Biology subjects

Langat, R.

Publications and source records attributed to Langat, R..

4 recordsLinked to original sources

bioRxiv2025

Gut barrier integrity biomarkers are associated with increased inflammation and predict disease status in hospitalized COVID-19 patients

The COVID-19 global pandemic persists as an endemic disease with frequent case spikes and a significant continued burden on public health. Although most COVID-19 cases are asymptomatic or mild, severe infections requiring hospitalization have resulted in likely more than 14 million cumulative deaths to date. One hallmark of severe COVID-19 is a dysregulated immune response that leads to systemic inflammation and contributes to disease severity and mortality but is not explained by viral replication alone. Severe COVID-19 has been shown to disrupt the gut microbiome and increase intestinal permeability which may contribute to immune dysregulation and systemic inflammation. In this study, we investigated the differences in plasma biomarkers for microbial translocation and gut barrier damage as well as circulating cytokines between healthy volunteers and patients hospitalized with COVID-19. We then performed a correlation analysis to understand how the relationships between these plasma biomarkers differed and used a random forest model to assess their accuracy in distinguishing between these two groups. Our results demonstrated that hospitalized COVID-19 patients have elevated concentrations of pro-inflammatory cytokines and markers of microbial translocation, and that the relationships between these biomarkers were significantly altered compared to healthy volunteers, especially those related to the mucosal associated homeostatic cytokines IL-17A and IL-23. Furthermore, IL-6 and LBP were the top biomarkers for prediction accuracy in our random forest model, highlighting the importance of managing microbial translocation in COVID-19 and its potential utility as a biomarker for disease severity. IMPORTANCECOVID-19 continues to be a burden on public health. Understanding how plasma biomarkers differ between healthy and acutely infected individuals can help in understanding pathogenesis and predict disease severity. It has been demonstrated that COVID-19 disrupts the gut microbiome and intestinal permeability, which contributes to systemic inflammation. Our study highlights the link between gut barrier integrity and inflammation in hospitalized SARS-CoV-2 cases, demonstrating the usefulness of gut barrier integrity biomarkers in predicting disease severity, and offers insights for therapeutic interventions in acute COVID-19 infection.

immunology↗

bioRxiv2023

SARS-CoV-2 infection is associated with intestinal permeability, systemic inflammation, and microbial dysbiosis in hospitalized COVID-19 patients

Coronavirus disease 2019 (COVID-19) and associated severity has been linked to uncontrolled inflammation and may be associated with changes in the microbiome of mucosal sites including the gastrointestinal tract and oral cavity. These sites play an important role in host-microbe homeostasis and disruption of epithelial barrier integrity during COVID-19 may potentially lead to exacerbated inflammation and immune dysfunction. Outcomes in COVID-19 are highly disparate, ranging from asymptomatic to fatal, and the impact of microbial dysbiosis on disease severity is unclear. Here, we obtained plasma, rectal swabs, oropharyngeal swabs, and nasal swabs from 86 patients hospitalized with COVID-19 and 12 healthy volunteers. We performed 16S rRNA sequencing to characterize the microbial communities in the mucosal swabs and measured circulating cytokines, markers of gut barrier integrity, and fatty acids in the plasma samples. We compared these plasma concentrations and microbiomes between healthy volunteers and the COVID-19 patients who had survived or unfortunately died by the end of study enrollment, and between severe disease and healthy controls, as well as performed a correlation analysis between plasma variables and bacterial abundances. The rectal swabs of COVID-19 patients had reduced abundances of several commensal bacteria including Faecalibacterium prausnitsii, and an increased abundance of the opportunistic pathogens Eggerthella lenta and Hungatella hathewayi. Furthermore, the oral pathogen Scardovia wiggsiae was more abundant in the oropharyngeal swabs of COVID-19 patients who died. The abundance of both H. hathewayi and S. wiggsiae correlated with circulating inflammatory markers including IL-6, highlighting the possible role of the microbiome in COVID-19 severity, and providing potential therapeutic targets for managing COVID-19.

microbiology↗

bioRxiv2023

Altered glucose utilization and disrupted mitochondrial homeostasis in CD4+ T cells from HIV-positive women on combination anti-retroviral therapy

BackgroundFor optimal functionality, immune cells require a robust and adaptable metabolic program that is fueled by dynamic mitochondrial activity. In this study, we investigate the metabolic alterations occurring in immune cells during HIV infection and antiretroviral therapy by analyzing the uptake of metabolic substrates and mitochondrial homeostasis. By delineating changes in immune cell metabolic programming during HIV, we may identify novel potential therapeutic targets to improve antiviral immune responses. MethodsWhole blood was drawn from HIV uninfected female volunteers and women with chronic HIV infection on combination antiretroviral therapy. Peripheral blood mononuclear cells-derived immune cells were directly incubated with different fluorescent markers: FITC-2-NBDG (2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-D-glucose), FITC-BODIPY (4,4-Difluoro-5,7-Dimethyl-4-Bora-3a,4a-Diaza-s-Indacene-3-Hexadecanoic Acid), FITC-MitoTracker Green and APC-MitoTracker Deep Red. The uptake of glucose and fats and the mitochondrial mass and potential were measured using flow cytometry. All values are reported quantitatively as geometric means of fluorescence intensity. ResultsDuring chronic HIV infection, cellular uptake of glucose increases in HIV+ dendritic cells (DCs) in particular. CD4+ T cells had the lowest uptake of glucose and fats compared to all other cells regardless of HIV status, while CD8+ T cells took up more fatty acids. Interestingly, despite the lower utilization of glucose and fats in CD4+ T cells, mitochondrial mass increased in HIV+ CD4+ T cells compared to HIV negative CD4+ T-cells. HIV+ CD4+ T cells also had the highest mitochondrial potential. ConclusionsSignificant disparities in the utilization of substrates by leukocytes during chronic HIV/cART exist. Innate immune cells increased utilization of sugars and fats while adaptive immune cells displayed lower glucose and fat utilization despite having a higher mitochondrial activity. Our findings suggest that cART treated HIV-infected CD4+ T cells may prefer alternative fuel sources not included in these studies. This underscores the importance of understanding the metabolic effects of HIV treatment on immune function.

immunology↗

bioRxiv2018

Performance of an IAVI-African Network of Clinical Research Laboratories in Standardized ELISpot and Peripheral Blood Mononuclear Cell Processing in Support of HIV Vaccine Clinical Trials

Immunological assays performed in different laboratories participating in multi-centre clinical trials must be standardized in order to generate comparable and reliable data. This entails standardized procedures for sample collection, processing, freezing and storage. The International AIDS Vaccine Initiative (IAVI) partnered with local institutions to establish Good Clinical Laboratory Practice (GCLP)-accredited laboratories to support clinical trials in Africa, Europe and Asia. Here we report on the performance of seven laboratories based in Africa and Europe in the interferon-gamma enzyme-linked immunospot (IFN-{gamma} ELISpot) assay and peripheral blood mononuclear cell (PBMC) processing over four years. Characterized frozen PBMC samples from 48 volunteer blood packs processed at a central laboratory were sent to participating laboratories. For each stimulus, there were 1751 assays performed over four years. 98% of these ELISpot data were within acceptable ranges with low responses to mock stimuli. There were no significant differences in ELISpot responses at five laboratories actively conducting immunological analyses in support of IAVI sponsored clinical trials or HIV research. In a separate study, 1,297 PBMC samples isolated from healthy HIV-1 negative participants in clinical trials of two prophylactic HIV vaccine candidates were analysed for PBMC yield from fresh blood and cell recovery and viability following freezing and thawing. 94 % and 96 % of samples had fresh PBMC viabilities and cell yields within the pre-defined acceptance criteria while for frozen PBMC, 99 % and 96 % of samples had acceptable viabilities and cell recoveries respectively, along with acceptable ELISpot responses in 95%. These findings demonstrate the competency of laboratories across different continents to generate comparable and reliable data in support of clinical trials.\n\nImportanceThere is a need for the establishment of an African network of laboratories to support large clinical trials across the continent to support and further the development of vaccine candidates against emerging infectious diseases such as Ebola, Zika and dengue viruses and the continued HIV-1 pandemic. This is particularly true in sub-Saharan Africa where the HIV-1 pandemic is most severe. In this report we have demonstrated by using standardized SOPs, training, equipment and reagents that GCLP-accredited clinical trial laboratories based in Africa and Europe can process clinical trial samples and maintain cell integrity and functionality demonstrated by IFN-{gamma} ELISpot testing, producing comparable and reliable data.

immunology↗