HIV-1 Tat Induces Dysregulation of PGC1-Alpha and Sirtuin 3 Expression in Neurons: The Role of Mitochondrial Biogenesis in HIV-Associated Neurocognitive Disorder (HAND).

During the antiretroviral era, individuals living with HIV continue to experience milder forms of HIV-associated neurocognitive disorder (HAND). Viral proteins, including Tat, play a pivotal role in the observed alterations within the central nervous system (CNS), with mitochondrial dysfunction emerging as a prominent hallmark. As a result, our objective was to examine the expression of genes associated with mitophagy and mitochondrial biogenesis in the brain exposed to the HIV-1 Tat protein. We achieved this by performing bilateral stereotaxic injections of 100 ng of HIV-1 Tat into the hippocampus of Sprague-Dawley rats, followed by immunoneuromagnetic cell isolation. Subsequently, we assessed the gene expression of Ppargc1a, Pink1, and Sirt1-3 in neurons using RT-qPCR. Additionally, to understand the role of Tert in telomeric dysfunction, we quantified the activity and expression of Tert. Our results revealed that only Ppargc1a, Pink1, and mitochondrial Sirt3 were downregulated in response to the presence of HIV-1 Tat in hippocampal neurons. Interestingly, we observed a reduction in the activity of Tert in the experimental group, while mRNA levels remained relatively stable. These findings support the compelling evidence of dysregulation in both mitophagy and mitochondrial biogenesis in neurons exposed to HIV-1 Tat, which in turn induces telomeric dysfunction.

Sirtuins Modulation: A Promising Strategy for HIV-Associated Neurocognitive Impairments.

HIV-Associated neurocognitive disorder (HAND) is one of the major concerns since it persists in 40% of this population. Nowadays, HAND neuropathogenesis is considered to be caused by the infected cells that cross the brain-blood barrier and produce viral proteins that can be secreted and internalized into neurons leading to disruption of cellular processes. The evidence points to viral proteins such as Tat as the causal agent for neuronal alteration and thus HAND. The hallmarks in Tat-induced neurodegeneration are endoplasmic reticulum stress and mitochondrial dysfunction. Sirtuins (SIRTs) are NAD+-dependent deacetylases involved in mitochondria biogenesis, unfolded protein response, and intrinsic apoptosis pathway. Tat interaction with these deacetylases causes inhibition of SIRT1 and SIRT3. Studies revealed that SIRTs activation promotes neuroprotection in neurodegenerative diseases such Alzheimer's and Parkinson's disease. Therefore, this review focuses on Tat-induced neurotoxicity mechanisms that involve SIRTs as key regulators and their modulation as a therapeutic strategy for tackling HAND and thereby improving the quality of life of people living with HIV.

Downregulation of SERINC5 expression in buffy coats of HIV-1-infected patients with detectable or undetectable viral load.

Among the host restriction factors against HIV, SERINC5 has been described in vitro, but the mRNA level of SERINC5 in vivo has been little studied. We compare SERINC5 expression in subjects with HIV-1 (highly active antiretroviral treatment (HAART) and HAART-naïve) with and without suppression of viral load. A cross-sectional study was performed with 107 individuals distributed as follows: 24 with HAART-naïve and detectable viral load (> 50 copies/mL), 13 with HAART and detectable viral load (> 50 copies/mL), 50 with HAART and undetectable viral load (≤ 50 copies/mL), and 20 without HIV-1. SERINC5 expression in buffy coats was determined using RT-qPCR. The viral load was determined using real-time PCR and the amount of CD4 + and CD8 + T-lymphocytes was measured using flow cytometry. The data were normalized with the Shapiro-Wilk test and the Kruskal-Wallis test was subsequently performed. The relative expression was compared with a T-test and the remaining data with the Mann-Whitney U-test. ANCOVA multiple linear regression analysis was performed between characteristics of patients with SERINC5 expression. The mean and SD of the SERINC5 expression in the three groups with HIV-1 was 0.9 ± 0.2 and without HIV-1 was 1.7 ± 0.14 (P < 0.001). Multiple linear regression did not show the participation of CD4 +, CD8 + , viral load, infection time, or treatment time. No differences in the SERINC5 expression were found among the studied groups of patients with HIV-1. When comparing the groups with and without HIV-1 infection, SERINC5 was downregulation in the HIV-1 groups.

Genomic instability in people living with HIV.

The increased life expectancy of people living with HIV (PLWH) receiving antiretroviral treatment (ART) has transformed HIV infection into a chronic disease. However, patients may be at risk of accelerated aging and the accumulation of cellular damage, which may trigger the development of cancer. We evaluated genomic instability in HIV-positive individuals with different viral loads receiving antiretroviral treatment (ART) and in HIV ART-naïve individuals. We included 67 participants divided into four groups: group 1 (n = 24) HIV patients receiving reverse-transcriptase inhibitors (tenofovir/ emtricitabine/ efavirenz and abacavir/ lamivudine/ efavirenz), group 2 (n = 22) HIV patients receiving protease inhibitors combined with other antiretroviral drugs (tenofovir/ emtricitabine with ritonavir/ atazanavir or lopinavir/ ritonavir, and darunavir/ ritonavir/ raltegravir), group 3 (n = 13) HIV ART-naïve patients, and group 4 (n = 8) healthy individuals (controls). Nuclear abnormalities in buccal mucosal samples (micronuclei, binucleated cells, nuclear buds, karyorrhexis, karyolysis, and pyknosis) were quantified. Simultaneously, blood samples were taken to quantify CD4+, CD8+, and HIV viral load. There was a significant age difference between HIV ART-naïve patients and receiving ART groups. Infection time was longer in HIV patients with ART than in ART-naïve patients. There were no differences in sex, smoking, alcohol consumption, or number of micronucleated cells between the study groups. We found higher frequencies of binucleated cells and nuclear buds in HIV patients, HIV ART-naïve, and HIV ART patients compared to the control group. We found a positive correlation between nuclear buds and CD4/CD8 ratio in the HIV ART-naïve group. In conclusion, PLWH showed increased genomic instability. The CD4/CD8 ratio affects the numbers of nuclear buds and binucleated cells. These findings are pertinent to mechanisms of damage and possible strategies to mitigate carcinogenesis in PLWH.

MicroRNA-296-5p is differentially expressed in individuals with and without HIV-1 infection.

MicroRNAs are considered as potential biomarkers, agents, or therapeutic targets; few studies have addressed the expression of miRNAs in treatment-naïve patients infected with HIV-1. The aim of this study was to assess plasma relative circulating miRNA expression profiles in treatment-naïve Mexican patients with HIV/AIDS and healthy individuals using a commercial array. A low CD4+ T cell count and high viral load were found in all patients. Decreased relative miRNA-296-5p expression was observed in patients; moreover, this was the only miRNA that showed differences between the two groups. Thus, we measured the absolute expression of miR-296-5p by qPCR, confirming the result with statistically significant differences (P < 0.05). There is evidence that miR-296-5p regulates the expression of the PIN1 gene, which encodes the peptidylprolyl Cis/Trans isomerase NIMA-Interacting-1, that is involved in different stages of the biological cycle of HIV-1, this relationship is corroborated by bioinformatics analysis and ELISA assay was used to measure plasma levels of PIN1. The decreased expression of miR-296-5p found in naïve patients with HIV infection suggests a regulatory activity of this miRNA on virus replication, making it a potential therapeutic agent against HIV. Finally, miR-296-5p could be inhibiting the virus transcription by regulating genes different than PIN1.

Plasma microRNA expression levels in HIV-1-positive patients receiving antiretroviral therapy.

MicroRNAs (miRNAs/miRs) may serve as therapeutic agents or targets in diseases in which the expression of proteins plays an important role. The aim of the present study was to compare the expression levels of specific miRNAs, as well as their correlation with markers of response to antiretroviral (ARV) therapy, in patients with human immunodeficiency virus type 1 (HIV-1) infection with and without resistance to highly active antiretroviral therapy (HAART). METHODS: miRNA assays were performed on plasma samples obtained from 20 HIV-1-positive patients. A total of ten patients were divided into two groups: HAART-responsive and HAART-resistant (n=5 per group). Commercial arrays were subsequently used to identify 84 miRNAs. A total of three differentially expressed miRNAs were selected and analyzed by quantitative PCR (qPCR). Five other patients were subsequently added to each group for a new relative expression analysis. The absolute expression level of the two miRNAs was obtained and compared using the Student's t test. Receiver operating characteristic (ROC) curves were used to identify patients with antiretroviral therapy (ART) resistance. RESULTS: The array analysis revealed that miR-15b-5p, miR-16-5p, miR-20a-5p, miR-26a-5p, miR-126-3p and miR-150-5p were down-regulated in patients with HAART-resistance comparing with HAART-responsive. The expression levels of miR-16-5p, miR-26a-5p and miR-150-5p were confirmed using qPCR. The area under the ROC curve was 1.0 for the three miRNAs. CONCLUSIONS: The lower expression levels of miR-16-5p and miR-26a-5p in patients with HAART-resistance suggested that these may serve as potential biomarkers for the identification of HAART-responsive patients.

SERINC as a Restriction Factor to Inhibit Viral Infectivity and the Interaction with HIV.

The serine incorporator 5 (SERINC5) is a recently discovered restriction factor that inhibits viral infectivity by preventing fusion. Retroviruses have developed strategies to counteract the action of SERINC5, such as the expression of proteins like negative regulatory factor (Nef), S2, and glycosylated Gag (glycoGag). These accessory proteins downregulate SERINC5 from the plasma membrane for subsequent degradation in the lysosomes. The observed variability in the action of SERINC5 suggests the participation of other elements like the envelope glycoprotein (Env) that modulates susceptibility of the virus towards SERINC5. The exact mechanism by which SERINC5 inhibits viral fusion has not yet been determined, although it has been proposed that it increases the sensitivity of the Env by exposing regions which are recognized by neutralizing antibodies. More studies are needed to understand the role of SERINC5 and to assess its utility as a therapeutic strategy.

Molecular profiling of a simple rat model of open tibial fractures with hematoma and periosteum disruption.

Bone fractures are a worldwide public health concern. Therefore, improving understanding of the bone healing process at a molecular level, which could lead to the discovery of potential therapeutic targets, is important. In the present study, a model of open tibial fractures with hematoma disruption, periosteal rupture and internal fixation in 6-month-old male Wistar rats was established, in order to identify expression patterns of key genes and their protein products throughout the bone healing process. A tibial shaft fracture was produced using the three-point bending technique, the hematoma was drained through a 4-mm incision on the medial aspect of the tibia and the fracture stabilized by inserting a needle into the medullary canal. Radiographs confirmed that the induced fractures were diaphyseal and this model was highly reproducible (kappa inter-rater reliability, 0.82). Rats were sacrificed 5, 14, 21, 28 and 35 days post-fracture to obtain samples for histological, immunohistochemical and molecular analysis. Expression of interleukin-1ß (Il-1ß), transforming growth factor-ß2 (Tgf-ß2), bone morphogenetic protein-6 (Bmp-6), bone morphogenetic protein-7 (Bmp-7) and bone γ-carboxyglutamic acid-containing protein (Bglap) genes was determined by reverse transcription quantitative polymerase chain reaction and protein expression was evaluated by immunohistochemistry, while histological examination allowed characterization of the bone repair process. Il-1ß showed a biphasic expression, peaking 5 and 28 days post-fracture. Expression of Tgf-ß2, Bmp-6 and Bmp-7 was restricted to the period 21 days post-fracture. Bglap expression increased gradually, peaking 21 days post-fracture, although it was expressed in all evaluated stages. Protein expression corresponded with the increased expression of their corresponding genes. In conclusion, a clear and well-defined expression pattern of the evaluated genes and proteins was observed, where their maximal expression correlated with their known participation in each stage of the bone healing process.

Contribution of TNF-308A and CCL2-2518A to carotid intima-media thickness in obese mexican children and adolescents.

BACKGROUND: Although commonly used in adults to detect early atherosclerosis, the value of the carotid intima-media thickness (CIMT) in children and adolescents is not clear. This marker has an inheritable component that supports the notion of a genetic influence. Among the genes studied as candidates for atherosclerosis development are those for chemokines, cytokines, and adhesion molecules because of their participation in atheroma formation through monocyte recruitment and migration. METHODS: We analyzed the relationship between CIMT and functional polymorphic variants in the genes for chemokines and proinflammatory cytokines associated with cardiovascular events in adults in lean and obese but otherwise healthy 6- to 19-year-old subjects. RESULTS: In the obese group, systolic blood pressure correlated negatively (r =-0.332; p = 0.008) and the TNF-308A allele correlated positively (r = 0.262; p = 0.040) with CIMT. The mean CIMT was higher in obese individuals with the TNF-308A allele than in those with TNF-308G allele (p = 0.041). In a multiple regression model for the total population, an increase in CIMT was explained by body mass index, systolic and diastolic blood pressure, and the TNF-308A and CCL2-2518A alleles (r(2) = 0.321; p = 0.022). CONCLUSIONS: This study contributes to the understanding of the pathophysiology of atherosclerosis and suggests that genetic markers of an increased inflammatory response and its deleterious effects are already present in obese children and adolescents.