Biology subjects

Wiegand, A.

Publications and source records attributed to Wiegand, A..

5 recordsLinked to original sources

bioRxiv2024

HIV-1 control in vivo is related to the number but not the fraction of infected cells with viral unspliced RNA

In the absence of antiretroviral therapy (ART), a subset of individuals, termed HIV controllers, have levels of plasma viremia that are orders of magnitude lower than non-controllers who are at higher risk for HIV disease progression. In addition to having fewer infected cells resulting in fewer cells with HIV RNA, it is possible that lower levels of plasma viremia in controllers is due to a lower fraction of the infected cells having HIV-1 unspliced RNA (HIV usRNA) compared with non-controllers. To directly test this possibility, we used sensitive and quantitative single cell sequencing methods to compare the fraction of infected cells that contain one or more copies of HIV usRNA in peripheral blood mononuclear cells (PBMC) obtained from controllers and non-controllers. The fraction of infected cells containing HIV usRNA did not differ between the two groups. Rather, the levels of viremia were strongly associated with the total number of infected cells that had HIV usRNA, as reported by others, with controllers having 34-fold fewer infected cells per million PBMC. These results reveal for the first time that viremic control is not associated with a lower fraction of proviruses expressing HIV usRNA, unlike what is reported for elite controllers, but is only related to having fewer infected cells overall, maybe reflecting greater immune clearance of infected cells. Our findings show that proviral silencing is not a key mechanism for viremic control and will help to refine strategies towards achieving HIV remission without ART.

microbiology↗

bioRxiv2022

Blood transcriptome analysis suggests an indirect molecular association of early life adversities and adult social anxiety disorder by immune-related signal transduction

Social anxiety disorder (SAD) is a psychiatric disorder characterized by severe fear in social situations and avoidance of these. Multiple genetic as well as environmental factors contribute to the etiopathology of SAD. One of the main risk factors for SAD is stress, especially during early periods of life (early life adversity; ELA). ELA leads to structural and regulatory alterations contributing to disease vulnerability. This includes the dysregulation of the immune response. However, the molecular link between ELA and the risk for SAD in adulthood remain largely unclear. Evidence is emerging that long-lasting changes of gene expression patterns play an important role in the biological mechanisms linking ELA and SAD. Therefore, we performed a transcriptome study of SAD and ELA using RNA sequencing. Analyzing differential gene expression, 13 significantly differentially expressed genes (DEGs) were identified with respect to SAD whilst no significant differences in expression were identified with respect to ELA. The most significantly expressed gene was MAPK3 being upregulated in the SAD group compared to control individuals. In contrary, weighted gene co-expression network analyses (WGCNA) identified only modules significantly associated with ELA, not with SAD. Furthermore, analyzing interaction networks of the genes from the ELA-associated modules and the SAD-related MAPK3) revealed complex interactions of those genes. Gene functional enrichment analyses indicate a role of signal transduction pathways as well as inflammatory responses supporting an involvement of the immune system in the association of ELA and SAD. In conclusion, we did not identify a direct molecular link between ELA and adult SAD by transcriptional changes. However, our data indicate an indirect association of ELA and SAD mediated by the interaction of genes involved in immune-related signal transduction.

genomics↗

bioRxiv2021

Dynamic DNA methylation changes in the COMT gene promoter region in response to mental stress and its modulation by transcranial direct current stimulation

Changes in epigenetic modifications present a mechanism how environmental factors like the experience of stress can alter gene regulation. While stress-related disorders have consistently been associated with differential DNA methylation, little is known about the time scale in which these alterations emerge. We investigated dynamic DNA methylation changes in whole blood of 42 healthy male individuals in response to a stressful cognitive task, its association with concentration changes in cortisol and its modulation by transcranial direct current stimulation (tDCS). We observed a continuous increase in COMT promotor DNA methylation which correlated with higher saliva cortisol levels and was still detectable one week later. However, this lasting effect was suppressed by concurrent activity-enhancing anodal tDCS to the dorsolateral prefrontal cortex. Our findings support the significance of gene-specific DNA methylation in whole blood as potential biomarkers for stress-related disorders. Moreover, they suggest alternative molecular mechanisms possibly involved in lasting behavioral effects of tDCS.

neuroscience↗

bioRxiv2020

Early Emergence and Long-Term Persistence of HIV-Infected T Cell Clones in Children

Little is known about the emergence and persistence of HIV-infected T cell clones in perinatally-infected children. We analyzed peripheral blood mononuclear cells for clonal expansion in 11 children who initiated antiretroviral therapy (ART) between 1.8-17.4 months of age and with viremia suppressed for 6-9 years. We obtained 8,662 HIV-1 integration sites from pre-ART and 1,861 sites on ART. Expanded clones of infected cells were detected pre-ART in 10/11 children. In 8 children, infected cell clones detected pre-ART persisted for 6-9 years on ART. A comparison of integration sites in the samples obtained on ART with healthy donor PBMC infected ex-vivo showed selection for cells with proviruses integrated in BACH2 and STAT5B. Our analyses indicate that, despite marked differences in T cell composition and dynamics between children and adults, HIV-infected cell clones are established early in children, persist for up to 9 years on ART, and can be driven by proviral integration in proto-oncogenes.

microbiology↗

bioRxiv2020

Mechanistic Analysis of the Broad Antiretroviral Resistance Conferred by HIV-1 Envelope Glycoprotein Mutations

Despite the effectiveness of antiretroviral (ARV) therapy, virological failure can occur in some HIV-1 infected patients in the absence of mutations in the proteins targeted by these drugs. We previously reported that, in vitro, the lab-adapted NL4-3 strain of HIV-1 can acquire resistance to the integrase inhibitor dolutegravir (DTG) by acquiring mutations in the envelope glycoprotein (Env) that enhance the ability of HIV-1 to spread via cell-cell transmission. In this study, we investigated whether Env-mediated drug resistance extends to ARVs other than DTG and whether it occurs in other HIV-1 isolates. We demonstrate that Env mutations can broadly confer resistance to multiple classes of ARVs in the context of cell-cell but not cell-free infection and also increase resistance to ARVs when coupled with target-gene drug resistance mutations. To investigate the mechanism of Env-mediated drug resistance, we evaluated the impact of the Env mutations on Env stability and conformational dynamics. We observe that the NL4-3 Env mutants display a more stable and closed Env conformation compared to WT virus and reduced rates of gp120 shedding. We also selected for mutations in the gp41 ectodomain of clinically relevant, CCR5-tropic isolates in the presence of DTG. These Env mutants exhibit reduced susceptibility to DTG, with effects on replication kinetics and Env structure that are HIV-1 strain-dependent. Finally, to examine a possible in vivo relevance of Env-mediated drug resistance, we performed single-genome sequencing of plasma-derived virus from five patients failing an integrase inhibitor-containing regimen. This analysis revealed the presence of several mutations in the highly conserved gp120-gp41 interface despite low frequency of resistance mutations in integrase. These results suggest a "stepping-stone" model whereby mutations in Env that enhance the ability of HIV-1 to spread via a cell-cell route increase the opportunity for the virus to acquire high-level drug resistance mutations in ARV-target genes. Author summaryAlthough combination antiretroviral (ARV) therapy has proven highly effective in controlling the progression of HIV disease, drug resistance can be a major obstacle to long-term treatment, particularly in resource-limited settings. In most cases, resistance arises from the accumulation of mutations in the ARV-target genes; however, in some cases, resistance develops without ARV target-gene mutations. We previously reported that mutations in the HIV-1 envelope glycoprotein (Env) confer resistance to an integrase inhibitor. Here we investigated the mechanism of Env-mediated drug resistance and the possible contribution of Env to virological failure in vivo. We demonstrate that Env mutations can confer broad resistance to multiple classes of ARVs and define the effect of the Env mutations on Env subunit interactions and sensitivity to neutralizing antibodies. We also selected for drug resistance mutations in Env in clinically relevant HIV-1 isolates. We observed that many Env mutations accumulated in individuals failing integrase inhibitor therapy despite a low frequency of resistance mutations in integrase. Our findings suggest that broad-based, Env-mediated drug resistance may impact current and possibly future therapeutic strategies. Our findings also provide clues towards understanding how ARV-treated patients can experience virological failure without acquiring drug resistance mutations in ARV-target genes.

microbiology↗