immune response by altering the ROS/Lyn/Syk/PI3K/Ca2+/K+ signals.