Integrated transcriptomic landscape of the effect of anti-steatotic treatments in high-fat diet mouse models of non-alcoholic fatty liver disease.

High-fat diet (HFD) mouse models are widely used in research to develop medications to treat non-alcoholic fatty liver disease (NAFLD), as they mimic the steatosis, inflammation, and hepatic fibrosis typically found in this complex human disease. The aims of this study were to identify a complete transcriptomic signature of these mouse models and to characterize the transcriptional impact exerted by different experimental anti-steatotic treatments. For this reason, we conducted a systematic review and meta-analysis of liver transcriptomic studies performed in HFD-fed C57BL/6J mice, comparing them with control mice and HFD-fed mice receiving potential anti-steatotic treatments. Analyzing 21 studies broaching 24 different treatments, we obtained a robust HFD transcriptomic signature that included 2,670 differentially expressed genes and 2,567 modified gene ontology biological processes. Treated HFD mice generally showed a reversion of this HFD signature, although the extent varied depending on the treatment. The biological processes most frequently reversed were those related to lipid metabolism, response to stress, and immune system, whereas processes related to nitrogen compound metabolism were generally not reversed. When comparing this HFD signature with a signature of human NAFLD progression, we identified 62 genes that were common to both; 10 belonged to the group that were reversed by treatments. Altered expression of most of these 10 genes was confirmed in vitro in hepatocytes and hepatic stellate cells exposed to a lipotoxic or a profibrogenic stimulus, respectively. In conclusion, this study provides a vast amount of information about transcriptomic changes induced during the progression and regression of NAFLD and identifies some relevant targets. Our results may help in the assessment of treatment efficacy, the discovery of unmet therapeutic targets, and the search for novel biomarkers. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Understanding the implication of autophagy in the activation of hepatic stellate cells in liver fibrosis: are we there yet?

Liver fibrosis (LF) occurs as a result of persistent liver injury and can be defined as a pathologic, chronic, wound-healing process in which functional parenchyma is progressively replaced by fibrotic tissue. As a phenomenon involved in the majority of chronic liver diseases, and therefore prevalent, it exerts a significant impact on public health. This impact becomes even more patent given the lack of a specific pharmacological therapy, with LF only being ameliorated or prevented through the use of agents that alleviate the underlying causes. Hepatic stellate cells (HSCs) are fundamental mediators of LF, which, activated in response to pro-fibrotic stimuli, transdifferentiate from a quiescent phenotype into myofibroblasts that deposit large amounts of fibrotic tissue and mediate pro-inflammatory effects. In recent years, much effort has been devoted to understanding the mechanisms through which HSCs are activated or inactivated. Using cell culture and/or different animal models, numerous studies have shown that autophagy is enhanced during the fibrogenic process and have provided specific evidence to pinpoint the fundamental role of autophagy in HSC activation. This effect involves - though may not be limited to - the autophagic degradation of lipid droplets. Several hepatoprotective agents have been shown to reverse the autophagic alteration present in LF, but clinical confirmation of these effects is pending. On the other hand, there is evidence that implicates autophagy in several anti-fibrotic mechanisms in HSCs that stimulate HSC cell cycle arrest and cell death or prevent the generation of pro-fibrotic mediators, including excess collagen accumulation. The objective of this review is to offer a comprehensive analysis of published evidence of the role of autophagy in HSC activation and to provide hints for possible therapeutic targets for the treatment and/or prevention of LF related to autophagy. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Pharmacology and safety of tofacitinib in ulcerative colitis. / Farmacología y seguridad de tofacitinib en colitis ulcerosa.

The use of Janus kinase (JAK) inhibitors is a new approach in the therapy of inflammatory diseases with immune base. Tofacitinib is one of these inhibitors targeting JAK1 and JAK3, and its efficacy has been demonstrated in the treatment of moderate to severe ulcerative colitis (UC). It is a small synthetic molecule administered orally, with a fast bioavailability and elimination rate, predictable pharmacokinetics and lack of immunogenicity, which are convenient characteristics for both efficacy and safety. This article reviews the pharmacological characteristics of tofacitinib and its safety profile.

Rilpivirine attenuates liver fibrosis through selective STAT1-mediated apoptosis in hepatic stellate cells.

OBJECTIVE: Liver fibrosis constitutes a major health problem worldwide due to its rapidly increasing prevalence and the lack of specific and effective treatments. Growing evidence suggests that signalling through cytokine-activated Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathways regulates liver fibrosis and regeneration. Rilpivirine (RPV) is a widely used anti-HIV drug not reported to produce hepatotoxicity. We aimed to describe the potential hepatoprotective effects of RPV in different models of chronic liver injury, focusing on JAK-STAT signalling regulation. DESIGN: The effects of RPV on hepatic steatosis, inflammation and fibrogenesis were studied in a nutritional mouse model of non-alcoholic fatty liver disease, carbon tetrachloride-induced fibrosis and bile duct ligation-induced fibrosis. Primary human hepatic stellate cells (hHSC) and human cell lines LX-2 and Hep3B were used to investigate the underlying molecular mechanisms. RESULTS: RPV exerted a clear anti-inflammatory and antifibrotic effect in all the in vivo models of liver injury employed, and enhanced STAT3-dependent proliferation in hepatocytes and apoptosis in HSC through selective STAT1 activation. These results were reproduced in vitro; RPV undermined STAT3 activation and triggered STAT1-mediated pathways and apoptosis in HSC. Interestingly, this selective pro-apoptotic effect completely disappeared when STAT1 was silenced. Conditioned medium experiments showed that HSC apoptosis activated STAT3 in hepatocytes in an interleukin-6-dependent mechanism. CONCLUSION: RPV ameliorates liver fibrosis through selective STAT1-dependent induction of apoptosis in HSC, which exert paracrinal effects in hepatocytes, thus promoting liver regeneration. RPV's actions may represent an effective strategy to treat chronic liver diseases of different aetiologies and help identify novel therapeutic targets.

Leukocyte-Endothelium Interaction Is Associated with Fat Mass in Children.

OBJECTIVE: To study leukocyte-endothelium interaction, a measure of the initial phase of atheromatosis, in children with overweight or obesity. STUDY DESIGN: A prospective study was conducted in 77 children aged 7-16 years; 47 were children with overweight/obesity and 30 were normal weight. Polymorphonuclear neutrophils (PMNs) and peripheral blood mononuclear cells were isolated from venous blood samples and the interaction of leukocytes over a monolayer of human umbilical vein endothelial cells was analyzed using flow chamber microscopy. The variables studied included leukocyte rolling velocity, rolling flux, and adhesion to endothelial cells. These were compared between children with overweight/obesity and control children. Correlation between the measures of leukocyte-endothelium interaction and anthropometric and biochemical variables was evaluated. RESULTS: In comparison with normal weight children, the PMNs and peripheral blood mononuclear cells of the overweight/obesity group showed a reduction in rolling velocity (P = .000 and P = .001, respectively) and an increase in rolling flux (P = .001 and P = .004), and adhesion (P = .003 and P = .002). The homeostasis model of insulin resistance was correlated inversely with rolling velocity and positively with rolling flux in PMNs. C-reactive protein was correlated positively with rolling flux and adhesion in both types of leucocytes. Fat mass index was correlated with all measures of leukocyte-endothelial interaction and proved to be the main predictor of leukocyte adhesion in the multiple regression analysis (P = .001 for PMNs and P = .006 for peripheral blood mononuclear cells). CONCLUSIONS: Excess fat mass in children is related to the activation of the leukocyte-endothelium interaction, potentially contributing to the development of atherosclerosis.

Abacavir Induces Arterial Thrombosis in a Murine Model.

Background: The purinergic system is known to underlie prothrombotic and proinflammatory vascular programs, making the profile of experimental actions demonstrated by abacavir compatible with thrombogenesis. However, direct evidence of a prothrombotic effect by the drug has been lacking. Methods: The present study appraised the effects of abacavir in a well-validated animal model of arterial thrombosis. The role of ATP-P2X7 receptors in the actions of the drug was also assessed, and the actions of recognized vascular-damaging agents and other nucleoside reverse-transcriptase inhibitors (NRTIs) were evaluated and compared to those of abacavir. Results: Abacavir dose-dependently promoted thrombus formation. This effect was reversed by a P2X7-receptor antagonist and was nonexistent in P2X7 knockout mice. The effects of abacavir were similar to those of diclofenac and rofecoxib. Other NRTIs had no thrombosis-related effects. Conclusion: Abacavir promotes arterial thrombosis through interference with purinergic signaling, suggesting a possible biological mechanism for the clinical association of abacavir with cardiovascular diseases.

The purine analogues abacavir and didanosine increase acetaminophen-induced hepatotoxicity by enhancing mitochondrial dysfunction.

BACKGROUND: NRTIs are essential components of HIV therapy with well-documented, long-term mitochondrial toxicity in hepatic cells, but whose acute effects on mitochondria are unclear. As acetaminophen-induced hepatotoxicity also involves mitochondrial interference, we hypothesized that it would be exacerbated in the context of ART. METHODS: We evaluated the acute effects of clinically relevant concentrations of the most widely used NRTIs, alone or combined with acetaminophen, on mitochondrial function and cellular viability. RESULTS: The purine analogues abacavir and didanosine produced an immediate and concentration-dependent inhibition of oxygen consumption and complex I and III activity. This inhibition was accompanied by an undermining of mitochondrial function, with increased production of reactive oxygen species and reduction of mitochondrial membrane potential and intracellular ATP levels. However, this interference did not compromise cell survival. Co-administration with concentrations of acetaminophen below those considered hepatotoxic exacerbated the deleterious effects of both compounds on mitochondrial function and compromised cellular viability, showing a clear correlation with diminished glutathione levels. CONCLUSIONS: The simultaneous presence of purine analogues and low concentrations of acetaminophen significantly potentiates mitochondrial dysfunction, increasing the risk of liver injury. This new mechanism is relevant given the liver's susceptibility to mitochondrial dysfunction-related toxicity and the tendency of the HIV infection to increase oxidative stress.

Involvement of nitric oxide in the mitochondrial action of efavirenz: a differential effect on neurons and glial cells.

The anti-human immunodeficiency virus (HIV) drug efavirenz (EFV) alters mitochondrial function in cultured neurons and glial cells. Nitric oxide (NO) is a mediator of mitochondrial dysfunction associated with HIV central nervous system symptoms. We show that EFV promotes inducible nitric oxide synthase (iNOS) expression in cultured glial cells and generated NO undermines their mitochondrial function, as inhibition of NOS partially reverses this effect. EFV inhibits mitochondrial Complex I in both neurons and glia; however, when the latter cells are treated for longer periods, other mitochondrial complexes are also affected in accordance with the increased NO production. These findings shed light on the mechanisms responsible for the frequent EFV-associated neurotoxicity.

Heat Stress Induces Extended Plateau of Hsp70 Accumulation--A Possible Cytoprotection Mechanism in Hepatic Cells.

The relevance of heat preconditioning resides in its ability to protect cells from different kinds of injury by induction of heat shock proteins, a process in which the intensity of heat stress (HS) and duration of subsequent recovery are vital. This study evaluates the effects of moderate HS (45 min/43°C) and the time-dependent changes during recovery period of HSP70, Bcl-2 and p53 gene and protein expression in HepG2 cells. We also evaluated the effects of 0.4 mM aspirin (ASA) as a potential pharmacological co-inducer of HSP, both alone and in a combination with HS (ASA + HS). HS alone and ASA + HS caused a major up-regulation of HSP70 mRNA in the first 2 h, while HSP70 protein increased gradually and was especially abundant from 2 h to 24 h. Regarding Bcl-2, all treatments rendered similar results: gene expression was down-regulated in the first 2 h, after which there was protein elevation (12-48 h after HS). mRNA expression of p53 in HS- and (ASA + HS)-cells was down-regulated in the first 12 h. The immediate decrease of p53 protein after HS was followed by a biphasic increase. In conclusion, 0.4 mM ASA + HS does not act as a co-inducer of HSP70 in HepG2 cells, but promotes Bcl-2 protein expression during prolonged treatment. Our suggestion is that hepatic cells are most vulnerable in the first 2-6 h, but may have a high capacity for combating stress 12-24 h after HS. Finally, short-term exposure HS might be a "physiological conditioner" for liver cells to accumulate HSP and Bcl-2 proteins and thus obtain cytoprotection against an additional stress.

Efavirenz alters mitochondrial respiratory function in cultured neuron and glial cell lines.

BACKGROUND: The NNRTI efavirenz is among the most widely employed antiretroviral drugs. Although it is considered safe, efavirenz has been linked with several adverse effects including neurological manifestations, which appear in the majority of the patients on efavirenz-containing regimens. The molecular mechanisms responsible for these manifestations are not understood, but mounting evidence points to altered brain bioenergetics. METHODS: We evaluated the effect of short-term efavirenz treatment on the mitochondrial respiratory function of cultured glioblastoma and differentiated neuroblastoma cell lines using a Seahorse Extracellular Flux Analyzer. RESULTS: Incubation with efavirenz provoked a significant and concentration-dependent decrease in basal respiration and specifically in ATP production-coupled O2 consumption in both SH-SY5Y and U-251MG cells, with the effect being more pronounced in the latter. In contrast, efavirenz did not alter mitochondrial proton leakage in either of the cell types. Efavirenz led to a decrease in the respiratory control ratio as well as to a reduction in the maximal respiration rate and spare respiratory capacity in both U-251MG and SH-SY5Y cells, the former cells being more susceptible. CONCLUSIONS: These findings reveal that efavirenz specifically alters mitochondrial respiration, which is of relevance for a better understanding of the molecular mechanisms responsible for the efavirenz-associated neurological effects that have been recorded in clinical situations.

Efavirenz and the CNS: what we already know and questions that need to be answered.

The NNRTI efavirenz has long been one of the most frequently employed antiretroviral drugs in the multidrug regimens used to treat HIV infection, in accordance with its well-demonstrated antiretroviral efficacy and favourable pharmacokinetics. However, growing concern about its adverse effects has sometimes led to efavirenz being replaced by other drugs in the initial treatment selection or to switching of therapy to efavirenz-free regimens in experienced patients. Neurological and neuropsychiatric reactions are the manifestations most frequently experienced by efavirenz-treated patients and range from transitory effects, such as nightmares, dizziness, insomnia, nervousness and lack of concentration, to more severe symptoms including depression, suicidal ideation or even psychosis. In addition, efavirenz has recently been associated with mild/moderate neurocognitive impairment, which is of specific relevance given that half of the patients receiving ART eventually suffer some form of HIV-associated neurocognitive disorder. The mechanisms responsible for efavirenz-induced neurotoxicity are unclear, although growing evidence points to disturbances in brain mitochondrial function and bioenergetics. This review offers a comprehensive overview of the current evidence on the interaction that efavirenz displays with the CNS, including the penetration and concentration of the drug in the brain. We discuss the prevalence, types and specificities of its side effects and recently uncovered cellular mechanisms that may be involved in their development.

Neuronal bioenergetics and acute mitochondrial dysfunction: a clue to understanding the central nervous system side effects of efavirenz.

BACKGROUND: Neurological pathogenesis is associated with mitochondrial dysfunction and differences in neuronal/glial handling of oxygen and glucose. The main side effects attributed to efavirenz involve the CNS, but the underlying mechanisms are unclear. METHODS: Human cell lines and rat primary cultures of neurons and astrocytes were treated with clinically relevant efavirenz concentration. RESULTS: Efavirenz alters mitochondrial respiration, enhances reactive oxygen species generation, undermines mitochondrial membrane potential, and reduces adenosine triphosphate (ATP) levels in a concentration-dependent fashion in both neurons and glial cells. However, it activates adenosine monophosphate-activated protein kinase only in glial cells, upregulating glycolysis and increasing intracellular ATP levels, which do not occur in neurons. To reproduce the conditions that often exist in human immunodeficiency virus-related neuroinflammatory disorders, the effects of efavirenz were evaluated in the presence of exogenous nitric oxide, an inflammatory mediator and mitochondrial inhibitor. The combination potentiated the effects on mitochondrial parameters in both neurons and glial cells, but ATP generation and lactate production were enhanced only in glial cells. CONCLUSIONS: Efavirenz affects the bioenergetics of neurons through a mechanism involving acute mitochondrial inhibition, an action exacerbated in neuroinflammatory conditions. A similar scenario of glial cells survival and degeneration of neurons with signs of mitochondrial dysfunction and oxidative stress has been associated with neurocognitive disorders.

Lack of mitochondrial toxicity of darunavir, raltegravir and rilpivirine in neurons and hepatocytes: a comparison with efavirenz.

OBJECTIVES: Growing evidence associates the non-nucleoside reverse transcriptase inhibitor efavirenz with several adverse events. Newer antiretrovirals, such as the integrase inhibitor raltegravir, the non-nucleoside reverse transcriptase inhibitor rilpivirine and the protease inhibitor darunavir, claim to have a better toxicological profile than efavirenz while producing similar levels of efficacy and virological suppression. The objective of this study was to determine the in vitro toxicological profile of these three new antiretrovirals by evaluating their effects on the mitochondrial and cellular parameters altered by efavirenz in hepatocytes and neurons. METHODS: Hep3B cells and primary rat neurons were treated with clinically relevant concentrations of efavirenz, darunavir, rilpivirine or raltegravir. Parameters of mitochondrial function, cytotoxicity and oxidative and endoplasmic reticulum stress were assessed using standard cell biology techniques. RESULTS: None of the new compounds altered the mitochondrial function of hepatic cells or neurons, while efavirenz decreased mitochondrial membrane potential and enhanced superoxide production in both cell types, effects that are known to significantly compromise the functioning of mitochondria, cell viability and, ultimately, cell number. Of the four drugs assayed, efavirenz was the only one to alter the protein expression of LC3-II, an indicator of autophagy, and CHOP, a marker of endoplasmic reticulum stress and the unfolded protein response. CONCLUSIONS: Darunavir, rilpivirine and raltegravir do not induce toxic effects on Hep3B cells and primary rat neurons, which suggests a safer hepatic and neurological profile than that of efavirenz.

Efavirenz induces interactions between leucocytes and endothelium through the activation of Mac-1 and gp150,95.

OBJECTIVES: The potential cardiovascular (CV) toxicity associated with combined antiretroviral therapy (cART) has been attributed mainly to the nucleoside reverse transcriptase inhibitors abacavir and didanosine. However, the other two components of cART--non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs)--may also be implicated, either directly or by influencing the action of the other drugs. This study evaluates the acute direct effects of the NNRTIs efavirenz and nevirapine and one of the most widely employed PIs, lopinavir, on leucocyte-endothelium interactions, a hallmark of CV disease. METHODS: Drugs were analysed in vitro in human cells (interactions of peripheral blood polymorphonuclear or mononuclear cells with human umbilical vein endothelial cells) using a flow chamber system, and in vivo in rat mesenteric vessels by means of intravital microscopy. The expression of adhesion molecules in leucocytes and endothelial cells was studied by flow cytometry, and the role of these molecules in white cell recruitment was evaluated by pre-treating human cells or rats with blocking antibodies. RESULTS: Efavirenz and nevirapine, but not lopinavir, increased the rolling flux and adhesion of leucocytes in vitro and in vivo while inducing emigration in rat venules. Efavirenz, but not nevirapine, augmented the levels of CD11b, CD11c and CD18 in neutrophils and monocytes. The actions of efavirenz, but not of nevirapine, were reversed by antibodies against Mac-1 (CD11b/CD18), gp150,95 (CD11c/CD18) or ICAM-1 (CD54). CONCLUSIONS: NNRTIs, but not PIs, interfere with leucocyte-endothelial interactions. However, differences between efavirenz and nevirapine suggest a specific CV profile for each compound.

Profile of leukocyte-endothelial cell interactions induced in venules and arterioles by nucleoside reverse-transcriptase inhibitors in vivo.

BACKGROUND: There is controversy regarding cardiovascular (CV) toxicity of the nucleoside reverse-transcriptase inhibitors used to treat human immunodeficiency virus infection. METHODS: We evaluated the effects of nucleoside reverse-transcriptase inhibitors on leukocyte-endothelium interactions, a hallmark of CV diseases, in rat mesenteric vessels using intravital microscopy and in human arterial cells using a flow chamber system. RESULTS: Abacavir and didanosine increased rolling, adhesion and emigration in rat vessels. These effects were reversed with antibodies against Macrophage-1 antigen (Mac-1) or intercellular adhesion molecule 1 and were reproduced in human cells. Lamivudine, zidovudine, emtricitabine, and tenofovir had no effects. CONCLUSIONS: Our results support the association of abacavir and didanosine with CV diseases.

Benefits of rilpivirine for liver stiffness in HIV/HCV-coinfected patients.

BACKGROUND: Rilpivirine (RPV) is an antiretroviral drug characterized by good tolerability and a favorable liver safety profile. Recent research has shown that RPV ameliorates liver fibrosis in animal models of various chronic liver diseases. Our study aimed to analyze the effect of RPV on liver fibrosis by assessing changes in liver stiffness using transient elastography. METHODS: Retrospective cohort study of HIV-infected patients who were exposed and not exposed to RPV. The change in liver stiffness during the period between two transient elastography measurements was analyzed and compared for patients exposed and not exposed to RPV. RESULTS: We selected 118 RPV-exposed and 118 non-RPV-exposed HIV-infected patients. Median time between transient elastography (TE) measurements was 50 (29-68) months. A repeated-measures general linear model based on the main clinical characteristics revealed a significant decrease in the TE value of -0.8kPa in non-RPV-exposed patients (p=0.254) and -1.6kPa in the RPV-exposed group (p<0.001). The subgroup analysis showed a significant reduction in the TE value only patients cured of hepatitis C (RPV-exposed, -2.8kPa [p<0.001]; non-RPV-exposed, -1.1kPa [p=0.22]). CONCLUSION: RPV-based antiretroviral regimens significantly reduced liver stiffness, as measured by TE, in patients cured of chronic hepatitis C.

Interference with mitochondrial function as part of the antifibrogenic effect of Rilpivirine: A step towards novel targets in hepatic stellate cell activation.

Activated hepatic stellate cells (aHSCs), the main perpetrators of liver fibrosis, are a promising therapeutic target in the treatment of chronic liver disease. During liver injury, HSCs transcend from a quiescent to a fibrotic phenotype, a process which involves major metabolic reprogramming with altered mitochondrial function. The antiretroviral drug Rilpivirine (RPV) has demonstrated a hepatoprotective and specifically antifibrotic effect in several animal models of chronic liver injury, as well as in vitro. Herein, we use HSCs activated with the profibrogenic cytokine TGF-ß to explore whether mitochondrial function is implicated in this effect. The mitochondrial bioenergetic profile, morphology and dynamics of TGF-ß-treated cells (48 h) were altered and these effects were prevented by co-treatment with clinically relevant concentrations of RPV. A MitoStress Test (Seahorse Analyzer) revealed that TGF-ß increased both oxygen consumption rate (basal respiration, maximal respiration and spare respiratory capacity) and extracellular acidification rate (indicative of increased glycolysis). Cells exposed to TGF-ß also displayed diminished mitochondrial membrane potential and enhanced mitochondrial fission. All of these effects were rescued with RPV. RNA sequencing analysis of cells exposed to TGF-ß revealed the presence of 338 differentially expressed genes that encode mitochondrial proteins (mito-DEGs), of which 139 and 199 were significantly up- and down-regulated (adjusted p<0.05). This alteration in 15 (10.79 %) and 31 (22.03 %) of the up-regulated and 16 (8.04 %) and 49 (24.62 %) of the down-regulated mitoDEGs was prevented with co-exposure to RPV 4µM or 8µM, respectively. In conclusion, alterations in mitochondrial function are implicated in the antifibrogenic action of RPV, pointing to potential novel antifibrotic targets.

Rilpivirine Activates STAT1 in Non-Parenchymal Cells to Regulate Liver Injury in People Living with HIV and MASLD.

Liver fibrosis is a key determinant of the progression of metabolic dysfunction-associated steatotic liver disease (MASLD). Its increasing prevalence and a lack of effective treatments make it a major health problem worldwide, particularly in people living with HIV, among whom the prevalence of advanced fibrosis is higher. We have published preclinical data showing that Rilpivirine (RPV), a widely used anti-HIV drug, selectively triggers hepatic stellate cell (HSC) inactivation and apoptosis through signal transducer and activator of transcription (STAT)1-mediated pathways, effects that clearly attenuate liver fibrosis and promote regeneration. We performed a retrospective, cross-sectional study of RPV-induced effects on steatosis, inflammation, and fibrosis in liver biopsies from well-controlled HIV-infected subjects diagnosed with MASLD. Patients on RPV exhibited similar levels of HIV-related parameters to those not receiving this drug, while showing a tendency toward improved liver function and lipid profile, as well as an enhanced activation of STAT1 in hepatic non-parenchymal cells in those with identified liver injury. This protective effect, promoting STAT1-dependent HSC inactivation, was observed at different stages of MASLD. Our results suggest that RPV-based therapy is especially indicated in HIV-infected patients with MASLD-derived liver injury and highlight the potential of RPV as a new therapeutic strategy for liver diseases.

ER stress in human hepatic cells treated with Efavirenz: mitochondria again.

BACKGROUND & AIMS: ER stress is associated with a growing number of liver diseases, including drug-induced hepatotoxicity. The non-nucleoside analogue reverse transcriptase inhibitor Efavirenz, a cornerstone of the multidrug strategy employed to treat HIV1 infection, has been related to the development of various adverse events, including metabolic disturbances and hepatic toxicity, the mechanisms of which remain elusive. Recent evidence has pinpointed a specific mitochondrial effect of Efavirenz in human hepatic cells. This study assesses the induction of ER stress by Efavirenz in the same model and the implication of mitochondria in this process. METHODS: Primary human hepatocytes and Hep3B were treated with clinically relevant concentrations of Efavirenz and parameters of ER stress were studied using standard cell biology techniques. RESULTS: ER stress markers, including CHOP and GRP78 expression (both protein and mRNA), phosphorylation of eIF2α, and presence of the spliced form of XBP1 were upregulated. Efavirenz also enhanced cytosolic Ca(2+) content and induced morphological changes in the ER suggestive of ER stress. This response was greatly attenuated in cells with altered mitochondrial function (Rho°). The effects of Efavirenz on the ER, and particularly in regard to the mitochondrial involvement, differed from those elicited by a standard pharmacological ER stressor. CONCLUSIONS: This newly discovered mechanism of cellular insult involving ER stress and UPR response may help comprehend the hepatic toxicity that has been associated with the widespread and life-long use of Efavirenz. In addition, the specificity of the actions of Efavirenz observed expands our knowledge of the mechanisms that trigger ER stress and shed some light on the mitochondria/ER interplay in drug-induced hepatic challenge.

Abacavir causes leukocyte/platelet crosstalk by activating neutrophil P2X7 receptors thus releasing soluble lectin-like oxidized low-density lipoprotein receptor-1.

BACKGROUND AND PURPOSE: Abacavir, an antiretroviral drug used in HIV therapy associated with myocardial infarction, promotes thrombosis through P2X7 receptors. The role of platelets as pro-thrombotic cells is acknowledged whereas that of neutrophils-due to their secretory capacity-is gaining recognition. This study analyses the role of neutrophils-specifically the secretome of abacavir-treated neutrophils (SNABC )-in platelet activation that precedes thrombosis. EXPERIMENTAL APPROACH: Effects of abacavir or SNABC on platelet activation and platelet-leukocyte interactions and expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) were analysed by flow cytometry. The secretome was analysed by proteomics. The role of leukocytes in the actions of abacavir was evaluated in a mouse model of thrombosis. KEY RESULTS: Abacavir induced platelet-leukocyte interactions, not directly via effects of abacavir on platelets, but via activation of neutrophils, which triggered interactions between platelet P-selectin and neutrophil P-selectin glycoprotein ligand-1 (PSGL-1). SNABC stimulated platelet activation and platelet-leukocyte interactions through a process that was dependent on LOX-1, neutrophil P2X7 and platelet P2Y1, P2Y12 and P2X1 receptors. Abacavir induced the expression of LOX-1 on neutrophils and of the soluble form of LOX-1 (sLOX-1) in SNABC . Neutrophils, LOX-1, P2X7, P2Y1, P2Y12 and P2X1 receptors were required for the pro-thrombotic actions of abacavir in vivo. CONCLUSION AND IMPLICATIONS: Neutrophils are target cells in abacavir-induced thrombosis. Abacavir released sLOX-1 from neutrophils via activation of their P2X7 receptors, which in turn activated platelets. Hence, sLOX-1 could be the missing link in the cardiovascular risk associated with abacavir.