Brief Report: Gut Structural Damage: an Ongoing Process in Chronically Untreated HIV Infection

Characterization of intestinal fungal community diversity in people living with HIV/AIDS (PLWHA)

Acquired Immune Deficiency Syndrome (AIDS) is a highly dangerous infectious disease caused by the Human Immunodeficiency Virus (HIV), a virus that attacks the human immune system. To explore the correlation between intestinal fungal community and immune function (Immune cells and inflammatory factors) in people living with HIV/AIDS (PLWHA). The feces and blood samples were collected from two groups of subjects: PLWHA and healthy controls. High-throughput sequencing of the internal transcribed spacer 1, flow cytometry, and ELISA were performed to analyze the differences and correlations between fungal microbiota, cellular immune status and serum inflammatory factors in the two groups. There were significant differences in the composition of fungal microbiota between the two groups. The relative abundance of Candida, Bjerkandera, and Xeromyces in PLWHA was significantly higher than that of healthy volunteers (P < 0.01), while the relative abundance of Mycospaerella, Xeroxysium, Penicillium, and Glomerella in PLWHA was significantly lower than that of healthy volunteers. The correlation analysis results show that Mycospaerella and Xeromyces are significantly positively correlated with CD4+/CD8+ T cells and the anti-inflammatory cytokine IL-4. On the other hand, Candida was positively correlated with pro-inflammatory factors negatively correlated with CD4+/CD8+ T cells and the anti-inflammatory cytokine IL-4, while it is positively correlated with pro-inflammatory cytokines. The significant increase in the relative abundance of Candida may be one of the important causes of intestinal damage in PLWHA. The results of this study contribute to the understanding of the relationship between fungal microbiota structure and immune function in the gut ecology of PLWHA.

Mass spectrometry analysis of gut tissue in acute SIV-infection in rhesus macaques identifies early proteome alterations preceding the interferon inflammatory response

HIV infection damages the gut mucosa leading to chronic immune activation, increased morbidities and mortality, and antiretroviral therapies, do not completely ameliorate mucosal dysfunction. Understanding early molecular changes in acute infection may identify new biomarkers underlying gut dysfunction. Here we utilized a proteomics approach, coupled with flow cytometry, to characterize early molecular and immunological alterations during acute SIV infection in gut tissue of rhesus macaques. Gut tissue biopsies were obtained at 2 times pre-infection and 4 times post-infection from 6 macaques. The tissue proteome was analyzed by mass spectrometry, and immune cell populations in tissue and blood by flow cytometry. Significant proteome changes (p < 0.05) occurred at 3 days post-infection (dpi) (13.0%), 14 dpi (13.7%), 28 dpi (16.9%) and 63 dpi (14.8%). At 3 dpi, proteome changes included cellular structural activity, barrier integrity, and activation of epithelial to mesenchymal transition (EMT) (FDR < 0.0001) prior to the antiviral response at 14 dpi (IFNa/g pathways, p < 0.001). Novel EMT proteomic biomarkers (keratins 2, 6A and 20, collagen 12A1, desmoplakin) and inflammatory biomarkers (PSMB9, FGL2) were associated with early infection and barrier dysfunction. These findings identify new biomarkers preceding inflammation in SIV infection involved with EMT activation. This warrants further investigation of the role of these biomarkers in chronic infection, mucosal inflammation, and disease pathogenesis of HIV.

Relevance of biomarkers indicating gut damage and microbial translocation in people living with HIV

The intestinal barrier has the daunting task of allowing nutrient absorption while limiting the entry of microbial products into the systemic circulation. HIV infection disrupts the intestinal barrier and increases intestinal permeability, leading to microbial product translocation. Convergent evidence has shown that gut damage and an enhanced level of microbial translocation contribute to the enhanced immune activation, the risk of non-AIDS comorbidity, and mortality in people living with HIV (PLWH). Gut biopsy procedures are invasive, and are not appropriate or feasible in large populations, even though they are the gold standard for intestinal barrier investigation. Thus, validated biomarkers that measure the degree of intestinal barrier damage and microbial translocation are needed in PLWH. Hematological biomarkers represent an objective indication of specific medical conditions and/or their severity, and should be able to be measured accurately and reproducibly via easily available and standardized blood tests. Several plasma biomarkers of intestinal damage, i.e., intestinal fatty acid-binding protein (I-FABP), zonulin, and regenerating islet-derived protein-3α (REG3α), and biomarkers of microbial translocation, such as lipopolysaccharide (LPS) and (1,3)-β-D-Glucan (BDG) have been used as markers of risk for developing non-AIDS comorbidities in cross sectional analyses and clinical trials, including those aiming at repair of gut damage. In this review, we critically discuss the value of different biomarkers for the estimation of gut permeability levels, paving the way towards developing validated diagnostic and therapeutic strategies to repair gut epithelial damage and to improve overall disease outcomes in PLWH.

Intestinal Fatty Acid Binding Protein (I-FABP) as a Prognostic Marker in Critically Ill COVID-19 Patients

Gastrointestinal symptoms are common in critically ill COVID-19 patients. There is currently no generally recognized method of assessing gastrointestinal injury in unconscious or sedated intensive care unit (ICU) patients. I-FABP (intestinal fatty acid binding protein) and citrulline have previously been studied as potential biomarkers of enterocyte damage in various gastrointestinal tract diseases, and changes in the levels of these markers may reflect intestinal wall damage in COVID-19. Patients with critical COVID-19, with diagnosed sepsis, or septic shock requiring ICU treatment were included in the study. Blood samples for citrulline and I-FABP were taken daily from day 1 to 5. I-FABP levels were significantly higher in patients who eventually died from COVID-19 than in survivors, and the optimal I-FABP cut-off point for predicting 28-day mortality was 668.57 pg/mL (sensitivity 0.739, specificity 0.765). Plasma levels of I-FABP, but not citrulline, were associated with significantly higher mortality and appeared to be a predictor of poor outcome in multivariate logistic regression analysis. In conclusion, I-FABP seems to be an effective prognostic marker in critically ill COVID-19 patients. Assessing mortality risk based on intestinal markers may be helpful in making clinical decisions regarding the management of intestinal injury, imaging diagnostics, and potential surgical interventions.

Alcohol Use and Abuse Conspires With HIV Infection to Aggravate Intestinal Dysbiosis and Increase Microbial Translocation in People Living With HIV: A Review

The intestinal microbiome is an essential so-called human "organ", vital for the induction of innate immunity, for metabolizing nutrients, and for maintenance of the structural integrity of the intestinal barrier. HIV infection adversely influences the richness and diversity of the intestinal microbiome, resulting in structural and functional impairment of the intestinal barrier and an increased intestinal permeability. Pathogens and metabolites may thus cross the "leaky" intestinal barrier and enter the systemic circulation, which is a significant factor accounting for the persistent underlying chronic inflammatory state present in people living with HIV (PLWH). Additionally, alcohol use and abuse has been found to be prevalent in PLWH and has been strongly associated with the incidence and progression of HIV/AIDS. Recently, converging evidence has indicated that the mechanism underlying this phenomenon is related to intestinal microbiome and barrier function through numerous pathways. Alcohol acts as a "partner" with HIV in disrupting microbiome ecology, and thus impairing of the intestinal barrier. Optimizing the microbiome and restoring the integrity of the intestinal barrier is likely to be an effective adjunctive therapeutic strategy for PLWH. We herein critically review the interplay among HIV, alcohol, and the gut barrier, thus setting the scene with regards to development of effective strategies to counteract the dysregulated gut microbiome and the reduction of microbial translocation and inflammation in PLWH.

Altered Intestinal Permeability and Fungal Translocation in Ugandan Children With Human Immunodeficiency Virus

BACKGROUND

Children with perinatally acquired human immunodeficiency virus (HIV; PHIVs) face a lifelong cumulative exposure to HIV and antiretroviral therapy (ART). The relationship between gut integrity, microbial translocation, and inflammation in PHIV is poorly understood.

METHODS

This is a cross-sectional study in 57 PHIVs, 59 HIV-exposed but uninfected children, and 56 HIV-unexposed and -uninfected children aged 2-10 years old in Uganda. PHIVs were on stable ART with HIV-1 RNA <400 copies/mL. We measured markers of systemic inflammation, monocyte activation, and gut integrity. Kruskal-Wallis tests were used to compare markers by group and the Spearman correlation was used to assess correlations between biomarkers.

RESULTS

The mean age of all participants was 7 years and 55% were girls. Among PHIVs, the mean CD4 % was 34%, 93% had a viral load ≤20 copies/mL, and 79% were on a nonnucleoside reverse transcriptase inhibitor regimen. Soluble cluster of differentiation 14 (sCD14), beta-D-glucan (BDG), and zonulin were higher in the PHIV group (P ≤ .01). Intestinal fatty acid binding protein (I-FABP) and lipopolysaccharide binding protein (LBP) did not differ between groups (P > .05). Among PHIVs who were breastfed, levels of sCD163 and interleukin 6 (IL6) were higher than levels in PHIV who were not breastfed (P < .05). Additionally, in PHIVs with a history of breastfeeding, sCD14, BDG, LBP, zonulin, and I-FABP correlated with several markers of systemic inflammation, including high-sensitivity C-reactive protein, IL6, d-dimer, and systemic tumor necrosis factor receptors I and II (P ≤ .05).

CONCLUSIONS

Despite viral suppression, PHIVs have evidence of altered gut permeability and fungal translocation. Intestinal damage and the resultant bacterial and fungal translocations in PHIVs may play a role in the persistent inflammation that leads to many end-organ diseases in adults.Despite viral suppression, children with perinatally acquired human immunodeficiency virus (HIV) in Uganda have evidence of alterations in intestinal permeability and fungal translocation, compared to HIV-exposed but uninfected and HIV-unexposed children, which may play a role in HIV-associated chronic inflammation.

Association of Plasma Soluble Vascular Cell Adhesion Molecule-1 and sCD14 With Mortality in HIV-1-Infected West African Adults With High CD4 Counts

BACKGROUND

Several biomarkers of inflammation and coagulation were reported to be associated with HIV disease progression in different settings. In this article, we report the association between 11 biomarkers and medium-term mortality in HIV-infected West African adults.

METHODS

In Temprano ANRS 12136, antiretroviral therapy (ART)-naive HIV-infected adults with high CD4 counts were randomly assigned either to start ART immediately or defer ART until the World Health Organization criteria were met. Participants who completed the 30-month trial follow-up were invited to participate in a posttrial phase. The posttrial phase end point was all-cause death. We used multivariate Cox proportional models to analyze the association between baseline plasma biomarkers [IL-1ra, IL-6, soluble vascular cell adhesion molecule 1 (sVCAM-1), sCD14, D-dimer, fibrinogen, IP-10, sCD163, albumin, high-sensitivity C-reactive protein, and 16S rDNA] and all-cause death in the Temprano participants randomized to defer ART.

RESULTS

Four hundred seventy-seven patients (median age 35 years, 78% women, and median CD4 count: 379 cells/mm) were randomly assigned to defer starting ART until the World Health Organization criteria were met. The participants were followed for 2646 person-years (median 5.8 years). In the follow-up, 89% of participants started ART and 30 died. In the multivariate analysis adjusted for the study center, sex, baseline CD4 count, isoniazid preventive therapy, plasma HIV-1 RNA, peripheral blood mononuclear cell HIV-1 DNA, and ART, the risk of death was significantly associated with baseline sVCAM-1 (≥1458 vs. <1458: adjusted hazard ratio 2.57, 95% confidence interval: 1.13 to 5.82) and sCD14 (≥2187 vs. <2187: adjusted hazard ratio 2.79, interquartile range 1.29-6.02) levels.

CONCLUSIONS

In these sub-Saharan African adults with high CD4 counts, pre-ART plasma sVCAM-1 and sCD14 levels were independently associated with mortality.

Persistence of monocyte activation under treatment in people followed since acute HIV-1 infection relative to participants at high or low risk of HIV infection

BACKGROUND

Interpretation of the increase in certain inflammatory markers in virally suppressed HIV-infected individuals must rely on an appropriate uninfected control group well characterized for non-HIV-related factors that contribute to chronic inflammation, e.g. smoking, alcohol consumption, or being overweight. We compared the inflammatory profiles of HIV-infected participants under long-term antiretroviral therapy (ART) with those of two HIV-uninfected groups with contrasting health behaviours.

METHODS

We studied 150 HIV-infected participants (42 women, 108 men) under long-term ART (median, 6 years) followed in the ANRS PRIMO cohort since acute/early HIV-1 infection (AHI) diagnosis. Sex and age-matched controls were sampled from i) the ANRS IPERGAY pre-exposure prophylaxis trial among men at high risk for HIV infection and with high frequencies of non-HIV factors of inflammation ii) the ANRS COHVAC cohort of volunteers in vaccine trials with a low-risk profile for HIV infection. We measured the plasma levels of ten inflammatory markers.

FINDINGS

After adjusting for smoking, alcohol use and body mass index, both HIV-infected men and women had higher levels of sCD14, sCD163, sTNFRII and I-FABP than their high-risk IPERGAY and low-risk COHVAC counterparts. Hierarchical clustering showed a subset of 15 PRIMO participants to have an inflammatory profile similar to that of most HIV-negative participants. These participants already had favourable markers at AHI diagnosis.

INTERPRETATION

Long-term ART, even when initiated at a low level of immunodeficiency, fails to normalize monocyte/macrophage activation and gut epithelial dysfunction. Persistent inflammation under treatment may be related to an increased inflammatory profile since AHI.

FUNDING

ANRS and Paris-Saclay University.

Endothelial Dysfunction Is Related to Monocyte Activation in Antiretroviral-Treated People With HIV and HIV-Negative Adults in Kenya

BACKGROUND

Residual monocyte activation may contribute to increased risk for endothelial dysfunction and subsequent atherosclerotic cardiovascular diseases (CVDs) among people with HIV (PWH) on antiretroviral therapy (ART). We examined the relationship between monocyte activation and endothelial activation in PWH in Kenya.

METHODS

Serum levels of markers of endothelial activation (soluble/circulating intercellular [sICAM-1] and vascular [sVCAM-1] cell adhesion molecule-1), intestinal barrier dysfunction (intestinal fatty acid binding protein [I-FABP]), and monocyte activation (soluble CD14 [sCD14]) were measured in 275 PWH on ART and 266 HIV-negative persons. Linear regression was used to evaluate associations, adjusting for demographic and traditional CVD risk factors.

RESULTS

Among 541 participants, the median age was 43 years, 50% were female, and most PWH were virally suppressed (97%). sICAM-1 and sVCAM-1 levels were significantly higher in PWH than in HIV-negative participants (P < .001 for both). After further adjustment for traditional CVD risk factors, HIV infection remained associated with 49% (95% CI, 33% to 67%) greater sICAM-1 and 30% (95% CI, 14% to 48%) greater sVCAM-1 relative to uninfected controls. Adjustment for sCD14 substantially attenuated the difference between PWH and HIV-negative individuals. In a stratified analysis of PWH, both sICAM-1 and sVCAM-1 were positively associated with sCD14 (P < .001).

CONCLUSIONS

Despite viral suppression, African PWH have evidence of enhanced endothelial activation associated with sCD14, suggesting that monocyte activation plays a role in atherosclerotic plaque development. Future studies are needed to determine mechanistic pathways leading to monocyte activation in this population.

Plasma Levels of C-Type Lectin REG3α and Gut Damage in People With Human Immunodeficiency Virus

BACKGROUND

Regenerating islet-derived protein 3α (REG3α) is an antimicrobial peptide secreted by intestinal Paneth cells. Circulating REG3α has been identified as a gut damage marker in inflammatory bowel diseases. People living with human immunodeficiency virus (PWH) on antiretroviral therapy (ART) present with an abnormal intestinal landscape leading to microbial translocation, persistent inflammation, and development of non-AIDS comorbidities. Herein, we assessed REG3α as a marker of gut damage in PWH.

METHODS

Plasma from 169 adult PWH, including 30 elite controllers (ECs), and 30 human immunodeficiency virus (HIV)-uninfected controls were assessed. REG3α plasma levels were compared with HIV disease progression, epithelial gut damage, microbial translocation, and immune activation markers.

RESULTS

Cross-sectionally, REG3α levels were elevated in untreated and ART-treated PWH compared with controls. ECs also had elevated REG3α levels compared to controls. Longitudinally, REG3α levels increased in PWH without ART and decreased in those who initiated ART. REG3α levels were inversely associated with CD4 T-cell count and CD4:CD8 ratio, while positively correlated with HIV viral load in untreated participants, and with fungal product translocation and inflammatory markers in all PWH.

CONCLUSIONS

Plasma REG3α levels were elevated in PWH, including ECs. The gut inflammatory marker REG3α may be used to evaluate therapeutic interventions and predict non-AIDS comorbidity risks in PWH.