Abnormalities in host defense associated with HIV infection

HIV Impairs Alveolar Macrophage Function via MicroRNA-144-Induced Suppression of Nrf2

BACKGROUND

Despite anti-retroviral therapy, HIV-1 infection increases the risk of pneumonia and causes oxidative stress and defective alveolar macrophage (AM) immune function. We have previously determined that HIV-1 proteins inhibit antioxidant defenses and impair AM phagocytosis by suppressing nuclear factor (erythroid-derived 2)-like 2 (Nrf2). Given its known effects on Nrf2, we hypothesize miR-144 mediates the HIV-1 induced suppression of Nrf2.

METHODS

Primary AMs isolated from HIV-1 transgenic (HIV-1 Tg) rats and wild type littermates (WT) as well as human monocyte-derived macrophages (MDMs) infected ex vivo with HIV-1 were used. We modulated miR-144 expression using a miR-144 mimic or an inhibitor to assay its effects on Nrf2/ARE activity and AM functions in vitro and in vivo.

RESULTS

MiR-144 expression was increased in AMs from HIV-1 Tg rats and in HIV-1-infected human MDMs compared to cells from WT rats and non-infected human MDMs, respectively. Increasing miR-144 with a miR-144 mimic inhibited the expression of Nrf2 and its downstream effectors in WT rat macrophages and consequently impaired their bacterial phagocytic capacity and H₂O₂ scavenging ability. These effects on Nrf2 expression and AM function were reversed by antagonizing miR-144 ex vivo or in the airways of HIV-1 Tg rats in vivo, but this protection was abrogated by silencing Nrf2 expression.

CONCLUSIONS

Our results suggest that inhibiting miR-144 or interfering with its deleterious effects on Nrf2 attenuates HIV-1-mediated AM immune dysfunction and improves lung health in individuals with HIV.

Hypersensitivity pneumonia and HIV infection in occupational settings: a case report from northern Italy

We describe a case of relapsing hypersensitivity pneumonitis (HP) manifesting as a reconstitution inflammatory syndrome (IRIS) in a HIV infected patient receiving antiretroviral therapy (HAART). The patient, who works as a farmer since the early 20s, was diagnosed with HP at age 23: after an initial steroid therapy, a long lasting clinical regression followed. At age 32, HIV positivity was diagnosed, with HAART starting only at age 38 (initially, lamivudine 300 mg/daily + zidovudine 300 mg b.i.d.). In the following 15 years, CD4+ count remained <500 cells/μL until therapy was shifted to ritonavir 100 mg b.i.d + fosamprenavir 700 mg b.i.d. A six-months long increase in the CD4+ count (>600 cells/μL) with undetectable viral load then followed. Eventually, the patient developed cough and slowly worsening dyspnoea. Laboratory exams (serum T cell lymphocyte count 83%, CD8+ 45-51%; serum IgG for M faeni=78 mg/L and P notatum >200 mg/L) and high-resolution computer tomography (HRCT) were compatible with relapsing HP. The working tasks were modified avoiding any contact with allergens, then achieving a 6 months long clinical regression. Detectable HIV load (62 copies/mL) was identified at follow-up, and emtricitabine 200 mg/tenofovir disoproxil fumarate 245 mg s.i.d. was added to HAART. Respiratory involvement newly relapsed. HAART was shifted to emtricitabine 200 mg/tenofovir disoproxil fumarate 245 mg s.i.d. and raltegravir 400 mg b.i.d. Within several weeks, signs and symptoms resolved almost completely (peripheral oxygen saturation >95%: CD4+ count remained >600 cells/μL with CD8+ count steadily <50% and CD4+/CD8+ ratio >55%). (www.actabiomedica.it)

Treating bacterial pneumonia in people living with HIV

Introduction: Bacterial pneumonia remains an important cause of morbidity and mortality in people living with HIV (PLWH) in the antiretroviral therapy (ART) era. In addition to being immunocompromised, as reflected by low CD4 cell counts and elevated HIV viral loads, PLWH often have other behaviors associated with an increased risk of pneumonia including smoking and injected drug use. As PLWH are aging, comorbid conditions such as chronic obstructive pulmonary disease (COPD), cancers, and cardiovascular, renal and liver diseases are emerging as additional risk factors for pneumonia. Pathogens are often similar to those in HIV-uninfected individuals; however, PLWH are at risk for unusual and/or multi-drug resistant organisms causing bacterial pneumonia based, in part, on their CD4 cell counts and other exposures. Areas covered: In this review, we focus on the recognition and management of bacterial community-acquired pneumonia (CAP) in PLWH. Along with antimicrobial treatment, we discuss prevention strategies such as vaccination and smoking cessation. Expert opinion: Early initiation of ART after HIV infection can decrease the risk of pneumonia. Improved efforts at vaccination, smoking cessation, and reduction of other substance use are urgently needed in PLWH to decrease the risk for bacterial pneumonia. As PLWH are aging, comorbidities are additional risk factors for bacterial CAP.

HIV and COPD: a conspiracy of risk factors

Chronic obstructive pulmonary disease (COPD) is an under recognized complication of HIV infection. It is estimated that up to 25% of HIV infected people may have COPD. HIV is associated with COPD as a result of a complex interplay of multiple factors such as pulmonary inflammation, recurrent pulmonary infections especially tuberculosis (TB), increased cigarette smoking, socio-economic status, childhood respiratory illnesses and industrial and environmental exposures; each of which are risk factors for COPD in their own right. COPD presents at an earlier age in people with HIV infection. There are over 35 million people living with HIV, and most people infected with HIV live in developing regions of the world where they are faced with multiple risk factors for COPD and suboptimal access to health care. TB is the commonest infectious complication of HIV, and HIV infected persons often experience multiple episodes of TB. Cigarette smoking is increasing in developing countries where the greatest burden of TB and HIV is experienced. Cigarette smoking is associated with increased risk of TB and may be associated with acquisition of HIV infection and progression. It is not clear whether non-infectious pulmonary inflammation persists in the lung when immune reconstitution occurs. Prevention and control of HIV infection must be part of the multiple interventions to reduce the global burden of COPD. A multidisciplinary approach, including behavioural science is required to address this challenge. It presents research opportunities that should be driven by the pulmonology community.

Human Immunodeficiency Virus Infection and Host Defense in the Lungs

Immunosuppression associated with human immunodeficiency virus (HIV) infection impacts all components of host defense against pulmonary infection. Cells within the lung have altered immune function and are important reservoirs for HIV infection. The host immune response to infected lung cells further compromises responses to a secondary pathogenic insult. In the upper respiratory tract, mucociliary function is impaired and there are decreased levels of salivary immunoglobulin A. Host defenses in the lower respiratory tract are controlled by alveolar macrophages, lymphocytes, and polymorphonuclear leukocytes. As HIV infection progresses, lung CD4 T cells are reduced in number causing a lack of activation signals from CD4 T cells and impaired defense by macrophages. CD8 T cells, on the other hand, are increased in number and cause lymphocytic alveolitis. Specific antibody responses by B-lymphocytes are decreased and opsonization of microorganisms is impaired. These observed defects in host defense of the respiratory tract explain the susceptibility of HIV-infected persons for oropharyngeal candidiasis, bacterial pneumonia, Pneumocystis pneumonia, and other opportunistic infections.

Association of COPD With Risk for Pulmonary Infections Requiring Hospitalization in HIV-Infected Veterans

BACKGROUND

Pulmonary infections remain more common in HIV-infected (HIV+) compared with uninfected individuals. The increase in chronic lung diseases among aging HIV+ individuals may contribute to this persistent risk. We sought to determine whether chronic obstructive pulmonary disease (COPD) is an independent risk factor for different pulmonary infections requiring hospitalization among HIV+ patients.

METHODS

We analyzed data from 41,993 HIV+ Veterans in the nationwide Veterans Aging Cohort Study Virtual Cohort from 1996 to 2009. Using International Classification of Diseases, Ninth Revision codes, we identified baseline comorbid conditions, including COPD, and incident community-acquired pneumonia (CAP), pulmonary tuberculosis (TB), and Pneumocystis jirovecii pneumonia (PCP) requiring hospitalization within 2 years after baseline. We used multivariable Poisson regression to determine incidence rate ratios (IRRs) associated with COPD for each type of pulmonary infection, adjusting for comorbidities, CD4 cell count, HIV viral load, smoking status, substance use, vaccinations, and calendar year at baseline.

RESULTS

Unadjusted incidence rates of CAP, TB, and PCP requiring hospitalization were significantly higher among persons with COPD compared to those without COPD (CAP: 53.9 vs. 19.4 per 1000 person-years; TB: 8.7 vs. 2.8; PCP: 15.5 vs. 9.2; P ≤ 0.001). In multivariable Poisson regression models, COPD was independently associated with increased risk of CAP, TB, and PCP (IRR: 1.94, 95% confidence interval [CI]: 1.64 to 2.30; IRR: 2.60, 95% CI: 1.70 to 3.97; and IRR: 1.48, 95% CI: 1.10 to 2.01, respectively).

CONCLUSIONS

COPD is an independent risk factor for CAP, TB, and PCP requiring hospitalization among HIV+ individuals. As the HIV+ population ages, the growing burden of COPD may confer substantial risk for pulmonary infections.

Chronic obstructive pulmonary disease in patients with HIV: an emerging problem

People with well-controlled HIV now have normal life expectancies and physicians managing these patients are increasingly encountering co-existing chronic obstructive pulmonary disease. This article reviews similarities with this disease in the general population and highlights key differences including significant drug-drug interactions.

A case report of severe paraquat poisoning in an HIV-positive patient: an unexpected outcome and inspiration

We described and analyzed the treatment process of an HIV-positive patient with severe paraquat (PQ) poisoning. A 34-year-old man ingested about 50 mL of a 20% solution of PQ in a suicide attempt. He was treated with gastric lavage, oral administration of adsorbent, and symptomatic treatments at the local hospital, and was transferred to our emergency department. Ten hours after the exposure, the concentration of plasma PQ was 2.17 mg/L and was substantially above the survival limits of the severity index for PQ poisoning (SIPP) curve (0.30 mg/L). The equation produced by Jones et al (Jones AL, Elton R, Flanagan R. Multiple logistic regression analysis of plasma paraquat concentrations as a predictor of outcome in 375 cases of paraquat poisoning. QJM. 1999:92;573-578) predicted a 20.5% probability of survival at admission. Unfortunately, the patient was diagnosed as HIV infected, and CD4 lymphocyte count also confirmed that the patient was in a state of mild suppression of immunological function. Immediately, the patient received normative immunosuppressive therapy and hemoperfusion (HP). On the 15th day after poisoning, the patient recovered well and was discharged. All along, the evolution of the patient's status was in accordance with the characteristics of PQ poisoning, but the extent and duration of damage was mismatching and drastically alleviative by the previous biological indices. The particular case of treatment may be indirectly supporting the effectiveness of immunosuppressive therapy in treating patients with PQ poisoning.