Differential effects of antiretroviral treatment on immunity and gut microbiome composition in people living with HIV in rural versus urban ZimbabweOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study asked whether living in a rural versus urban area of Zimbabwe changes how the immune system and gut microbiome respond to HIV treatment. It measured T-cell activation, exhaustion and trafficking, plasma inflammatory markers, and fecal microbiome composition. The design was a prospective longitudinal observational study across urban and rural hospitals. Stool 16S rRNA sequencing of the V4 region profiled bacteria. Immune phenotyping used flow cytometry, and IL-6 and CRP were measured by ELISA at baseline and after 24 weeks.
Who was studied?
The study enrolled 162 adults from an urban clinic in Harare and a rural district hospital 146 km away. After exclusions, baseline analysis covered 142 people: 67 antiretroviral-naive, 33 antiretroviral-experienced, and 42 HIV-negative controls. Naive patients started efavirenz, lamivudine and tenofovir plus the antibiotic cotrimoxazole, then were resampled at 24 weeks. Median age was about 35 in naive patients and controls, and 46 in the experienced group. Sexes were roughly balanced across cohorts.
What were the most important findings?
Antiretroviral therapy lowered IL-6, T-cell activation and exhaustion, but improvements were far more pronounced in urban than rural patients, despite equal rates of viral control. In the rural area, only CD8 T-cell activation fell significantly with 24 weeks of treatment. The study population had a Prevotella-rich, Bacteroides-poor microbiome, with mean Prevotella abundance near 17.7%. Treatment-experienced patients showed the most altered microbiome, with reduced alpha diversity and greater deviation from controls. Elevated immune exhaustion at 24 weeks tracked with both rural residence and a more Prevotella-rich, Bacteroides-poor microbiome type.
What are the greatest implications of this study?
The results suggest that people on effective HIV treatment in rural Zimbabwe may retain more inflammation and immune exhaustion, leaving them more vulnerable to non-AIDS comorbidities. Viral suppression alone did not guarantee full immune recovery. Gut microbiome differences, cotrimoxazole exposure and rural environment appear to shape this gap. The authors used only 16S sequencing, so fungi, viruses and strain-level effects were not assessed, and causation cannot be confirmed. Findings highlight the microbiome as a possible target to improve treated-HIV outcomes.