HIV-1 viral protein R (Vpr) induces fatty liver in mice via LXRα and PPARα dysregulation: implications for HIV-specific pathogenesis of NAFLD

Emerging role of natural killer cells in non-AIDS comorbidities during suppressive antiretroviral therapy

PURPOSE OF REVIEW

Despite decades of insights about the role of natural killer (NK) cells in HIV infection, their persistent dysregulation despite antiretroviral therapy (ART) and its pathological consequences have been incompletely delineated. In this review, we highlight recent findings on the immunophenotypic and functional alterations of NK cells during virally suppressed HIV infection and explore their potential impact on promoting non-AIDS related comorbidities among people living with HIV (PLWH).

RECENT FINDINGS

Of note are the apparent persistent activated profiles of NK cells and pathophysiological events such as endoplasmic reticulum (ER) stress in potentially driving NK cell derived inflammation and tissue destruction. Additionally, recent interest in trained immunity is discussed as a potential mediator of ongoing NK cell dysregulation, contributing to comorbidities such as cardiovascular disease and neurocognitive disorders, both with an inflammatory etiology.

SUMMARY

Clinical and mechanistic evidence suggests persistent activation and dysregulation of the innate immune system are major drivers of non-AIDS comorbidities during virally suppressed HIV infection. Delineating the mechanistic role of specific components of innate immunity such as NK cells in inducing these pathologies will lead to the identification of novel therapeutic/prophylactic strategies to improve the overall health of PLWH.

Pathophysiology and Clinical Management of Dyslipidemia in People Living with HIV: Sailing through Rough Seas

Infections with human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) represent one of the greatest health burdens worldwide. The complex pathophysiological pathways that link highly active antiretroviral therapy (HAART) and HIV infection per se with dyslipidemia make the management of lipid disorders and the subsequent increase in cardiovascular risk essential for the treatment of people living with HIV (PLHIV). Amongst HAART regimens, darunavir and atazanavir, tenofovir disoproxil fumarate, nevirapine, rilpivirine, and especially integrase inhibitors have demonstrated the most favorable lipid profile, emerging as sustainable options in HAART substitution. To this day, statins remain the cornerstone pharmacotherapy for dyslipidemia in PLHIV, although important drug-drug interactions with different HAART agents should be taken into account upon treatment initiation. For those intolerant or not meeting therapeutic goals, the addition of ezetimibe, PCSK9, bempedoic acid, fibrates, or fish oils should also be considered. This review summarizes the current literature on the multifactorial etiology and intricate pathophysiology of hyperlipidemia in PLHIV, with an emphasis on the role of different HAART agents, while also providing valuable insights into potential switching strategies and therapeutic options.

Adipose Tissue Dysfunction and Energy Balance Paradigms in People Living With HIV

Over the past 4 decades, the clinical care of people living with HIV (PLWH) evolved from treatment of acute opportunistic infections to the management of chronic, noncommunicable comorbidities. Concurrently, our understanding of adipose tissue function matured to acknowledge its important endocrine contributions to energy balance. PLWH experience changes in the mass and composition of adipose tissue depots before and after initiating antiretroviral therapy, including regional loss (lipoatrophy), gain (lipohypertrophy), or mixed lipodystrophy. These conditions may coexist with generalized obesity in PLWH and reflect disturbances of energy balance regulation caused by HIV persistence and antiretroviral therapy drugs. Adipocyte hypertrophy characterizes visceral and subcutaneous adipose tissue depot expansion, as well as ectopic lipid deposition that occurs diffusely in the liver, skeletal muscle, and heart. PLWH with excess visceral adipose tissue exhibit adipokine dysregulation coupled with increased insulin resistance, heightening their risk for cardiovascular disease above that of the HIV-negative population. However, conventional therapies are ineffective for the management of cardiometabolic risk in this patient population. Although the knowledge of complex cardiometabolic comorbidities in PLWH continues to expand, significant knowledge gaps remain. Ongoing studies aimed at understanding interorgan communication and energy balance provide insights into metabolic observations in PLWH and reveal potential therapeutic targets. Our review focuses on current knowledge and recent advances in HIV-associated adipose tissue dysfunction, highlights emerging adipokine paradigms, and describes critical mechanistic and clinical insights.

Hepatic steatosis and nonalcoholic fatty liver disease are common and associated with cardiometabolic risk in a primary prevention cohort of people with HIV

BACKGROUND

Hepatic steatosis, including nonalcoholic fatty liver disease (NAFLD), is common among people with HIV (PWH). We present baseline steatosis prevalence and cardiometabolic characteristics among REPRIEVE substudy participants.

METHODS

REPRIEVE is an international, primary cardiovascular disease prevention, randomized, controlled trial of pitavastatin calcium vs. placebo among 7769 PWH ages 40-75 years on antiretroviral therapy (ART) and with low-to-moderate cardiovascular risk. A subset of participants underwent noncontrast computed tomography, with hepatic steatosis defined as mean hepatic attenuation less than 40 HU or liver/spleen ratio less than 1.0, and NAFLD defined as steatosis in the absence of frequent alcohol use or viral hepatitis.

RESULTS

Of 687 evaluable persons, median age was 51 years, BMI 27 kg/m 2 , CD4 + T-cell count 607 cells/μl; 17% natal female sex, 36% Black, 24% Hispanic, and 98% HIV-1 RNA less than 400 copies/ml. Hepatic steatosis prevalence was 22% (149/687), and NAFLD 21% (96/466). Steatosis/NAFLD prevalence was higher in men and with older age, non-Black race, and higher BMI and waist circumference. Both were associated with BMI greater than 30 kg/m 2 , metabolic syndrome components, higher atherosclerotic cardiovascular disease (ASCVD) risk score, HOMA-IR, LpPLA-2 and hs-CRP, and lower high-density lipoprotein cholesterol. Of HIV-specific/ART-specific characteristics, only history of an AIDS-defining illness was more common among persons with steatosis/NAFLD. After adjusting for age, sex and race/ethnicity, BMI greater than 30 kg/m 2 , HOMA-IR greater than 2.0, Metabolic syndrome and each of its components were associated with NAFLD prevalence.

CONCLUSION

In this cohort with controlled HIV and low-to-moderate cardiovascular risk, hepatic steatosis and NAFLD were common and associated with clinically relevant metabolic and inflammatory disturbances but not current HIV-related or ART-related factors.

Performance of an automated deep learning algorithm to identify hepatic steatosis within noncontrast computed tomography scans among people with and without HIV

PURPOSE

Hepatic steatosis (fatty liver disease) affects 25% of the world's population, particularly people with HIV (PWH). Pharmacoepidemiologic studies to identify medications associated with steatosis have not been conducted because methods to evaluate liver fat within digitized images have not been developed. We determined the accuracy of a deep learning algorithm (automatic liver attenuation region-of-interest-based measurement [ALARM]) to identify steatosis within clinically obtained noncontrast abdominal CT images compared to manual radiologist review and evaluated its performance by HIV status.

METHODS

We performed a cross-sectional study to evaluate the performance of ALARM within noncontrast abdominal CT images from a sample of patients with and without HIV in the US Veterans Health Administration. We evaluated the ability of ALARM to identify moderate-to-severe hepatic steatosis, defined by mean absolute liver attenuation <40 Hounsfield units (HU), compared to manual radiologist assessment.

RESULTS

Among 120 patients (51 PWH) who underwent noncontrast abdominal CT, moderate-to-severe hepatic steatosis was identified in 15 (12.5%) persons via ALARM and 12 (10%) by radiologist assessment. Percent agreement between ALARM and radiologist assessment of absolute liver attenuation <40 HU was 95.8%. Sensitivity, specificity, positive predictive value, and negative predictive value of ALARM were 91.7% (95%CI, 51.5%-99.8%), 96.3% (95%CI, 90.8%-99.0%), 73.3% (95%CI, 44.9%-92.2%), and 99.0% (95%CI, 94.8%-100%), respectively. No differences in performance were observed by HIV status.

CONCLUSIONS

ALARM demonstrated excellent accuracy for moderate-to-severe hepatic steatosis regardless of HIV status. Application of ALARM to radiographic repositories could facilitate real-world studies to evaluate medications associated with steatosis and assess differences by HIV status.

Downregulated Acetyl-CoA Acyltransferase 2 Promoted the Progression of Hepatocellular Carcinoma and Participated in the Formation of Immunosuppressive Microenvironment

Background

The aim of this study is to explore the role of acetyl-CoA acyltransferase 2 (ACAA2) in the progression of hepatocellular carcinoma (HCC).

Methods

Bulk RNA data and single-cell RNA data were acquired from The Cancer Genome Atlas and Gene Expression Omnibus. Both in vitro and in vivo studies were used to determine the effect of ACAA2 on the progression of HCC, and RNA sequencing analysis was performed to explore the mechanism.

Results

We found downregulation of ACAA2 was involved in the malignant progression of HCC. The patient with low ACAA2 level had an immunosuppressive microenvironment in the HCC and predicted to have a poor prognosis. Decreased ACAA2 facilitated HCC proliferation and metastasis by activating the nuclear factor-κB (NFκB) signaling pathway. And increased CXCL1 induced by NFκB signaling pathway might be responsible for low level of ACAA2 related immunosuppressive microenvironment. Furthermore, the expression of ACAA2 was also detected in immune cells. The expression of ACAA2 in CD4+TCF7+T, CD4+FOXP3+T, CD8+GZMK+T, and CD8+KLRD1+T cells was inversely correlated with the composition of CD8+PDCD1+T cells in HCC. This effect might be due to the CCL5-CCRs and HLA-E-KLRCs ligand-receptor networks.

Conclusion

In a conclusion, downregulated ACAA2 promoted the progression of hepatocellular carcinoma and might be participated in the formation of immunosuppressive microenvironment. ACAA2 could be served as a favorable indicator for the prognosis of HCC and an ideal biomarker for immunotherapy.

Innovative Therapeutic Approaches in Non-Alcoholic Fatty Liver Disease: When Knowing Your Patient Is Key

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of disorders ranging from simple steatosis to non-alcoholic steatohepatitis (NASH). Hepatic steatosis may result from the dysfunction of multiple pathways and thus multiple molecular triggers involved in the disease have been described. The development of NASH entails the activation of inflammatory and fibrotic processes. Furthermore, NAFLD is also strongly associated with several extra-hepatic comorbidities, i.e., metabolic syndrome, type 2 diabetes mellitus, obesity, hypertension, cardiovascular disease and chronic kidney disease. Due to the heterogeneity of NAFLD presentations and the multifactorial etiology of the disease, clinical trials for NAFLD treatment are testing a wide range of interventions and drugs, with little success. Here, we propose a narrative review of the different phenotypic characteristics of NAFLD patients, whose disease may be triggered by different agents and driven along different pathophysiological pathways. Thus, correct phenotyping of NAFLD patients and personalized treatment is an innovative therapeutic approach that may lead to better therapeutic outcomes.

HIV and liver disease: a comprehensive update

Despite substantial advances in the field, liver disease morbidity and mortality remain serious issues among people with HIV. The causes of liver disease are often multifactorial and include hepatitis viruses, hepatic steatosis and oxidative stress, bacterial translocation with activation of hepatic macrophages and stellate cells, and direct toxicities from alcohol and drugs of abuse. Biopsychosocial factors including a high prevalence of psychiatric disorders, food insecurity, insufficient access to care and medications, and social stigma all play roles in the persistence of liver injury and hepatic fibrosis development among people with HIV. Rising rates of hepatocellular carcinoma have been observed, suggesting that the epidemiology of liver disease is evolving.

The Immune Response in Adipocytes and Their Susceptibility to Infection: A Possible Relationship with Infectobesity

The current obesity pandemic has been expanding in both developing and developed countries. This suggests that the factors contributing to this condition need to be reconsidered since some new factors are arising as etiological causes of this disease. Moreover, recent clinical and experimental findings have shown an association between the progress of obesity and some infections, and the functions of adipose tissues, which involve cell metabolism and adipokine release, among others. Furthermore, it has recently been reported that adipocytes could either be reservoirs for these pathogens or play an active role in this process. In addition, there is abundant evidence indicating that during obesity, the immune system is exacerbated, suggesting an increased susceptibility of the patient to the development of several forms of illness or death. Thus, there could be a relationship between infection as a trigger for an increase in adipose cells and the impact on the metabolism that contributes to the development of obesity. In this review, we describe the findings concerning the role of adipose tissue as a mediator in the immune response as well as the possible role of adipocytes as infection targets, with both roles constituting a possible cause of obesity.

Heightened levels of plasma growth differentiation factor 15 in men living with HIV

Plasma biomarkers that reflect energy balance disorders in people living with HIV (PLWH) remain limited. Growth differentiation factor 15 (GDF15) abundance in plasma of mice and humans induces negative energy balance but also becomes highly elevated in obesity and other metabolic diseases. We sought to compare plasma GDF15 levels in PLWH and HIV-negative persons and mouse models expressing the HIV accessory protein Vpr (that recapitulate HIV-associated metabolic disorders) and determine their relationship to metabolic parameters. We measured liver Gdf15 mRNA levels and plasma GDF15 levels in male Vpr mice and littermate controls. In parallel, we analyzed plasma GDF15 levels in 18 male PLWH on stable, long-term antiretroviral therapy and 13 HIV-negative men (6 healthy controls and 7 with metabolic syndrome). Plasma GDF15 levels were correlated with anthropometric and immune cell parameters in humans. Gene expression analysis of Vpr mouse liver demonstrated elevated Gdf15 mRNA. Plasma GDF15 levels were also higher in Vpr mouse models. Levels of plasma GDF15 in PLWH were greater than in both HIV-negative groups and correlated positively with the CD4/CD8 T cell ratio in PLWH. Plasma GDF15 levels correlated positively with age in the HIV-negative subjects but not in PLWH. Since GDF15 levels predict fatty liver disease and energy balance disorders, further studies are warranted to determine the effect of GDF15 in mediating the metabolic disturbances that occur in Vpr mice and PLWH.

Dysregulation of fatty acid metabolism associated with esophageal inflammation of ICR mice induced by nitrosamines exposure

Nitrosamines, as ubiquitous environmental carcinogens with adverse impact on human health, were crucial inducers of esophageal cancer (EC). Esophageal inflammation (EI) was an important biological process and considered to be associated with the progression of EC. However, the underlying regulatory mechanism of EI process caused by nitrosamines exposure remained largely unclear. In this study, a metabolomics approach based on mass spectrometry was utilized to explore the effect of nitrosamines exposure to ICR mice. Also, the changes of pivotal metabolic enzyme levels, urinary nitrosamines and histopathological analysis were evaluated. The results showed that nitrosamines exposure was intimately interrelated with EI process in mice. Metabolomics profiling analysis indicated that nitrosamines caused significant alterations of metabolic pathway predominantly enriched in fatty acid metabolism. Targeted metabolomics analysis revealed that nitrosamines promoted decomposition of fatty acids and facilitated fatty acid β-oxidation (FAO) of mice. The significant increase of carnitine palmitoyltransferase 1 (CPT1) and downregulation of acetyl-CoA acyltransferase 2 (ACAA2) would promote FAO in EI process induced by nitrosamines. Additionally, the exposure levels of more than half of nitrosamines in urine were correlated with inflammatory fatty acid biomarkers. Overall, this study found that EI triggered by nitrosamines may be associated with the promotion of FAO, and provided novel insights for evaluating the underlying mechanism of environmental pollutant-caused toxicity based on metabolomics.

Cardiovascular computed tomography and HIV: The evolving role of imaging biomarkers in enhanced risk prediction

The treatment of human immunodeficiency virus (HIV) with antiretroviral (ARV) medications has revolutionised the care for these patients. The dramatic increase in life expectancy has brought new challenges in treating diseases of aging in this cohort. Cardiovascular disease (CVD) is now a leading cause of morbidity and mortality with risk matched HIV-positive patients having double the risk of MI compared to HIV-negative patients. This enhanced risk is secondary to the interplay the virus (and accessory proteins), ARV medications and traditional risk factors. The culmination of these factors can lead to a hybrid metabolic syndrome characterised by heightened ectopic fat. Cardiovascular computed tomography (CT) is ideal for quantifying epicardial adipose tissue volumes, hepatosteatosis and cardiovascular disease burden. The CVD risk attributed to disease burden and plaque morphology is well established in general populations but is less clear in HIV populations. The purpose of this review article is to appraise the latest data on CVD development in HIV-positive patients and how the use of cardiovascular CT may be used to enhance risk prediction in this population. This may have important implications on individualised treatment decisions and risk reduction strategies which will improve the care of these patients.

Sirtuins as Interesting Players in the Course of HIV Infection and Comorbidities

The sirtuins (SIRTs) are a family of enzymes from the group of NAD⁺-dependent deacetylases. Through the reaction of splitting the acetyl group of various transcription factors and histones they regulate many processes in the organism. The activity of sirtuins is linked to metabolic control, oxidative stress, inflammation and apoptosis, and they also affect the course of viral infections. For this reason, they may participate in the pathogenesis and development of many diseases, but little is known about their role in the course of human immunodeficiency virus (HIV) infection, which is the subject of this review. In the course of HIV infection, comorbidities such as: neurodegenerative disorders, obesity, insulin resistance and diabetes, lipid disorders and cardiovascular diseases, renal and bone diseases developed more frequently and faster compared to the general population. The role of sirtuins in the development of accompanying diseases in the course of HIV infection may also be interesting. There is still a lack of detailed information on this subject. The role of sirtuins, especially SIRT1, SIRT3, SIRT6, are indicated to be of great importance in the course of HIV infection and the development of the abovementioned comorbidities.

HIV-1 Viral Protein R Couples Metabolic Inflexibility With White Adipose Tissue Thermogenesis

Persons living with HIV (PLWH) manifest chronic disorders of brown and white adipose tissues that lead to diabetes and metabolic syndrome. The mechanisms that link viral factors to defective adipose tissue function and abnormal energy balance in PLWH remain incompletely understood. Here, we explored how the HIV accessory protein viral protein R (Vpr) contributes to adaptive thermogenesis in two mouse models and human adipose tissues. Uncoupling protein 1 (UCP1) gene expression was strongly increased in subcutaneous white adipose tissue (WAT) biopsy specimens from PLWH and in subcutaneous WAT of the Vpr mice, with nearly equivalent mRNA copy number. Histology and functional studies confirmed beige transformation in subcutaneous but not visceral WAT in the Vpr mice. Measurements of energy balance indicated Vpr mice displayed metabolic inflexibility and could not shift efficiently from carbohydrate to fat metabolism during day-night cycles. Furthermore, Vpr mice showed a marked inability to defend body temperature when exposed to 4°C. Importantly, Vpr couples higher tissue catecholamine levels with UCP1 expression independent of β-adrenergic receptors. Our data reveal surprising deficits of adaptive thermogenesis that drive metabolic inefficiency in HIV-1 Vpr mouse models, providing an expanded role for viral factors in the pathogenesis of metabolic disorders in PLWH.

Derangement of Liver Enzymes, Hyperglycemia, Anemia, and Associated Factors among HIV-Infected Patients Treated with Tenofovir Disoproxil Fumarate-Based Regimen in Ethiopia: A Prospective Cohort Study

Hepatotoxicity was found in different case reports and studies in tenofovir disoproxil fumarate- (TDF-) based regimen. However, there was no data regarding liver enzymes, glucose, and hemoglobin in Ethiopian patients receiving TDF-based regimen. The aim of this study was to determine elevated liver enzymes and its associated factors as well as elevated fasting plasma glucose and anemia. A hospital-based observational prospective cohort study was conducted on conveniently selected 63 patients in Tikur Anbessa Specialized Hospital (TASH) from January to September 2019. Laboratory values were determined at pre-TDF-based regimen baseline and six-month follow-up. The data was analyzed by using SPSS version 21.0, and multivariate logistic regression was used to determine associated factors with elevated liver enzymes. The overall elevated liver enzymes were found in 26 (41.3%) participants. From this, elevated alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) comprise 3 (4.8%), 3 (4.8%), and 20 (31.8%), respectively. Elevated fasting plasma glucose (FPG) was found in 9 (14.3%) and 14 (22.2%) of participants at baseline and six-month visit, respectively. At six-month visit, 4 (6.4%) of participants experienced anemia. The mean value of ALP and FPG at six months was significantly higher than their respective baseline mean values (mean difference (MD) = +63.38, 95% CI (39.84, 86.92), p = 0.0001; MD = +6.64, 95% CI (2.63, 10.64), p = 0.002, respectively). The mean value of ALT, AST, and Hg at six months was slightly increased compared to their respective baseline mean values, but the difference was not significant. In multivariate analysis, only female sex was significantly associated with elevated ALP (AOR = 4.5, 95% CI (1.03, 19.6), p = 0.045). Overall mild and moderate hepatotoxicity was found to be high (26, 41.3%) in the present study, and from this, the majority was comprised by elevated ALP (20, 31.8%). The proportion of participants with hyperglycemia was increased at the end of follow-up compared to its baseline value, but anemia was not. Female sex was significantly associated with elevated ALP. This study warrants monitoring of liver enzymes and glucose in TDF-based regimen.

The pharmacodynamic and differential gene expression analysis of PPAR α/δ agonist GFT505 in CDAHFD-induced NASH model

Peroxisome proliferator-activated receptor α/δ (PPAR α/δ), regulating glucolipid metabolism and immune inflammation, has been identified as an effective therapeutic target in non-alcoholic steatohepatitis (NASH). Dual PPAR α/δ agonist, such as GFT505 (also known as elafibranor), demonstrated potential therapeutic effect for NASH in clinical trials. To profile the regulatory network of PPAR α/δ agonist in NASH, the choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) induced NASH model was used to test the pharmacodynamics and transcriptome regulation of GFT505 in this study. The results showed that GFT505 ameliorated hepatic steatosis, inflammation and fibrosis in CDAHFD mice model. RNA-sequencing yielded 3995 up-regulated and 3576 down-regulated genes with GFT505 treatment. And the most significant differentialy expressed genes involved in glucolipid metabolism (Pparα, Acox1, Cpt1b, Fabp4, Ehhadh, Fabp3), inflammation (Ccl6, Ccl9, Cxcl14) and fibrosis (Timp1, Lamc3, Timp2, Col3a1, Col1a2, Col1a1, Hapln4, Timp3, Pik3r5, Pdgfα, Pdgfβ, Tgfβ1, Tgfβ2) were confirmed by RT-qPCR. The down-regulated genes were enriched in cytokine-cytokine receptor interaction pathway and ECM-receptor interaction pathway, while the up-regulated genes were enriched in PPAR signaling pathway and fatty acid degradation pathway. This study provides clues and basis for further understanding on the mechanism of PPAR α/δ agonist on NASH.

Insights Into the Pathophysiology of Liver Disease in HCV/HIV: Does it End With HCV Cure?

HCV-HIV coinfected patients exhibit rapid progression of liver damage relative to HCV monoinfected patients. The availability of new directly acting antiviral agents has dramatically improved outcomes for coinfected patients as sustained virologic response rates now exceed 95% and fibrosis-related parameters are improved. Nevertheless, coinfected patients still have a higher mortality risk and more severe hepatocellular carcinoma compared to HCV monoinfected patients, implying the existence of pathways unique to people living with HIV that continue to promote accelerated liver disease. In this article, we review the pathobiology of liver disease in HCV-HIV coinfected patients in the directly acting antiviral era and explore the mechanisms through which HIV itself induces liver damage. Since liver disease is one of the leading causes of non-AIDS-related mortality in HIV-positive patients, enhancing our understanding of HIV-associated fibrotic pathways will remain important for new diagnostic and therapeutic strategies to slow or reverse liver disease progression, even after HCV cure.

Effect of Bile Duct Ligation-induced Liver Dysfunction on Methamphetamine Pharmacokinetics and Locomotor Activity in Rats

PURPOSE

Methamphetamine (METH) abuse is associated with hepatic dysfunction related comorbidities such as HIV, hepatitis C, and polysubstance abuse with acetaminophen-containing opioid formulations. We aimed to develop a bile duct ligation (BDL)-induced hepatic dysfunction model for studying both METH and experimental treatments for METH abuse in this comorbidity.

METHODS

Sham or BDL surgery was performed in male Wistar rats on day 0. Liver function was measured throughout the study. On days 7 and 19, serum pharmacokinetics studies were performed with 1 mg/kg subcutaneous (sc) METH. On day 21, this dose was repeated to determine 2 h post-METH brain concentrations. METH-induced open field behaviors were measured every other day (days 12 - 16) with ascending sc doses (0.3 - 3 mg/kg).

RESULTS

BDL transiently increased alanine aminotransferase levels and altered liver structure, which resulted in significantly greater METH serum and brain exposure. In the BDL compared to sham group, there was a longer duration of METH-induced locomotor activity (after 1 and 3 mg/kg) and stereotypy (after 3 mg/kg).

CONCLUSIONS

In rats, liver dysfunction reduced METH clearance, increased brain METH concentrations, and enhanced METH effects on locomotor activity in a dose dependent manner. In addition, this model could be further developed to simulate the associated hepatic dysfunction of key METH abuse comorbidities for preclinical testing of novel pharmacotherapies for effectiveness and/or toxicity in vulnerable populations.

Evolution of a concept: From accessory protein to key virulence factor, the case of HIV-1 Vpr

Back in 1989 some studies have shown that the viral protein Vpr was dispensable for HIV-1 replication in vitro. From then the concept of accessory or auxiliary protein for Vpr has emerged and it is still used to date. However, Vpr soon appeared to be very important for in vivo virus spread and pathogenesis. Vpr has been involved in many biological functions including regulation of reverse transcriptase activity, the nuclear import of the pre-integration complex (PIC), HIV-1 transcription, gene splicing, apoptosis and in cell cycle arrest. Thus, we might rather consider Vpr as a true virulence factor instead of just an accessory factor. At present, Vpr can be regarded as a potential and promising target in different strategies aiming to fight infected cells including latently infected cells.

Retrotransposition and senescence in mouse heart tissue by viral protein R of human immunodeficiency virus-1

Combination antiretroviral therapy (cART) has greatly improved the prognosis of patients with human immunodeficiency virus type-1 (HIV-1) infection. However, cardiovascular disease (CVD) remains a serious issue even in the post-cART era. Viral protein R (Vpr), an accessory gene product of HIV-1, exerts pleiotropic activities such as the induction of DNA damage signals, apoptosis by mitochondrial membrane depolarization, G2/M-phase cell cycle abnormalities, and retrotransposition. Importantly, some of these cellular responses are induced by the trans-acting activity of Vpr. Recently, we established an enzyme-linked immunosorbent assay to detect Vpr and reported that about 22% of blood samples from 100 HIV-1-positive patients were positive for Vpr. Here, we investigated the biological effects of recombinant Vpr (rVpr) in vivo. We observed that repeated injections of rVpr increased the copy number of long interspersed element-1 (L1) in the heart genome in mice. rVpr also increased the number of cells positive for senescence-associated β-galactosidase (SA-β-gal) and fibrosis in the heart. Notably, co-administration of a reverse transcriptase inhibitor reduced the number of rVpr-induced SA-β-gal-positive cells and fibrosis concomitantly with the attenuation of L1 retrotransposition. Interestingly, a Vpr mutant defective for mitochondrial dysfunction also induced heart senescence and increased L1 copy number. Together with a recent report that L1 retrotransposition functions as a molecular basis of senescence, our current data suggest that rVpr-induced L1 retrotransposition is linked with senescence in heart tissue. We would propose that Vpr in the bloodstream may be one of risk factors for CVD, and that its monitoring will lead to well understanding of the heterogeneity and multifactorial mechanisms of CVD in HIV-1 patients.

Tryptophan Metabolism Activates Aryl Hydrocarbon Receptor-Mediated Pathway To Promote HIV-1 Infection and Reactivation

Multiple cellular metabolic pathways are altered by HIV-1 infection, with an impact on immune activation, inflammation, and acquisition of non-AIDS comorbid diseases. The dysfunction of tryptophan (Trp) metabolism has been observed clinically in association with accelerated HIV-1 pathogenesis, but the underlying mechanism remains unknown. In this study, we demonstrated that the aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor, is activated by Trp metabolites to promote HIV-1 infection and reactivation. AHR directly binds to the HIV-1 5' long terminal repeat (5'-LTR) at the molecular level to activate viral transcription and infection, and AHR activation by Trp metabolites increases its nuclear translocation and association with the HIV 5'-LTR; moreover, the binding of AHR with HIV-1 Tat facilitates the recruitment of positive transcription factors to viral promoters. These findings not only elucidate a previously unappreciated mechanism through which cellular Trp metabolites affect HIV pathogenesis but also suggest that a downstream target AHR may be a potential target for modulating HIV-1 infection.IMPORTANCE Cellular metabolic pathways that are altered by HIV-1 infection may accelerate disease progression. Dysfunction in tryptophan (Trp) metabolism has been observed clinically in association with accelerated HIV-1 pathogenesis, but the mechanism responsible was not known. This study demonstrates that Trp metabolites augment the activation of aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor, to promote HIV-1 infection and transcription. These findings not only elucidate a previously unappreciated mechanism through which cellular Trp metabolites affect HIV pathogenesis but also suggest that a downstream target AHR may be a potential target for modulating HIV-1 infection.

Intramyocardial Triglycerides Among Women With vs Without HIV: Hormonal Correlates and Functional Consequences

CONTEXT

Women with HIV (WHIV) on anti-retroviral therapy (ART) are living longer but facing heightened vulnerability to heart failure.

OBJECTIVE

We investigated metabolic/hormonal/immune parameters relating to diastolic dysfunction-a precursor to heart failure-among WHIV without known cardiovascular disease (CVD).

DESIGN AND OUTCOME MEASURES

Nineteen ART-treated WHIV and 11 non-HIV-infected women without known CVD enrolled and successfully completed relevant study procedures [cardiac magnetic resonance spectroscopy (MRS) and cardiac MRI]. Groups were matched on age and body mass index. Primary outcome measures included intramyocardial triglyceride content (cardiac MRS) and diastolic function (cardiac MRI). Relationships between intramyocardial triglyceride content and clinical parameters were also assessed.

RESULTS

Among WHIV (vs non-HIV-infected women), intramyocardial triglyceride content was threefold higher [1.2 (0.4, 3.1) vs 0.4 (0.1, 0.5)%, P = 0.01], and diastolic function was reduced (left atrial passive ejection fraction: 27.2 ± 9.6 vs 35.9 ± 6.4%, P = 0.007). There was a strong inverse relationship between intramyocardial triglyceride content and diastolic function (ρ = -0.62, P = 0.004). Among the whole group, intramyocardial triglyceride content did not relate to chronologic age but did increase across the reproductive aging spectrum (P = 0.02). HIV status and reproductive aging status remained independent predictors of intramyocardial triglyceride content after adjusting for relevant cardiometabolic parameters (overall model R2 = 0.56, P = 0.003; HIV status P = 0.01, reproductive aging status P = 0.02).

CONCLUSIONS

For asymptomatic WHIV, increased intramyocardial triglyceride content is associated with diastolic dysfunction. Moreover, relationships between intramyocardial triglyceride accumulation and women's reproductive aging are noted.

Obesity and Fat Metabolism in Human Immunodeficiency Virus-Infected Individuals: Immunopathogenic Mechanisms and Clinical Implications

Metabolic complications relating to complex effects of viral and immune-mediated mechanisms are now a focus of clinical care among persons living with human immunodeficiency virus (PLHIV), and obesity is emerging as a critical problem. To address knowledge gaps, the US National Institutes of Health sponsored a symposium in May 2018 entitled "Obesity and Fat Metabolism in HIV-infected Individuals." Mechanisms relating to adipose dysfunction and fibrosis, immune function, inflammation, and gastrointestinal integrity were highlighted as contributors to obesity among PLHIV. Fibrotic subcutaneous adipose tissue is metabolically dysfunctional and loses its capacity to expand, leading to fat redistribution, including visceral obesity and ectopic fat accumulation, promoting insulin resistance. Viral proteins, including viral protein R and negative regulatory factor, have effects on adipogenic pathways and cellular metabolism in resident macrophages and T cells. HIV also affects immune cell trafficking into the adipose compartments, with effects on adipogenesis, lipolysis, and ectopic fat accumulation. Key cellular metabolic functions are likely to be affected in PLHIV by gut-derived cytokines and altered microbiota. There are limited strategies to reduce obesity specifically in PLHIV. Enhancing our understanding of critical pathogenic mechanisms will enable the development of novel therapeutics that may normalize adipose tissue function and distribution, reduce inflammation, and improve insulin sensitivity in PLHIV.

Clinical significance of elevated liver transaminases in HIV-infected patients

: Elevation of liver transaminases is common in patients infected with the HIV. Although this is usually an incidental finding during regular work-up, HIV-infected patients with transaminase elevations require additional visits for laboratory studies and clinical assessments, and often undergo interruptions and changes in antiretroviral therapy (ART). Alanine aminotransferase is present primarily in the liver, thus being a surrogate marker of hepatocellular injury. Aspartate aminotransferase is present in the liver and other organs, namely cardiac and skeletal muscle, kidney and brain. Serum levels of both liver transaminases predict liver-related mortality. Moreover, serum fibrosis biomarkers based on alanine aminotransferase and aspartate aminotransferase predict all-cause mortality. In a busy clinical setting, a diagnostic approach to elevated liver transaminases could be complicated given the frequency and nonspecificity of this finding. Indeed, HIV-infected individuals present multiple risk factors for liver damage and chronic elevation of transaminases, including coinfection with hepatitis B and C viruses, alcohol abuse, hepatotoxicity due to ART, HIV itself and frequent metabolic comorbidities leading to nonalcoholic fatty liver disease. This review provides an update on epidemiology of elevated liver transaminases, summarizes the main etiologic contributors and discusses the prognostic significance and a pragmatic approach to this frequent finding in the clinical practice of HIV medicine. With the aging of the HIV-infected population following the successful implementation of ART in Western countries, liver-related conditions are now a major comorbidity in this setting. As such, clinicians should be aware of the frequency, clinical significance and diagnostic approach to elevated liver transaminases.

HIV Persistence in Adipose Tissue Reservoirs

PURPOSE OF REVIEW

The purpose of this review is to examine the evidence describing adipose tissue as a reservoir for HIV-1 and how this often expansive anatomic compartment contributes to HIV persistence.

RECENT FINDINGS

Memory CD4 T cells and macrophages, the major host cells for HIV, accumulate in adipose tissue during HIV/SIV infection of humans and rhesus macaques. Whereas HIV and SIV proviral DNA is detectable in CD4 T cells of multiple fat depots in virtually all infected humans and monkeys examined, viral RNA is less frequently detected, and infected macrophages may be less prevalent in adipose tissue. However, based on viral outgrowth assays, adipose-resident CD4 T cells are latently infected with virus that is replication-competent and infectious. Additionally, adipocytes interact with CD4 T cells and macrophages to promote immune cell activation and inflammation which may be supportive for HIV persistence. Antiviral effector cells, such as CD8 T cells and NK/NKT cells, are abundant in adipose tissue during HIV/SIV infection and typically exceed CD4 T cells, whereas B cells are largely absent from adipose tissue of humans and monkeys. Additionally, CD8 T cells in adipose tissue of HIV patients are activated and have a late differentiated phenotype, with unique TCR clonotypes of less diversity relative to blood CD8 T cells. With respect to the distribution of antiretroviral drugs in adipose tissue, data is limited, but there may be class-specific penetration of fat depots. The trafficking of infected immune cells within adipose tissues is a common event during HIV/SIV infection of humans and monkeys, but the virus may be mostly transcriptionally dormant. Viral replication may occur less in adipose tissue compared to other major reservoirs, such as lymphoid tissue, but replication competence and infectiousness of adipose latent virus are comparable to other tissues. Due to the ubiquitous nature of adipose tissue, inflammatory interactions among adipocytes and CD4 T cells and macrophages, and selective distribution of antiretroviral drugs, the sequestration of infected immune cells within fat depots likely represents a major challenge for cure efforts.

Examining Relationships between Metabolism and Persistent Inflammation in HIV Patients on Antiretroviral Therapy

With the advent of antiretroviral therapy (ART), HIV-infected individuals are now living longer and healthier lives. However, ART does not completely restore health and treated individuals are experiencing increased rates of noncommunicable diseases such as dyslipidemia, insulin resistance, type 2 diabetes, cardiovascular disease, and nonalcoholic fatty liver disease. While it is well known that persistent immune activation and inflammation contribute to the development of these comorbid diseases, the mechanisms underlying this chronic activation remain incompletely understood. In this review, we will discuss emerging evidence that suggests that alterations in cellular metabolism may play a central role in driving this immune dysfunction in HIV patients on ART.

NAFLD and HIV: Do Sex, Race, and Ethnicity Explain HIV-Related Risk?

PURPOSE OF REVIEW

Here, we review the epidemiology, diagnosis, and management of non-alcoholic fatty liver disease (NAFLD) in the general population, discuss HIV-specific differences in NAFLD pathogenesis, and summarize what is known regarding differences in NAFLD by race/ethnicity and sex.

RECENT FINDINGS

The reported prevalence of NAFLD among people living with HIV varies by age, body mass index, comorbidity, and method of NAFLD diagnosis, but is generally thought to be greater among HIV-infected compared to HIV-uninfected populations. Minorities and women tend to experience poorer HIV treatment outcomes (Meditz et al. J Infect Dis. 203(4):442-51, 2011; Beer et al. Medicine (Baltimore). 95(13):e 3171, 2016; Gant et al. MMWR Morb Mortal Wkly Rep. 66(40):1065-72, 2017; Millett et al. Lancet. 380(9839):341-8, 2012; Wejnert et al. J Infect Dis. 213(5):776-83, 2016), and are at the greatest risk for significant weight gain with HIV treatment (Erlandson et al. Medicine (Baltimore). 95(46):e 5399, 2016). Thus, women and minorities living with HIV may be at a higher risk of developing NAFLD and progressive liver disease. Disparities in the diagnosis, progression, and prognosis of NAFLD and HIV-associated NAFLD may be, in part, explained by genetic and sex differences; however, data is limited.