The HIV infection and immune activation: "to fight and burn"

Inflammatory and Immune Mechanisms for Atherosclerotic Cardiovascular Disease in HIV

Atherosclerotic vascular disease disproportionately affects persons living with HIV (PLWH) compared to those without. The reasons for the excess risk include dysregulated immune response and inflammation related to HIV infection itself, comorbid conditions, and co-infections. Here, we review an updated understanding of immune and inflammatory pathways underlying atherosclerosis in PLWH, including effects of viral products, soluble mediators and chemokines, innate and adaptive immune cells, and important co-infections. We also present potential therapeutic targets which may reduce cardiovascular risk in PLWH.

Soybean-derived Bowman-Birk Inhibitor (BBI) Inhibits HIV Replication in Macrophages

The Bowman-Birk inhibitor (BBI), a soybean-derived protease inhibitor, is known to have anti-inflammatory effect in both in vitro and in vivo systems. Macrophages play a key role in inflammation and immune activation, which is implicated in HIV disease progression. Here, we investigated the effect of BBI on HIV infection of peripheral blood monocyte-derived macrophages. We demonstrated that BBI could potently inhibit HIV replication in macrophages without cytotoxicity. Investigation of the mechanism(s) of BBI action on HIV showed that BBI induced the expression of IFN-β and multiple IFN stimulated genes (ISGs), including Myxovirus resistance protein 2 (Mx2), 2',5'-oligoadenylate synthetase (OAS-1), Virus inhibitory protein (viperin), ISG15 and ISG56. BBI treatment of macrophages also increased the expression of several known HIV restriction factors, including APOBEC3F, APOBEC3G and tetherin. Furthermore, BBI enhanced the phosphorylation of IRF3, a key regulator of IFN-β. The inhibition of IFN-β pathway by the neutralization antibody to type I IFN receptor (Anti-IFNAR) abolished BBI-mediated induction of the anti-HIV factors and inhibition of HIV in macrophages. These findings that BBI could activate IFN-β-mediated signaling pathway, initialize the intracellular innate immunity in macrophages and potently inhibit HIV at multiple steps of viral replication cycle indicate the necessity to further investigate BBI as an alternative and cost-effective anti-HIV natural product.

Mitral Annular and Coronary Artery Calcification Are Associated with Mortality in HIV-Infected Individuals

BACKGROUND

HIV infection increases cardiovascular risk. Coronary artery calcification (CAC) and mitral annular calcification (MAC) identify patients at risk for cardiovascular disease (CVD). The purpose of this study was to examine the association between MAC, CAC and mortality in HIV-infected individuals.

METHODS AND RESULTS

We studied 152 asymptomatic HIV-infected individuals with transthoracic echocardiography (TTE) and computed tomography (CT). MAC was identified on TTE using standardized criteria. Presence of CAC, CAC score and CAC percentiles were determined using the modified Agatston criteria. Mortality data was obtained from the Social Security and National Death Indices (SSDI/NDI). The median age was 49 years; 87% were male. The median duration of HIV was 16 years; 84% took antiretroviral therapy; 64% had an undetectable viral load. CVD risk factors included hypertension (35%), smoking (62%) and dyslipidemia (35%). Twenty-five percent of individuals had MAC, and 42% had CAC. Over a median follow-up of 8 years, 11 subjects died. Subjects with CAC had significantly higher mortality compared to those with MAC only or no MAC. The Harrell's C-statistic of CAC was 0.66 and increased to 0.75 when MAC was added (p = 0.05). MAC, prior CVD, age and HIV viral load were independently associated with higher age- and gender-adjusted CAC percentiles in an adjusted model (p < 0.05 for all).

CONCLUSION

In HIV patients, the presence of MAC, traditional risk factors and HIV viral load were independently associated with CAC. Presence of CAC and MAC may be useful in identifying HIV-infected individuals at higher risk for death.

HIV-associated lipodystrophy: impact of antiretroviral therapy

In the late 1990s, reports of unusual changes in body fat distribution named 'lipodystrophy' (LD) began to appear in HIV patients mitigating the enormous enthusiasm about improvement of survival and quality of life provided by the combinations of antiretroviral (ARV) drug classes, the so-called highly active antiretroviral therapy (HAART), which had just become available at that time. The objective of this paper is to critically review the literature on LD and to discuss the impact of newer ARV agents, namely atazanavir, darunavir and raltegravir, as well as strategies of the late HAART era, including single-tablet regimens and nucleoside-sparing regimens. Studies in which LD was measured by dual-energy x-ray absorptiometry or by abdominal computed tomography or magnetic resonance imaging scan only, were included. We were unable to identify studies depicting a negative impact of drugs or ARV regimens on limb fat loss. On the contrary, a few studies identified a negative impact of atazanavir/ritonavir or darunavir/ritonavir on trunk fat increase. It should be noted that this anthropometric measure is a poor instrument since it cannot distinguish between subcutaneous and visceral fat. We conclude that presumably the body fat changes currently observed in HIV-infected patients is the net result of competing phenomena: on one side the natural history of lipohypertrophy as a result of HIV and HAART impact, and on the other side the physiological body fat changes observed in the aging population.

Taking stock of infections and antibiotic resistance in the elderly and long-term care facilities: A survey of existing and upcoming challenges

Treating elderly patients with infections represents one of the greatest challenges to health-care providers. Older adults are the largest growing sector of the population and suffer excessively from infectious diseases such as pneumonia, urinary tract infections (UTIs), and skin and soft-tissue infections. Often because of disabilities, the elderly require treatment of infectious diseases in long-term care facilities (LTCFs). As a result of antibiotic use, LTCFs have become "reservoirs of resistance" and multi-drug resistant (MDR) pathogens are frequently recovered. Clinicians also need to be aware of the impairment of immune function and other emerging chronic infections (HIV, HCV) that are now present in the elderly. Despite vigilance regarding this issue, delays in diagnosis and initiation of therapy are common. This article reviews the changing landscape of infections in the elderly and the challenge these syndromes present in the context of an increasing older population that requires dedicated resources.

Kinetics of plasma cytokines and chemokines during primary HIV-1 infection and after analytical treatment interruption

BACKGROUND

There are strong theoretical arguments for initiating antiretroviral therapy (ART) during primary HIV-1 infection (PHI) to preserve HIV-1-specific T-cell responses and to decrease immune activation.

METHODS

We assessed the degree of immune activation during PHI and after analytical treatment interruption (ATI) in plasma samples from 22 subjects by measuring 13 cytokines/chemokines with the Luminex system. Subjects initiated quadruple ART at PHI (the QUEST cohort) and were classified as responders or nonresponders according to their HIV-1 viral load (VL) 6 months post-ATI.

RESULTS

During PHI, nonresponders had higher levels of HIV-1 RNA, interferon (IFN)-gamma, tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-10 and eotaxin than responders (P</=0.05). A positive correlation was found between VL and IFN-alpha, TNF-alpha, IL-1beta, macrophage inflammatory protein (MIP)-1alpha and MIP-1beta, respectively. Post ATI, responders had higher levels of IFN-gamma, MIP-1beta and monocyte chemotactic protein (MCP)-1 than nonresponders, while nonresponders had higher levels of HIV-1 RNA, IL-15 and eotaxin. Cytokine/chemokine levels were higher during PHI than post-ATI.

CONCLUSIONS

High levels of immune activation during PHI are associated with a worse virological outcome post-ATI. In contrast, VL post-ATI is negatively correlated with IFN-gamma and chemokines. Therefore, the degree of immune activation during PHI is associated with both the VL at PHI and the viral set-point post-ART.

Effect of Immunomodulating Adjuvant Dzherelo (Immunoxel) in HIV Infected Patients Receiving Standard Antiretroviral Therapy

Open-label, matched-case, comparative trial was conducted in 40 HIV-infected patients to evaluate the adjunct effect of Dzherelo (Immunoxel) on immune and viral parameters. Arm A (n=20) received anti-retroviral therapy (ART) consisting of zidovudine, lamivudine, and efavirenz and arm B (n=20) received ART with Dzherelo. After 2 months total T-lymphocytes increased in ART recipients from 664 to 819 cells/μl (P=0.06), whereas in Dzherelo recipients they rose from 595 to 785(P=0.03). The CD4 T-cells expanded by 57.3% (218 to 343; P=0.002) in the ART arm and by 93.5% (184 to 356; P=0.004) in the Dzherelo arm. The accrual in absolute and relative number of CD8+ lymphocytes in ART and in the Dzherelo recipients was 43.2% (2.7%) and 50.4% (-0.5%) respectively. The CD4/CD8 ratio in Dzherelo recipients increased from 1.495 to 1.940 (P=0.03) but insignificant in the control: 1.418 to 1.613 (P=0.14). Activated CD3+ HLADR+ T-cells increased from 209 to 264 (P=0.02) and from 161 to 348 (P=0.0007) in ART and Dzherelo recipients respectively. No changes in CD20+ B-lymphocytes were seen in the control, but in Dzherelo patients they declined from 509 to 333 (P=0.00008). The proportion of CD3- CD16+CD56+ NK cells was not affected by ART but addition of Dzherelo raised NK cells from 11.2% to 17.1% (P=0.0001). About three-quarters (14/19) of patients on ART displayed decrease in viral load (1718 to 1419 copies/ml; P=0.008), while 95% of patients on Dzherelo had a decrease (1793 to 1368; P=0.001). Dzherelo has a favorable effect on the immune status and viral burden when given as an immunomodulating adjunct to ART.

Should antiretroviral therapy be started earlier?

Current treatment guidelines recommend that antiretroviral therapy be deferred until the CD4 count has fallen into the 200 to 350 cells/mm(3) range. However, treatment has become simpler, less toxic, and more forgiving of missed doses. Longer-term follow-up data from clinical cohorts are now showing better outcomes when therapy is started at higher CD4 cell counts. Therapy initiated early has better virologic and immunologic responses, is better tolerated, and is cost-effective. Recent developments and clinical data support a return to earlier initiation of therapy.

Progressive CD4+ central memory T cell decline results in CD4+ effector memory insufficiency and overt disease in chronic SIV infection

Primary simian immunodeficiency virus (SIV) infections of rhesus macaques result in the dramatic depletion of CD4⁺ CCR5⁺ effector–memory T (T_EM) cells from extra-lymphoid effector sites, but in most infections, an increased rate of CD4⁺ memory T cell proliferation appears to prevent collapse of effector site CD4⁺ T_EM cell populations and acute-phase AIDS. Eventually, persistent SIV replication results in chronic-phase AIDS, but the responsible mechanisms remain controversial. Here, we demonstrate that in the chronic phase of progressive SIV infection, effector site CD4⁺ T_EM cell populations manifest a slow, continuous decline, and that the degree of this depletion remains a highly significant correlate of late-onset AIDS. We further show that due to persistent immune activation, effector site CD4⁺ T_EM cells are predominantly short-lived, and that their homeostasis is strikingly dependent on the production of new CD4⁺ T_EM cells from central–memory T (T_CM) cell precursors. The instability of effector site CD4⁺ T_EM cell populations over time was not explained by increasing destruction of these cells, but rather was attributable to progressive reduction in their production, secondary to decreasing numbers of CCR5⁻ CD4⁺ T_CM cells. These data suggest that although CD4⁺ T_EM cell depletion is a proximate mechanism of immunodeficiency, the tempo of this depletion and the timing of disease onset are largely determined by destruction, failing production, and gradual decline of CD4⁺ T_CM cells.

Elevated plasma levels of high mobility group box protein 1 in patients with HIV-1 infection

High mobility group box protein 1 (HMGB1) is a potent proinflammatory mediator. It has a dichotomic effect on HIV-1 replication in vitro but its role in vivo is unknown. Here we report the novel finding that plasma HMGB1 levels are elevated in HIV-1-infected patients, with the highest concentrations in patients with clinical complications. HMGB1 is likely to contribute to immunoactivation in HIV-1 infection in vivo.

Diminished production of monocyte proinflammatory cytokines during human immunodeficiency virus viremia is mediated by type I interferons

The effect of human immunodeficiency virus (HIV) infection and high-level HIV replication on the function of monocytes was investigated. HIV-positive patients had elevated levels of spontaneous production of some or all of the monocyte proinflammatory cytokines measured (interleukin-1beta [IL-1beta], IL-6, and tumor necrosis factor alpha [TNF-alpha]) compared to uninfected controls. In patients on therapy with high frequencies of monocytes producing proinflammatory cytokines, this frequency was diminished in the context of viremia during an interruption of therapy. Diminished production of proinflammatory cytokines during viremia was restored by culture with autologous CD4(+) T cells or monocytes from an on-therapy time point or lipopolysaccharide (LPS). Microarray analysis demonstrated that diminished monocyte production of proinflammatory cytokines was correlated with elevated type I interferon-stimulated gene transcripts. The addition of exogenous alpha 2A interferon diminished the spontaneous production of IL-1beta, IL-6, and TNF-alpha but did not affect responses to LPS, recapitulating the changes observed for HIV-viremic patients. These results suggest that monocyte function is diminished during high-level HIV viremia and that this effect is mediated by chronic stimulation by type I interferons. This effect on monocytes during viremia may play a role in diminished innate or adaptive immune system functions in HIV-infected patients. In addition, the restoration of these functions may also play a role in some immune reconstitution syndromes observed during initiation of therapy.