Daily variations of gut microbial translocation markers in ART-treated HIV-infected people

Translocation of bacterial LPS is associated with self-reported cognitive abilities in men living with HIV receiving antiretroviral therapy

BACKGROUND

Gut damage allows translocation of bacterial lipopolysaccharide (LPS) and fungal β-D-glucan (BDG) into the blood. This microbial translocation contributes to systemic inflammation and risk of non-AIDS comorbidities in people living with HIV, including those receiving antiretroviral therapy (ART). We assessed whether markers of gut damage and microbial translocation were associated with cognition in ART-treated PLWH.

METHODS

Eighty ART-treated men living with HIV from the Positive Brain Health Now Canadian cohort were included. Brief cognitive ability measure (B-CAM) and 20-item patient deficit questionnaire (PDQ) were administered to all participants. Three groups were selected based on their B-CAM levels. We excluded participants who received proton pump inhibitors or antiacids in the past 3 months. Cannabis users were also excluded. Plasma levels of intestinal fatty acid binding protein (I-FABP), regenerating islet-derived protein 3 α (REG3α), and lipopolysaccharides (LPS = were quantified by ELISA, while 1-3-β-D-glucan BDG) levels were assessed using the Fungitell assay. Univariable, multivariable, and splines analyses were performed.

RESULTS

Plasma levels of I-FABP, REG3α, LPS and BDG were not different between groups of low, intermediate and high B-CAM levels. However, LPS and REG3α levels were higher in participants with PDQ higher than the median. Multivariable analyses showed that LPS association with PDQ, but not B-CAM, was independent of age and level of education. I-FABP, REG3α, and BDG levels were not associated with B-CAM nor PDQ levels in multivariable analyses.

CONCLUSION

In this well characterized cohort of ART-treated men living with HIV, bacterial but not fungal translocation was associated with presence of cognitive difficulties. These results need replication in larger samples.

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.

Cocaine use associated gut permeability and microbial translocation in people living with HIV in the Miami Adult Study on HIV (MASH) cohort

OBJECTIVE

Determine if cocaine use impacts gut permeability, promotes microbial translocation and immune activation in people living with HIV (PLWH) using effective antiretroviral therapy (ART).

METHODS

Cross-sectional analysis of 100 PLWH (ART ≥6 months, HIV-RNA <200 copies/mL) from the Miami Adult Studies on HIV (MASH) cohort. Cocaine use was assessed by self-report, urine screen, and blood benzoylecgonine (BE). Blood samples were collected to assess gut permeability (intestinal fatty acid-binding protein, I-FABP), microbial translocation (lipopolysaccharide, LPS), immune activation (sCD14, sCD27, and sCD163) and markers of inflammation (hs-CRP, TNF-α and IL-6). Multiple linear regression models were used to analyze the relationships of cocaine use.

RESULTS

A total of 37 cocaine users and 63 cocaine non-users were evaluated. Cocaine users had higher levels of I-FABP (7.92±0.35 vs. 7.69±0.56 pg/mL, P = 0.029) and LPS (0.76±0.24 vs. 0.54±0.27 EU/mL, P<0.001) than cocaine non-users. Cocaine use was also associated with the levels of LPS (P<0.001), I-FABP (P = 0.033), and sCD163 (P = 0.010) after adjusting for covariates. Cocaine users had 5.15 times higher odds to exhibit higher LPS levels than non-users (OR: 5.15 95% CI: 1.89-13.9; P<0.001). Blood levels of BE were directly correlated with LPS (rho = 0.276, P = 0.028), sCD14 (rho = 0.274, P = 0.031), and sCD163 (rho = 0.250, P = 0.049).

CONCLUSIONS

Cocaine use was associated with markers of gut permeability, microbial translocation, and immune activation in virally suppressed PLWH. Mitigation of cocaine use may prevent further gastrointestinal damage and immune activation in PLWH.

Circulating (1 → 3)-β-D-Glucan as an immune activation marker decreased after ART in people living with HIV

Background

Plasma level of polysaccharide (1 → 3)-β-D-Glucan (βDG), as a diagnostic marker of invasive fungal infection has been reported to be elevated in people living with HIV (PLWH). We assessed the association of circulating βDG to inflammation and systemic immune activation and the effect of antiretroviral therapy (ART) on βDG in PLWH.

Method

Plasma and peripheral blood monocular cell samples from 120 PLWH naive to ART and after 1 year's ART were collected. Plasma levels of βDG, markers of bacterial translocation, gut damage, and cellular immune activation were quantified.

Result

The plasma βDG levels were negatively correlated with CD4+ T cells count (r = -0.25, p = 0.005) and positively with HIV viral load (r = 0.28, p = 0.002) before ART. It was also positively correlated with immune activation markers, including PD-1 expression on CD4+ T cell (r = 0.40, p = 0.01) and CD8+ T cell (r = 0.47, p = 0.002), as well as HLADR+CD38+ co-expression on CD8+ T cell (r = 0.56, p = 0.0002), but not with the plasma levels of LPS (r = 0.02, p = 0.84), LPS binding protein (LBP, r = 0.11, p = 0.36), soluble LPS receptor sCD14 (r = 0.04, p = 0.68), intestinal fatty acid binding protein (IFABP, r = -0.12, p = 0.18), and regenerating islet-derived protein 3α (REG3α, r = 0.18, p = 0.06). After 1 year's ART, the levels of βDG were significantly decreased compared to that in pre-ART (1.31 ± 0.24 Log10 pg/ml vs. 1.39 ± 0.18 Log10 pg/ml, p < 0.001).

Conclusion

The level of plasma βDG was associated with cellular immune activation and decreased after ART in PLWH, suggesting it could serve as a biomarker of immune activation and efficacy monitoring.

Markers of fungal translocation are elevated during post-acute sequelae of SARS-CoV-2 and induce NF-κB signaling

Long COVID, a type of post-acute sequelae of SARS-CoV-2 (PASC), has been associated with sustained elevated levels of immune activation and inflammation. However, the mechanisms that drive this inflammation remain unknown. Inflammation during acute coronavirus disease 2019 could be exacerbated by microbial translocation (from the gut and/or lung) to blood. Whether microbial translocation contributes to inflammation during PASC is unknown. We did not observe a significant elevation in plasma markers of bacterial translocation during PASC. However, we observed higher levels of fungal translocation - measured as β-glucan, a fungal cell wall polysaccharide - in the plasma of individuals experiencing PASC compared with those without PASC or SARS-CoV-2-negative controls. The higher β-glucan correlated with higher inflammation and elevated levels of host metabolites involved in activating N-methyl-d-aspartate receptors (such as metabolites within the tryptophan catabolism pathway) with established neurotoxic properties. Mechanistically, β-glucan can directly induce inflammation by binding to myeloid cells (via Dectin-1) and activating Syk/NF-κB signaling. Using a Dectin-1/NF-κB reporter model, we found that plasma from individuals experiencing PASC induced higher NF-κB signaling compared with plasma from negative controls. This higher NF-κB signaling was abrogated by piceatannol (Syk inhibitor). These data suggest a potential targetable mechanism linking fungal translocation and inflammation during PASC.

Aging With Grace for People Living With HIV: Strategies to Overcome Leaky Gut and Cytomegalovirus Coinfection

ABSTRACT

The intestinal epithelial layer acts as a mechanical and functional barrier between the intraluminal microbiota and the immunologically active submucosa. A progressive loss of gut barrier function (leaky gut) leads to enhanced translocation of microbial products, which in turn contributes as endotoxins to inflammaging. Th17 T cell represents the main immune sentinels in the gut epithelium, preventing aggression from commensal and pathogenic microbes. As HIV infection deeply affects gut Th17 function and increases gut permeability, microbial translocation occurs at high level in people living with HIV (PLWH) and has been associated with the development of non-AIDS comorbidities. Although the inflammatory role of endotoxins like lipopolysaccharide produced by Gram-negative bacteria is well-established, fungal products such as β-D-glucan emerge as new contributors. In addition, PLWH are more frequently infected with cytomegalovirus (CMV) than the general population. CMV infection is a well-described accelerator of immune aging, through the induction of expansion of dysfunctional CD8 T-cells as well as through enhancement of gut microbial translocation. We critically review immune mechanisms related to bacterial and fungal translocation, with a focus on the contribution of CMV coinfection in PLWH. Improving gut barrier dysfunction, microbial composition, and reducing microbial translocation constitute emerging strategies for the prevention and treatment of HIV-associated inflammation and may be relevant for age-related inflammatory conditions.

Cell-associated HIV RNA has a Circadian Cycle in Males Living with HIV on Antiretroviral Therapy

BACKGROUND

Circadian transcription factors that regulate cell-autonomous circadian clocks can also increase HIV transcription in vitro. We aimed to determine if circadian variation in HIV transcription exists in people living with HIV (PLHIV) on antiretroviral therapy (ART).

METHODS

We performed a prospective observational study of male PLHIV on ART, sampling blood every four hours for 24 hours. Using qPCR, we quantified expression of circadian associated genes, HIV DNA and cell-associated unspliced (CA-US) RNA in peripheral blood CD4+ T-cells. Plasma sex hormones were quantified alongside plasma and salivary cortisol. The primary outcome was to identify temporal variations in CA-US HIV RNA using a linear mixed effect regression framework and maximum likelihood estimation.

RESULTS

Salivary and plasma cortisol, and circadian genes including Clock, Bmal1, and Per3 varied with a circadian rhythm. CA-US HIV RNA and the ratio of CA-US HIV RNA-to-DNA in CD4+ T-cells also demonstrated circadian variations, with no variation in HIV DNA. Circulating oestradiol was highly predictive of CA-US HIV RNA variation in vivo.

CONCLUSION

CA-US HIV RNA in PLHIV on ART varies temporally with a circadian rhythm. These findings have implications for the design of clinical trials and biomarkers to assess HIV cure interventions.

Inflammation and microbial translocation measured prior to combination antiretroviral therapy (cART) and long-term probability of clinical progression in people living with HIV

BACKGROUND

Despite the effectiveness of cART, people living with HIV still experience an increased risk of serious non-AIDS events, as compared to the HIV negative population. Whether pre-cART microbial translocation (MT) and systemic inflammation might predict morbidity/mortality during suppressive cART, independently of other known risk factors, is still unclear. Thus, we aimed to investigate the role of pre-cART inflammation and MT as predictors of clinical progression in HIV+ patients enrolled in the Icona Foundation Study Cohort.

METHODS

We included Icona patients with ≥2 vials of plasma stored within 6 months before cART initiation and at least one CD4 count after therapy available. Circulating biomarker: LPS, sCD14, EndoCab, hs-CRP. Kaplan-Meier curves and Cox regression models were used. We defined the endpoint of clinical progression as the occurrence of a new AIDS-defining condition, severe non-AIDS condition (SNAEs) or death whichever occurred first. Follow-up accrued from the data of starting cART and was censored at the time of last available clinical visit. Biomarkers were evaluated as both binary (above/below median) and continuous variables (logescale).

RESULTS

We studied 486 patients with 125 clinical events: 39 (31%) AIDS, 66 (53%) SNAEs and 20 (16%) deaths. Among the analyzed MT and pro-inflammatory markers, hs-CRP seemed to be the only biomarker retaining some association with the endpoint of clinical progression (i.e. AIDS/SNAEs/death) after adjustment for confounders, both when the study population was stratified according to the median of the distribution (1.51 mg/L) and when the study population was stratified according to the 33% percentiles of the distribution (low 0.0-1.1 mg/L; intermediate 1.2-5.3 mg/L; high > 5.3 mg/L). In particular, the higher the hs-CRP values, the higher the risk of clinical progression (p = 0.056 for median-based model; p = 0.002 for 33% percentile-based model).

CONCLUSIONS

Our data carries evidence for an association between the risk of disease progression after cART initiation and circulating pre-cART hs-CRP levels but not with levels of MT. These results suggest that pre-therapy HIV-driven pro-inflammatory milieu might overweight MT and its downstream immune-activation.

Clinical characteristics and risk factors for poor prognosis among HIV patients with Talaromyces marneffei bloodstream infection

Background

Talaromyces marneffei (TM) bloodstream infection is common in Acquired Immunodeficiency Syndrome (AIDS) patients with extreme immunodeficiency in Southeast Asia and South China, however, clinical case study on TM bloodstream infection is scarce. We retrospectively analyzed the clinical characteristics of TM bloodstream infection in hospitalized AIDS patients and determined the outcomes of hospitalization after diagnosis in our hospital over the past 5 years.

Methods

From January 2015 to July 2020, 87 cases of TM detected by blood culture in patients admitted to our center were collected. The admission complaints, blood cells, biochemistry, CD4 and CD8 cell counts and 1,3-β-D-glucan (BDG), procalcitonin (PCT), CRP level on the day of blood culture test, and outcomes during hospitalization were analyzed. Logistic regression analysis was performed for the risk factors for poor prognosis (60 cases). Spearman correlation analysis was used to analyze the correlation between peripheral blood cells, albumin and the time required for TM turnaround in blood culture. The difference was statistically significant when the P value was < 0.05.

Results

A total of 87 patients were collected, with a median age of 34 years, a median hemoglobin of 94 g/L and CD4 count of 7/μl. The rate of TM bloodstream infection among all in-hospital patients increased from 0.99% in 2015 to 2.09% in 2020(half year). Patients with TM bloodstream infection with CD8 count < 200/μl had a 12.6-fold higher risk of poor prognosis than those with CD8 count > 200/μl (p = 0.04), and those with BDG < 100 pg/mL had a 34.9-fold higher risk of poor prognosis than those with BDG > 100 pg/mL (p = 0.01).

Conclusions

TM bloodstream infection is becoming more common in advanced AIDS patients in endemic areas. For those patients with extremely low CD4 and CD8 cell counts below 200/μl is with an increased risk of poor prognosis.

Gut Leakage of Fungal-Related Products: Turning Up the Heat for HIV Infection

The intestinal epithelial layer serves as a physical and functional barrier between the microbiota in the lumen and immunologically active submucosa. Th17 T-cell function protects the gut epithelium from aggression from microbes and their by-products. Loss of barrier function has been associated with enhanced translocation of microbial products which act as endotoxins, leading to local and systemic immune activation. Whereas the inflammatory role of LPS produced by Gram-negative bacteria has been extensively studied, the role of fungal products such as β-D-glucan remains only partially understood. As HIV infection is characterized by impaired gut Th17 function and increased gut permeability, we critically review mechanisms of immune activation related to fungal translocation in this viral infection. Additionally, we discuss markers of fungal translocation for diagnosis and monitoring of experimental treatment responses. Targeting gut barrier dysfunction and reducing fungal translocation are emerging strategies for the prevention and treatment of HIV-associated inflammation and may prove useful in other inflammatory chronic diseases.

Potential benefit of β-glucans as adjuvant therapy in immuno-oncology: a review

Fungal compounds have long been used for centuries as food supplements. β-glucans have been identified as the most interesting molecules with beneficial effects in several chronic diseases. In vitro studies have shown that they are able to elicit the immune cells maturation and activation with the result of an increased release of proinflammatory cytokines and chemokines and a stimulation of anti-bacterial activity of macrophages and neutrophils. As β-glucans enhance pathogen elimination through non-self antigens identification, they can also direct immune response against tumor cells. These compounds also stimulate the activity on adaptive immune cells and they have been regarded as biological response modifiers. In this way, β-glucans can be exploited as adjuvant cancer therapy, in particular by a synergic action with chemotherapy or immunotherapy. In the immuno-oncology era, the need is to identify innovative drugs that can simultaneously target and inhibit different biological processes relevant for cancer cells survivors. Recent clinical studies showed promising results about the combination of β-glucans and immune checkpoint inhibitors for patients affected by different solid tumors. This review aims to investigate molecular mechanisms of action of β-glucans and is focused on their application in clinical practice as immune-adjuvants for treatment of cancer patients.

Circulating β-d-Glucan as a Marker of Subclinical Coronary Plaque in Antiretroviral Therapy-Treated People With Human Immunodeficiency Virus

Background

Despite antiretroviral therapy (ART), people with human immunodeficiency virus (PWH) have increased risk of inflammatory comorbidities, including cardiovascular diseases. Gut epithelial damage, and translocation of bacterial lipopolysaccharide (LPS) or fungal β-d-glucan (BDG) drive inflammation in ART-treated PWH. In this study, we investigated whether markers of gut damage and microbial translocation were associated with cardiovascular risk in asymptomatic ART-treated PWH.

Methods

We cross-sectionally analyzed plasma from 93 ART-treated PWH and 52 uninfected controls older than 40 years of age from the Canadian HIV and Aging Cohort. Participants were cardiovascular disease free and underwent a cardiac computed tomography (CT) to measure total coronary atherosclerotic plaque volume (TPV). Levels of bacterial LPS and gut damage markers REG3α and I-FABP were measured by enzyme-linked immunosorbent assay. Fungal BDG levels were analyzed using the Fungitell assay.

Results

β-d-glucan levels but not LPS were significantly elevated in ART-treated PWH with coronary artery plaque (P = .0007). Moreover, BDG but not LPS levels correlated with TPV (r = 0.26, P = .01). Intestinal fatty acid binding protein (I-FABP) but not REG3α levels correlated with TPV (r = 0.23, P = .03). However, BDG and LPS levels were not elevated in uninfected controls with plaque. In multivariable models, elevated BDG levels were independently associated with the presence of coronary atherosclerosis in PWH but not in uninfected controls.

Conclusions

Translocation of fungal BDG was associated with coronary atherosclerosis assessed by CT-scan imaging in ART-treated PWH, suggesting a human immunodeficiency virus-specific pathway leading to cardiovascular disease. Further investigation is needed to appraise causality of this association. Translocation of fungal products may represent a therapeutic target to prevent cardiovascular disease in ART-treated PWH.

Plasma levels of the fungal product β-D-Glucan, but not the bacterial product lipopolysaccharide, are associated with the presence and the size of subclinical coronary atherosclerosis plaque in people living with HIV taking antiretroviral therapy, independently of classical cardiovascular risk factors.

Glucan rich nutrition does not increase gut translocation of beta-glucan

BACKGROUND

(1-3)-b-D-glucan (BDG) is a fungal cell wall component and, in the absence of invasive fungal infection, a novel biomarker for microbial translocation of endogenous fungal products from the gastrointestinal tract into systemic circulation. However, its value as a marker of fungal translocation is limited by a concern that plant BDG-rich food influences blood BDG levels.

METHODS

We conducted a pilot clinical trial to evaluate the impact of a standardised oral BDG challenge on blood BDG levels in participants with and without elevated microbial translocation. We enrolled 14 participants including 8 with HIV infection, 2 with advanced liver cirrhosis, and 4 healthy controls. After obtaining a baseline blood sample, participants received a standardised milkshake containing high levels of BDG followed by serial blood samples up to 8 hours after intake.

RESULTS

The standardised oral BDG challenge approach did not change the blood BDG levels over time in all participants. We found consistently elevated blood BDG levels in one participant with advanced liver cirrhosis and a single person with HIV with a low CD4 count of 201 cells/mm3 .

CONCLUSION

Our findings indicate that BDG blood levels were not influenced by plant origin BDG-rich nutrition in PWH, people with advanced liver cirrhosis, or healthy controls. Future studies are needed to analyse gut mycobiota populations in individuals with elevated blood BDG levels.