In vitro production of type 1 and type 2 cytokines by peripheral blood mononuclear cells from subjects coinfected with human immunodeficiency virus and Leishmania infantum

The cytokine/chemokine response in Leishmania/HIV infection and co-infection

HIV infection progressively weakens the immune system by infecting and destroying cells involved in host defense. Viral infection symptoms are generated and aggravated as immunosuppression progresses, triggered by the presence of opportunistic infections: among these is leishmaniasis, a disease caused by the intracellular parasite Leishmania. The incidence of this co-infection is growing progressively due to the geographic distribution overlap. Both pathogens infect monocytes/macrophages and dendritic cells, although they can also modulate the activity of other cells without co-infecting, such as T and B lymphocytes. Leishmania/HIV co-infection could be described as a system comprising modulations of cell surface molecule expression, production of soluble factors, and intracellular death activities, leading ultimately to the potentiation of infectivity, replication, and spread of both pathogens. This review describes the cytokine/chemokine response in Leishmania/HIV infection and co-infection, discussing how these molecules modulate the course of the disease and analyzing the therapeutic potential of targeting this network.

Higher levels of TNF and IL-4 cytokines and low miR-182 expression in visceral leishmaniasis-HIV co-infected patients

AIMS

The aim of the present study was to assess serum cytokine and miRNA expression in visceral leishmaniasis-HIV (VL-HIV) co-infection and HIV mono-infection.

METHODS AND RESULTS

We analysed 113 serum samples from HIV patients in areas endemic for leishmaniasis. The diagnosis of VL was confirmed in 65 of these 113 samples. The VL-HIV and HIV groups presented significant differences regarding haemoglobin level (P < .0001), lymphocyte count (P = .0444), white blood cell count (P = .0108), weight loss (P = .0310), HIV load (P < .0001) and CD4+ T-lymphocytes count (P = .0003). Levels of IL-6 and IL-10, IFN-γ and IL-6, IFN-γ and IL-10, TNF and IL-2 were positively correlated in VL-HIV co-infection, indicating higher serum levels of TNF and IL-4 (P < .0001). In addition, miR-182 expression was found to be significantly higher in HIV (P = .009), miR-210 exhibited no statistically significant difference between groups, and nonexpression of miR-122 was found in both groups.

CONCLUSION

Together, TNF, IL-4 and miR-182 may represent circulatory biomarkers of VL-HIV co-infection.

ART Regimen and Other Sociodemographics Do Not Affect Cytokine Expression in HIV Patients in Ghana

BACKGROUND

HIV infection is marked by the production of cytokines by infected cells and cells of the immune system. Variations in the levels of cytokine in HIV-infected individuals significantly impact the role of the immune system with the possibility to affect the course of HIV disease by either exacerbating or suppressing HIV replication.

AIM

The study sought to investigate the effect of sociodemographic indices, clinical laboratory parameters, and ART regimen on Th1, Th2, and Th17 cytokines in HIV patients.

MATERIALS AND METHODS

A total of two hundred (200) HIV patients on either the first or second line of ART were recruited into the study. Sociodemographic indices were collected using researcher-administered questionnaires. Serum concentrations of two major immune-promoting cytokines, IL-12 and IFN-γ, and immune-suppressive cytokines, IL-10 and IL-17, were measured using enzyme-linked immunosorbent assay (ELISA). T-test and chi-square were used to compare mean scores, while correlation (Pearson's correlation) and linear regression analyses were also performed with the statistical significance set at p < 0.05.

RESULTS

The mean age of the participants was (45.54 ± 0.7846) years with a greater proportion (84.5%) between 31 and 60 years. The mean interferon-gamma (INF-γ), interleukin- (IL-) 10, interleukin-12, and interleukin-17 were estimated to be 349.9 ± 8.391 pg/ml, 19.32 ± 0.4593 pg/ml, 19.23 ± 0.3960 pg/ml, and 24.6 ± 0.6207 pg/ml, respectively. Although INF-γ and IL-17 levels were relatively higher in males compared to females, it was vice versa for IL-10 and IL-12. However, none of these was statistically significant. Again, no significant difference was observed among all the cytokines stratified by the duration of ART, stage of HIV, and smoking status. Most importantly, stratification by either first- or second-line ART regimens recorded no significant difference in cytokine levels. Age significantly correlated inversely with IFN-γ (r = -0.27, p ≤ 0.001), IL-10 (r = -0.24, p ≤ 0.001), and IL-12 (r = -0.18, p=0.01) while duration on ART significantly correlated inversely with IFN-γ (r = -0.16, p=0.02). CD4 counts at 6 months and 12 months on ART correlated inversely with IL-17 (r = -0.17, p=0.02) and plasma viral load at 1 year (r = -0.22, p ≤ 0.001), respectively. A positive correlation was observed between IFN-γ and IL-12 (r = -0.84, p ≤ 0.001) and IL-17 (r = -0.50, p ≤ 0.001). This positive trend was repeated between IL-10 and IL-12 (r = -0.92, p ≤ 0.001) and IL-17 (r = -0.61, p ≤ 0.001).

CONCLUSION

The levels of IFN-γ, IL-12, IL-17, and IL-10 are not significantly affected by sociodemographics and ART regimen. This observation shows that no significant difference was observed in cytokine levels stratified by ART regiments. This means that both regimens are effective in the suppression of disease progression.

The immunology of Leishmania/HIV co-infection

Leishmaniases are emerging as an important disease in human immunodeficiency virus (HIV)-infected persons living in several sub-tropical and tropical regions around the world, including the Mediterranean. The HIV/AIDS pandemic is spreading at an alarming rate in Africa and the Indian subcontinent, areas with very high prevalence of leishmaniases. The spread of HIV into rural areas and the concomitant spread of leishmaniases to suburban/urban areas have helped maintain the occurrence of Leishmania/HIV co-infection in many parts of the world. The number of cases of Leishmania/HIV co-infection is expected to rise owing to the overlapping geographical distribution of the two infections. In Southwestern Europe, there is also an increasing incidence of Leishmania/HIV co-infection (particularly visceral leishmaniasis) in such countries as France, Italy, Spain and Portugal. Studies suggest that in humans, very complex mechanisms involving dysregulation of host immune responses contribute to Leishmania-mediated immune activation and pathogenesis of HIV. In addition, both HIV-1 and Leishmania infect and multiply within cells of myeloid or lymphoid origin, thereby presenting a perfect recipe for reciprocal modulation of Leishmania and HIV-1-related disease pathogenesis. Importantly, because recovery from leishmaniases is associated with long-term persistence of parasites at the primary infection sites and their draining lymph nodes, there is very real possibility that HIV-mediated immunosuppression (due to CD4(+) T cell depletion) could lead to reactivation of latent infections (reactivation leishmaniasis) in immunocompromised patients. Here, we present an overview of the immunopathogenesis of Leishmania/HIV co-infection and the implications of this interaction on Leishmania and HIV disease outcome.

Decreased memory T-cell response and function in human immunodeficiency virus-infected patients with tegumentary leishmaniasis

The effects of human immunodeficiency virus (HIV) on the immune response in patients with cutaneous leishmaniasis have not yet been fully delineated. This study quantified and evaluated the function of memory T-cell subsets in response to soluble Leishmania antigens (SLA) from patients coinfected with HIV and Leishmania with tegumentary leishmaniasis (TL). Eight TL/HIV coinfected subjects and 10 HIV seronegative subjects with TL were evaluated. The proliferative response of CD4+and CD8+T-cells and naïve, central memory (CM) and effector memory (EM) CD4+T-cells in response to SLA were quantified using flow cytometry. The median cell division indices for CD4+and CD8+T-cells of coinfected patients in response to SLA were significantly lower than those in patients with Leishmania monoinfection (p < 0.05). The proportions of CM and EM CD4+T-cells in response to SLA were similar between the coinfected patients and patients with Leishmania monoinfection. However, the median CM and EM CD4+T-cell counts from coinfected patients were significantly lower (p < 0.05). The reduction in the lymphoproliferative response to Leishmania antigens coincides with the decrease in the absolute numbers of both EM and CM CD4+T-cells in response to Leishmania antigens in patients coinfected with HIV/Leishmania.

Visceral leishmaniasis mimicking as second line anti retroviral therapy failure

Visceral leishmaniasis (VL) has increased as a complicating infection in subjects with human immunodeficiency virus (HIV) in developing countries. Both infections tend to lower the cell-mediated immunity resulting in poor drug response. In HIV-positive subjects the clinical course as well as organ involvement of VL simulates tuberculosis, another very common tropical infection. We present a case of VL/HIV co-infection where the individual failed to respond to first and second line antiretroviral therapy with persistently low CD4 counts. This patient was also subjected empirically to antitubercular therapy with no clinical improvement; he was finally diagnosed as a case of VL in HIV upon revelation of amastigotes in bone marrow despite the initial negative serology on two occasions. He showed dramatic improvement in CD4 counts and clinical status on Amphotericin B therapy. In endemic areas and in HIV positive subjects a systemic and careful parasitology follow-up is necessary to ensure that no clinical form of leishmaniasis is overlooked.

The relationship between leishmaniasis and AIDS: the second 10 years

To date, most Leishmania and human immunodeficiency virus (HIV) coinfection cases reported to WHO come from Southern Europe. Up to the year 2001, nearly 2,000 cases of coinfection were identified, of which 90% were from Spain, Italy, France, and Portugal. However, these figures are misleading because they do not account for the large proportion of cases in many African and Asian countries that are missed due to a lack of diagnostic facilities and poor reporting systems. Most cases of coinfection in the Americas are reported in Brazil, where the incidence of leishmaniasis has spread in recent years due to overlap with major areas of HIV transmission. In some areas of Africa, the number of coinfection cases has increased dramatically due to social phenomena such as mass migration and wars. In northwest Ethiopia, up to 30% of all visceral leishmaniasis patients are also infected with HIV. In Asia, coinfections are increasingly being reported in India, which also has the highest global burden of leishmaniasis and a high rate of resistance to antimonial drugs. Based on the previous experience of 20 years of coinfection in Europe, this review focuses on the management of Leishmania-HIV-coinfected patients in low-income countries where leishmaniasis is endemic.

Cytokine and chemokine responses in patients co-infected with Entamoeba histolytica/dispar, Necator americanus and Mansonella perstans and changes after anti-parasite treatment

This study examined the impact of concurrent parasite infections (amoebiasis, filariasis, necatoriasis) and the effect of anti-parasite treatment on cytokine and chemokine responses in singly and poly-parasitized patients. Cellular reactivity and parasite-specific Th1- and Th2-type cytokine and chemokine profiles were investigated before and six weeks after treatment. In those patients infected with three parasite species, cellular secretion of interleukin 5 (IL-5) and IL-12p40 by PBMC was strongly diminished (p<0.005) but IL-10 was elevated in parasite-infected patients (p<0.0001) in response to protozoa- and helminth-specific as well as bacteria-specific antigens. Macrophage inflammatory chemokines (MIP-1alpha/CCL3 and MIP-1beta/CCL4), macrophage-derived chemokine (MDC/CCL22) and neutrophil activating chemokine (IL-8/CXCL8) were produced by PBMC in similar amounts in endemic controls and singly and poly-parasitized patients, but thymus and activation-regulated chemokine (TARC/CCL17) was produced the highest by PBMC from patients with triple parasite infections (p<0.0001). Following anti-parasite therapy, secretion of IL-12p40 and IL-5 augmented significantly in treated patients while IL-10, MDC, MIP-1alpha, TARC and IL-8 substantially diminished (all p<10(-5)) when their PBMC were activated with parasite- and bacteria-specific antigens. In summary, PBMC from poly-parasitized patients responded to protozoa- and helminth-specific antigens with a compromised IL-5 and IL-12p40 but high IL-10 and a substantial chemokine release. Chemokines may attract and activate effector cells in peri-parasitic tissues to limit parasite proliferation and dissemination, while depressed IL-5 and IL-12p40 but prominent IL-10 may prevent eosinophil and cytotoxic cell-mediated inflammatory processes and pathogenesis to the host. The changes in this profile following anti-parasite therapy disclosed the dynamics of an immune adaptation associated with parasite accumulation and also with clearance of parasite infections.

Visceral leishmaniasis in those infected with HIV: clinical aspects and other opportunistic infections

Cases of visceral leishmaniasis (VL) in HIV-positive individuals have been reported from most areas of the world where the geographical distributions of the two infections overlap. The majority of the co-infected cases that have been recorded, however, live around the Mediterranean basin. In these subjects, the length of the incubation period of VL is presumably very short, particularly in those who have severe immunodepression. At diagnosis, almost all cases of VL/HIV co-infection have been found to have fewer than 200 CD4+ cells/microl blood, and about 50% meet the AIDS-defining criteria during their first episode of VL. The clinical manifestations of VL in HIV-infected individuals may be similar to those seen in HIV-negative cases; fever, pancytopenia and hepato-splenomegaly, for example, are found in 75% of all the HIV-positive cases. Following the dissemination of the parasites, however, the HIV-positive cases may develop unusual, multi-organ pathology. Almost all the cases of co-infection are very prone to VL relapses, even after carefully managed antileishmanial treatment. The opportunistic infections that are often seen in HIV-positives frequently develop during VL episodes, the signs and symptoms of the leishmaniasis then confusingly overlapping with those of the other infections.

The impact of highly active antiretroviral therapy (HAART) on visceral leishmaniasis in Spanish patients who are co-infected with HIV

Clinicians in Madrid have been observing and treating HIV-positive patients with visceral leishmaniasis (VL) for over a decade. As their records cover some of the co-infection cases that occurred before and after highly active antiretroviral therapy (HAART) was introduced into Spain, retrospective analysis of the records has allowed some of the effects of HAART on local VL to be determined. Encouragingly, HAART appears to have decreased the annual incidence of VL among local AIDS cases, from 4.81 cases/100 to just 0.8 case/100 (P <0.0005), a first episode of VL now appearing only when there is obvious HAART failure. Unfortunately, it does not seem to be very good at preventing VL relapses; within 24 months of antileishmanial treatment, 70% of patients who were receiving HAART had such relapses. The mean time between antileishmanial treatment and VL relapse was, however, longer when HAART was used than when it was not (20 v. 13 months). In those receiving HAART, relapses of the VL often occurred despite increasing CD4+ cell counts and undetectable HIV loads, indicating that successful treatment of the viral infection is insufficient to prevent the relapse of the leishmaniasis. These results are in general agreement with other observations made in Spain. VL relapses are possible and even frequent in HIV-positives who have no more than 200 CD4+ cells/microl, but secondary prophylaxis to prevent VL relapses may be safely suspended if a CD4+ count of >200 cells/microl can be maintained using HAART. VL also seems to hamper the immunological recovery of the HIV-positive, although HAART appears to have little effect on the clinical manifestations of VL.

The pathogenesis of Leishmania/HIV co-infection: cellular and immunological mechanisms

The intracellular protozoan parasites of the genus Leishmania have been recognized as opportunistic pathogens in immunosuppressed individuals, including those infected with human immunodeficiency virus type-1 (HIV-1). Leishmaniasis and AIDS overlap in several sub-tropical and tropical regions around the world, including the Mediterranean area. In 1994, 3%-7% of HIV-1-infected individuals in southern Europe developed visceral leishmaniasis. In humans, interestingly, both HIV-1 and Leishmania interact with, invade, and multiply within cells of myeloid or lymphoid origin. The combined modulation of Leishmania - and HIV-1-related pathogenesis in the co-infected cases is therefore probably a realistic goal. In the light of the recent demonstration that L. donovani can up-regulate HIV-1 replication, both in monocytoid and lymphoid cells in vitro and in co-infected individuals, it is clear from the epidemiological data available that Leishmania can probably act as a powerful co-factor in the pathogenesis of HIV-1 infection. In those who are co-infected, complex mechanisms involving cytokine secretion and cellular-signalling events play pivotal roles in the Leishmania-mediated activation and pathogenesis of HIV-1. An overview of the recent findings concerning this Leishmania/HIV-1 interaction is presented here.