Effect of two different combinations of antiretrovirals (AZT+ddI and AZT+3TC) on cytokine production and apoptosis in asymptomatic HIV infection

Nineteen HIV-seropositive antiretroviral therapy-naive and asymptomatic individuals (200-500 CD4/microl) were enrolled in a prospective study aimed at analyzing the immunologic and virologic effects of two different combinations of nucleoside reverse transcriptase inhibitors (AZT+ddI and AZT+3TC), and randomly assigned to one of the treatment group. Immunologic (CD4 and CD8 counts, mitogen-stimulated cytokine production, unstimulated and mitogen-stimulated apoptosis) and virologic (HIV viral load) determinations were performed pre-therapy and 15, 30, 90, 200 and 360 days after initiation of therapy. Results showed that the two combinations had comparable effects on increasing CD4 counts and the CD4/CD8 ratio and in reducing HIV viral load. In contrast, AZT+3TC was more efficient in improving interleukin-2 (IL-2) and interferon gamma (IFNgamma) production as well as the type 1/type 2 cytokine ratio and in down modulating the susceptibility of peripheral blood mononuclear cells to in vitro mitogen-stimulated apoptotic cell death. These data suggest that the combination of AZT+3TC has a stronger effect on potentially beneficial immune parameters (IL-2 production; reduction of apoptosis) than the one between AZT+ddI. The combination of AZT+3TC could be more advantageous in the therapy of HIV infection even when used in association with a protease inhibitor.

Augmented type 1 cytokines and human endogenous retroviruses specific immune responses in patients with acute multiple sclerosis

In vitro antigen- and mitogen-stimulated cytokine production were analysed in multiple sclerosis (MS) patients with either acute (AMS) or stable (SMS) disease and in healthy controls (HC). We also investigated whether immune responses to human endogenous retroviruses (HERV) could be detected in MS and whether these immune responses would be correlated with disease status by analysing cytokine production after stimulation of PBMC with HERV peptides. Results showed that mitogen-stimulated IL-2 and IFN-gamma was augmented and IL-10 was decreased in AMS compared to both SMS and healthy controls. Whereas the production of the metabolically active IL-12 (p70 heterodimer), was comparable in SMS, AMS and HC, production of the total IL-12 (p70 heterodimer and the p40 chain) were augmented in SMS compared to both AMS and HC. HERV-peptides IL-2 and IFN-gamma production was more frequent and more potent in AMS compared to both SMS patients and HC. HERV-specific type 2 cytokine production was more frequent and potent in SMS compared to AMS and HC. Thus a prevalent type 1 cytokine profile was seen in AMS patients, while IL-10 production predominated in SMS individuals.

Study of immunological and virological parameters during thalidomide treatment of SIV-infected cynomolgus monkeys

The potential therapeutic utility of thalidomide (Thd), an effective inhibitor of tumor necrosis factor (TNF)-alpha in vitro, was investigated in cynomolgus monkeys (Macaca fascicularis) at 10 months after infection with simian immunodeficiency virus (SIV). Thd-treated macaques (n = 8) received an oral dose (10 mg) daily for 7 days, followed by a wash-out period of 5 weeks. A 2nd cycle of treatment was performed on the same animals at higher doses (20 mg Thd/day) for 14 days. The control monkeys (n = 7) received a placebo for the same period of time. In the present study, we show that Thd, in addition to inhibiting TNF-alpha production after in vitro mitogen stimulation of peripheral blood mononuclear cells (PBMCs), was able to restore the proliferative responses to SIV peptides in monkeys that were infected with SIV. Interestingly, we found that such effects are associated with an increased expression of CD28 cell surface receptors on CD4+ T-cells paralleled by a decrease on CD8+ T-cells. At the same time, significant reduction in either cell-associated viral load or plasma viral RNA was not observed among the SIV-infected monkeys during the two treatment cycles, when compared with the placebo group.

Immune responses to antigens of human endogenous retroviruses in patients with acute or stable multiple sclerosis

A possible role for human endogenous retroviruses (HERV) in the pathogenesis of MS was investigated by analyzing HERV peptides-stimulated proliferation and cytokine production in MS patients with acute (AMS) or stable (SMS) disease. HERV peptides specific-proliferation and type 1 cytokine production by peripheral blood mononuclear cells was observed in AMS but not in SMS individuals, in whom a type 2 cytokine profile dominates. HERV peptides-stimulated immune responses were modified by changes in disease expression; mediated by CD4+ T lymphocytes; and not related to HLA class II molecules. These data suggest the possibility of a pathogenic role for HERV and HERV-specific immune responses in MS.

Altered signaling lymphocytic activation molecule (SLAM) expression in HIV infection and redirection of HIV-specific responses via SLAM triggering

Signaling lymphocytic activation molecule (SLAM) is a transmembrane lymphocytic receptor which gets rapidly upregulated following cell activation. SLAM engagement augments T cell expansion and interferon-gamma (IFN-gamma) production independently of CD28. SLAM signaling is regulated by the SLAM-associated protein. We evaluated the expression and function of SLAM on CD4(+) and CD8(+) lymphocytes in HIV-infected individuals with either recently acquired infection (Group A) or asymptomatic HIV infection (Group B) and in healthy controls (HC). Soluble antigen (HIV env peptides and tetanus toxoid)- and mitogen-stimulated proliferation and IFN-gamma and IL-10 production upon SLAM costimulation were also measured. Results showed that: (1) SLAM-expressing CD4(+) and CD8(+) lymphocytes diminish in group A patients compared to both group B patients and HC; (2) SLAM expression on CD4(+) lymphocytes is preferentially associated with the lack of CD7 on cell surface (CD4(+)CD7(-) produce IL-10 but not IFN-gamma); (3) SLAM engagement increases HIV env peptide-stimulated, but neither tetanus toxoid- nor PHA-stimulated proliferation of peripheral blood mononuclear cells (PBMC) in patients but not in HC; and (4) SLAM engagement augments IFN-gamma and reduces IL-10 production by env peptide-stimulated PBMC of HIV-infected individuals. These results demonstrate that early HIV infection results in an altered SLAM expression which correlates with a time-limited impairment of cell-mediated immunity. Furthermore, they show that triggering via SLAM potentiates HIV-specific proliferative responses with simultaneous downregulation of IL-10 and redirection of the response to TH0/TH1.

Intractable pruritus in HIV infection: immunologic characterization

BACKGROUND

Severe, intractable pruritus, often associated with erythematopapular skin lesions and hypereosinophilia, is a condition observed in some nonatopic, HIV-infected patients. We performed immunovirologic analyses of this condition.

METHODS

Immunologic (mitogen-stimulated production of cytokines, tumor necrosis factor-alpha [TNF-alpha], and soluble CD23; serum levels of soluble CD23, ICAM-1, TNF-alpha, IgG, IgE, and IgA) and virologic (HIV viral load) parameters were analyzed in six patients with therapy-resistant pruritus. Hypereosinophilia was present in all these patients. Results were compared to those of seven HIV-seropositive individuals similar to the first one in terms of CD4 counts and clinical staging, but without pruritus.

RESULTS

Hypereosinophilia; hyper-IgE and hyper-IgA; augmented interleukin (IL)-4, IL-5, and sCD23; and reduced interferon-gamma production by mitogen-stimulated peripheral blood mononuclear cells (PBMC) were detected when patients with pruritus were compared to HIV controls. HIV viral load was also augmented in patients in whom pruritus was present.

CONCLUSIONS

The results suggest that therapy-resistant, intractable pruritus accompanied by hypereosinophilia may be used to define a subset of HIV-seropositive individuals showing prototypic hyperactivation of humoral immunity, and in whom augmented HIV viral load is present.

Cytokine production and surface marker expression in acute and stable multiple sclerosis: altered IL-12 production and augmented signaling lymphocytic activation molecule (SLAM)-expressing lymphocytes in acute multiple sclerosis

Ag-stimulated IL-2 production and mitogen-stimulated type 1 and type 2 cytokine production by PBMC, as well as expression of Th1- and Th2-associated phenotypical markers, of B7-1, B7-2, and CD95 (Fas) on the surface of immune cells, and the serum concentration of soluble Apo-1/Fas were evaluated in multiple sclerosis (MS) patients with either acute (AMS) or stable (SMS) disease and in healthy controls (HC). Results showed that 1) Ag-stimulated IL-2 production is reduced in MS patients compared with that in HC; 2) mitogen-stimulated type 1 cytokine production is increased, and IL-10 production is reduced in MS patients compared with those in HC, and in AMS patients compared with those in SMS; 3) whereas production of the metabolically active p70 heterodimers is comparable in SMS, AMS, and HC, production of the p70 heterodimer and the p40 chains (total IL-12) is increased in SMS compared with that in AMS and HC; 4) CD4+, CD4+ SLAM+, and CD4+ CD7+ lymphocytes (preferentially type 1 cytokine-producing lymphocytes) are increased in MS compared with levels in HC; 5) B7-2- as well as Fas+-expressing monocytes are augmented in MS compared with those in HC, and serum soluble Apo-1/Fas is augmented in AMS compared with SMS and HC. These results confirm that a complex imbalance in both cytokine production and the Fas system is present in MS and indicate that different cytokine profiles may be observed in patients with acute or stable disease. The data also suggest that peculiar phenotypic populations are over-represented in MS patients, and for the first time show that SLAM expression is correlated with dysregulation of type 1 and type 2 cytokine production in human pathology.

Long-term resistance to HIV infection in vertical HIV infection: cytokine production, HIV isolation, and HIV phenotype define long-term resistant hosts

We analyzed immunologic (CD4 and CD8 slopes; interferon-gamma, interleukin-2, interleukin-10, and chemokines production; concentration of IgE; beta 2-microglobulin) and virologic (p24; HIV isolability and phenotype; plasma viremia) parameters in HIV vertically infected children > or = 8 years of age without disease progression or mild symptoms and an absolute CD4+ count > or = 500/microliter with CD4+ percentage > or = 25%. The results were compared to those of two control groups: (1) slow progressors, children > or = 8 years of age with moderate symptomatology and/or moderate CD4 depletion, and (2) progressors, children > or = 8 years of age with severe clinical disease and/or severe CD4 depletion. Pediatric long-term resistant hosts were characterized by higher production of interleukin-2 and interferon-gamma and lower production of interleukin-10, normal concentration of IgE, HIV isolates with a non-syncytium-inducing phenotype, and lower plasma viremia. This condition was not associated with the concentration of beta 2-microglobulin, p24, and chemokines, or with HIV isolability. The IL-10/IL-2 ratio best correlated with both CD4 counts and disease progression. Thus, vertically infected children showing resistance to disease progression are immunologically and virologically distinct from those in whom progressive HIV infection is observed.

HIV-specific mucosal and cellular immunity in HIV-seronegative partners of HIV-seropositive individuals

HIV-specific mucosal and cellular immunity was analyzed in heterosexual couples discordant for HIV status in serum and in HIV-unexposed controls. HIV-specific IgA but not IgG was present in urine and vaginal wash samples from HIV-exposed seronegative individuals (ESN), whereas both IgA and IgG were observed in their HIV-seropositive partners; antibodies were not detected in low-risk controls. Envelope protein (Env) peptide-stimulated interleukin-2 (IL-2) production by peripheral blood mononuclear cells (PBMCs) was detected in 9 out of 16 ESNs, 5 out of 16 HIV-infected patients and 1 out of 50 controls. Env peptide-stimulated PBMCs of ESNs produced more IL-2 and less IL-10 compared with those of HIV-infected individuals; no differences were observed in chemokine production or in CCR5 expression. These data demonstrate that a compartmentalized immune response to pathogens is possible in humans and raise the possibility of protective roles for cell-mediated immunity and mucosal IgA in HIV-seronegative individuals exposed to HIV.

Type 1 and type 2 cytokines in HIV infection -- a possible role in apoptosis and disease progression

The progression of HIV-infected subjects to AIDS was recently postulated to be controlled by the balance between type 1 cytokines (mainly enhancing cell-mediated immunity) and type 2 cytokines (mainly augmenting antibody production). Thus, progression of HIV infection was suggested to be accompanied by a decline of in vitro production of interleukin-2 (IL-2), IL-12 and interferon gamma (IFN-gamma) (type 1 cytokines) and an increase in the production of IL-4, IL-5, IL-6 and IL-10 (type 2 cytokines) by peripheral blood mononuclear cells of HIV-seropositive patients. According to this hypothesis, clinical markers of progression would be considered the loss of the ability to elicit a delayed-type hypersensitivity reaction to ubiquitous antigens (secondary to defective IL-2 production), hyper-IgE (secondary to increased IL-4 production) and hypereosynophilia (secondary to increased IL-5 production). The type 1 to type 2 shift was suggested to be predictive for the following events: (i) reduction in CD4 counts; (ii) time to AIDS diagnosis; (iii) time to death. Support for this hypothesis stems from the recent observation that a strong type 1/weak type 2 cytokine production profile was observed in HIV-seropositive patients with delayed or absent disease progression, whereas progression of HIV infection was characterized by a weak type 1/strong type 2 cytokine production profile. PBMC of HIV-seropositive individuals are susceptible to antigen-induced cell death (AICD) after antigen recognition via T-cell receptor (TcR). While TcR-induced AICD is seen in CD4+ and CD8+ cells programmed cell death induced by recall antigens is preferentially observed in CD4+ cells, a situation more closely resembling the CD4 depletion of HIV infection. Because type 1 cytokines reduce, whereas type 2 cytokines augment T-lymphocyte AICD, an increase in the concentration of type 2 cytokines could result in the decline in CD4+ cells seen in HIV infection.

Pentoxifylline improves cell-mediated immunity and reduces human immunodeficiency virus (HIV) plasma viremia in asymptomatic HIV-seropositive persons

The effects of pentoxifylline on immunologic and virologic parameters were evaluated in 10 human immunodeficiency virus-infected patients not receiving antiretroviral treatment. Patients were asymptomatic, had 300-500 CD4 cells/microL, and received pentoxifylline (1200 mg/day orally) for 4 months. Peripheral blood mononuclear cells were tested before and at five time points during therapy. A transient increase in CD4 cells was observed in 8 of 9 patients, and CD8 cells increased in 7 of 9 patients. These increases were negatively correlated with susceptibility to in vitro mitogen-stimulated apoptotic cell death. Pentoxifylline had a temporary effect on mitogen-stimulated cytokine production; thus, interferon-gamma, interleukin (IL)-2, tumor necrosis factor-alpha, and lymphotoxin increased more than IL-10. Pentoxifylline also potentiated antigen-stimulated IL-2 production and proliferation in 8 of 9 patients and induced significant but transient decreases in plasma viremia in 7 of 9 patients. These preliminary findings suggest that pentoxifylline in vivo has an interesting but temporary influence on both immunologic and virologic parameters.

A possible role for the cortisol/anticortisols imbalance in the progression of human immunodeficiency virus

The progression of HIV infection is accompanied by complex alterations in the production of adrenal steroids. Cortisol levels are increased in HIV infection whereas those of dehydroepiandrosterone (DHEA), a physiologic antagonist of the immunoregulatory activities of cortisol, decrease. The progression of HIV infection to AIDS is also characterised by a shift from a type 1 to type 2 cytokine production. Thus, defective production of interferon gamma (IFN gamma), interleukin (IL)-2, and IL-12 as well as increased production of IL-4, IL-5, IL-6, and IL-10 are observed in HIV-seropositive individuals and are proposed to be in vitro immunologic marker of progression. Cortisol and pharmacological doses of glucocorticoids (GC) suppress IL-2 and IFN gamma production and favour the production of IL-4. Furthermore, GC and IL-4 stimulate the differentiation of B lymphocytes into IgE producing plasma cells, the concentration of which augments in HIV infection. Finally, GC induce programmed cell death (PCD) in a variety of different cells, including mature T lymphocytes, and type 2 cytokines were recently proposed to augment the susceptibility of T lymphocytes to PCD. It was suggested that the progressive shift from type 1 to type 2 cytokine production characteristic of HIV infection could be at least partially provoked by the increase in the production of cortisol and the reduction of DHEA. This hypothesis is discussed within the scenario of an endrocrinologic imbalance being responsible for HIV progression at least partially via increased susceptibility of HIV + CD4 lymphocyte to PCD.

Immunological activation markers in the serum of African and European HIV-seropositive and seronegative individuals

OBJECTIVE

The concentration of type 1 and type 2 cytokines and fibroblast-associated apoptosis-1 soluble receptor (sAPO-1/Fas) was analysed in the sera of Ugandan and Italian HIV-1-seropositive and seronegative individuals. The data were compared to determine whether the immunological status of these groups was different.

METHODS

Sixty-seven Ugandan and 30 Italian HIV-positive patients were analysed and stratified according to CD4 counts (group 1, > 500 x 10(6)/l; group 2, 200-500 x 10(6)/l; group 3, < 200 x 10(6)/l). Sera from 15 Ugandan and 11 Italian HIV-negative blood donors were also analysed. Serum concentration of type 1 cytokines [interleukin (IL)-2, IL-12, and interferon (IFN)-gamma] and type 2 cytokines (IL-4 and IL-10), and sAPO-1/Fas were measured by enzyme-linked immunosorbent assay.

RESULTS

Serum levels of IL-2, IFN-gamma and IL-10 but not of IL-4 and IL-12, were elevated in HIV-positive group 1 and 2 Africans compared with HIV-positive Italian individuals. IL-4 was mildly augmented in HIV-positive group 3 African patients. Serum concentration of sAPO-1/Fas was reduced in HIV-positive Africans compared with HIV-positive Italian individuals. Finally, serum levels of IL-2 and IL-10 were increased and sAPO-1/Fas reduced when sera of HIV-negative African healthy controls were compared with their Italian counterparts. The ratio of type 1/type 2 cytokines was roughly 1.0 in HIV-negative African controls, and much greater than 1.0 in HIV-negative Italian controls.

CONCLUSIONS

These preliminary findings indicate that immune activation is present in African HIV infection. Furthermore, these data raise the possibility that abnormal immune activation and increased susceptibility to antigen-induced cell death is present even in HIV-negative African controls.