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•Galectin-9 is known for its immunomodulatory role in innate and adaptive immunity.•Plasma levels of Galectin-9 are elevated in various pathophysiological conditions.•Galectin-9 ...levels correlate positively with parameters of disease severity.•Galectin-9 is a potentially reliable, sensitive and non-invasive biomarker.
Galectin-9 (Gal-9) is a β-galactoside binding lectin known for its immunomodulatory role in various microbial infections. Gal-9 is expressed in all organ systems and localized in the nucleus, cell surface, cytoplasm and the extracellular matrix. It mediates host-pathogen interactions and regulates cell signalling via binding to its receptors. Gal-9 is involved in many physiological functions such as cell growth, differentiation, adhesion, communication and death. However, recent studies have emphasized on the elevated levels of Gal-9 in autoimmune disorders, viral infections, parasitic invasion, cancer, acute liver failure, atopic dermatitis, chronic kidney disease, type-2 diabetes, coronary artery disease, atherosclerosis and benign infertility-related gynecological disorders. In this paper we have reviewed the potential of Gal-9 as a reliable, sensitive and non-invasive biomarker of disease severity. Tracking changes in Gal-9 levels and its implementation as a biomarker in clinical practice will be an important tool to monitor disease activity and facilitate personalized treatment decisions.
Multiple cellular HIV reservoirs in diverse anatomical sites can undergo clonal expansion and persist for years despite suppressive antiretroviral therapy, posing a major barrier toward an HIV cure. ...Commonly adopted assays to assess HIV reservoir size mainly consist of PCR-based measures of cell-associated total proviral DNA, intact proviruses and transcriptionally competent provirus (viral RNA), flow cytometry and microscopy-based methods to measure translationally competent provirus (viral protein), and quantitative viral outgrowth assay, the gold standard to measure replication-competent provirus; yet no assay alone can provide a comprehensive view of the total HIV reservoir or its dynamics. Furthermore, the detection of extant provirus by these measures does not preclude defects affecting replication competence. An accurate measure of the latent reservoir is essential for evaluating the efficacy of HIV cure strategies. Recent approaches have been developed, which generate proviral sequence data to create a more detailed profile of the latent reservoir. These sequencing approaches are valuable tools to understand the complex multicellular processes in a diverse range of tissues and cell types and have provided insights into the mechanisms of HIV establishment and persistence. These advancements over previous sequencing methods have allowed multiplexing and new assays have emerged, which can document transcriptional activity, chromosome accessibility, and in-depth cellular phenotypes harboring latent HIV, enabling the characterization of rare infected cells across restrictive sites such as the brain. In this manuscript, we provide a review of HIV sequencing-based assays adopted to address challenges in quantifying and characterizing the latent HIV reservoir.
Cyclic nucleotide, such as cyclic GMP, is a secondary messenger that regulates a wide range of biological process via the diverse signaling cascades. Photoactivated adenylyl cyclases (PACs), ...constituted of blue light utilizing flavin (BLUF) and cyclase homology domain (CHD), are used as an optogenetic tool to modulate the cyclic AMP (cAMP) level and to study cAMP-mediated signal transduction mechanisms. Here, we have engineered photoactivated adenylyl cyclases (PACs) from microbes to photoactivated guanylyl cyclases (PGCs) via mutagenesis of the substrate binding-specific residues in cyclase homology domain. We demonstrate purification, photodynamic, and detailed biochemical characterization of the engineered PGCs that can serve as optogenetic tool for manipulation of cGMP level in the cells. Engineered PGCs show typical BLUF photoreceptor properties with different recovery kinetics and varying light-regulated guanylyl cyclase activities.
Background: Helicobacter pylori are gram-negative bacteria, which colonize the human stomach. More than 50% of the world’s population is infected by H. pylori. Based on the high prevalence of H. ...pylori, it is very likely that HIV and H. pylori infection may coexist. However, the molecular events that occur during HIV-H. pylori co-infection remain unclear. Latent HIV reservoirs are the major obstacle in HIV cure despite effective therapy. Here, we explored the effect of H. pylori stimulation on latently HIV-infected monocytic cell line U1.
Methods: High throughput RNA-Seq using Illumina platform was performed to analyse the change in transcriptome between unstimulated and H. pylori-stimulated latently HIV-infected U1 cells. Transcriptome analysis identified potential genes and pathways involved in the reversal of HIV latency using bioinformatic tools that were validated by real-time PCR.
Results: H. pylori stimulation increased the expression of HIV-1 Gag, both at transcription (p<0.001) and protein level. H. pylori stimulation also increased the expression of proinflammatory cytokines IL-1β, CXCL8 and CXCL10 (p<0.0001). Heat-killed H. pylori retained their ability to induce HIV transcription. RNA-Seq analysis revealed 197 significantly upregulated and 101 significantly downregulated genes in H. pylori-stimulated U1 cells. IL-1β and CXCL8 were found to be significantly upregulated using transcriptome analysis, which was consistent with real-time PCR data.
Conclusion: H. pylori reactivate HIV-1 in latently infected monocytes with the upregulation of IL-1β and CXCL8, which are prominent cytokines involved in the majority of inflammatory pathways. Our results warrant future in vivo studies elucidating the effect of H. pylori in HIV latency and pathogenesis.
Latent HIV reservoir is a major barrier to absolute HIV cure. Studies on latency reversal agents (LRA) have by far focused mainly on CD4+ T-lymphocytes, while myeloid reservoirs remain ...under-represented despite their persistence and key contribution to HIV pathogenesis. cAMP has been shown to increase HIV-1 transcription in latently-infected monocytes/macrophages. In this communication, we explored the potential of commercially available pharmacological drugs and phosphodiesterase inhibitors to reactivate HIV in latently-infected monocytic cell-line, U1. We showed that increased levels of intracellular cAMP reverse HIV latency in vitro, which is specific to cells of the myeloid lineage. High throughput RNA-seq analysis revealed that cAMP modulates transcriptional profile of latently HIV-infected cells and provides favourable cellular environment for HIV to produce viral proteins. This reactivation of latent HIV was inhibited by Mithramycin A, a selective Sp1 inhibitor, indicating that the reversal of HIV latency in monocytes is driven by transcription factor Sp1.
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•Increase in levels of intracellular cAMP reactivates HIV in latently infected U1 cells.•PDE inhibitor drugs enhance HIV reactivation in myeloid cells and can be further explored for latency reversal properties.•cAMP modulates transcriptional profile of latently HIV-infected monocytes.•cAMP reverses HIV latency in myeloid cells through transcription factor Sp1.
Abstract
Background:
High levels of Galectin-9 (Gal-9), a β-galactoside-binding mammalian lectin, are associated with systemic inflammation in chronic viral infections like HIV, despite viral ...suppression by ART. Gut-systemic microbial translocation is a major contributor of persistent inflammation. Whether Gal-9 influences the integrity of the gut during viral infections remains unknown.
Objective:
Here we investigated the impact of Gal-9 in the interplay between gut-systemic microbial translocation in the setting of well-treated chronic HIV infection.
Method:
We assessed the levels of Gal-9 and sCD14 in the plasma of people with HIV on ART (PWH; n=25) and people without HIV (PWOH; n=15) by ELISA. The integrity of the gut epithelium in the presence and absence of rGal-9 was assessed in the HT-29 cell line by immunofluorescence. TNFa was used as a positive control to disrupt gut integrity. The levels of TNFa were measured by qPCR. Non parametric tests were used in the analysis.
Results:
Plasma Gal-9 and sCD14 were elevated in PWH compared to PWOH (all p<0.0001). Further, high Gal-9 levels correlated with high sCD14 in both the PWH (r=0.43, p=0.0317) and PWOH (r=0.79, p=0.0006) groups. Immunofluorescence revealed disruption of the Claudin tight junctions in vitroafter 24 hrs of rGal-9 treatment. rGal-9 also induced a 6-fold increase in the expression of TNFα in HT-29 cells.
Conclusion:
Our results show that Gal-9 is associated with markers of gut-systemic microbial translocation irrespective of HIV status and given the direct effects of rGal-9 on tight junction barrier function, targeting Gal-9 either by exploiting its secretory pathways or competitive blockade may serve as a novel therapeutic approach to control gut-associated inflammation.
Perinatal HIV infection is characterized by faster HIV disease progression and higher initial rate of HIV replication compared to adults. While antiretroviral therapy (ART) has greatly reduced HIV ...replication to undetectable levels, there is persistent elevated inflammation associated with HIV disease progression. Alteration of gut microbiota is associated with increased inflammation in chronic adult HIV infection. Here, we aim to study the gut microbiome and its role in inflammation in treated and untreated HIV-infected children. Examination of fecal microbiota revealed that perinatally infected children living with HIV had significantly higher levels of genus Prevotella that persisted despite ART. These children also had higher levels of soluble CD14 (sCD14), a marker of microbial translocation, and IP-10 despite therapy. The Prevotella positively correlated with IP-10 levels in both treated and untreated HIV-infected children, while genus Prevotella and species Prevotella copri was inversely associated with CD4 count. Relative abundance of genus Prevotella and species Prevotella copri showed positive correlation with sCD14 in ART-suppressed perinatally HIV-infected children. Our study suggests that gut microbiota may serve as one of the driving forces behind the persistent inflammation in children despite ART. Reshaping of microbiota using probiotics may be recommended as an adjunctive therapy along with ART.
Adolescents with perinatally-acquired HIV (AWH) are at an increased risk of poor cognitive development but the underlying mechanisms remain unclear. Circulating galectin-9 (Gal-9) has been associated ...with increased inflammation and multi-morbidity in adults with HIV despite anti-retroviral therapy (ART), however, relationship between Gal-9 in AWH and cognition remain unexplored.
A cross-sectional study of two independent age-matched cohorts from India AWH on ART (n = 15), ART-naïve (n = 15), and adolescents without HIV (AWOH; n = 10) and Myanmar AWH on ART (n = 54) and AWOH (n = 22) were studied. Adolescents from Myanmar underwent standardized cognitive tests.
Plasma Gal-9 and soluble mediators were measured by immunoassays and cellular immune markers by flow cytometry. We used Mann-Whitney U tests to determine group-wise differences, Spearman's correlation for associations and machine learning (ML) to identify a classifier of cognitive status (impaired vs. unimpaired) built from clinical (age, sex, HIV status) and immunological markers.
Gal-9 levels were elevated in ART-treated AWH compared to AWOH in both cohorts (all p < 0.05). Higher Gal-9 in AWH correlated with increased levels of inflammatory mediators (sCD14, TNFα, MCP-1, IP-10, IL-10) and activated CD8 T cells (all p < 0.05). Irrespective of HIV status, higher Gal-9 levels correlated with lower cognitive test scores in multiple domains (verbal learning, visuospatial learning, memory, motor skills (all p < 0.05). ML classification identified Gal-9, CTLA-4, HVEM, and TIM-3 as significant predictors of cognitive deficits in adolescents (mean AUC = 0.837).
Our results highlight a potential role of Gal-9 as a biomarker of inflammation and cognitive health among adolescents with perinatally acquired HIV.
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