Reduced Plasma Levels of sCD14 and I-FABP in HIV-infected Patients with Mesalazine-treated Ulcerative Colitis

Comparison of Integrase Strand Transfer Inhibitors (INSTIs) and Protease-Boosted Inhibitors (PIs) on the Reduction in Chronic Immune Activation in a Virally Suppressed, Mainly Male Population Living with HIV (PLWH)

Background and Objectives: The success of combined antiretroviral therapy (cART) has led to a dramatic improvement in the life expectancy of people living with HIV (PLWH). However, there has been an observed increase in cardiometabolic, bone, renal, hepatic, and neurocognitive manifestations, as well as neoplasms, known as serious non-AIDS events/SNAEs, compared to the general population of corresponding age. This increase is linked to a harmful phenomenon called inflammaging/immunosenescence, which is driven by chronic immune activation and intestinal bacterial translocation. In this study, we examined immunological and metabolic parameters in individuals receiving current cART. Materials and Methods: The study was conducted at Laiko General Hospital in Athens, Greece. Plasma concentrations of sCD14, IL-6, SuPAR, I-FABP, and LBP were measured in virally suppressed PLWH under cART with at least 350 CD4 lymphocytes/μL. We compared these levels between PLWH receiving integrase strand transfer inhibitors (INSTIs) and protease inhibitors (PIs) and attempted to correlate them with chronic immune activation and metabolic parameters. Results: Data from 28 PLWH were analyzed, with a mean age of 52 and 93% being males. Among the two comparison groups, IL-6 levels were higher in the PIs group (5.65 vs. 7.11 pg/mL, p = 0.03). No statistically significant differences were found in the other measured parameters. A greater proportion of PLWH under INSTIs had normal-range LBP (33% vs. 0%, p = 0.04). When using inverse probability of treatment weighting, no statistically significant differences in the measured parameters were found between the two groups (sCD14 p = 0.511, IL-6 p = 0.383, SuPAR p = 0.793, I-FABP p = 0.868, and LBP p = 0.663). Glucose levels were found to increase after viral suppression in the entire sample (92 mg/dL vs. 98 mg/dL, p = 0.009). Total (191 mg/dL vs. 222 mg/dL, p = 0.005) and LDL cholesterol (104 mg/dL vs. 140 mg/dL, p = 0.002) levels were higher in the PIs group. No significant differences were observed in liver and renal function tests. Conclusions: Further investigation is warranted for PLWH on cART-containing INSTI regimens to explore potential reductions in chronic immune activation and intestinal bacterial translocation.

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.

Gastrointestinal Dysfunction and HIV Comorbidities

PURPOSE OF REVIEW

Gut dysfunction and resulting chronic low-grade inflammation have been linked to metabolic and chronic diseases in the general population. In this review, we present recently published studies of HIV-associated gut dysfunction and comorbidities including obesity, diabetes, cardiovascular disease, liver disease, and neurocognitive disease.

RECENT FINDINGS

Biomarkers of microbial translocation, dysbiosis, or intestinal epithelial integrity have been used to investigate relationships between HIV-associated gut dysfunction and metabolic, cardiovascular, and neurologic complications. Many studies point to worsened comorbidities associated with gut dysfunction in people with HIV (PWH), but some studies show mixed results, and thus, the data are still inconclusive and limited to surrogate biomarkers rather than direct intestinal assessments. Inflammation and immune activation stemming from changes in intestinal epithelial integrity and dysbiosis are present in PWH and relate to metabolic, cardiovascular, and neurologic complications of HIV. However, future investigations, especially future studies that directly assess intestinal pathology, are needed to investigate the direct contributory role of gastrointestinal dysfunction to comorbidities of HIV.

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.

Contribution of the Microbiota to Intestinal Homeostasis and its Role in the Pathogenesis of HIV-1 Infection

During HIV infection, massive destruction of CD4+ T cells ensues, preferentially depleting the Th17 subset at the gut-associated lymphoid tissue (GALT), leading to a loss of mucosal integrity and an increase in cell permeability. This process favors microbial translocation between the intestinal lumen and the circulatory system, contributing to persistent immune activation and chronic inflammation characteristic of HIV infection. Thus, the gut microbiota plays an integral role in maintaining the structure and function of the mucosal barrier, a critical factor for immune homeostasis. However, in the context of HIV infection, changes in the gut microbiota have been reported and have been linked to disease progression. Here, we review evidence for the role of the gut microbiota in intestinal homeostasis, its contribution to HIV pathogenesis, as well as its use in the development of therapeutic strategies.

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

OBJECTIVE

To investigate the longitudinal changes of gut structural damage in chronically untreated HIV infection.

DESIGN

This is a 96-week prospective, single-site, cohort study of antiretroviral therapy-naive HIV-infected participants.

METHODS

Intestinal fatty acid-binding proteins (I-FABP) were used as a surrogate marker of gut structural damage. We assessed changes in I-FABP over 96 weeks and examined the associations between I-FABP, HIV variables, and inflammation. Spearman's correlations and linear mixed-effect models were used to study relationships among variables.

RESULTS

A total of 63 HIV-infected, antiretroviral therapy-naive patients were included in this analysis. At baseline, 76% were male; 62% were African American, with median age and body mass index of 40 years and 27 kg/m, respectively. Median HIV-RNA and CD4 T-cell counts were 5520 copies per milliliter and 588 cells per mm, respectively. I-FABP significantly increased from baseline to week 96 (mean change +333.9 pg/mL; P = 0.03), and this increase was associated with viral replication (rho = +0.4; P = 0.03). I-FABP levels were found to be associated with markers of inflammation: sTNFR-II (rho = 0.4, P = 0.02) and sVCAM-1 (rho = 0.04; P < 0.01) at all study time points. Lower baseline CD4 T-cell counts was found to be independently associated with I-FABP progression after adjusting for baseline characteristic variables (P = 0.02).

CONCLUSION

Gut structural damage is an ongoing process in the chronic phase of untreated HIV infection and is largely dependent on viral replication. I-FABP was found to be associated with worse immune function, increased inflammation, and viremia in chronically untreated HIV infection, supporting its role as a biomarker of intestinal barrier dysfunction.

Gut Microbiome, Short-Chain Fatty Acids, and Mucosa Injury in Young Adults with Human Immunodeficiency Virus Infection

BACKGROUND

HIV progression is characterized by immune activation and microbial translocation from the gut. Short-chain fatty acids (SCFAs) are essential for gut homeostasis. Decreased intestinal SCFAs play a role in rapid HIV progression.

AIMS

To compare the SCFA profile, intestinal microbiome, and intestinal mucosal injury between patients with HIV (but not AIDS) and healthy controls.

METHODS

This was a prospective study of 15 patients without AIDS and 10 controls conducted between July 2016 and January 2017 at the Institute of Dermatology and Venereology (Sichuan Academy of Medical Sciences). Stool specimens were collected to analyze the microbiome and SCFAs. Blood I-FABP and D-lactate (gut injury markers) were measured as well as T cells in HIV-positive patients. Intestinal mucosa was observed by colonoscopy.

RESULTS

Rikenellaceae, Microbacteriaceae, Roseburia, Lachnospiraceae, Alistipes, and Ruminococcaceae were decreased, while Moraxellaceae and Psychrobacter were increased in HIV-positive patients. Butyric acid (p = 0.04) and valeric acid (p = 0.03) were reduced in HIV-positive patients. Colonoscopy revealed no visible damage in all subjects. There were no differences in I-FABP and D-lactate between groups. Butyric and valeric acids mainly positively correlated with Rikenellaceae, Ruminococcaceae, Alistipes, Roseburia, and Lachnospiraceae. CD8+ cells were positively correlated with Proteobacteria. CD4+ cells, and CD4/CD8 were negatively correlated with acetic acid. CD8+ cells were positively correlated with valeric acid.

CONCLUSION

The differences in the distribution of intestinal flora between HIV-infected and healthy individuals, especially some SCFAs, suggest that there is already a predisposition to intestinal mucosa damage in HIV-infected individuals.

Alterations in bacterial communities, SCFA and biomarkers in an elderly HIV-positive and HIV-negative population in western Mexico

BACKGROUND

The study of stool microbiota has taken great relevance in the last years, given its role in the maintenance of the intestinal metabolic, physiological, and immunological homeostasis, as well as, its effect over HIV biomarkers levels such as CD4/CD8 ratio, high sensitivity C-Reactive Protein (hs-CRP), related to poor outcomes (rapid progression to AIDS). Several efforts have been made to characterize the gut microbiome. In HIV infection, most of the studies report the presence of a dysbiotic pattern; however, few of them have made an approach in elderly HIV-positive subjects despite the fact that nowadays this subgroup is rising. In this study, we compared the composition of faecal microbiota, Short Chain Fatty Acids (SCFAs), and systemic biomarkers between elderly HIV-positive and HIV-negative subjects.

METHODS

A cross-sectional study with 18 HIV-negative controls and 20 HIV-positive patients. The quantification of Bacteroidetes, Firmicutes, Proteobacteria, Actinobacteria, Lactobacillus, Enterobacteriaceae, Bifidobacterium, Escherichia coli, Clostridium leptum, Clostridium coccoides was performed in faecal samples by qPCR. The analysis was performed by calculating the ΔCq of each microorganism using 16S rDNA as a reference gene. Faecal SCFAs were measured by HPLC. The hs-CRP and sCD14 were performed by ELISA.

RESULTS

An increase in the Firmicutes/Bacteroidetes ratio, coupled with a significant increase in the proteobacteria phylum was detected in HIV-positive subjects. In contrast, a decrease in the Clostridium leptum group was observed. Nevertheless, these elderly HIV-positive patients showed higher levels of total SCFAs mainly by an augmented propionic acid values, compared to HIV-negative subjects. Whereas high levels of hs-CRP were positively correlated with sCD14 in the HIV-positive group.

CONCLUSIONS

Alterations in bacterial communities reveals a dysbiotic state related to an unbalance of faecal SCFAs. Therefore, these intestinal conditions might drive an increase of poor prognostic biomarkers in elderly HIV-positive subjects.

I-FABP Is Higher in People With Chronic HIV Than Elite Controllers, Related to Sugar and Fatty Acid Intake and Inversely Related to Body Fat in People With HIV

Background

Intestinal fatty acid binding protein (I-FABP) has been shown to be a marker of intestinal damage among people living with HIV. We hypothesized that I-FABP would be increased in chronically HIV-infected patents more than elite controllers and would relate to specific nutrient intake and body composition.

Methods

In an observational study, serum I-FABP was measured by enzyme-linked immunosorbent assay. Anthropometric measurements, dual-energy x-ray absorptiometry, and single-slice abdominal computed tomography were obtained to assess body composition, as well as visceral and subcutaneous adipose tissue areas (VAT and SAT). Dietary intake was assessed using 4-day food records.

Results

One hundred forty-nine people with chronic HIV (65% male, 47 ± 7 years of age, 54.7% white, and 14 ± 6 years of known HIV), 10 elite controllers (60% male, 53 ± 8 years, 60% white, and 20 ± 7 years of known HIV), and 69 HIV-negative controls (59.4% male, 46 ± 7 years, and 52.2% white) were included in the analysis. I-FABP was significantly higher in HIV progressors relative to HIV-negative controls and elite controllers. In the chronic HIV group, I-FABP was positively associated with dietary intake of added sugar and with saturated fatty acids. I-FABP was inversely associated with body mass index, VAT, and SAT. I-FABP also correlated with MCP-1, CXCL10, sCD163, and lipopolysaccharide (LPS) among all participants.

Conclusions

I-FABP was increased among chronically HIV-infected patients to a greater degree than in elite controllers and was related to nutrient intake and body composition in HIV progressors. Future studies to investigate the role of intestinal damage on nutrient absorption are needed to elucidate the mechanisms of these relationships.

Trial Registration Identifier

NCT00455793.