Plasma levels of bacterial DNA correlate with immune activation and the magnitude of immune restoration in persons with antiretroviral-treated HIV infection

The role of serum I-FABP concentration in assessment of small intestine mucosa among HIV-infected patients

Objectives:

The intestinal fatty acid binding protein (I-FABP) is a useful marker in the assessment of damages and inflammation to the small intestinal mucosa. We have investigated the influence of HIV infections and antiretroviral treatment on the small intestine mucosa aided by the evaluation of I-FABP concentration levels.

Methods:

We included in the study: 31 HIV-infected patients with antiretroviral therapy (ART) treatment (T), 32 HIV-infected patients not treated with ART (NT), and 18 healthy volunteers as a control group. The concentrations of I-FABP were measured in serum using a sandwich enzyme immunoassay kit: Human I-FABP.

Results:

The median level of I-FABP in the serum of HIV-infected patients was 2.10 ± 2.56 ng/mL and did not significantly differ between T and NT (2.32 ± 2.69 ng/mL vs. 1.89 ± 2.45 ng/mL). However, the I-FABP serum level was significantly higher in HIV-infected patients when compared to the group control (2.10 ± 2.56 ng/mL vs. 1.26 ± 1.18 ng/mL; P = 0.048). We recorded a correlation for treated HIV-infected patients between Viral load and I-FABP serum level (r = −0.66; P <0.05).

Conclusions:

Elevated serum I-FABP level in HIV-infected patients confirm that HIV causes damage to the intestinal mucosa. I-FAB is a useful marker in the assessment of intestinal damage in HIV-infected patients.

Increased inflammation but similar physical composition and function in older-aged, HIV-1 infected subjects

Background

Systemic immune activation (inflammation) and immunosenescence develop in some people with advancing age. This process, known as “inflamm-aging,” is associated with physical frailty and sarcopenia. Meanwhile, successful antiretroviral therapy has led to a growing number of older HIV-1-infected individuals who face both age-related and HIV-1-related inflammation, which may synergistically promote physical decline, including frailty and sarcopenia. The purpose of our study was to determine if inflammation during treated HIV-1 infection worsens physical impairment in older individuals.

Methods

We determined the severity of HIV-associated inflammation and physical performance (strength and endurance) in 21 older HIV-infected individuals (54–69 years) receiving suppressive antiretroviral therapy, balanced for confounding variables including age, anthropometrics, and co-morbidities with 10 uninfected control individuals. Biomarkers for microbial translocation (lipopolysaccharide [LPS]), inflammation (soluble CD14 [sCD14], osteopontin, C-reactive protein [CRP], interleukin-6 [IL-6], soluble ICAM-1 [sICAM-1] and soluble VCAM-1 [sVCAM-1]), and coagulopathy (D-dimer) were assayed in plasma. Activation phenotypes of CD4⁺T cells, CD8⁺ T cells and monocytes were measured by flow cytometry. Physical performance was measured by 400 m walking speed, a short physical performance battery [SPPB], and lower extremity muscle strength and fatigue.

Results

Overall physical function was similar in the uninfected and HIV-infected groups. Compared to uninfected individuals, the HIV-infected group had elevated levels of sCD14 (P < 0.001), CRP (P < 0.001) and IL-6 (P = 0.003) and an increased frequency of CD4⁺ and CD8⁺ T cells with an immunosenescent CD57⁺ phenotype (P = 0.004 and P = 0.043, respectively). Neither plasma inflammatory biomarkers nor CD57⁺ T cells correlated with CD4⁺ T cell counts. Furthermore, none of the elevated inflammatory biomarkers in the HIV-infected subjects were associated with any of the physical performance results.

Conclusions

When age-related co-morbidities were carefully balanced between the uninfected and HIV-infected groups, no evidence of inflammation-associated physical impairment was detected. Despite careful balancing for age, BMI, medications and co-morbidities, the HIV-infected group still displayed evidence of significant chronic inflammation, including elevated sCD14, CRP, IL-6 and CD57⁺ T cells, although the magnitude of this inflammation was unrelated to physical impairment.

Individuality, phenotypic differentiation, dormancy and 'persistence' in culturable bacterial systems: commonalities shared by environmental, laboratory, and clinical microbiology

For bacteria, replication mainly involves growth by binary fission. However, in a very great many natural environments there are examples of phenotypically dormant, non-growing cells that do not replicate immediately and that are phenotypically 'nonculturable' on media that normally admit their growth. They thereby evade detection by conventional culture-based methods. Such dormant cells may also be observed in laboratory cultures and in clinical microbiology. They are usually more tolerant to stresses such as antibiotics, and in clinical microbiology they are typically referred to as 'persisters'. Bacterial cultures necessarily share a great deal of relatedness, and inclusive fitness theory implies that there are conceptual evolutionary advantages in trading a variation in growth rate against its mean, equivalent to hedging one's bets. There is much evidence that bacteria exploit this strategy widely. We here bring together data that show the commonality of these phenomena across environmental, laboratory and clinical microbiology. Considerable evidence, using methods similar to those common in environmental microbiology, now suggests that many supposedly non-communicable, chronic and inflammatory diseases are exacerbated (if not indeed largely caused) by the presence of dormant or persistent bacteria (the ability of whose components to cause inflammation is well known). This dormancy (and resuscitation therefrom) often reflects the extent of the availability of free iron. Together, these phenomena can provide a ready explanation for the continuing inflammation common to such chronic diseases and its correlation with iron dysregulation. This implies that measures designed to assess and to inhibit or remove such organisms (or their access to iron) might be of much therapeutic benefit.

Altered metabolism of gut microbiota contributes to chronic immune activation in HIV-infected individuals

Altered interplay between gut mucosa and microbiota during treated HIV infection may possibly contribute to increased bacterial translocation and chronic immune activation, both of which are predictors of morbidity and mortality. Although a dysbiotic gut microbiota has recently been reported in HIV+ individuals, the metagenome gene pool associated with HIV infection remains unknown. The aim of this study is to characterize the functional gene content of gut microbiota in HIV+ patients and to define the metabolic pathways of this bacterial community, which is potentially associated with immune dysfunction. We determined systemic markers of innate and adaptive immunity in a cohort of HIV-infected individuals on successful antiretroviral therapy without comorbidities and in healthy non-HIV-infected subjects. Metagenome sequencing revealed an altered functional profile, with enrichment of the genes involved in various pathogenic processes, lipopolysaccharide biosynthesis, bacterial translocation, and other inflammatory pathways. In contrast, we observed depletion of genes involved in amino acid metabolism and energy processes. Bayesian networks showed significant interactions between the bacterial community, their altered metabolic pathways, and systemic markers of immune dysfunction. This study reveals altered metabolic activity of microbiota and provides novel insight into the potential host-microbiota interactions driving the sustained inflammatory state in successfully treated HIV-infected patients.

Molecular Analyses Define Vα7.2-Jα33+ MAIT Cell Depletion in HIV Infection: A Case-Control Study

Mucosal-associated invariant T (MAIT) cells are an abundant antibacterial innate-like lymphocyte population. There are conflicting reports as to their fate in HIV infection. The objective of this study was to determine whether MAIT cells are truly depleted in HIV infection. In this case-control study of HIV-positive patients and healthy controls, quantitative real-time polymerase chain reaction was used to assess the abundance of messenger RNA (mRNA) and genomic DNA (gDNA) encoding the canonical MAIT cell T cell receptor (Vα7.2-Jα33). Comparison was made with flow cytometry. Significant depletion of both Vα7.2-Jα33 mRNA and gDNA was seen in HIV infection. Depletion of Vα7.2+CD161++ T cells was confirmed by flow cytometry. In HIV infection, the abundance of Vα7.2-Jα33 mRNA correlated most strongly with the frequency of Vα7.2+CD161++ cells. No increase was observed in the frequency of Vα7.2+CD161- cells among CD3+CD4- lymphocytes. MAIT cells are depleted from blood in HIV infection as confirmed by independent assays. Significant accumulation of a CD161- MAIT cell population is unlikely. Molecular approaches represent a suitable alternative to flow cytometry-based assays for tracking of MAIT cells in HIV and other settings.

Individuality, phenotypic differentiation, dormancy and 'persistence' in culturable bacterial systems: commonalities shared by environmental, laboratory, and clinical microbiology

For bacteria, replication mainly involves growth by binary fission. However, in a very great many natural environments there are examples of phenotypically dormant, non-growing cells that do not replicate immediately and that are phenotypically 'nonculturable' on media that normally admit their growth. They thereby evade detection by conventional culture-based methods. Such dormant cells may also be observed in laboratory cultures and in clinical microbiology. They are usually more tolerant to stresses such as antibiotics, and in clinical microbiology they are typically referred to as 'persisters'. Bacterial cultures necessarily share a great deal of relatedness, and inclusive fitness theory implies that there are conceptual evolutionary advantages in trading a variation in growth rate against its mean, equivalent to hedging one's bets. There is much evidence that bacteria exploit this strategy widely. We here bring together data that show the commonality of these phenomena across environmental, laboratory and clinical microbiology. Considerable evidence, using methods similar to those common in environmental microbiology, now suggests that many supposedly non-communicable, chronic and inflammatory diseases are exacerbated (if not indeed largely caused) by the presence of dormant or persistent bacteria (the ability of whose components to cause inflammation is well known). This dormancy (and resuscitation therefrom) often reflects the extent of the availability of free iron. Together, these phenomena can provide a ready explanation for the continuing inflammation common to such chronic diseases and its correlation with iron dysregulation. This implies that measures designed to assess and to inhibit or remove such organisms (or their access to iron) might be of much therapeutic benefit.

HIV-associated memory B cell perturbations

Memory B-cell depletion, hyperimmunoglobulinemia, and impaired vaccine responses are the hallmark of B cell perturbations inhuman immunodeficiency virus (HIV) disease. Although B cells are not the targets for HIV infection, there is evidence for B cell, especially memory B cell dysfunction in HIV disease mediated by other cells or HIV itself. This review will focus on HIV-associated phenotypic and functional alterations in memory B cells. Additionally, we will discuss the mechanism underlying these perturbations and the effect of anti-retroviral therapy (ART) on these perturbations.

Role of intestinal myofibroblasts in HIV-associated intestinal collagen deposition and immune reconstitution following combination antiretroviral therapy

OBJECTIVE

To investigate the potential role of mucosal intestinal myofibroblasts (IMFs) in HIV and associated fibrosis in gut-associated lymphoid tissue.

DESIGN

Profibrotic changes within the secondary lymphoid organs and mucosa have been implicated in failed immune reconstitution following effective combination antiretroviral therapy (cART). Microbial translocation is believed to be sustaining these systemic inflammatory pathways. IMFs are nonprofessional antigen-presenting cells with both immunoregulatory and mesenchymal functions that are ideally positioned to respond to translocating microbial antigen.

METHODS

Duodenal biopsies, obtained from patients naive to cART, underwent trichrome staining and were examined for tissue growth factor-beta (TGF-β) expression. Combined immunostaining and second harmonic generation analysis were used to determine IMF activation and collagen deposition. Confocal microscopy was performed to examine IMF activation and Toll-like receptor (TLR)4 expression. Finally, primary IMF cultures were stimulated with lipopolysaccharide to demonstrate the expression of the inflammatory biomarkers.

RESULTS

The expression of the fibrosis-promoting molecule, TGF-β1, is significantly increased in duodenal biopsies from HIV patients naïve to cART, and negatively correlated with subsequent peripheral CD4(+) recovery. The increase in TGF-β1 coincided with an increase in collagen deposition in the duodenal mucosa in the tissue area adjacent to the IMFs. We also observed that IMFs expressed TLR4 and had an activated phenotype since they were positive for fibroblast activation protein. Finally, stimulation of IMFs from HIV patients with TLR4 resulted in significantly increased expression of profibrotic molecules, TGF-β1, and interleukin-6.

CONCLUSION

Our data support the hypothesis that activated IMFs may be among the major cells contributing to the profibrotic changes, and thus, the establishment and maintenance of systemic inflammation interfering with immune reconstitution in HIV patients.

The dormant blood microbiome in chronic, inflammatory diseases

Blood in healthy organisms is seen as a ‘sterile’ environment: it lacks proliferating microbes. Dormant or not-immediately-culturable forms are not absent, however, as intracellular dormancy is well established. We highlight here that a great many pathogens can survive in blood and inside erythrocytes. ‘Non-culturability’, reflected by discrepancies between plate counts and total counts, is commonplace in environmental microbiology. It is overcome by improved culturing methods, and we asked how common this would be in blood. A number of recent, sequence-based and ultramicroscopic studies have uncovered an authentic blood microbiome in a number of non-communicable diseases. The chief origin of these microbes is the gut microbiome (especially when it shifts composition to a pathogenic state, known as ‘dysbiosis’). Another source is microbes translocated from the oral cavity. ‘Dysbiosis’ is also used to describe translocation of cells into blood or other tissues. To avoid ambiguity, we here use the term ‘atopobiosis’ for microbes that appear in places other than their normal location. Atopobiosis may contribute to the dynamics of a variety of inflammatory diseases. Overall, it seems that many more chronic, non-communicable, inflammatory diseases may have a microbial component than are presently considered, and may be treatable using bactericidal antibiotics or vaccines.

Atopobiosis of microbes (the term describing microbes that appear in places other than where they should be), as well as the products of their metabolism, seems to correlate with, and may contribute to, the dynamics of a variety of inflammatory diseases.

Differential effects of viremia and microbial translocation on immune activation in HIV-infected patients throughout ritonavir-boosted darunavir monotherapy

The purpose of this article is to evaluate the evolution of microbial translocation (MT) and its role in CD4 and CD8 T cells immune activation (IA) in HIV-1-infected patients on ritonavir-boosted darunavir monotherapy (mtDRV/rtv).Prospective study of consecutive HIV-1-infected patients switched to mtDRV/rtv as a simplification regimen. Subjects were classified according to the virological behavior during a 24-month follow-up as continuous undetectable viral load, blips, intermittent viremia, and virological failure (VF). MT was evaluated by plasma LPS and 16S genomic rDNA (16S rDNA) levels, whereas IA was assessed by the coexpression of HLA-DR and CD38 in CD4 and CD8 T cells, and plasma sCD14 levels.Seventy-one patients were included in this substudy of the MonDar cohort (ClinicalTrials.gov: NCT01505722). At baseline, CD4 (ρ = -0.352, P = 0.01) and CD8 T-cell activation (ρ = -0.468, P < 0.001) were correlated with time with viral suppression, but not with MT markers. A significant decrease in plasma LPS levels was found only in patients without VF (baseline, 77.8 vs month 24, 60.4 pg/mL; P < 0.001]. Both plasma 16S rDNA and sCD14 levels were unchanged irrespective of the viral behavior. The only variable independently associated with a decrease in CD4 and CD8 T cells activation was an undetectable HIV-1 viremia (β = 4.78, P < 0.001 and β = 2.93, P = 0.005, respectively).MT does not have a pivotal role in T-cell activation, at least in patients with long-term viral suppression. The viremic episodes and VF are the main factors related to CD4 and CD8 T-cells IA, even during mtDRV/rtv.

Immune Reconstitution but Persistent Activation After 48 Weeks of Antiretroviral Therapy in Youth With Pre-Therapy CD4 >350 in ATN 061

BACKGROUND

Measures of immune outcomes in youth who initiate combination antiretroviral therapy (cART) early in HIV infection are limited.

DESIGN

Adolescent Trials Network 061 examined changes over 48 weeks of cART in T-cell subsets and markers of T-cell and macrophage activation in subjects with pre-therapy CD4 > 350 cells/mm. All subjects had optimal viral suppression from weeks 24 through 48.

METHODS

Subjects (n = 48) initiated cART with tenofovir/emtricitabine plus ritonavir-boosted atazanavir. Data were collected at baseline and weeks 12, 24, and 48. Trends were compared to uninfected controls.

RESULTS

Significant increases over 48 weeks were noted in all CD4 populations, including total, naive, central memory (CM), and effector memory RO (EM RO) and effector memory RA (EM RA), whereas numbers of CM and EM RO CD8 cells declined significantly. By week 48, CD4 naive cells were similar to controls, whereas CM CD4 cells remained significantly lower and EM RO and EM RA subsets were significantly higher. CD38 and HLA DR expression, both individually and when co-expressed, decreased over 48 weeks of cART on CD8 cells but remained significantly higher than controls at week 48. In contrast, markers of macrophage activation measured by sCD14 and sCD163 in plasma did not change with cART and were significantly higher than controls.

CONCLUSIONS

In youth initiating early cART, CD4 cell reconstitution is robust with decreases in CD8 cells. However, CD8 T-cell and macrophage activation persists at higher levels than uninfected controls.

Effect of probiotics (Saccharomyces boulardii) on microbial translocation and inflammation in HIV-treated patients: a double-blind, randomized, placebo-controlled trial

BACKGROUND

Microbial translocation has been associated with an increase in immune activation and inflammation in HIV infection despite effective highly active antiretroviral therapy. It has been shown that some probiotics have a beneficial effect by reducing intestinal permeability and, consequently, microbial translocation.

OBJECTIVES

To assess changes in microbial translocation and inflammation after treatment with probiotics (Saccharomyces boulardii) in HIV-1-infected patients with virologic suppression.

METHODS

A double-blind, randomized, placebo-controlled trial was conducted in 44 nonconsecutive HIV-1-infected patients with viral load of <20 copies per milliliter for at least 2 years. Patients were randomized to oral supplementation with probiotics or placebo during 12 weeks. Markers of microbial translocation (lipopolysaccharide-binding protein [LBP] and soluble CD14), inflammation (interleukin 6 [IL-6], tumor necrosis factor alpha, interferon gamma, high-sensitivity C-reactive protein), and immunological and clinical data were determined before and after the intervention and 3 months after treatment discontinuation. Quantitative variables were compared using the Mann-Whitney U test, and categorical variables were compared using the Fisher exact test.

RESULTS

After 12 weeks of treatment, differences between the probiotic arm and the placebo arm were observed in LBP values (-0.30 vs +0.70 pg/mL) and IL-6 (-0.60 vs +0.78 pg/mL). These differences were also noted at 3 months after treatment withdrawal. Qualitative analysis was performed, defining a variable as "decreased" or "increased" from baseline LBP. A significant decrease of LBP at 12 weeks of treatment was observed (57.9% patients in the probiotic group vs 6.2% in the placebo group, P = 0.002).

CONCLUSIONS

Treatment with S. boulardii decreases microbial translocation (LBP) and inflammation parameters (IL-6) in HIV-1-infected patients with long-term virologic suppression.

CD8 T cell persistence in treated HIV infection

PURPOSE OF REVIEW

Many treated HIV-infected persons maintain persistently high circulating CD8 T cell numbers, even after many years of therapy. Recent reports have suggested that persistent CD8 T cell expansion is associated with higher risk of morbid non-AIDS events. Thus, assessing the mechanisms of CD8 T cell expansion and persistence may give insights into a feature of HIV disease that is clinically important.

RECENT FINDINGS

Acute HIV infection is associated with activation and expansion of the CD8 T cell compartment. Expanded CD8 T cells persist throughout the disease course, and in contrast to the plasticity that typically characterizes immune responses to most other pathogens, circulating CD8 T cell numbers do not normalize in many patients despite pharmacologic suppression of HIV replication. We suspect that residual inflammation in treated HIV infection contributes to antigen-independent CD8 T cell expansion and persistence as most of these cells are not HIV-reactive.

SUMMARY

Circulating CD8 T cell numbers remain abnormally elevated in many treated HIV-infected patients and this elevation is associated with adverse clinical events. Future studies will be needed to assess the mechanisms of CD8 T cell expansion and to define the role of CD8 lymphocytosis in the clinical course of treated HIV disease.

Immune activation response in chronic HIV-infected patients: influence of Hepatitis C virus coinfection

Objectives

We have analyzed the parameters (bacterial translocation, immune activation and regulation, presence of HCV coinfection) which could be implicated in an inappropriate immune response from individuals with chronic HIV infection. The influence of them on the evolution of CD4+ T cell count has been investigated.

Patients and methods

Seventy HIV-infected patients [monoinfected by HIV (n = 20), HCV-coinfected (with (n = 25) and without (n = 25) liver cirrhosis)] and 25 healthy controls were included. Median duration of HIV infection was 20 years. HIV- and HCV-related parameters, as well as markers relative to bacterial translocation, monocyte and lymphocyte activation and regulation were considered as independent variables. Dependent variables were the increase of CD4+ T cell count during the follow-up (12 months).

Results

Increased values of bacterial translocation, measured by lipopolysaccharide-binding protein, monocyte and lymphocyte activation markers and T regulatory lymphocytes were detected in HIV-monoinfected and HIV/HCV coinfected patients. Serum sCD14 and IL-6 were increased in HIV/HCV-coinfected patients with liver cirrhosis in comparison with those with chronic hepatitis or HIV-monoinfected individuals. Time with undetectable HIV load was not related with these parameters. The presence of cirrhosis was negatively associated with a CD4+ T cell count increase.

Conclusion

In patients with a chronic HIV infection, a persistent increase of lipopolysaccharide-binding protein and monocyte and lymphocyte modifications are present. HCV-related cirrhosis is associated with more elevated serum concentrations of monocyte-derived markers. Cirrhosis influences the continued immune reconstitution of these patients.

HIV-associated neurocognitive disorders: the relationship of HIV infection with physical and social comorbidities

The prevalence of HIV (human immunodeficiency virus) associated neurocognitive disorders (HAND) will undoubtedly increase with the improved longevity of HIV-infected persons. HIV infection, itself, as well as multiple physiologic and psychosocial factors can contribute to cognitive impairment and neurologic complications. These comorbidities confound the diagnosis, assessment, and interventions for neurocognitive disorders. In this review, we discuss the role of several key comorbid factors that may contribute significantly to the development and progression of HIV-related neurocognitive impairment, as well as the current status of diagnostic strategies aimed at identifying HIV-infected individuals with impaired cognition and future research priorities and challenges.

Regulation of Leishmania (L.) amazonensis protein expression by host T cell dependent responses: differential expression of oligopeptidase B, tryparedoxin peroxidase and HSP70 isoforms in amastigotes isolated from BALB/c and BALB/c nude mice

Leishmaniasis is an important disease that affects 12 million people in 88 countries, with 2 million new cases every year. Leishmania amazonensis is an important agent in Brazil, leading to clinical forms varying from localized (LCL) to diffuse cutaneous leishmaniasis (DCL). One interesting issue rarely analyzed is how host immune response affects Leishmania phenotype and virulence. Aiming to study the effect of host immune system on Leishmania proteins we compared proteomes of amastigotes isolated from BALB/c and BALB/c nude mice. The athymic nude mice may resemble patients with diffuse cutaneous leishmaniasis, considered T-cell hyposensitive or anergic to Leishmania's antigens. This work is the first to compare modifications in amastigotes' proteomes driven by host immune response. Among the 44 differentially expressed spots, there were proteins related to oxidative/nitrosative stress and proteases. Some correspond to known Leishmania virulence factors such as OPB and tryparedoxin peroxidase. Specific isoforms of these two proteins were increased in parasites from nude mice, suggesting that T cells probably restrain their posttranslational modifications in BALB/c mice. On the other hand, an isoform of HSP70 was increased in amastigotes from BALB/c mice. We believe our study may allow identification of potential virulence factors and ways of regulating their expression.

Anatomical localization of commensal bacteria in immune cell homeostasis and disease

The mammalian gastrointestinal (GI) tract is colonized by trillions of beneficial commensal bacteria that are essential for promoting normal intestinal physiology. While the majority of commensal bacteria are found in the intestinal lumen, many species have also adapted to colonize different anatomical locations in the intestine, including the surface of intestinal epithelial cells (IECs) and the interior of gut-associated lymphoid tissues. These distinct tissue localization patterns permit unique interactions with the mammalian immune system and collectively influence intestinal immune cell homeostasis. Conversely, dysregulated localization of commensal bacteria can lead to inappropriate activation of the immune system and is associated with numerous chronic infectious, inflammatory, and metabolic diseases. Therefore, regulatory mechanisms that control proper anatomical containment of commensal bacteria are essential to maintain tissue homeostasis and limit pathology. In this review, we propose that commensal bacteria associated with the mammalian GI tract can be anatomically defined as (i) luminal, (ii) epithelial-associated, or (iii) lymphoid tissue-resident, and we discuss the role and regulation of these microbial populations in health and disease.

The CD14 C-260T single nucleotide polymorphism (SNP) modulates monocyte/macrophage activation in treated HIV-infected individuals

Background

HIV-infected individuals have an increased risk of cardiovascular disease (CVD). T-allele carriers of the CD14 C-260T single-nucleotide polymorphism (SNP) have reported increased expression of the LPS-binding receptor, CD14 and inflammation in the general population. Our aim was to explore the relationship of this SNP with monocyte/macrophage activation and inflammation and its association with sub-clinical atherosclerosis in HIV-infected individuals.

Methods

Patients with no pre-existing CVD risk factors on suppressive antiretroviral therapy were recruited from University Malaya Medical Centre, Malaysia (n = 84). The CD14 C-260T and TLR4 SNPs, Asp299Gly and Thr399Ile were genotyped and soluble(s) CD14 and sCD163 and high-sensitivity C-reactive protein, hsCRP were measured in plasma. Subclinical atherosclerosis was assessed by measuring carotid intima media thickness (cIMT). The association between CD14 C-260T SNP carriage and cIMT was assessed in a multivariable quantile regression model where a p-value of <0.05 was considered significant.

Results

We found the CD14 C-260T T-allele in 56% of the cohort and evidence of subclinical atherosclerosis in 27%. TT genotype was associated with higher sCD163 (p = 0.009) but only marginally higher sCD14 (p = 0.209) and no difference in hsCRP (p = 0.296) compared to CC/CT. In multivariable analysis, only Framingham risk score was independently associated with higher cIMT while lower sCD163 was trending towards significance. No association was found in TT-genotype carriers and cIMT measurements.

Conclusion

The CD14 C-260T SNP was associated with increased monocyte activation but not systemic inflammation or cIMT in this HIV-infected cohort with low CVD risk profile.

Monocyte activation, but not microbial translocation, is independently associated with markers of endovascular dysfunction in HIV-infected patients receiving cART

BACKGROUND

Microbial translocation has been suggested as a driver of cardiovascular disease in HIV infection. We hypothesized that microbial translocation and the resulting monocyte activation would be associated with markers of endovascular dysfunction.

METHODS

In 60 HIV-infected patients on combination antiretroviral therapy, plasma levels of lipopolysaccharide, soluble CD14 (sCD14), asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) were measured.

RESULTS

ADMA and SDMA were associated with sCD14 but not lipopolysaccharide. There was a significant increase in ADMA and SDMA through tertiles of sCD14, and both markers were associated with sCD14 in multivariate linear regression analyses.

CONCLUSIONS

Monocyte activation as measured by sCD14 is associated with endovascular dysfunction in HIV infection.

Soluble T cell immunoglobulin mucin domain 3 is shed from CD8+ T cells by the sheddase ADAM10, is increased in plasma during untreated HIV infection, and correlates with HIV disease progression

Chronic HIV infection results in a loss of HIV-specific CD8(+) T cell effector function, termed "exhaustion," which is mediated, in part, by the membrane coinhibitory receptor T cell immunoglobulin mucin domain-3 (Tim-3). Like many other receptors, a soluble form of this protein has been described in human blood plasma. However, soluble Tim-3 (sTim-3) is poorly characterized, and its role in HIV disease is unknown. Here, we show that Tim-3 is shed from the surface of responding CD8(+) T cells by the matrix metalloproteinase ADAM10, producing a soluble form of the coinhibitory receptor. Despite previous reports in the mouse model, no alternatively spliced, soluble form of Tim-3 was observed in humans. Shed sTim-3 was found in human plasma and was significantly elevated during early and chronic untreated HIV infection, but it was not found differentially modulated in highly active antiretroviral therapy (HAART)-treated HIV-infected subjects or in elite controllers compared to HIV-uninfected subjects. Plasma sTim-3 levels were positively correlated with HIV load and negatively correlated with CD4 counts. Thus, plasma sTim-3 shedding correlated with HIV disease progression. Despite these correlations, we found that shedding Tim-3 did not improve the function of CD8(+) T cells in terms of gamma interferon production or prevent their apoptosis through galectin-9. Further characterization studies of sTim-3 function are needed to understand the contribution of sTim-3 in HIV disease pathogenesis, with implications for novel therapeutic interventions.

IMPORTANCE

Despite the overall success of HAART in slowing the progression to AIDS in HIV-infected subjects, chronic immune activation and T cell exhaustion contribute to the eventual deterioration of the immune system. Understanding these processes will aid in the development of interventions and therapeutics to be used in combination with HAART to slow or reverse this deterioration. Here, we show that a soluble form of T cell exhaustion associated coinhibitory molecule 3, sTim-3, is shed from the surface of T cells. Furthermore, sTim-3 is elevated in the plasma of treatment-naive subjects with acute or chronic HIV infection and is associated with markers of disease progression. This is the first study to characterize sTim-3 in human plasma, its source, and mechanism of production. While it is still unclear whether sTim-3 contributes to HIV pathogenesis, sTim-3 may represent a new correlate of HIV disease progression.

Gut epithelial barrier and systemic inflammation during chronic HIV infection

OBJECTIVE

Microbial translocation and innate immune action characterize HIV infection. Continued gut mucosal dysfunction during treatment and its relationship to CD4 T-cell recovery has not been well described.

DESIGN

A cross-sectional study was performed of antiretroviral therapy (ART)-suppressed (immunologic responders with CD4 > 500 cells/μl and immunologic nonresponders with CD4 < 350 cells/μl), untreated HIV-infected, and seronegative participants consenting to gut biopsies and a blood draw.

METHODS

Neutrophil infiltration as a surrogate response to epithelial breach, colorectal epithelial proliferation as a measure of repair, and mucosal apoptosis by immunohistochemistry were determined in gut biopsies. Plasma markers of monocyte activation (sCD14), immune activation (interleukin-6), and indoleamine 2,3-dioxygenase-1 activity (plasma kynurenine/tryptophanratio) were concurrently measured.

RESULTS

Each HIV-infected group had greater neutrophil infiltration than controls. Similarly, untreated HIV-infected participants and ART-suppressed immunologic responders had increased epithelial proliferation compared with controls, but immunologic nonresponders had no appreciable increase in epithelial proliferation despite elevated neutrophil infiltration. The CD4 T-cell count was positively correlated with epithelial proliferation and was modestly negatively correlated with neutrophil infiltration in ART-suppressed patients. Epithelial proliferation was inversely correlated with mucosal apoptosis, and apoptosis was linked to plasma sCD14 and modestly to kynurenine/tryptophan ratio.

CONCLUSIONS

Neutrophil infiltration and mucosal apoptosis remain abnormally high despite ART. Epithelial proliferation increases in HIV, but may be impaired in immunologic nonresponders. Whether mucosal apoptosis is a cause or consequence of epithelial proliferative defects is unclear, but appears to be associated with systemic inflammation. The impact of ART and interventions targeting the gut epithelial barrier in treated HIV infection warrant further investigation.

Potential implication of residual viremia in patients on effective antiretroviral therapy

The current antiretroviral therapy (ART) has suppressed viremia to below the limit of detection of clinical viral load assays; however, it cannot eliminate viremia completely in the body even after prolonged treatment. Plasma HIV-1 loads persist at extremely low levels below the clinical detection limit. This low-level viremia (termed "residual viremia") cannot be abolished in most patients, even after the addition of a new class of drug, i.e., viral integrase inhibitor, to the combined antiretroviral regimens. Neither the cellular source nor the clinical significance of this residual viremia in patients on ART remains fully clear at present. Since residual plasma viruses generally do not evolve with time in the presence of effective ART, one prediction is that these viruses are persistently released at low levels from one or more stable but yet unknown HIV-1 reservoirs in the body during therapy. This review attempts to emphasize the source of residual viremia as another important reservoir (namely, "active reservoir") distinct from the well-known latent HIV-1 reservoir in the body, and why its elimination should be a priority in the effort for HIV-1 eradication.

The immunologic effects of mesalamine in treated HIV-infected individuals with incomplete CD4+ T cell recovery: a randomized crossover trial

The anti-inflammatory agent, mesalamine (5-aminosalicylic acid) has been shown to decrease mucosal inflammation in ulcerative colitis. The effect of mesalamine in HIV-infected individuals, who exhibit abnormal mucosal immune activation and microbial translocation (MT), has not been established in a placebo-controlled trial. We randomized 33 HIV-infected subjects with CD4 counts <350 cells/mm3 and plasma HIV RNA levels <40 copies/ml on antiretroviral therapy (ART) to add mesalamine vs. placebo to their existing regimen for 12 weeks followed by a 12 week crossover to the other arm. Compared to placebo-treated subjects, mesalamine-treated subjects did not experience any significant change in the percent CD38+HLA-DR+ peripheral blood CD4+ and CD8+ T cells at week 12 (P = 0.38 and P = 0.63, respectively), or in the CD4+ T cell count at week 12 (P = 0.83). The percent CD38+HLA-DR+ CD4+ and CD8+ T cells also did not change significantly in rectal tissue (P = 0.86, P = 0.84, respectively). During the period of mesalamine administration, plasma sCD14, IL-6, D-dimer, and kynurenine to tryptophan ratio were not changed significantly at week 12 and were similarly unchanged at week 24. This study suggests that, at least under the conditions studied, the persistent immune activation associated with HIV infection is not impacted by the anti-inflammatory effects of mesalamine.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01090102.

Associations of cocaine use and HIV infection with the intestinal microbiota, microbial translocation, and inflammation

OBJECTIVE

HIV and illicit drug use have been associated with altered nutrition, immune function, and metabolism. We hypothesized that altered composition and decreased diversity of the intestinal microbiota, along with microbial translocation, contribute to nutritional compromise in HIV-infected drug users.

METHOD

We enrolled 26 men and 6 women, 15 HIV infected and 17 HIV uninfected, in this exploratory, cross-sectional study; 7 HIV-infected and 7 HIV-uninfected participants had used cocaine within the previous month. We examined the independent effects of cocaine use and HIV infection on the composition and diversity of the intestinal microbiota, determined by 16S rRNA gene pyrosequencing. Using dietary records, anthropometrics, and dual x-ray absorptiometry, we examined the additional effects of nutritional indices on the intestinal microbiota. We compared markers of inflammation and microbial translocation between groups.

RESULTS

Cocaine users had a higher relative abundance of Bacteroidetes (M ± SD = 57.0% ± 21 vs. 37.1% ± 23, p = .02) than nonusers. HIV-infected individuals had a higher relative abundance of Proteobacteria (Mdn [interquartile range] = 1.56% [0.5, 2.2] vs. 0.36% [0.2, 0.7], p = .03), higher levels of soluble CD14 and tumor necrosis factor-α, and lower levels of anti-endotoxin core antibodies than uninfected subjects. HIV-infected cocaine users had higher interferon-γ levels than all other groups. Food insecurity was higher in HIV-infected cocaine users.

CONCLUSIONS

We identified differences in the relative abundance of major phyla of the intestinal microbiota, as well as markers of inflammation and microbial translocation, based on cocaine use and HIV infection. Nutritional factors, including alcohol use and lean body mass, may contribute to these differences.

Effects of atorvastatin and pravastatin on immune activation and T-cell function in antiretroviral therapy-suppressed HIV-1-infected patients

This retrospective study was designed to assess statin effects on T-cell activation from HIV-infected individuals. Peripheral blood mononuclear cells from antiretroviral therapy suppressed HIV-infected individuals receiving atorvastatin or pravastatin were evaluated for T-cell activation, exhaustion and function. Atorvastatin was associated with a significant reduction in CD8 T-cell activation (HLA-DR, CD38/HLA-DR) and exhaustion (TIM-3, TIM-3/PD-1) whereas pravastatin had no effect. In contrast, pravastatin increased antigen specific interferon γ production. These results suggest a differential effect of statins on immune activation and function.

Effectiveness of HCV core antigen and RNA quantification in HCV-infected and HCV/HIV-1-coinfected patients

Background

The measurement of hepatitis C virus core antigen (HCV-coreAg) has been shown to be an indicator of active HCV infection. The aim of the present study was 1) to investigate the stability and effectiveness of HCV-coreAg and HCV-RNA quantification in HCV infection with or without HIV-1 coinfection, 2) to explore the association between the HCV-coreAg/HCV-RNA (Ag/RNA) ratio and the immune status in chronic HCV/HIV-1-coinfected patients.

Methods

A longitudinal investigation comprised of 227 HCV-monoinfected (n = 129) and HCV/HIV-1-coinfected (n = 98) patients was initiated in August 2009, and 139 (73 with HCV monoinfection and 66 with HCV/HIV-1 coinfection) were followed up in August 2012. Both HCV core antigen and HCV RNA quantification were determined on this cryopreserved plasma. HCV core antigen and HCV RNA quantification were performed subsequently. In addition, an in vitro experiment investigating the possibility of degradation of HCV components (core antigen and RNA) were conducted.

Results

Significant and stable correlations (p < 0.001) were observed both in chronic HCV-monoinfected and HCV/HIV-1-coinfected patients over the 3-year observation. Coinfected patients with immunocompromised condition had a significantly higher (p < 0.05) Ag/RNA ratios than those patients with immunocompetent condition both at two time points (2009 and 2012). Moreover, the Ag/RNA ratios were negatively correlated with CD4+ T-cell counts (p < 0.001). An in vitro experiment investigated the possibility of the slower degradation of HCV particles under HIV-related immunocompromised condition was conducted and the data demonstrated that the Ag/RNA ratios were significantly higher in HIV-1-positive plasma than in healthy plasma (p = 0.005) in this study.

Conclusions

Our longitudinal study indicated that the HCV-coreAg presented comparable dynamics over time as HCV RNA in chronic HCV-infected patients. Meanwhile, the HCV-coreAg/HCV-RNA ratio was closely associated with immune status in HCV/HIV-1-coinfected patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0577-1) contains supplementary material, which is available to authorized users.

MAIT cells are depleted early but retain functional cytokine expression in HIV infection

Mucosal-associated invariant T (MAIT) cells home to mucosal sites and exert antimicrobial activity against bacteria and other microorganisms. HIV infection leads to early depletion of gut T cells and translocation of bacterial products. There are reports that MAIT cells, defined by coexpression of Vα7.2 and CD161, are depleted during HIV infection and residual MAIT cells are functionally impaired. However, one study suggested that MAIT cells might remain after HIV infection but evade detection through CD161 downregulation. Thus, the impact of HIV infection on MAIT cells is unclear. We studied longitudinal blood samples from 31 HIV-infected subjects for MAIT cell numbers, phenotype and function using both standard Vα7.2/CD161 surface markers and an MR1 tetramer. We found that MAIT cells were depleted early during HIV infection, and although there was a concomitant rise in Vα7.2(+)CD161(-) cells, these were MR1 tetramer negative, indicating that these are unlikely to be altered MAIT cells. Antigen-mediated activation of residual MAIT cells showed that they remained functional out to 2 years following HIV infection. Although MAIT cells are depleted in HIV infection, residual and functionally active MAIT cells persist and may still be able to assist in controlling bacterial translocation during HIV infection.

Reconstitution of intestinal CD4 and Th17 T cells in antiretroviral therapy suppressed HIV-infected subjects: implication for residual immune activation from the results of a clinical trial

Introduction

During HIV infection the severe depletion of intestinal CD4⁺ T-cells is associated with microbial translocation, systemic immune activation, and disease progression. This study examined intestinal and peripheral CD4⁺ T-cell subsets reconstitution under combined antiretroviral therapy (cART), and systemic immune activation markers.

Methods

This longitudinal single-arm pilot study evaluates CD4⁺ T cells, including Th1 and Th17, in gut and blood and soluble markers for inflammation in HIV-infected individuals before (M0) and after eight (M8) months of cART. From January 2010 to December 2011, 10 HIV-1 naïve patients were screened and 9 enrolled. Blood and gut CD4⁺ T-cells subsets and cellular immune activation were determined by flow-cytometry and plasma soluble CD14 by ELISA. CD4⁺ Th17 cells were detected in gut biopsies by immunohistochemistry. Microbial translocation was measured by limulus-amebocyte-lysate assay to detect bacterial lipopolysaccharide (LPS) and PCR Real Time to detect plasma bacterial 16S rDNA.

Results

Eight months of cART increased intestinal CD4⁺ and Th17 cells and reduced levels of T-cell activation and proliferation. The magnitude of intestinal CD4⁺ T-cell reconstitution correlated with the reduction of plasma LPS. Importantly, the magnitude of Th17 cells reconstitution correlated directly with blood CD4⁺ T-cell recovery.

Conclusion

Short-term antiretroviral therapy resulted in a significant increase in the levels of total and Th17 CD4⁺ T-cells in the gut mucosa and in decline of T-cell activation. The observation that pre-treatment levels of CD4⁺ and of CD8⁺ T-cell activation are predictors of the magnitude of Th17 cell reconstitution following cART provides further rationale for an early initiation of cART in HIV-infected individuals.

Trial Registration

ClinicalTrials.gov NCT02097381

Inflammatory co-morbidities in HIV+ individuals: learning lessons from healthy ageing

Increased life expectancy due to improved efficacy of cART has uncovered an increased risk of age-related morbidities in HIV+ individuals and catalyzed significant research into mechanisms driving these diseases. HIV infection increases the risk of non-communicable diseases common in the aged, including cardiovascular disease, neurocognitive decline, non-AIDS malignancies, osteoporosis, and frailty. These observations suggest that HIV accelerates immunological ageing, and there are many immunological similarities with the aged, including shortened telomeres, accumulation of senescent T cells and altered monocyte phenotype/function. However, the most critical similarity between HIV+ individuals and the elderly, which most likely underpins the heightened risk of non-communicable diseases, is chronic inflammation and associated immune activation. Here, we review the similarities between HIV+ individuals and the aged regarding the pathogenesis of inflammatory diseases, the current evidence for mechanisms driving these processes and discuss current and potential therapeutic strategies for addressing inflammatory co-morbidity in HIV+ infection.

Plasmacytoid dendritic cells mediate synergistic effects of HIV and lipopolysaccharide on CD27+ IgD- memory B cell apoptosis

The effects of heightened microbial translocation on B cells during HIV infection are unknown. We examined the in vitro effects of HIV and lipopolysaccharide (LPS) on apoptosis of CD27+ IgD- memory B (mB) cells from healthy controls. In vivo analysis was conducted on a cohort of 82 HIV+ donors and 60 healthy controls. In vitro exposure of peripheral blood mononuclear cells (PBMCs) to LPS and HIV led to mB cell death via the Fas/Fas ligand (FasL) pathway. Plasmacytoid dendritic cells (pDCs) produced FasL in response to HIV via binding to CD4 and chemokine coreceptors. HIV and LPS increased Fas expression on mB cells in PBMCs, which was dependent on the presence of pDCs and monocytes. Furthermore, mB cells purified from PBMCs and pretreated with both HIV and LPS were more sensitive to apoptosis when cocultured with HIV-treated pDCs. Blocking the interferon receptor (IFNR) prevented HIV-stimulated FasL production in pDCs, HIV-plus-LPS-induced Fas expression, and apoptosis of mB cells. In vivo or ex vivo, HIV+ donors have higher levels of plasma LPS, Fas expression on mB cells, and mB cell apoptosis than controls. Correspondingly, in HIV+ donors, but not in controls, a positive correlation was found between plasma FasL and HIV RNA levels and between Fas expression on mB cells and plasma LPS levels. This work reveals a novel mechanism of mB cell apoptosis mediated by LPS and HIV through the Fas/FasL pathway, with key involvement of pDCs and type I IFN, suggesting a role for microbial translocation in HIV pathogenesis.

IMPORTANCE

This study demonstrates that lipopolysaccharide (LPS) and type I interferon (IFN) play an important role in memory B cell apoptosis in HIV infection. It reveals a previously unrecognized role of microbial translocation in HIV pathogenesis.

Minocycline attenuates HIV-1 infection and suppresses chronic immune activation in humanized NOD/LtsZ-scidIL-2Rγ(null) mice

More than a quarter of a century of research has established chronic immune activation and dysfunctional T cells as central features of chronic HIV infection and subsequent immunodeficiency. Consequently, the search for a new immunomodulatory therapy that could reduce immune activation and improve T-cell function has been increased. However, the lack of small animal models for in vivo HIV study has hampered progress. In the current study, we have investigated a model of cord blood haematopoietic progenitor cells (CB-HPCs) -transplanted humanized NOD/LtsZ-scidIL-2Rγ(null) mice in which progression of HIV infection is associated with widespread chronic immune activation and inflammation. Indeed, HIV infection in humanized NSG mice caused up-regulation of several T-cell immune activation markers such as CD38, HLA-DR, CD69 and co-receptor CCR5. T-cell exhaustion markers PD-1 and CTLA-4 were found to be significantly up-regulated on T cells. Moreover, increased plasmatic levels of lipopolysaccharide, sCD14 and interleukin-10 were also observed in infected mice. Treatment with minocycline resulted in a significant decrease of expression of cellular and plasma immune activation markers, inhibition of HIV replication and improved T-cell counts in HIV-infected humanized NSG mice. The study demonstrates that minocycline could be an effective, low-cost adjunctive treatment to regulate chronic immune activation and replication of HIV.

Rifaximin has a marginal impact on microbial translocation, T-cell activation and inflammation in HIV-positive immune non-responders to antiretroviral therapy - ACTG A5286

BACKGROUND

Rifaximin, a nonabsorbable antibiotic that decreases lipopolysaccharide (LPS) in cirrhotics, may decrease the elevated levels of microbial translocation, T-cell activation and inflammation in human immunodeficiency virus (HIV)-positive immune nonresponders to antiretroviral therapy (ART).

METHODS

HIV-positive adults receiving ART for ≥96 weeks with undetectable viremia for ≥48 weeks and CD4(+) T-cell counts <350 cells/mm(3) were randomized 2:1 to rifaximin versus no study treatment for 4 weeks. T-cell activation, LPS, and soluble CD14 were measured at baseline and at weeks 2, 4, and 8. Wilcoxon rank sum tests compared changes between arms.

RESULTS

Compared with no study treatment (n = 22), rifaximin (n = 43) use was associated with a significant difference between study arms in the change from baseline to week 4 for CD8(+)T-cell activation (median change, 0.0% with rifaximin vs +0.6% with no treatment; P = .03). This difference was driven by an increase in the no-study-treatment arm because there was no significant change within the rifaximin arm. Similarly, although there were significant differences between study arms in change from baseline to week 2 for LPS and soluble CD14, there were no significant changes within the rifaximin arm.

CONCLUSIONS

In immune nonresponders to ART, rifaximin minimally affected microbial translocation and CD8(+)T-cell activation. Trial registration number. NCT01466595.

Enteric mucosa integrity in the presence of a preserved innate interleukin 22 compartment in HIV type 1-treated individuals

BACKGROUND

Interleukin 22 (IL-22) is emerging as a key cytokine for gut epithelial homeostasis and mucosal repair. Gut disruption is a hallmark of human immunodeficiency virus (HIV) infection. Here, we investigated IL-22 production and gut mucosal integrity in HIV type 1 (HIV-1)-infected individuals receiving long-term antiretroviral therapy (ART).

METHODS

Biopsy specimens from 37 individuals who underwent colonoscopy primarily for cancer screening and from 17 HIV-1-infected and 20 healthy age-matched controls were assessed.

RESULTS

We found significant depletion of sigmoid IL-22-producing CD4(+) T cells (T-helper type 22 [Th22] cells) even after prolonged ART, contrasting with the apparently normal compartments of regulatory and interleukin 17 (IL-17)-producing CD4(+) T cells, as well as total mucosal CD4(+) T cells. Despite the preferential Th22 cell depletion, IL-22 production by innate lymphoid cells (ILCs) was similar to that observed in HIV-1-seronegative subjects, and transcription of genes encoding molecules relevant for IL-22 production (ie, AHR, IL23, IL23R, IL1B, IL6, and TGFB1) was preserved. Remarkably, levels of transcripts of IL-22-target genes (ie, REG3G, DEFB4A, S100A9, MUC1, and MUC13) were unaltered, suggesting an adequate production of antimicrobial peptides and mucins. In agreement, enteric epithelial architecture was fully preserved.

CONCLUSIONS

Despite the reduced Th22 cell subset, innate IL-22-mediated mechanisms, essential for sigmoid mucosa integrity, were fully operational in long-term-treated HIV-1-infected individuals. Our data highlight IL-22 production by ILCs as an important target for therapies aimed at facilitating human mucosal reconstitution.

Expression of Toll-Like Receptors in peripheral blood mononuclear cells and response to cognitive-behavioral therapy in major depressive disorder

In recent years, increased attention has been paid to the inflammatory mechanisms of major depressive disorder (MDD). The aim of the present study was to investigate pro-inflammatory pathways related to the "leaky gut" hypothesis of MDD, which is based on the putative intestinal translocation of Gram-negative bacteria and a subsequent abnormal immune response mediated by the Toll-Like Receptor-4 (TLR-4) pathway. 50 patients with first-episode MDD and 30 healthy control subjects participated in the study. Real-time quantitative PCR was used to measure TLR-4 and TLR-2 RNA from peripheral mononuclear blood cells, as well as the expression of NF-κβ, a key transcription factor of the pro-inflammatory response. TLR-4 protein expression was determined by using flow cytometry. TLR-2 served as a control molecule. Low-grade inflammation was characterized by the measurement of interleukin-6 (IL-6) and C-reactive protein (CRP). Bacterial translocation was investigated by the measurement of the 16S rRNA subunit (16S rDNA) of intestinal microbiota in the blood plasma of the participants. We performed these analyses before (t1) and after (t2) cognitive-behavioral therapy (CBT) in MDD. The healthy control subjects were also assessed two times. We found significantly elevated expressions of all three markers (TLR-4 RNA and protein, NF-κβ RNA) and 16S rDNA in MDD at t1 relative to healthy control subjects. These markers showed a significant decrease during CBT (t1>t2 in MDD). We observed no between-group differences and changes in the case of TLR-2. Greater reduction of pro-inflammatory markers during CBT was associated with more pronounced clinical improvement. IL-6 and CRP displayed a moderately elevated level in MDD and did not change during CBT. In conclusion, TLR-4 signaling is up-regulated in newly diagnosed patients with MDD, which may be related to bacterial translocation or to the presence of various damage-associated molecular patterns. Clinical improvement during psychotherapy is associated with decreased expression of pro-inflammatory markers.

Stool microbiota and vaccine responses of infants

OBJECTIVE

Oral vaccine efficacy is low in less-developed countries, perhaps due to intestinal dysbiosis. This study determined if stool microbiota composition predicted infant oral and parenteral vaccine responses.

METHODS

The stool microbiota of 48 Bangladeshi infants was characterized at 6, 11, and 15 weeks of age by amplification and sequencing of the 16S ribosomal RNA gene V4 region and by Bifidobacterium-specific, quantitative polymerase chain reaction. Responses to oral polio virus (OPV), bacille Calmette-Guérin (BCG), tetanus toxoid (TT), and hepatitis B virus vaccines were measured at 15 weeks by using vaccine-specific T-cell proliferation for all vaccines, the delayed-type hypersensitivity skin-test response for BCG, and immunoglobulin G responses using the antibody in lymphocyte supernatant method for OPV, TT, and hepatitis B virus. Thymic index (TI) was measured by ultrasound.

RESULTS

Actinobacteria (predominantly Bifidobacterium longum subspecies infantis) dominated the stool microbiota, with Proteobacteria and Bacteroidetes increasing by 15 weeks. Actinobacteria abundance was positively associated with T-cell responses to BCG, OPV, and TT; with the delayed-type hypersensitivity response; with immunoglobulin G responses; and with TI. B longum subspecies infantis correlated positively with TI and several vaccine responses. Bacterial diversity and abundance of Enterobacteriales, Pseudomonadales, and Clostridiales were associated with neutrophilia and lower vaccine responses.

CONCLUSIONS

Bifidobacterium predominance may enhance thymic development and responses to both oral and parenteral vaccines early in infancy, whereas deviation from this pattern, resulting in greater bacterial diversity, may cause systemic inflammation (neutrophilia) and lower vaccine responses. Vaccine responsiveness may be improved by promoting intestinal bifidobacteria and minimizing dysbiosis early in infancy.

Intestinal barrier dysfunction in HIV infection: pathophysiology, clinical implications and potential therapies

INTRODUCTION

Current pathogenetic aspects on HIV infection highlight the importance of a chronic immune activation ultimately leading to T lymphocyte homeostasis disruption and immune deregulation associated with disease manifestations and progression. It is widely accepted that this continuous immune activation in HIV infection is principally driven by the phenomenon of pathological microbial translocation (MT).

METHODS

Review of the literature on the role of intestinal barrier dysfunction in HIV infection, with emphasis on the implicated pathophysiological mechanisms, clinical implications and potentially effective therapeutic interventions.

FINDINGS

MT in HIV infection is promoted by a multifactorial disruption of all major levels comprising the intestinal barrier defense. Specifically, HIV infection disrupts the integrity of the intestinal biological (quantitative and qualitative alterations of gut microecology, overgrowth of pathogenic bacteria), immune (depletion of CD4(+) T cells, especially Th17 cells, increased CD4+ FoxP3+ Tregs, decreased mucosal macrophages phagocytic capacity, development of intestinal proinflammatory milieu) and mechanical barrier (enterocytes' apoptosis, disruption of tight junctions). Intestinal barrier dysfunction allows the passage of microbes and immunostimulatory bioproducts from the gut lumen first in the lamina propria and thereafter in the systemic circulation, thus continuously promoting a local and systemic inflammatory response. This chronic immune activation is associated with HIV disease progression, suboptimal response to HAART and development of non-AIDS comorbidities.

CONCLUSIONS

We have reached a point where the effective control of HIV viremia by HAART should be combined with emerging pharmacological approaches aiming at the restoration of the intestinal barrier, targeting its diverse levels of structure and function. Elimination of the MT phenomenon would mitigate its effect on immune homeostasis, which might improve the prognosis of the HIV-infected patient in terms of morbidity and mortality.

IFN-α exerts opposing effects on activation-induced and IL-7-induced proliferation of T cells that may impair homeostatic maintenance of CD4+ T cell numbers in treated HIV infection

To determine whether IFN-α is a cause of the T cell hyperactivation and IL-7 signaling pathway defects that are observed in some HIV patients receiving antiretroviral therapy, we have investigated the effect of IFN-α on the proliferation of CD4(+) and CD8(+) T cells from healthy donors (n = 30) and treated HIV(+) donors (n = 20). PBMC were cultured for 7 d with staphylococcal enterotoxin B or IL-7 in the absence or presence of 100 U/ml IFN-α8. Total and naive CD4(+) and CD8(+) T cells were assessed for proliferation (via Ki67 expression), CD127 expression, and phosphorylated STAT5 levels using flow cytometry. IFN-α significantly enhanced activation-induced proliferation (via staphylococcal enterotoxin B stimulation) but inhibited homeostatic proliferation (IL-7 induced) of CD4(+) and CD8(+) T cells. Both of these effects may adversely affect CD4(+) T cell homeostasis in HIV patients. CD127 expression was increased in both healthy and HIV(+) donors following culture with IFN-α8, and levels of IL-7-induced phosphorylated STAT5 were increased by IFN-α8 in healthy donors only. Hence, the inhibitory effects of IFN-α on IL-7-induced proliferation of CD4(+) T cells are unlikely to be mediated by downregulation of CD127 expression or inhibition of STAT5 phosphorylation. These data suggest that increased IFN-α activity may promote the loss of T cells by accelerating cell turnover and activation-induced cell death while decreasing the renewal of T cells by inhibiting the proliferative effect of IL-7.

Intestinal microbiota, microbial translocation, and systemic inflammation in chronic HIV infection

BACKGROUND

Despite effective antiretroviral therapy (ART), patients with chronic human immunodeficiency virus (HIV) infection have increased microbial translocation and systemic inflammation. Alterations in the intestinal microbiota may play a role in microbial translocation and inflammation.

METHODS

We profiled the fecal microbiota by pyrosequencing the gene encoding 16S ribosomal RNA (rRNA) and measured markers of microbial translocation and systemic inflammation in 21 patients who had chronic HIV infection and were receiving suppressive ART (cases) and 16 HIV-uninfected controls.

RESULTS

The fecal microbial community composition was significantly different between cases and controls. The relative abundance of Proteobacteria, Gammaproteobacteria, Enterobacteriales, Enterobacteriaceae, Erysipelotrichi, Erysipelotrichales, Erysipelotrichaceae, and Barnesiella was significantly enriched in cases, whereas that of Rikenellaceae and Alistipes was depleted. The plasma soluble CD14 level (sCD14) was significantly higher and the endotoxin core immunoglobulin M (IgM) level lower in cases, compared with controls. There were significant positive correlations between the relative abundances of Enterobacteriales and Enterobacteriaceae and the sCD14 level; the relative abundances of Gammaproteobacteria, Enterobacteriales, and Enterobacteriaceae and the interleukin 1β (IL-1β) level; the relative abundances of Enterobacteriales and Enterobacteriaceae and the interferon γ level; and the relative abundances of Erysipelotrichi and Barnesiella and the TNF-α level. There were negative correlations between endotoxin core IgM and IL-1β levels.

CONCLUSIONS

Patients who have chronic HIV infection and are receiving suppressive ART display intestinal dysbiosis associated with increased microbial translocation and significant associations between specific taxa and markers of microbial translocation and systemic inflammation. This was an exploratory study, the findings of which need to be confirmed.

Immunodiscordant responses to HAART--mechanisms and consequences

A relevant fraction of HIV-1-infected individuals (ranging from 15 to 30%) presenting virologically successful highly active antiretroviral therapy fail to recover CD4 T-cell counts. These individuals, called immunodiscordant or immunological nonresponders, are at increased risk of clinical progression and death. Although older age, lower nadir CD4 T-cell count and HCV co-infection are some of clinical predictive factors, immunological mechanisms rely on impaired thymic production and accumulation of apoptosis-prone CD4 T cells. Indeed, immunodiscordant individuals may show increased tissue fibrosis and damage of gut-associated lymphoid tissue that results in higher hyperactivation, inflammation and immunosenescence, altered Treg/Th17 ratio and increased T-cell death. A better knowledge of the final pathogenic mechanism and factors influencing CD4 T-cell recovery will help to select the optimal therapeutic strategies for them.

Markers of coagulation and inflammation often remain elevated in ART-treated HIV-infected patients

PURPOSE OF REVIEW

Current antiretroviral therapies have dramatically changed the disease course of HIV infection. Although antiretroviral therapy is effective at decreasing viral replication and preserving CD4 T-cell numbers, low-level immune activation and inflammation persist in virally suppressed HIV-infected patients. This chronic immune activation/inflammation may contribute to an increased risk for venous and arterial thrombosis.

RECENT FINDINGS

Several markers of coagulation and inflammation are increased in HIV-infected patients. The Strategies for the Management of Antiretroviral Therapy study reported that plasma D-dimer levels, a marker of fibrinolysis, independently predicted morbidity in HIV-infected patients. Increased plasma and cell surface levels of the procoagulant tissue factor have also been reported in patients with HIV disease. Fibrinogen, von Willebrand factor, and P-selectin are likewise increased in plasma samples of HIV-infected patients; all of these markers suggest HIV-infection results in a procoagulant state. Treatment with antiretroviral therapy reduces, but does not always normalize, levels of biomarkers associated with inflammation and coagulation in HIV+ patients.

SUMMARY

HIV-infected patients are at greater risk for both venous and arterial thrombosis. Chronic immune activation and inflammation in these patients appears to contribute to coagulation risk. Antiretroviral therapy reduces viral replication, immune activation, and markers of coagulation, but these indices do not always return to normal, even after several years of viremic control.

Aging of the human innate immune system in HIV infection

HIV infection is associated with a chronic inflammatory state arising from multiple factors, including innate immune recognition of HIV, increased microbial translocation, and release of endogenous ligands from damaged cells (such as CD4 T cells). In many respects, this heightened pro-inflammatory environment resembles that associated with aging in the absence of HIV infection, and evidence of dysregulated innate immune responses can be found in not only older HIV-negative adults, but also adults with HIV infection. While the study of innate immune aging in HIV infection is still in its early stages, it seems likely that at least additive, or potentially synergistic effects of aging and HIV infection will be found.

An altered intestinal mucosal microbiome in HIV-1 infection is associated with mucosal and systemic immune activation and endotoxemia

Human immunodeficiency virus-1 (HIV-1) infection disrupts the intestinal immune system, leading to microbial translocation and systemic immune activation. We investigated the impact of HIV-1 infection on the intestinal microbiome and its association with mucosal T-cell and dendritic cell (DC) frequency and activation, as well as with levels of systemic T-cell activation, inflammation, and microbial translocation. Bacterial 16S ribosomal DNA sequencing was performed on colon biopsies and fecal samples from subjects with chronic, untreated HIV-1 infection and uninfected control subjects. Colon biopsies of HIV-1-infected subjects had increased abundances of Proteobacteria and decreased abundances of Firmicutes compared with uninfected donors. Furthermore at the genus level, a significant increase in Prevotella and decrease in Bacteroides was observed in HIV-1-infected subjects, indicating a disruption in the Bacteroidetes bacterial community structure. This HIV-1-associated increase in Prevotella abundance was associated with increased numbers of activated colonic T cells and myeloid DCs. Principal coordinates analysis demonstrated an HIV-1-related change in the microbiome that was associated with increased mucosal cellular immune activation, microbial translocation, and blood T-cell activation. These observations suggest that an important relationship exists between altered mucosal bacterial communities and intestinal inflammation during chronic HIV-1 infection.

Use of first-generation HCV protease inhibitors in patients coinfected by HIV and HCV genotype 1

BACKGROUND

In HCV genotype 1-infected patients with HIV co-infection, tritherapy [HCV protease inhibitors (PIs) plus peg-interferon and ribavirin] has been shown to have an increased rate of sustained virological response. However, complex drug-to-drug interactions and tolerability issues remain a concern.

METHODS

Under the auspices of four French scientific societies of medicine, a committee was charged of establishing guidelines on the use of first-generation HCV PIs in these patients. This scientific committee based its work on preliminary results from tritherapy clinical trials in co-infected patients and, since data on these patients are still scarce, on the statements already made by the French Association for the Study of the Liver (AFEF) on the use of tritherapy in HCV mono-infected patients, written in May 2011 and updated in 2012. Each AFEF guideline concerning HCV monoinfection was examined to determine whether it could be used in the context of HIV/HCV coinfection.

RESULTS

These guidelines are addressed for the treatment of coinfected patients with various profiles, including treatment-naïve or patients with failure to previous bitherapy and mention those patients for whom tritherapy should start or those for whom it should be delayed. Preliminary results of triple therapy as well as factors associated to virological response are also discussed. Other issues include virological monitoring, clinical and virological criteria to stop therapy, practical treatment management, treatment adherence and the management of side effects and interactions with antiretroviral drugs. These guidelines were submitted for critical review to independent experts.

Progressive proximal-to-distal reduction in expression of the tight junction complex in colonic epithelium of virally-suppressed HIV+ individuals

Effective antiretroviral therapy (ART) dramatically reduces AIDS-related complications, yet the life expectancy of long-term ART-treated HIV-infected patients remains shortened compared to that of uninfected controls, due to increased risk of non-AIDS related morbidities. Many propose that these complications result from translocated microbial products from the gut that stimulate systemic inflammation--a consequence of increased intestinal paracellular permeability that persists in this population. Concurrent intestinal immunodeficiency and structural barrier deterioration are postulated to drive microbial translocation, and direct evidence of intestinal epithelial breakdown has been reported in untreated pathogenic SIV infection of rhesus macaques. To assess and characterize the extent of epithelial cell damage in virally-suppressed HIV-infected patients, we analyzed intestinal biopsy tissues for changes in the epithelium at the cellular and molecular level. The intestinal epithelium in the HIV gut is grossly intact, exhibiting no decreases in the relative abundance and packing of intestinal epithelial cells. We found no evidence for structural and subcellular localization changes in intestinal epithelial tight junctions (TJ), but observed significant decreases in the colonic, but not terminal ileal, transcript levels of TJ components in the HIV+ cohort. This result is confirmed by a reduction in TJ proteins in the descending colon of HIV+ patients. In the HIV+ cohort, colonic TJ transcript levels progressively decreased along the proximal-to-distal axis. In contrast, expression levels of the same TJ transcripts stayed unchanged, or progressively increased, from the proximal-to-distal gut in the healthy controls. Non-TJ intestinal epithelial cell-specific mRNAs reveal differing patterns of HIV-associated transcriptional alteration, arguing for an overall change in intestinal epithelial transcriptional regulation in the HIV colon. These findings suggest that persistent intestinal epithelial dysregulation involving a reduction in TJ expression is a mechanism driving increases in colonic permeability and microbial translocation in the ART-treated HIV-infected patient, and a possible immunopathogenic factor for non-AIDS related complications.

Do the epidemiology, physiological mechanisms and characteristics of hepatocellular carcinoma in HIV-infected patients justify specific screening policies?

Reducing the incidence of hepatocellular carcinoma (HCC) in HIV-infected patients has become a serious problem when managing these patients. There are many explanations for this disease evolution, which notably include their longer survival under effective antiviral therapy and also the more rapid evolution of chronic liver disease. Despite recent advances in the management of hepatitis B (HBV) and hepatitis C (HCV) viral diseases, which will probably increase the number of patients achieving a virological response, HIV-infected patients with cirrhosis are still at risk of the onset of HCC. This evolution to HCC is also correlated to other comorbidities such as excessive alcohol consumption and nonalcoholic steatohepatitis (NASH). HCC thus remains a public health issue in this population. The poor prognosis and aggressiveness of HCC have been fully demonstrated, but the mechanisms underlying this aggressiveness are not yet well defined. As well as underlying mechanisms that contribute to accelerating hepatocarcinogenesis in HIV-infected patients, there are other reasons why HIV-infected patients should be considered a higher risk population. This review discusses the principal epidemiological determinants; the mechanisms of pathogenesis; and the treatment of HCC in HIV/HBV and HIV/HCV coinfected patients. It also discusses the probable need to develop a specific screening policy for HCC in this population in order to prevent the rapid development and to make them more amenable to a curative treatment.

Gut Microbiota in HIV Infection: Implication for Disease Progression and Management

Survival rates among HIV patients have significantly improved since the introduction of antiretroviral therapy (ART) in HIV management. However, persistent disease progression and clinical complications in virally suppressed individuals point to additional contributing factors other than HIV replication; microbial translocation is one such factor. The role of underlying commensal microbes and microbial products that traverse the intestinal lumen into systemic circulation in the absence of overt bacteraemia is under current investigation. This review focuses on current knowledge of the complex microbial communities and microbial markers involved in the disruption of mucosal immune T-cells in the promotion of inflammatory processes in HIV infections. Unanswered questions and aims for future studies are addressed. We provide perspective for discussing potential future therapeutic strategies focused on modulating the gut microbiota to abate HIV disease progression.

Lipopolysaccharide induces immune activation and SIV replication in rhesus macaques of Chinese origin

Background

Chronic immune activation is a hallmark of progressive HIV infection and a key determinant of immunodeficiency in HIV-infected individuals. Bacterial lipopolysaccharide (LPS) in the circulation has been implicated as a key factor in HIV infection-related systemic immune activation. We thus investigate the impact of LPS on systemic immune activation in simian immunodeficiency virus (SIV)-infected rhesus macaques of Chinese origin.

Methods

The animals were inoculated intravenously with SIVmac239. The levels of plasma viral load and host inflammatory cytokines in PBMC were measured by real-time RT-PCR. CD4/CD8 ratio and systemic immune activation markers were examined by flow cytometric analysis of PBMCs. White blood cell and neutrophil counts and C Reactive Protein levels were determined using biochemistry analyzer. The plasma levels of LPS were determined by Tachypleus Amebocyte Lysate (TAL) test.

Results

The animals inoculated with SIVmac239 became infected as evidenced by the increased plasma levels of SIV RNA and decreased CD4/CD8 ratio. LPS administration of SIV-infected animals induced a transient increase of plasma SIV RNA and immune activation, which was indicated by the elevated expression of the inflammatory cytokines and CD4+HLA-DR+ T cells in PBMCs.

Conclusions

These data support the concept that LPS is a driving factor in systemic immune activation of HIV disease.