Antibody and markers of T-cell activation illuminate the pathogenesis of HCV immune restoration disease in HIV/HCV co-infected patients commencing ART

The dynamics of HCV-specific antibody responses in HIV/HCV patients on long-term antiretroviral therapy

Antibody responses have not been fully characterised in chronically HIV/HCV patients receiving antiretroviral therapy (ART). Seventeen HIV/HCV patients receiving ART were followed for a median (range) interval of 597 (186-766) weeks. Prior to ART, HIV/HCV patients had lower levels of antibodies reactive with HCV core and JFH-1, and lower genotype cross-reactive neutralising antibodies (nAb) titres, than HCV patients. Levels of JFH-1 reactive antibody increased on ART, irrespective of CD4⁺ T-cell counts or changes in serum ALT levels. The appearance of nAb coincided with control of HCV viral replication in five HIV/HCV patients. In other patients, HCV viral loads remained elevated despite nAb responses. Sustained virological responses following HCV therapy were associated with reduced antibody responses to JFH-1 and core but elevated responses to non-structural proteins. We conclude that nAb responses alone may fail to clear HCV, but contribute to control of viral replication in some HIV/HCV patients responding to ART.

Naive and Memory CD4⁺ T Cells Are Differentially Affected in Indonesian HIV Patients Responding to ART

While most HIV patients beginning antiretroviral therapy (ART) with advanced immunodeficiency recover CD4(+) T cell numbers, the profiles and functions of the newly acquired CD4(+) T cells have not been monitored in a resource-limiting setting. In this study, HIV patients (n = 31) from Jakarta, Indonesia, were studied 9 months after commencing ART with nadir CD4(+) T cell counts <200 cells/μL. All patients were hepatitis C virus (HCV) seropositive, but asymptomatic. Twelve healthy age-matched controls from the same community were included. CD4(+) T cell subsets, immune activation (HLA-DR), and expression of the interleukin (IL)-7 receptor α chain (CD127) were quantitated by flow cytometry. Proliferation (expression of Ki67) was measured following in vitro stimulation (5 days) with anti-CD3 antibody or IL-7. Fifty-two percent of patients recovered CD4(+) T cell counts >200 cells/μL over 12 months. At 9 months, patients had fewer naive and CD31(+)-naive CD4(+) T cells, more effector memory (EM) CD4(+) T cells, and higher HLA-DR expression on CD4(+) T cells than controls. CD127 expression was low on all CD4(+) T cell subsets except for naive cells, where it was similar to controls. Similarly, after anti-CD3 antibody or IL-7 stimulation, patients had lower Ki67 expression than controls in all subsets, except naive CD4(+) T cells where it was normal or elevated. Overall in the first year of ART, patients had fewer naive and more EM CD4(+) T cells. Ongoing immune activation and, antigen-driven stimulation and differentiation of naive T cells may reduce the naive T cell pool, while driving the maturation and accumulation of memory cells with proliferative defects.

Short Communication: Few Liver-Infiltrating Cells Express CXCR3 in HIV/HCV Patients Commencing Antiretroviral Therapy

Coinfections with Hepatitis C virus and human immunodeficiency virus accelerate the progression of both conditions and hamper effective treatment. Here we describe expression of CXCR3 on liver-infiltrating cells and peripheral T cells from coinfected patients commencing antiretroviral therapy (ART) in Indonesia. CXCR3 was expressed by small number of intrahepatic inflammatory cells, mostly in the portal areas. The number of cells did not change on ART and was markedly lower than the number of CD4⁺ and CD8⁺ cells in the liver. Data suggest that CXCR3 may contribute to liver infiltration but demonstrate a dynamic situation, changing as the immune system recovers on ART.

T-Cell Surface Antigens and sCD30 as Biomarkers of the Risk of Rejection in Solid Organ Transplantation

T-cell activation is a characteristic of organ rejection. T cells, located in the draining lymph nodes of the transplant recipient, are faced with non-self-molecules presented by antigen presenting cells and become activated. Activated T cells are characterized by up-regulated surface antigens, such as costimulatory molecules, adhesion molecules, chemokine receptors, and major histocompatibility complex class II molecules. Surface antigen expression can be followed by flow cytometry using monoclonal antibodies in either cell function assays using donor-specific or nonspecific stimulation of isolated cells or whole blood and without stimulation on circulating lymphocytes. Molecules such as CD30 can be proteolytically cleaved off the surface of activated cells in vivo, and the determination of the soluble protein (sCD30) in serum or plasma is performed by immunoassays. As promising biomarkers for rejection and long-term transplant outcome, CD28 (costimulatory receptor for CD80 and CD86), CD154 (CD40 ligand), and sCD30 (tumor necrosis factor receptor superfamily, member 8) have been identified. Whereas cell function assays are time-consuming laboratory-developed tests which are difficult to standardize, commercial assays are frequently available for soluble proteins. Therefore, more data from clinical trials have been published for sCD30 compared with the surface antigens on activated T cells. This short review summarizes the association between selected surface antigens and immunosuppression, and rejection in solid organ transplantation.

Increased proportions of dendritic cells and recovery of IFNγ responses in HIV/HCV co-infected patients receiving ART

Dendritic cell (DC) numbers and functions can be affected by HIV and HCV disease, but the effects of antiretroviral therapy (ART) on DC and the implications of these changes are unclear. We examined circulating DC in samples from Indonesian patients beginning ART with advanced HIV disease and documented mild/moderate HCV hepatitis. Frequencies of myeloid and plasmacytoid DC increased after 6 months on ART, but frequencies of DC producing IL-12 or IFNα following stimulation with TLR agonists (CL075, CpG) did not change. IFNγ responses to CL075, HCV and other antigens rose over this period. Hence increased IFNγ responses during ART may be associated with increased DC frequencies rather than changes in their functional capacity.

Lymphocyte surface molecules as immune activation biomarkers

Immunosuppression is mandatory after solid organ transplantation between HLA mismatched individuals. It is a lifelong therapy that needs to be closely monitored to avoid under- and over-immunosuppression. For many drugs, pharmacokinetic monitoring has been proven to be beneficial. However, the therapeutic ranges are statistically derived surrogate markers for the effects that cannot predict the individual response of single patients. Better tailored immunosuppression biomarkers are needed that indicate immune activation. T cells are critically involved in organ rejection, and the means to assess their activation state may be promising to individualize immunosuppressive therapies. Activated T cells can be monitored with flow cytometry based on surface molecules that are typically up regulated or with molecules that are cleaved off the cell surface. Among these molecules are the interleukin-2 receptor (CD25); transferrin receptor (CD71); the T cell co-stimulatory molecules CD28, CD69, and CD154 and sCD30, which is a member of the TNF-alpha family. The effect of immunosuppressive drugs on T cell activation can be recorded with indirect cell function assays or by directly monitoring activated T cells in whole blood. Soluble proteins can be measured with immunoassays. This review provides a summary of the experimental and clinical studies investigating the potential of surface molecules as a tool for immune monitoring. It critically discusses the obstacles and shortcomings from an analytical and diagnostic perspective that are currently preventing their use in multicenter trials and clinical routine monitoring of transplant patients.

Cellular immune activation in cerebrospinal fluid from ugandans with cryptococcal meningitis and immune reconstitution inflammatory syndrome

Background. Human immunodeficiency virus (HIV)-associated cryptococcal meningitis (CM) is characterized by high fungal burden and limited leukocyte trafficking to cerebrospinal fluid (CSF). The immunopathogenesis of CM immune reconstitution inflammatory syndrome (IRIS) after initiation of antiretroviral therapy at the site of infection is poorly understood.

Methods. We characterized the lineage and activation status of mononuclear cells in blood and CSF of HIV-infected patients with noncryptococcal meningitis (NCM) (n = 10), those with CM at day 0 (n = 40) or day 14 (n = 21) of antifungal therapy, and those with CM-IRIS (n = 10).

Results. At diagnosis, highly activated CD8⁺ T cells predominated in CSF in both CM and NCM. CM-IRIS was associated with an increasing frequency of CSF CD4⁺ T cells (increased from 2.2% to 23%; P = .06), a shift in monocyte phenotype from classic to an intermediate/proinflammatory, and increased programmed death ligand 1 expression on natural killer cells (increased from 11.9% to 61.6%, P = .03). CSF cellular responses were distinct from responses in peripheral blood.

Conclusions. After CM, T cells in CSF tend to evolve with the development of IRIS, with increasing proportions of activated CD4⁺ T cells, migration of intermediate monocytes to the CSF, and declining fungal burden. These changes provide insight into IRIS pathogenesis and could be exploited to more effectively treat CM and prevent CM-IRIS.

Patients co-infected with hepatitis C virus (HCV) and human immunodeficiency virus recover genotype cross-reactive neutralising antibodies to HCV during antiretroviral therapy

When severely immunodeficient HIV/HCV co-infected patients are treated with antiretroviral therapy, it is important to know whether HCV-specific antibody responses recover and whether antibody profiles predict the occurrence of HCV-associated immune restoration disease (IRD). In 50 HIV/HCV co-infected patients, we found that antibody reactivity and titres of neutralising antibodies (nAb) to JFH-1 (HCV genotype 2a virus) increased over 48 weeks of therapy. Development of HCV IRD was associated with elevated reactivity to JFH-1 before and during the first 12 weeks of therapy. Individual analyses of HCV IRD and non-HCV IRD patients revealed a lack of an association between nAb responses and HCV viral loads. These results showed that increased HCV-specific antibody levels during therapy were associated with CD4(+) T-cell recovery. Whilst genotype cross-reactive antibody responses may identify co-infected patients at risk of developing HCV IRD, neutralising antibodies to JFH-1 were not involved in suppression of HCV replication during therapy.

HIV and co-infections

Despite significant reductions in morbidity and mortality secondary to availability of effective combination anti-retroviral therapy (cART), human immunodeficiency virus (HIV) infection still accounts for 1.5 million deaths annually. The majority of deaths occur in sub-Saharan Africa where rates of opportunistic co-infections are disproportionately high. In this review, we discuss the immunopathogenesis of five common infections that cause significant morbidity in HIV-infected patients globally. These include co-infection with Mycobacterium tuberculosis, Cryptococcus neoformans, hepatitis B virus, hepatitis C virus, and Plasmodium falciparum. Specifically, we review the natural history of each co-infection in the setting of HIV, the specific immune defects induced by HIV, the effects of cART on the immune response to the co-infection, the pathogenesis of immune restoration disease (IRD) associated with each infection, and advances in the areas of prevention of each co-infection via vaccination. Finally, we discuss the opportunities and gaps in knowledge for future research.

HIV and hepatitis C co-infection: the role of HAART in HIV/hepatitis C virus management

PURPOSE OF REVIEW

Highly active antiretroviral therapy (HAART)-related hepatotoxicity, a relevant side effect in HIV/hepatitis C virus (HCV) co-infected patients, has evolved over time. Antiretroviral therapy might have a positive effect on the liver of HIV/HCV co-infected patients, but data are conflicting.

RECENT FINDINGS

HIV treatments have evolved and we have currently a drug armamentarium with a good liver safety profile. Most of the current first-line HAART regimens recommended by guidelines fit well to HIV/HCV co-infected patients. There are now multiple retrospective studies that suggest a possible benefit of HIV control and protection of CD4 cell counts to the liver of HIV/HCV co-infected patients. However, data are conflicting at times. This factor along with the methodological limitations of these studies prevent us from drawing definitive conclusions. Even assuming a positive effect, HAART does not appear to fully correct the adverse effect of HIV infection on HCV-related outcomes. In the era of HCV direct antiviral agents, the timing of HIV and HCV therapies has to be individualized in HIV/HCV co-infected patients given the variety of scenarios.

SUMMARY

With current HIV drug armamentarium it is possible to construct HAART regimens with optimal liver safety profile for HCV co-infected patients. The possible positive effect of HAART on the HCV-infected liver should not distract from the main intervention, which is HCV eradication with specific treatment.

Mycobacterial antibody levels and immune restoration disease in HIV patients treated in South East Asia

AIM

Immune restoration disease (IRD) associated with Mycobacterium tuberculosis parallels the reconstitution of a pathogen-specific Th1 response. However, it is not clear whether humoral responses to M. tuberculosis antigens also rise, or whether antibody levels predict IRD. Here, humoral immunity to M. tuberculosis antigens was investigated in four Asian cohorts.

METHODS

Plasma samples were obtained from longitudinal prospective studies of HIV patients beginning antiretroviral therapy (ART) in New Delhi (India), Kuala Lumpur (Malaysia), Jakarta (Indonesia) and Phnom Penh (Cambodia). IgG antibodies to purified protein derivative, lipoarabinomannan and 38-kDa antigens of M. tuberculosis were quantitated using in-house ELISAs. IRD was defined as exacerbated symptoms of tuberculosis in patients on anti-tuberculosis therapy or a novel presentation of tuberculosis on ART.

RESULTS

Pre-ART IgG levels to purified protein derivative, lipoarabinomannan and 38-kDa antigen were similar in the IRD and control groups from each site. Compared with non-IRD controls, a higher proportion of IRD patients had elevated IgG levels to lipoarabinomannan (defined as a greater than twofold increase) over 12 weeks of ART. However, this trend was not significant for the other antigens and longitudinal analyses did not reveal clear rises in antibody levels at the time of IRD.

CONCLUSION

Levels of antibody to mycobacterial antigens do not predict IRD, but levels of antibody reactive with lipoarabinomannan rise during an IRD in some patients.