Liver fibrosis, microbial translocation and immune activation markers in HIV and HCV infections and in HIV/HCV co-infection

Neuro-HIV-New insights into pathogenesis and emerging therapeutic targets

HIV-associated neurocognitive disorders (HAND) is a term describing a complex set of cognitive impairments accompanying HIV infection. Successful antiretroviral therapy (ART) reduces the most severe forms of HAND, but milder forms affect over 50% of people living with HIV (PLWH). Pathogenesis of HAND in the ART era remains unknown. A variety of pathogenic factors, such as persistent HIV replication in the brain reservoir, HIV proteins released from infected brain cells, HIV-induced neuroinflammation, and some components of ART, have been implicated in driving HAND pathogenesis in ART-treated individuals. Here, we propose another factor-impairment of cholesterol homeostasis and lipid rafts by HIV-1 protein Nef-as a possible contributor to HAND pathogenesis. These effects of Nef on cholesterol may also underlie the effects of other pathogenic factors that constitute the multifactorial nature of HAND pathogenesis. The proposed Nef- and cholesterol-focused mechanism may provide a long-sought unified explanation of HAND pathogenesis that takes into account all contributing factors. Evidence for the impairment by Nef of cellular cholesterol balance, potential effects of this impairment on brain cells, and opportunities to therapeutically target this element of HAND pathogenesis are discussed.

The Role of Mesenchymal Stem Cells and Imatinib in the Process of Liver Fibrosis Healing Through CCL2-CCR2 and CX3CL1-CX3CR1 Axes

Background

Persistent liver damage contributes to the development of liver fibrosis, marked by an accumulation of extracellular matrix. Macrophages play a pivotal role in this process, with the CCL2-CCR2 and CX3CR1-CX3CL1 axes serving as key regulators of macrophage recruitment, liver infiltration, and differentiation. In this study, utilizing a rat model of carbon tetrachloride (CCL4)-induced liver fibrosis, we aimed to investigate the impact of imatinib and bone marrow-derived mesenchymal stem cells (BM-MSCs) on the expression of these axis.

Methods

Sixteen Sprague-Dawley rats were divided into four groups: healthy, liver fibrosis, imatinib-recipient, and BM-MSC-recipient. Treatment effects were evaluated using histopathology and Sirus-red staining. Quantitative real-time PCR was employed to analyze changes in the expression of the genes CCL2, CCR2, CX3CL1, and CX3CR1.

Results

Histopathological assessments revealed the efficacy of imatinib and BM-MSCs in mitigating liver fibrosis. Our findings demonstrated a significant reduction in CCL2 and CCR2 expression in both imatinib and BM-MSCs treatment groups compared to the liver fibrosis group. Conversely, the gene expression of CX3CL1 and CX3CR1 increased in both therapeutic groups compared to the liver fibrosis groups.

Conclusions

The notable decrease in CCL2-CCR2 genes in both therapeutic groups suggests that BM-MSCs and imatinib may contribute to a decline in inflammatory macrophages within the liver. The lower CCL2-CCR2 expression in imatinib-recipient rats indicates better efficacy in modulating the recruitment of inflammatory macrophages. The elevated expression of CX3CL1 in BM-MSC-recipient rats suggests a greater impact on the polarization of LY6Chigh (inflammatory) to LY6Clow (anti-inflammatory) macrophages, warranting further investigation.

Pro-fibrogenic role of alarmin high mobility group box 1 in HIV-hepatitis B virus coinfection

OBJECTIVE

Liver disease is accelerated in people with HIV (PWH) with hepatitis B virus (HBV) coinfection. We hypothesized that liver fibrosis in HIV-HBV is triggered by increased hepatocyte apoptosis, microbial translocation and/or HIV/HBV viral products.

DESIGN

Sera from PWH with HBV coinfection versus from those with HBV only or putative mediators were used to examine the pathogenesis of liver disease in HIV-HBV.

METHODS

We applied sera from PWH and HBV coinfection versus HBV alone, or putative mediators (including HMGB1), to primary human hepatic stellate cells (hHSC) and examined pro-fibrogenic changes at the single cell level using flow cytometry. High mobility group box 1 (HMGB1) levels in the applied sera were assessed according to donor fibrosis stage.

RESULTS

Quantitative flow cytometric assessment of pro-fibrogenic and inflammatory changes at the single cell level revealed an enhanced capacity for sera from PWH with HBV coinfection to activate hHSC. This effect was recapitulated by lipopolysaccharide, HIV-gp120, hepatocyte conditioned-media and the alarmin HMGB1. Induction of hepatocyte cell death increased their pro-fibrogenic potential, an effect blocked by HMGB1 antagonist glycyrrhizic acid. Consistent with a role for this alarmin, HMGB1 levels were elevated in sera from PWH and hepatitis B coinfection compared to HBV alone and higher in those with HIV-HBV with liver fibrosis compared to those without.

CONCLUSIONS

Sera from PWH and HBV coinfection have an enhanced capacity to activate primary hHSC. We identified an increase in circulating HMGB1 which, in addition to HIV-gp120 and translocated microbial products, drove pro-fibrogenic changes in hHSC, as mechanisms contributing to accelerated liver disease in HIV-HBV.

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.

Special Considerations in the Management of HIV and Viral Hepatitis Coinfections in Liver Transplantation

Modern therapies for hepatitis B virus, hepatitis C virus, and human immunodeficiency virus have become so effective that patients treated for these conditions can have normal life-expectancies. Suitable livers for transplantation remain a scarce and valuable resource. As such, significant efforts have been made to expand donation criteria at many centers. This constant pressure, coupled with the increasing effectiveness of antiviral therapies, has meant that more and more patients infected with hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) may be considered appropriate donors in the right circumstances. Patients with these infections are also more likely to be considered appropriate transplantation recipients than in the past. The treatment of HBV, HCV, and HIV after liver transplantation (LT) can be challenging and complicated by viral coinfections. The various pharmaceutical agents used to treat these infections, as well as the immunosuppressants used post-LT must be carefully balanced for maximum efficacy, and to avoid resistance and drug–drug interactions.

HIV Infection Predisposes to Increased Chances of HBV Infection: Current Understanding of the Mechanisms Favoring HBV Infection at Each Clinical Stage of HIV Infection

Human immunodeficiency virus (HIV) selectively targets and destroys the infection-fighting CD4+ T-lymphocytes of the human immune system, and has a life cycle that encompasses binding to certain cells, fusion to that cell, reverse transcription of its genome, integration of its genome into the host cell DNA, replication of the HIV genome, assembly of the HIV virion, and budding and subsequent release of free HIV virions. Once a host is infected with HIV, the host’s ability to competently orchestrate effective and efficient immune responses against various microorganisms, such as viral infections, is significantly disrupted. Without modern antiretroviral therapy (ART), HIV is likely to gradually destroy the cellular immune system, and thus the initial HIV infection will inexorably evolve into acquired immunodeficiency syndrome (AIDS). Generally, HIV infection in a patient has an acute phase, a chronic phase, and an AIDS phase. During these three clinical stages, patients are found with relatively specific levels of viral RNA, develop rather distinctive immune conditions, and display unique clinical manifestations. Convergent research evidence has shown that hepatitis B virus (HBV) co-infection, a common cause of chronic liver disease, is fairly common in HIV-infected individuals. HBV invasion of the liver can be facilitated by HIV infection at each clinical stage of the infection due to a number of contributing factors, including having identical transmission routes, immunological suppression, gut microbiota dysbiosis, poor vaccination immune response to hepatitis B immunization, and drug hepatotoxicity. However, there remains a paucity of research investigation which critically describes the influence of the different HIV clinical stages and their consequences which tend to favor HBV entrenchment in the liver. Herein, we review advances in the understanding of the mechanisms favoring HBV infection at each clinical stage of HIV infection, thus paving the way toward development of potential strategies to reduce the prevalence of HBV co-infection in the HIV-infected population.

Cannabis and Inflammation in HIV: A Review of Human and Animal Studies

Persistent inflammation occurs in people with HIV (PWH) and has many downstream adverse effects including myocardial infarction, neurocognitive impairment and death. Because the proportion of people with HIV who use cannabis is high and cannabis may be anti-inflammatory, it is important to characterize the impact of cannabis use on inflammation specifically in PWH. We performed a selective, non-exhaustive review of the literature on the effects of cannabis on inflammation in PWH. Research in this area suggests that cannabinoids are anti-inflammatory in the setting of HIV. Anti-inflammatory actions are mediated in many cases through effects on the endocannabinoid system (ECS) in the gut, and through stabilization of gut–blood barrier integrity. Cannabidiol may be particularly important as an anti-inflammatory cannabinoid. Cannabis may provide a beneficial intervention to reduce morbidity related to inflammation in PWH.

Modifications of liver stiffness and CXCL4, TGF-β1 and HGF are similar in HCV- and HIV/HCV-infected patients after DAAs

The objective of this work was to identify predictive factors of fibrosis regression after direct antiviral agents (DAAs) in HCV-monoinfected and HIV/HCV-coinfected patients. This was a prospective study of HCV-monoinfected (n = 20), HIV/HCV-co-infected (n = 66) patients and healthy controls (n = 15). Patients had started DAAs and achieved sustained virological response. Liver stiffness (LS) and serum concentrations of profibrotic transforming growth factor (TGF)-β1 and CXC chemokine ligand 4 (CXCL4) and antifibrotic HGF hepatocyte growth factor (HGF) were analyzed at baseline (M0) and 12 months after starting DAAs (M12). A M12 LS achievement of ≤ 9.5 kPa was considered the cutoff point to discharge from a liver clinic. The LS decrease from M0 to M12 was 34%. No significant differences were observed in LS decline between HCV- and HIV/HCV-infected individuals. Changes of serum CXCL4, TGF-β1 and HGF levels did not correlate with LS improvement. 16 out from 56 patients (28%) with a baseline LS > 9.5 achieved a M12 LS ≤ 9.5. HCV-monoinfected and HIV/HCV coinfected patients experienced a significant reduction of LS after sustained virological response. This improvement did not correlate with changes in serum profibrotic or antifibrotic markers. A 29% of those with a baseline LS > 9.5 achieved a LS under this cutoff point.

HBcAb Positivity Increases the Risk of Severe Hepatic Fibrosis Development in HIV/HCV-Positive Subjects From the ICONA Italian Cohort of HIV-Infected Patients

Background

The aim of this study was to investigate the impact of anti-HBc (HBcAb) positivity on the progression of liver fibrosis (Fibrosis-4 score >3.25) in the Italian cohort of HIV-infected individuals naïve to antiretroviral treatment (ICONA).

Methods

All patients with FIB-4 <3.25 at baseline were evaluated prospectively: 6966 people with HIV (PWH) were screened and classified based on hepatitis B virus (HBV) and hepatitis C virus (HCV) serology.

Results

Patients who were HBcAb+/HCV-/HBs antigen (HBsAg)- and HCV+/HBcAb+/HBsAg- or HBsAg+/HBcAb+/HCV- had CD4+ cell counts below the nadir and significantly higher prevalence of AIDS diagnosis at baseline than the other groups (P < .0001). A Cox regression model adjusted for age, HIV transmission mode, country of birth, and alcohol consumption showed a higher relative risk (HR) of progression to FIB-4 >3.25 in HCV+/HBcAb+/HBsAg- patients (HR, 7.2; 95% CI, 3 8–13.64).

Conclusions

HBcAb+ contributes to liver damage in HIV+/HCV+/HBcAb+/HBsAg- subjects. A careful monitoring for signs of previous HBV infection is needed in this kind of patients.

Therapeutic potential of bone marrow-derived mesenchymal stem cells and imatinib in a rat model of liver fibrosis

Considering the global increase in the prevalence of hepatic fibrosis and ineffective disease treatment, novel therapies are urgently needed. The current study is focused on comparing the therapeutic effects of mesenchymal stem cells (MSC)/imatinib combination therapy to single (MSCs or imatinib) therapy, in a rat model of carbon tetrachloride (CCL4)-induced liver fibrosis. Using rats, hepatic fibrosis was induced by injection of CCL4. Rats were divided into 5 groups: CCL4-induced hepatic fibrosis, phosphate buffered saline (PBS) treatment (vehicle control), Bone marrow-MSCs (BM_MSCs), imatinib, and bone marrow-MSCs/imatinib co-treatment. The therapeutic impact of these approaches was determined using histopathology, sirius-red staining, serum markers, and qRT-PCR for over expression of matrix components. IHC and Western blot were conducted for further confirmation of the results. Single treatment with MSCs or imatinib and the combination therapy, all significantly reduced serum levels of ALT, AST, and ALP concomitant with down-regulation of α-SMA, pro-collagen I, pro-collagen III, collagen IV, and laminin. A significant reduction of ECM components deposits and a decrease in α-SMA expression were detected in all treatment groups. Pathological observations demonstrated that 20% and 40% of the rats in the MSC and MSC/imatinib group were in grade F0 respectively, while 80% of the rats of the imatinib group were in grade 2. Even though all treatment strategies studied resulted in an equally potent reduction in the mRNA and protein expression levels of pro-fibrotic markers, in aspect of pathological observations, our results demonstrate the highest therapeutic potential of utilizing combination of BM-MSCs and imatinib.

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

Background

Increased intestinal barrier permeability and subsequent gut microbial translocation are significant contributors to inflammatory non-AIDS comorbidities in people living with HIV (PLWH). Evidence in animal models have shown that markers of intestinal permeability and microbial translocation vary over the course of the day and are affected by food intake and circadian rhythms. However, daily variations of these markers are not characterized yet in PLWH. Herein, we assessed the variation of these markers over 24 h in PLWH receiving antiretroviral therapy (ART) in a well-controlled environment.

Methods

As in Canada, PLWH are predominantly men and the majority of them are now over 50 years old, we selected 11 men over 50 receiving ART with undetectable viremia for more than 3 years in this pilot study. Blood samples were collected every 4 h over 24 h before snacks/meals from 8:00 in the morning to 8:00 the next day. All participants consumed similar meals at set times, and had a comparable amount of sleep, physical exercise and light exposure. Plasma levels of bacterial lipopolysaccharide (LPS) and fungal (1→3)-β-D-Glucan (BDG) translocation markers, along with markers of intestinal damage fatty acid binding protein (I-FABP) and regenerating islet-derived protein-3α (REG3α) were assessed by ELISA or the fungitell assay.

Results

Participants had a median age of 57 years old (range 50 to 63). Plasma levels of BDG and REG3α did not vary significantly over the course of the study. In contrast, a significant increase of LPS was detected between 12:00 and 16:00 (Z-score: − 1.15 ± 0.18 vs 0.16 ± 0.15, p = 0.02), and between 12:00 and 24:00 (− 1.15 ± 0.18 vs 0.89 ± 0.26, p < 0.001). The plasma levels of I-FABP at 16:00 (− 0.92 ± 0.09) were also significantly lower, compared to 8:00 the first day (0.48 ± 0.26, p = 0.002), 4:00 (0.73 ± 0.27, p < 0.001) or 8:00 on secondary day (0.88 ± 0.27, p < 0.001).

Conclusions

Conversely to the fungal translocation marker BDG and the gut damage marker REG3α, time of blood collection matters for the proper evaluation for LPS and I-FABP as markers for the risk of inflammatory non-AIDS co-morbidities. These insights are instrumental for orienting clinical investigations in PLWH.

The Role of Microbial Translocation and Immune Activation in AIDS-Associated Non-Hodgkin Lymphoma Pathogenesis: What Have We Learned?

Human immunodeficiency virus (HIV) infection is associated with greatly increased risk for development of non-Hodgkin lymphoma (NHL). Nearly all acquired immunodeficiency syndrome (AIDS)-associated NHL (AIDS-NHL) is of B-cell origin. Two major mechanisms are believed to contribute to the genesis of AIDS-NHL: (1) loss of immunoregulation of Epstein-Barr virus (EBV)+ B cells, resulting from impaired T-cell function late in the course of HIV disease and (2) chronic B-cell activation, leading to DNA-modifying events that contribute to oncogene mutations/ translocations. HIV infection has long been known to be associated with chronic inflammation and polyclonal B-cell activation, and more recently, microbial translocation. Microbial translocation is bacterial product leakage from gut lumen into the peripheral circulation, resulting in high levels of lipopolysaccharide (LPS) in the peripheral circulation, leading to chronic immune activation and inflammation. We review recent literature linking microbial translocation to lymphom-agenesis. This includes epidemiological studies of biomarkers of microbial translocation with risk of AIDS-NHL and emerging data on the mechanisms by which microbial translocation may lead to AIDS-NHL development.

High Kynurenine:Tryptophan Ratio Is Associated With Liver Fibrosis in HIV-Monoinfected and HIV/Hepatitis C Virus-Coinfected Women

Background

Tryptophan catabolism, measured by the kynurenine:tryptophan (kyn/trp) ratio, is associated with gut microbiota alterations in people with HIV (PWH). We examined the association of the kyn/trp ratio with liver fibrosis in women with/without HIV infection.

Methods

The plasma kyn/trp ratio was measured in 137 HIV-monoinfected, HIV/hepatitis C virus (HCV)–coinfected, and uninfected women in the Women’s Interagency HIV Study. Fibrosis was estimated using FIB-4 in all participants and vibration-controlled transient elastography liver stiffness measurement (LSM) in a subset (n = 83). We used multivariable linear regression to evaluate the associations of infection status and kyn/trp ratio with relative differences in fibrosis estimates.

Results

The median kyn/trp ratio (interquartile range) was 0.056 (0.045–0.066) in HIV/HCV-coinfected, 0.038 (0.032–0.046) in HIV-monoinfected, and 0.031 (0.025–0.034) in uninfected women (P < .001). After adjustment for sociodemographic, lifestyle, and metabolic factors, HIV monoinfection and HIV/HCV coinfection were associated with 37% (95% confidence interval [CI], 9% to 73%) and 164% (95% CI, 100% to 250%) greater FIB-4, respectively. When kyn/trp ratio was included, higher kyn/trp ratio was associated with greater FIB-4 (27% per kyn/trp doubling; 95% CI, 5% to 53%), and the associations of HIV monoinfection (29% per kyn/trp doubling; 95% CI, 2% to 63%) and HIV/HCV coinfection (123% per kyn/trp doubling; 95% CI, 63% to 203%) with greater FIB-4 were attenuated. Among those with LSM, higher kyn/trp ratio was associated with greater LSM (43% per kyn/trp doubling; 95% CI, 15% to 79%) in multivariable analysis.

Conclusions

The kyn/trp ratio is elevated in PWH and is associated with greater liver fibrosis. Tryptophan catabolism may modify the relationships between HIV, HCV, and fibrosis.

The Possible Role of Gut Microbiota and Microbial Translocation Profiling During Chemo-Free Treatment of Lymphoid Malignancies

The crosstalk between gut microbiota (GM) and the immune system is intense and complex. When dysbiosis occurs, the resulting pro-inflammatory environment can lead to bacterial translocation, systemic immune activation, tissue damage, and cancerogenesis. GM composition seems to impact both the therapeutic activity and the side effects of anticancer treatment; in particular, robust evidence has shown that the GM modulates the response to immunotherapy in patients affected by metastatic melanoma. Despite accumulating knowledge supporting the role of GM composition in lymphomagenesis, unexplored areas still remain. No studies have been designed to investigate GM alteration in patients diagnosed with lymphoproliferative disorders and treated with chemo-free therapies, and the potential association between GM, therapy outcome, and immune-related adverse events has never been analyzed. Additional studies should be considered to create opportunities for a more tailored approach in this set of patients. In this review, we describe the possible role of the GM during chemo-free treatment of lymphoid malignancies.

Influence of hepatitis C virus eradication with direct-acting antivirals on the gut microbiota in patients with cirrhosis

BACKGROUND

The cure of hepatitis C virus (HCV) infection may contribute to the reduction of liver fibrosis progression and potentially influence the gut-liver axis.

AIM

To investigate the influence of HCV infection eradication with direct-acting antivirals (DAAs) on the gut microbiota composition as well as on intestinal and systemic inflammatory parameters in patients with cirrhosis.

METHODS

Consecutive patients with HCV-related cirrhosis receiving DAA treatment were included. The gut microbiota composition, intestinal permeability, and inflammation were assessed before treatment and after 1 year. Clinical outcomes such as episodes of decompensation and markers of liver fibrosis were evaluated over a 2-year follow-up period.

RESULTS

The gut microbiota alpha diversity in cirrhotic patients, which was lower than that in healthy subjects, was significantly improved by the cure of HCV infection and a shift in the overall gut microbiota composition was observed compared to baseline. The abundance of potentially pathogenic bacteria (Enterobacteriaceae, Enterococcus, and Staphylococcus) was decreased after treatment. The gut microbiota composition was associated with the inflammatory profile and markers of liver fibrosis. Although a significant reduction in the serum levels of cytokines and chemokines was observed post-DAA treatment, measures of intestinal permeability and inflammation remained unchanged.

CONCLUSIONS

Cure of HCV infection with DAAs in patients with cirrhosis is associated with a modification of the gut microbiota, which correlates with fibrosis and inflammation but does not improve intestinal barrier function.

Liver as a target of human immunodeficiency virus infection

Liver injury is a characteristic feature of human immunodeficiency virus (HIV) infection, which is the second most common cause of mortality in HIV-infected patients. Now it is recognized that liver plays a key role in HIV infection pathogenesis. Antiretroviral therapy (ART), which suppresses HIV infection in permissive immune cells, is less effective in hepatocytes, thereby making these cells a silent reservoir of HIV infection. In addition to direct hepatotoxic effects of HIV, certain ART treatment modalities provide hepatotoxic effects. The exact mechanisms of HIV-triggered chronic hepatitis progression are not elucidated, but the liver is adversely affected by HIV-infection and liver cells are prominently involved in HIV-elicited injury. These effects are potentiated by second hits like alcohol. Here, we will focus on the incidence of HIV, clinical evidence of HIV-related liver damage, interactions between HIV and liver cells and the role of alcohol and co-infection with hepatotropic viruses in liver inflammation and fibrosis progression.

HIV infection and care pathway: From guidelines to clinical practice

OBJECTIVES

To quantify within a cohort of HIV-infected individuals the number of medical visits and procedures to be carried out according to comorbidities and risk factors to implement a personalized care pathway.

PATIENTS AND METHODS

Retrospective study of 915 patients consulting from January 1 to December 31, 2016 at an outpatient unit of multidisciplinary consultations, using an electronic patient record. We built an algorithm using parameters required for the application of the national guidelines for the management of HIV-infected individuals. The frequency of comorbidities was measured according to gender, transmission risk group, and nadir CD4 (<or>200/mm³).

RESULTS

Patients were mostly men (median age: 52 years), of whom 16% were aged≥60 years. Viral load was<40 copies/mL in 93.5% of treated patients and CD4 cell count≥500/mm³ for 73%. Overall, 74.5% of patients had at least one comorbidity. The number of comorbidities was similar in men and women but was significantly higher in patients with a nadir CD4 <200/mm3 and increased with age (irrespective of gender). The minimum number of consultations to be scheduled per year was 8123: 70% for the management of comorbidities with an average of six consultations/year/patient. Overall, 53% of patients should attend a proctology consultation. The minimum number of paramedical procedures to be performed was 5115.

CONCLUSION

The implementation of a personalized multidisciplinary management within a single facility seems to be a suitable care model to address the needs of HIV-infected individuals.

Aging of the Liver: What This Means for Patients with HIV

As the HIV population continues to live longer as a result of antiretroviral therapy, liver-related mortality has become one of the leading causes of non-AIDS related death in this patient population. The liver possesses a remarkable regenerative capacity but undergoes complex biological changes in response to aging and inflammation that result in decreased cellular regeneration and a tipping of the scales towards fibrogenesis. Patients with HIV infection have serological evidence of ongoing inflammation, with elevations in some biomarkers persisting despite adequate virologic control. In addition, HIV-co-infected patients have markers of advanced age on liver biopsy and increased prevalence of fibrosis as compared to an age-matched HCV mono-infected cohort. In this review, we will discuss the biology of aging, age-related changes in the liver, and the relevant mechanisms by which HIV causes inflammation in the context of accelerated aging, fibrosis of the liver, and other viral co-infection.

Active HCV infection is associated with increased circulating levels of interferon-gamma (IFN-γ)-inducible protein-10 (IP-10), soluble CD163 and inflammatory monocytes regardless of liver fibrosis and HIV coinfection

BACKGROUND AND OBJECTIVE

Interferon-gamma (IFN-γ)-inducible protein-10 (IP-10), soluble (s) CD163 and sCD14 play an important role in the pathogenesis of HCV and HIV infection and are involved in inflammation and liver fibrosis. The aim of the present study was to evaluate at a single time point, plasma soluble biomarkers and inflammatory monocytes subsets in different groups of subjects: (i) HIV monoinfected patients on suppressive ART; (ii) HIV/HCV coinfected patients on ART, with undetectable HIV viremia (including either subjects who had active HCV replication or those who cleared HCV); (iii) HCV monoinfected individual with active viral replication.

METHODS

Hundred and twenty-nine plasma samples were analyzed including HCV and HIV monoinfected patients, HIV/HCV coinfected patients, with active HCV infection (AHI) or with HCV viral clearance (VHC) and healthy donors (HD). Levels of IP-10, sCD163 and sCD14 were measured by ELISA. Absolute cell counts of monocyte subpopulations were enumerated in whole blood by using flow cytometric analyses.

RESULTS

IP-10 and sCD163 plasma levels were higher in HCV monoinfected and in AHI coinfected pts compared to HIV monoinfected and HD, whereas sCD14 levels were higher only in HIV monoinfected patients. Considering the degree of fibrosis, sCD163 and sCD14 levels positively correlated with kPa values (as assessed by fibroscan) and FIB-4 in HCV monoinfected group. On the other hand, IP-10 did not correlate with the fibrosis stage and it was found increased also in patients with low fibrosis. Moreover, we found an increase of the inflammatory NCM subset, in non-cirrhotic HCV subjects, while no alterations were observed in HIV, AHI and VHC.

CONCLUSIONS

Our study suggests a scenario in which active HCV infection is associated with a strong pro-inflammatory state, even in the initial stage of liver fibrosis, regardless the presence of HIV coinfection, thus underlying the need of an early anti-HCV treatment.

The Role of Transforming Growth Factor Beta-1 in the Progression of HIV/AIDS and Development of Non-AIDS-Defining Fibrotic Disorders

Even after attainment of sustained viral suppression following implementation of highly active antiretroviral therapy, HIV-infected persons continue to experience persistent, low-grade, systemic inflammation. Among other mechanisms, this appears to result from ongoing microbial translocation from a damaged gastrointestinal tract. This HIV-related chronic inflammatory response is paralleled by counteracting, but only partially effective, biological anti-inflammatory processes. Paradoxically, however, this anti-inflammatory response not only exacerbates immunosuppression but also predisposes for development of non-AIDS-related, non-communicable disorders. With respect to the pathogenesis of both sustained immunosuppression and the increased frequency of non-AIDS-related disorders, the anti-inflammatory/profibrotic cytokine, transforming growth factor-β1 (TGF-β1), which remains persistently elevated in both untreated and virally suppressed HIV-infected persons, may provide a common link. In this context, the current review is focused on two different, albeit related, harmful activities of TGF-β1 in HIV infection. First, on the spectrum of anti-inflammatory/immunosuppressive activities of TGF-β1 and the involvement of this cytokine, derived predominantly from T regulatory cells, in driving disease progression in HIV-infected persons via both non-fibrotic and profibrotic mechanisms. Second, the possible involvement of sustained elevations in circulating and tissue TGF-β1 in the pathogenesis of non-AIDS-defining cardiovascular, hepatic, pulmonary and renal disorders, together with a brief comment on potential TGF-β1-targeted therapeutic strategies.

Mechanisms of liver disease in patients infected with HIV

Objective

To describe the various mechanisms of liver disease in patients with HIV infection, and to link these mechanisms to disease states which may utilise them.

Background

Non-AIDS causes of morbidity and mortality are becoming increasingly common in patients chronically infected with HIV. In particular, liver-related diseases have risen to become one of the leading causes of non-AIDS-related death. A thorough understanding of the mechanisms driving the development of liver disease in these patients is essential when evaluating and caring for these patients.

Methods

The literature regarding mechanisms of liver disease by which different disease entities may cause hepatic injury and fibrosis was reviewed and synthesised.

Results

A number of discrete mechanisms of injury were identified, to include: oxidative stress, mitochondrial injury, lipotoxicity, immune-mediated injury, cytotoxicity, toxic metabolite accumulation, gut microbial translocation, systemic inflammation, senescence and nodular regenerative hyperplasia. Disease states may use any number of these mechanisms to exert their effect on the liver.

Conclusions

The mechanisms by which liver injury may occur in patients with HIV infection are numerous. Most disease states use multiple mechanisms to cause hepatic injury and fibrosis.

Microbial translocation is correlated with HIV evolution in HIV-HCV co-infected patients

Microbial translocation (MT) is characterized by bacterial products passing into the blood through the gut barrier and is a key phenomenon in the pathophysiology of Human Immunodeficiency Virus (HIV) infection. MT is also associated with liver damage in Hepatitis C Virus (HCV) patients. The aim of the study was to assess MT in plasma of HIV-HCV co-infected patients. 16S rDNA (16 S Ribosomal DNA subunit) marker and other markers of MT such as Lipopolysaccharide (LPS)-binding protein (LBP), soluble CD14 (sCD14), intestinal fatty acid binding protein (I-FABP) were used. Clinical, biological and immunological characteristics of the population were studied in order to correlate them with the intensity of the MT. We demonstrate that indirect markers of MT, LBP and CD14s, and a marker of intestinal permeability (I-FABP) are significantly higher in HIV-HCV co-infected patients than in healthy controls (17.0 vs 2.6 μg/mL, p < 0.001; 1901.7 vs 1255.0 ng/mL, p = 0.018); 478.3 vs 248.1 pg/mL, p < 0.001, respectively), while a direct marker of MT (16S rDNA copies) is not different between these two populations. However, plasma 16S rDNA was significantly higher in co-infected patients with long-standing HIV infections (RGM = 1.47 per 10 years, CI95% = [1.04:2.06], p = 0.03). Our findings show that in HIV-HCV co-infected patients, plasma 16S rDNA levels, directly reflecting MT, seem to be linked to the duration of HIV infection, while elevated levels of LBP and sCD14 reflect only a persistence of immune activation. The levels of these markers were not correlated with HCV evolution.

Liver stiffness is not associated with short- and long-term plasma HIV RNA replication in immunocompetent patients with HIV infection and with HIV/HCV coinfection

Background

Human immunodeficiency virus (HIV) may be directly responsible for liver damage but there are contrasting data regarding the influence of detectable plasma viremia. We analyzed the influence of plasma HIV RNA (pHIV) detectability and of other clinical and viro-immunological variables on liver stiffness (LS) measurement in adult immunocompetent HIV-monoinfected patients and in patients coinfected with hepatitis C virus (HCV).

Methods

Logistic regression analysis was performed using the value of LS>7.1 kPa as the dependent variable. A linear regression model was applied using LS measurement after log₁₀ transformation (lkpa) as the dependent variable and we analyzed the predicted values versus the observed lkpa values; pHIV was classified as detectable or undetectable in the 12- and 36-month study periods before LS measurement.

Results

We studied 251 patients (178 with HIV monoinfection), most of whom were on antiviral treatment; 36-month study time was available for 154 subjects. The mean CD4+ cell count was 634 cells/mm³ in HIV-monoinfected patients and 606 cells/mm³ in coinfected patients. No difference in LS was found between patients with detectable or undetectable pHIV in either the 12- or the 36-month study period before transient elastography. The mean LS was higher in HIV/HCV coinfected patients (P<0.0001) than in the HIV-monoinfected subjects; lkpa was positively correlated with HCV coinfection (P<0.0001) and aspartate aminotransferase levels (P<0.0001). Detectable pHIV failed to reach significance. Eight HIV-monoinfected patients had a predicted LS measurement lower than the observed one, while eight patients had the opposite result.

Conclusion

LS was not correlated with ongoing HIV replication during the 12- and 36-month study periods in immunocompetent HIV-monoinfected and HIV/HCV-coinfected patients.

Changes in inflammatory biomarkers in HCV-infected patients undergoing direct acting antiviral-containing regimens with or without interferon

Background and aims

Increased levels of chemokine interferon-gamma (IFN-γ)-inducible protein-10 (CXCL10), soluble CD163 (sCD163) and soluble CD14 (sCD14) have been reported in HCV infection. The aim of this study was to compare, sCD163 and sCD14 levels in HCV-infected patients undergoing direct acting antiviral (DAA)-containing regimens with or without interferon (IFN).

Methods

sCD163, sCD14 and CXCL10 were longitudinally measured by ELISA in 159 plasma samples from 25 HCV-infected patients undergoing IFN-based treatment plus telaprevir or boceprevir and 28 HCV infected subjects treated with DAA IFN-free regimens. Twenty-five healthy donors (HD) were included as controls.

Results

At baseline CXCL10, sCD163 and sCD14 levels were higher in HCV-infected patients than in HD. CXCL10 and sCD163 levels were significantly decreased in responder (R) patients who achieved sustained virological response (SVR), with both IFN-based and IFN-free regimens, while they were persistently elevated in non-responders (NR) patients who stopped IFN-based treatments because of failure or adverse events. Conversely, sCD14 levels were apparently unchanged during therapy, but at the end of treatment the levels reached normal ranges. Comparing the two regimens, the extent of CXCL10 reduction was more pronounced in patients undergoing DAA IFN-free therapies, whereas sCD163 and sCD14 reduction was similar in the two groups.

Interestingly, only in IFN-based regimens baseline sCD163 levels were significantly higher in NR than in R patients, while in the IFN-free treatment group also patients with high sCD163 plasma levels obtained SVR. At the end of therapy, even if the biomarkers were largely decreased, their levels remained significantly higher compared to HD. Only in the early fibrosis stages, sCD163 values tended to normalize.

Conclusions

These results indicate that IFN-free regimens including newer DAA induce an early and marked decrease in circulating inflammatory biomarkers. However, the full normalization of biomarkers was not obtained, especially in patients with advanced fibrosis, thus underlying the need for a treatment in the early stages of HCV infection.

Is it enough to eliminate hepatitis C virus to reverse the damage caused by the infection?

Hepatitis C virus (HCV) infection represents one of the major causes of chronic liver disease, hepatocellular carcinoma and morbidity/mortality worldwide. It is also a major burden to the healthcare systems. A complete elimination of the HCV from the body through treatment is now possible. However, HCV not only alters the hepatic function. Several extra-hepatic manifestations are present in HCV-infected patients, which increase the mortality rate. Liver and gut are closely associated in what is called the “gut-liver axis”. A disrupted gut barrier leads to an increase in bacterial translocation and an activation of the mucosal immune system and secretion of inflammatory mediators that plays a key role in the progression of liver disease towards decompensated cirrhosis in HCV-infected patients. In addition, both qualitative and quantitative changes in the composition of the gut microbiota (GM) and states of chronic inflammation have been observed in patients with cirrhosis. Thus, a successful treatment of HCV infection should be also accompanied by a complete restoration of GM composition in order to avoid activation of the mucosal immune system, persistent inflammation and the development of long-term complications. Evaluation of GM composition after treatment could be of interest as a reliable indicator of the total or partial cure of these patients. However, studies focused on microbiota composition after HCV eradication from the body are lacking, which opens unique opportunities to deeply explore and investigate this exciting field.

Interferon-free regimens improve portal hypertension and histological necroinflammation in HIV/HCV patients with advanced liver disease

BACKGROUND

HIV/HCV co-infected patients show accelerated fibrosis progression and higher risk for complications of portal hypertension (PHT).

AIM

To assess the effects of interferon-free therapy on portal pressure, liver histology and plasma biomarkers in HIV/HCV-coinfected patients with PHT.

METHODS

Twenty-two patients with paired hepatic venous pressure gradient (HVPG) measurements prior and after successful treatment (SVR) with interferon-free regimens were included. Liver stiffness was assessed by transient elastography and biopsies were scored according to METAVIR. Plasma biomarkers were determined by ELISA.

RESULTS

Overall, HVPG decreased from 10.7 ± 4.1 mmHg at baseline to 7.4 ± 4.2 mmHg after HCV treatment (Δ:-3.3 ± 2.7 mmHg; p < 0.001). In patients with clinically significant PHT (HVPG≥10 mmHg, n = 11), HVPG decreased from 14.1 ± 2.9 to 10.4 ± 3.9 mmHg (Δ:-3.7 ± 3.3 mmHg; p = 0.004) and a haemodynamic response (HVPG decrease ≥10%) was observed in 73%. In 64% of patients with subclinical PHT (HVPG 6-9 mmHg, n = 11), portal pressure normalised at SVR. Mean liver stiffness decreased from 20.8 kPa to 11.5 kPa (Δ:-8.8 ± 7.4 kPa; p < 0.001). Fifty percent (7/14) of patients with cirrhosis were re-classified as METAVIR ≤F3 and all patients with decompensated cirrhosis improved their Child-Pugh stage. After successful HCV treatment, 39% still had persistent histological necroinflammatory activity (METAVIR A1), which correlated with less HVPG response and more steatosis. While most biomarkers improved with SVR, METAVIR A1 patients had significantly higher plasma levels of fibrogenic (PDGF, TGF-β) and angiogenic (VEGF, Angiopoietin1) biomarkers.

CONCLUSIONS

Interferon-free therapy reduces PHT and halts histological necroinflammatory activity in the majority of HIV/HCV-coinfected patients after SVR, which may lead to re-compensation of liver function in cirrhosis. Biomarkers could identify patients with persisting hepatic necroinflammation.

Liver fibrosis and hepatic stellate cells: Etiology, pathological hallmarks and therapeutic targets

Liver fibrosis is a reversible wound-healing process aimed at maintaining organ integrity, and presents as the critical pre-stage of liver cirrhosis, which will eventually progress to hepatocellular carcinoma in the absence of liver transplantation. Fibrosis generally results from chronic hepatic injury caused by various factors, mainly viral infection, schistosomiasis, and alcoholism; however, the exact pathological mechanisms are still unknown. Although numerous drugs have been shown to have antifibrotic activity in vitro and in animal models, none of these drugs have been shown to be efficacious in the clinic. Importantly, hepatic stellate cells (HSCs) play a key role in the initiation, progression, and regression of liver fibrosis by secreting fibrogenic factors that encourage portal fibrocytes, fibroblasts, and bone marrow-derived myofibroblasts to produce collagen and thereby propagate fibrosis. These cells are subject to intricate cross-talk with adjacent cells, resulting in scarring and subsequent liver damage. Thus, an understanding of the molecular mechanisms of liver fibrosis and their relationships with HSCs is essential for the discovery of new therapeutic targets. This comprehensive review outlines the role of HSCs in liver fibrosis and details novel strategies to suppress HSC activity, thereby providing new insights into potential treatments for liver fibrosis.

Liver fibrosis and hepatic stellate cells: Etiology, pathological hallmarks and therapeutic targets

Liver fibrosis is a reversible wound-healing process aimed at maintaining organ integrity, and presents as the critical pre-stage of liver cirrhosis, which will eventually progress to hepatocellular carcinoma in the absence of liver transplantation. Fibrosis generally results from chronic hepatic injury caused by various factors, mainly viral infection, schistosomiasis, and alcoholism; however, the exact pathological mechanisms are still unknown. Although numerous drugs have been shown to have antifibrotic activity in vitro and in animal models, none of these drugs have been shown to be efficacious in the clinic. Importantly, hepatic stellate cells (HSCs) play a key role in the initiation, progression, and regression of liver fibrosis by secreting fibrogenic factors that encourage portal fibrocytes, fibroblasts, and bone marrow-derived myofibroblasts to produce collagen and thereby propagate fibrosis. These cells are subject to intricate cross-talk with adjacent cells, resulting in scarring and subsequent liver damage. Thus, an understanding of the molecular mechanisms of liver fibrosis and their relationships with HSCs is essential for the discovery of new therapeutic targets. This comprehensive review outlines the role of HSCs in liver fibrosis and details novel strategies to suppress HSC activity, thereby providing new insights into potential treatments for liver fibrosis.

Role of microbial translocation in soluble CD14 up-regulation in HIV-, but not in HCV-, infected chimpanzees

During human immunodeficiency virus (HIV) infection, soluble CD14 (sCD14) is up-regulated as a consequence of pathological disruption of the gut epithelial barrier, and subsequent increased microbial translocation. Also in hepatitis C virus (HCV)-infected patients with advanced liver fibrosis, increased levels of sCD14 have been reported. Since the liver plays an important role in clearance of translocated bacterial products, hepatic fibrosis may negatively affect clearance and thus contribute to higher sCD14 levels. Chimpanzees (Pan troglodytes) infected with HCV typically show no signs of liver fibrosis. Here, we have tested the hypothesis that increased levels of sCD14 occur in the absence of hepatic fibrosis or microbial translocation in chimpanzees chronically infected with HCV. sCD14 was up-regulated in both HIV/simian immunodeficiency virus (SIV)- and HCV-infected chimpanzees. In HIV/SIV-infected chimpanzees, intestinal fatty acid-binding protein, a marker for gut perturbation, lipopolysaccharide (LPS)-binding-protein and LPS core antibodies, confirm that sCD14 up-regulation was caused by increased microbial translocation. In HCV-infected chimpanzees, no evidence was found for increased microbial translocation despite up-regulation of sCD14. Additionally, the impact of liver fibrosis on microbial translocation was addressed by direct comparison of chimpanzees with a high HCV load and human patients with advanced fibrosis. These data suggest that only in a small minority of HCV patients, hepatic fibrosis corroborates microbial translocation.

Intestinal tract and acquired immunodeficiency syndrome

The intestinal tract is closely associated with the transmission, disease progression and the prevention and control of acquired immune deficiency syndrome (AIDS). It has been noticed early in AIDS research that a large percent of AIDS patients presented abnormalities in their intestinal tract, such as diarrhea. Now it is known that the intestinal tract has close and complex relationships with AIDS: (1) the intestinal tract is directly involved in the transmission of human immunodeficiency virus-1 (HIV-1); (2) the damage of the intestinal barrier of HIV/AIDS patients directly promotes AIDS disease progression; and (3) most importantly, the intestinal tract is an important target for the treatment and prevention of HIV/AIDS. The author has previously reviewed the progress in understanding the roles of the intestinal tract in HIV-1 infection and the changes of the intestinal tract after HIV-1 infection. In the current review, I discuss the progress in understanding the roles of the damage of the intestinal mucosal immune system in AIDS disease progression, and the potential application value of the restoration of intestinal mucosal immunity in the treatment of AIDS.

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.