Pulmonary complications of HIV infection. Report of the Fourth NHLBI Workshop

Correlates of Breakthrough SARS-CoV-2 Infections in People with HIV: Results from the CIHR CTN 328 Study

COVID-19 breakthrough infection (BTI) can occur despite vaccination. Using a multi-centre, prospective, observational Canadian cohort of people with HIV (PWH) receiving ≥2 COVID-19 vaccines, we compared the SARS-CoV-2 spike (S) and receptor-binding domain (RBD)-specific IgG levels 3 and 6 months post second dose, as well as 1 month post third dose, in PWH with and without BTI. BTI was defined as positivity based on self-report measures (data up to last study visit) or IgG data (up to 1 month post dose 3). The self-report measures were based on their symptoms and either a positive PCR or rapid antigen test. The analysis was restricted to persons without previous COVID-19 infection. Persons without BTI remained COVID-19-naïve until ≥3 months following the third dose. Of 289 participants, 92 developed BTI (31.5 infections per 100 person-years). The median days between last vaccination and BTI was 128 (IQR 67, 176), with the most cases occurring between the third and fourth dose (n = 59), corresponding to the Omicron wave. In analyses adjusted for age, sex, race, multimorbidity, hypertension, chronic kidney disease, diabetes and obesity, a lower IgG S/RBD (log10 BAU/mL) at 1 month post dose 3 was significantly associated with BTI, suggesting that a lower IgG level at this time point may predict BTI in this cohort of PWH.

The 'pulmonary diseases spectrum' in HIV infected children

Despite advances in diagnostic, therapeutic and preventive strategies for HIV, pulmonary diseases continue to be the major cause of morbidity and mortality in infants and children infected with HIV. With effective programs to prevent perinatal HIV-1 transmission to early diagnosis in infants, we have seen a substantial decline in paediatric HIV incidence. Early initiation of Highly Active Anti-Retroviral Therapy (HAART) in all HIV infected children coupled with consistent use of Pneumocystis prophylaxis in all HIV exposed/infected children under 5 years of age has considerably reduced associated infections overall and respiratory infections in particular. In developing countries already burdened with poverty, malnutrition, suboptimal immunization coverage and limited access to health care and treatment, acute and chronic HIV-associated respiratory disease remain a major cause for concern. Prevention of severe respiratory infections in advanced HIV disease among children consists mostly of rapid and optimal HAART initiation & continuation, preventing severe TB disease with BCG and TB preventive treatment, preventing Pneumocystis jirovecii pneumonia with cotrimoxazole prophylaxis and administering age-appropriate vaccinations and catch-up vaccines as per National Immunization schedule.

Association Between HIV and Prevalence and Manifestations of Asthma: Analysis of the Multicenter AIDS Cohort Study and Women's Interagency HIV Study

BACKGROUND

The association between HIV and asthma prevalence and manifestations remains unclear, with few studies including women.

SETTING

A retrospective observational cohort study from the Multicenter AIDS Cohort Study and Women's Interagency HIV Study.

METHODS

Asthma was defined in 2 ways: (1) self-report and (2) robust criteria requiring all the following: lack of fixed airflow obstruction, presence of wheeze on the St. George's Respiratory Questionnaire (SGRQ), and report of asthma therapies. Estimates of asthma prevalence and asthma-related manifestations were compared by HIV serostatus.

RESULTS

A total of 1815 men and 2122 women were included. Asthma prevalence did not differ between people with HIV (PWH) and people without HIV regardless of definition: self-report (men, 12.0% vs. 11.2%; women, 24.3% vs. 27.5%) and robust criteria (men, 5.0% vs. 3.4%; women, 12.8% vs. 13.2%). Among men with asthma, worse respiratory symptom burden was reported among those with HIV, regardless of asthma definition. Among women with self-reported asthma, those with HIV had less respiratory symptom burden. Regardless of serostatus, women with robust-defined asthma had similar respiratory symptoms across SGRQ domains and similar frequencies of phlegm, shortness of breath, and wheezing.

CONCLUSIONS

Among PWH and people without HIV, asthma prevalence was 2-fold to 3-fold higher using self-reported definition rather than robust definition. In men and women, HIV was not associated with increased asthma prevalence. In men, HIV was associated with more respiratory symptoms when asthma was self-reported; the relationship was attenuated with the robust criteria. Further studies are needed to explore asthma phenotypes among PWH.

A Nomogram Based on Comorbidities and Infection Location to Predict 30 Days Mortality of Immunocompromised Patients in ICU: A Retrospective Cohort Study

Background

The existing comorbidity indexes, like Charlson Comorbidity Index (CCI) and the Elixhauser Comorbidity Index (ECI), do not take infection factors into account for critically ill patients with immunocompromise, bringing about a decrease of prediction accuracy. Therefore, we attempted to incorporate infection location into the analysis to construct a rapid comorbidity scoring system independent of laboratory tests.

Methods

Data were extracted from the Multiparameter Intelligent Monitoring in Intensive Care III database. A total of 3904 critically ill patients with immunocompromise admitted to ICU were enrolled and assigned into training or validation sets according to the date of ICU admission. The predictive nomogram was constructed in the training set based on logistic regression analysis and then undergone validation in the validation set in comparison with SOFA, CCI and ECI.

Results

Factors eligible for the nomogram included patient’s age, gender, ethnicity, underlying disease of immunocompromise like metastatic cancer and leukemia, possible infection on admission including pulmonary infection, urinary tract infection and blood infection, and one comorbidity, coagulopathy. The nomogram we developed exhibited better discrimination than SOFA, CCI and ECI with an area under the receiver operating characteristic curve (AUC) of 0.739 (95% CI 0.707–0.771) and 0.746 (95% CI 0.713–0.779) in the training and validation sets, respectively. Combining the nomogram and SOFA could bring a new prediction model with a superior predictive effect in both sets (training set AUC = 0.803 95% CI 0.777–0.828, validation set AUC = 0.818 95% CI 0.783–0.854). The calibration curve exhibited coherence between the nomogram and ideal observation for two cohorts (p>0.05). Decision curve analysis revealed the clinical usefulness of the nomogram in both sets.

Conclusion

We established a nomogram that could provide an accurate assessment of 30 days ICU mortality in critically ill patients with immunocompromise, which can be employed to evaluate the short-term prognosis of those patients and bring more clinical benefits without dependence on laboratory tests.

Exhausting T Cells During HIV Infection May Improve the Prognosis of Patients with COVID-19

T-cell reduction is an important characteristic of coronavirus disease 2019 (COVID-19), and its immunopathology is a subject of debate. It may be due to the direct effect of the virus on T-cell exhaustion or indirectly due to T cells redistributing to the lungs. HIV/AIDS naturally served as a T-cell exhaustion disease model for recognizing how the immune system works in the course of COVID-19. In this study, we collected the clinical charts, T-lymphocyte analysis, and chest CT of HIV patients with laboratory-confirmed COVID-19 infection who were admitted to Jin Yin-tan Hospital (Wuhan, China). The median age of the 21 patients was 47 years [interquartile range (IQR) = 40-50 years] and the median CD4 T-cell count was 183 cells/μl (IQR = 96-289 cells/μl). Eleven HIV patients were in the non-AIDS stage and 10 were in the AIDS stage. Nine patients received antiretroviral treatment (ART) and 12 patients did not receive any treatment. Compared to the reported mortality rate (nearly 4%-10%) and severity rate (up to 20%-40%) among COVID-19 patients in hospital, a benign duration with 0% severity and mortality rates was shown by 21 HIV/AIDS patients. The severity rates of COVID-19 were comparable between non-AIDS (median CD4 = 287 cells/μl) and AIDS (median CD4 = 97 cells/μl) patients, despite some of the AIDS patients having baseline lung injury stimulated by HIV: 7 patients (33%) were mild (five in the non-AIDS group and two in the AIDS group) and 14 patients (67%) were moderate (six in the non-AIDS group and eight in the AIDS group). More importantly, we found that a reduction in T-cell number positively correlates with the serum levels of interleukin 6 (IL-6) and C-reactive protein (CRP), which is contrary to the reported findings on the immune response of COVID-19 patients (lower CD4 T-cell counts with higher levels of IL-6 and CRP). In HIV/AIDS, a compromised immune system with lower CD4 T-cell counts might waive the clinical symptoms and inflammatory responses, which suggests lymphocyte redistribution as an immunopathology leading to lymphopenia in COVID-19.

Contrasting Inflammatory Signatures in Peripheral Blood and Bronchoalveolar Cells Reveal Compartment-Specific Effects of HIV Infection

The mechanisms by which HIV increases susceptibility to tuberculosis and other respiratory infections are incompletely understood. We used transcriptomics of paired whole bronchoalveolar lavage cells (BLCs) and peripheral blood mononuclear cells to compare the effect of HIV at the lung mucosal surface and in peripheral blood. The majority of HIV-induced differentially expressed genes (DEGs) were specific to either the peripheral or lung mucosa compartments (1,307/1,404, 93%). Type I interferon signaling was the dominant signature of DEGs in HIV-positive blood but not in HIV-positive BLCs. DEGs in the HIV-positive BLCs were significantly enriched for infiltration with cytotoxic CD8+ T cells. Higher expression of type 1 interferon transcripts in peripheral CD8+ T cells and representative transcripts and proteins in BLCs-derived CD8+ T cells during HIV infection, including IFNG (IFN-gamma), GZMB (Granzyme B), and PDCD1 (PD-1), was confirmed by cell-subset specific transcriptional analysis and flow cytometry. Thus, we report that a whole transcriptomic approach revealed qualitatively distinct effects of HIV in blood and bronchoalveolar compartments. Further work exploring the impact of distinct type I interferon programs and functional features of CD8+ T cells infiltrating the lung mucosa during HIV infection may provide novel insights into HIV-induced susceptibility to respiratory pathogens.

Burden of respiratory viral infection in persons with human immunodeficiency virus

This study was conducted to determine the prevalence of respiratory viral infections (RVI) in persons living with HIV (PLH) admitted with a respiratory complaint using real-time reverse transcription polymerase chain reaction and primer-independent next-generation sequencing (NGS). Of 82 subjects, respiratory viruses were the most common pathogen identified in 27 (33%), followed by fungus and bacteria in 8 (10%) and 4 (5%) subjects, respectively. Among subjects with RVI, 11 (41%) required ICU admission and 16 (59%) required mechanical ventilation. The proportion of respiratory viruses identified, and the associated complicated hospital course highlights the significant role that RVIs play in the lung health of PLH.

HIV-related Malignancies and Mimics: Imaging Findings and Management

The risk of developing malignancy is higher in patients with human immunodeficiency virus (HIV) infection than in non-HIV-infected patients. Several factors including immunosuppression, viral coinfection, and high-risk lifestyle choices lead to higher rates of cancer in the HIV-infected population. A subset of HIV-related malignancies are considered to be acquired immunodeficiency syndrome (AIDS)-defining malignancies, as their presence confirms the diagnosis of AIDS in an HIV-infected patient. The introduction of highly active antiretroviral therapy (HAART) has led to a significant drop in the rate of AIDS-defining malignancies, including Kaposi sarcoma, non-Hodgkin lymphoma, and invasive cervical carcinoma. However, non-AIDS-defining malignancies (eg, Hodgkin lymphoma, lung cancer, hepatocellular carcinoma, and head and neck cancers) now account for an increasing number of cancer cases diagnosed in HIV-infected patients. Although the number has decreased, AIDS-defining malignancies account for 15%-19% of all deaths in HIV-infected patients in the post-HAART era. Most HIV-related malignancies in HIV-infected patients manifest at an earlier age with a more aggressive course than that of non-HIV-related malignancies. Understanding common HIV-related malignancies and their specific imaging features is crucial for making an accurate and early diagnosis, which impacts management. Owing to the weakened immune system of HIV-infected patients, other entities such as various infections, particularly opportunistic infections, are prevalent in these patients. These processes can have confounding clinical and imaging manifestations that mimic malignancy. This article reviews the most common AIDS-defining and non-AIDS-defining malignancies, the role of imaging in their diagnosis, and the imaging mimics of malignancies in HIV-infected patients. ^©RSNA, 2018.

Pulmonary Infections in Immunocompromised Hosts: Clinical

Pulmonary infections in immunocompromised patients remain a significant contributor to mortality, morbidity, and health care-associated costs in such a vulnerable patient population. Their epidemiology is changing, set forth by new trends in immunosuppressive regimens and also prophylaxis. The host characteristics, presenting clinical symptomatology, along with radiographic patterns, have also evolved. The microbiology diagnostics are now enriched with nonculture methods for better identification of the causative pathogens. Chest imaging remains the cornerstone of the initial workup. Our article will examine the new trends in epidemiology, clinical findings, and diagnostics for immunocompromised patients with pulmonary infections (transplant recipients, neutropenic hosts, HIV-infected patients, and patients with autoimmune conditions). We will also review the differential diagnosis that most of the times includes malignancies and drug or radiation-related toxicities.

HIV Reprograms Human Airway Basal Stem/Progenitor Cells to Acquire a Tissue-Destructive Phenotype

While highly active anti-retroviral therapy has dramatically improved the survival of HIV-infected individuals, there is an increased risk for other co-morbidities, such as COPD, manifesting as emphysema. Given that emphysema originates around the airways and that human airway basal cells (BCs) are adult airway stem/progenitor cells, we hypothesized that HIV reprograms BCs to a distinct phenotype that contributes to the development of emphysema. Our data indicate that HIV binds to but does not replicate in BCs. HIV binding to BCs induces them to acquire an invasive phenotype, mediated by upregulation of MMP-9 expression through activation of MAPK signaling pathways. This HIV-induced "destructive" phenotype may contribute to degradation of extracellular matrix and tissue damage relevant to the development of emphysema commonly seen in HIV⁺ individuals.

Concurrent Pneumocystis jirovecii and pulmonary histoplasmosis in an undiagnosed HIV patient

Concurrent Pneumocystis jirovecii (PJ) and pulmonary histoplasmosis (PHP) are rare in a single HIV individual. We present a challenging case of concomitant PJ and PHP in a young HIV individual. A 44-year-old man presented to the emergency department with progressive pulmonary symptoms. He was hypoxic with bilateral pulmonary opacities on chest radiograph. CT of the chest showed a geographical pattern of ground-glass attenuation. He started receiving intravenous antibiotics in addition to oral Bactrim for suspected PJ. He also began receiving itraconazole, given suspected PHP with recent bat-droppings exposure. HIV test was positive, though history was negative; the CD4 count was 5 cells/mm³ Later, he developed respiratory failure without clinical improvement. First bronchoalveolar lavage (BAL) failed to confirm opportunistic pathogens. Repeat BAL revealed PJ but no Histoplasma. Histoplasma antigens were positive, confirming histoplasmosis. The patient died despite aggressive treatment with intravenous Bactrim and amphotericin B.

Association Between CD4+, Viral Load, and Pulmonary Function in HIV

PURPOSE

The antiretroviral therapy era has shifted the epidemiology of HIV-associated diseases, increasing the recognition of non-infectious pulmonary complications secondary to HIV. We aimed to determine the association between CD4⁺, viral load, and pulmonary function in individuals with uncontrolled HIV, and determine how changes in these parameters are associated with pulmonary function longitudinally.

METHODS

This is a retrospective observational study of individuals with HIV who underwent pulmonary function testing in an urban medical center between August 1997 and November 2015.

RESULTS

Of the 146 participants (mean age 52 ± 10 years), 49% were Hispanic, 56% were men, and 44% were current smokers. CD4⁺ <200 cells/μl was associated with significant diffusion impairment compared to CD4⁺ ≥200 cells/μl (DL_CO 56 vs. 70%, p = <0.01). VL (viral load) ≥75 copies/ml was associated with significant diffusion impairment compared to VL <75 copies/ml (DL_CO 60 vs. 71%, p = <0.01). No difference in FEV1, FEV1/FVC, or TLC was noted between groups. In univariate analysis, CD4⁺ and VL correlated with DL_CO (r = +0.33; p = <0.01; r = -0.26; p = <0.01) and no correlation was noted with FEV₁, FEV₁/FVC, or TLC. Current smoking and history of AIDS correlated with DL_CO (r = -0.20; p = 0.03; r = -0.20; p = 0.04). After adjusting for smoking and other confounders, VL ≥75 copies/ml correlated with a 11.2 (CI 95% [3.03-19.4], p = <0.01) decrease in DL_CO. In Spearman's Rank correlation, there was a negative correlation between change in VL and change in DL_CO over time (ρ = -0.47; p = <0.01).

CONCLUSION

The presence of viremia in individuals with HIV is independently associated with impaired DL_CO. Suppression of VL may allow for recovery in diffusing capacity over time, though the degree to which this occurs requires further investigation.

Oxidative Stress during HIV Infection: Mechanisms and Consequences

It is generally acknowledged that reactive oxygen species (ROS) play crucial roles in a variety of natural processes in cells. If increased to levels which cannot be neutralized by the defense mechanisms, they damage biological molecules, alter their functions, and also act as signaling molecules thus generating a spectrum of pathologies. In this review, we summarize current data on oxidative stress markers associated with human immunodeficiency virus type-1 (HIV-1) infection, analyze mechanisms by which this virus triggers massive ROS production, and describe the status of various defense mechanisms of the infected host cell. In addition, we have scrutinized scarce data on the effect of ROS on HIV-1 replication. Finally, we present current state of knowledge on the redox alterations as crucial factors of HIV-1 pathogenicity, such as neurotoxicity and dementia, exhaustion of CD4+/CD8+ T-cells, predisposition to lung infections, and certain side effects of the antiretroviral therapy, and compare them to the pathologies associated with the nitrosative stress.

Retrospective cohort evaluation on risk of pneumonia in patients with pulmonary tuberculosis

Pulmonary tuberculosis (PTb) and pneumonia are diseases that may exist concomitantly. Population study investigating the subsequent pneumonia development in PTb patients is limited. This study compares the risk of pneumonia between cohorts with and without PTb.We used the claims data of the Taiwan National Health Insurance to identify a cohort with PTb (N = 3417) newly diagnosed in 2000-2006 without pneumonia history, and a randomly selected comparison cohort (N = 6834) free of PTb and pneumonia, frequency matched by propensity score. Incidence rates and hazard ratios of pneumonia were calculated by sex, age, and comorbidity starting in the 7th month after the cohorts being established until the end of 2011.We found the incidence of pneumonia to be 1.9-fold higher in the PTb cohort than in the PTb free cohort (51.6 vs 27.0 per 1000 person-years). The PTb cohort had a Cox method estimated adjusted hazard ratio of 2.14 (95% confidence interval = 1.96-2.32). We also found that the risk was greater for men than for women, but lower for young adults aged 20-39 years. Comorbidity interacted with PTb by aggravating the pneumonia risk, particularly for those with asthma. For PTb patients comorbid with asthma, the pneumonia incidence was 2.5-fold higher than for PTb patients free of comorbidities (75.9 vs 29.3 per 1000 person-years).Our results display that PTb patients have an elevated risk of developing pneumonia. Adequate follow-up should be provided to the PTb patients, especially those with comorbidity.

Preferential Destruction of Interstitial Macrophages over Alveolar Macrophages as a Cause of Pulmonary Disease in Simian Immunodeficiency Virus-Infected Rhesus Macaques

To our knowledge, this study demonstrates for the first time that the AIDS virus differentially impacts two distinct subsets of lung macrophages. The predominant macrophages harvested by bronchoalveolar lavage (BAL), alveolar macrophages (AMs), are routinely used in studies on human lung macrophages, are long-lived cells, and exhibit low turnover. Interstitial macrophages (IMs) inhabit the lung tissue, are not recovered with BAL, are shorter-lived, and exhibit higher baseline turnover rates distinct from AMs. We examined the effects of SIV infection on AMs in BAL fluid and IMs in lung tissue of rhesus macaques. SIV infection produced massive cell death of IMs that contributed to lung tissue damage. Conversely, SIV infection induced minimal cell death of AMs, and these cells maintained the lower turnover rate throughout the duration of infection. This indicates that SIV produces lung tissue damage through destruction of IMs, whereas the longer-lived AMs may serve as a virus reservoir to facilitate HIV persistence.

Therapeutic efficacies of chitosan against Pneumocystis pneumonia of immunosuppressed rat

This study was designed to investigate the therapeutic efficacy of chitosan on Pneumocystis pneumonia (PCP) in immunosuppressed rats. The PCP rat model was established using intramuscular injections of dexamethasone sodium phosphate. To estimate treatment effects of chitosan on rat PCP, weight gain, lung weight, lung weight/body weight (LW/BW) ratio and per cent survival were measured and the HSP70 mRNA expression of Pneumocystis carinii was detected using real-time PCR analysis. Rat lung tissues were stained with HE, and their pathological changes, inflammatory cells and alveolar macrophages were observed by light microscopy. Rat lymphocyte numbers and the concentrations of IL-10, IFN-γ and TNF-α were measured by flow cytometry and ELISA analysis. Additionally, the ultrastructure of P. carinii was examined by electron microscopy to evaluate the effects of chitosan on the protist. Our results demonstrated that chitosan has some apparent treatment effects on rat PCP by reducing HSP70 mRNA expression and lung inflammation, increasing the concentrations of IL-10 and IFN-γ as well as CD4(+) T-lymphocyte numbers, reducing the CD8(+) T-lymphocyte numbers and the concentration of TNF-α and inducing significant ultrastructural damage to P. carinii. Although its precise therapeutic mechanism has yet to be determined, these results lay a theoretical foundation for PCP chitosan therapy.

High level antibody avidity is achieved in HIV-seropositive recipients of an inactivated split adjuvanted (AS03A) influenza vaccine

PURPOSE

More severe influenza disease and poor vaccine immunogenicity is reported in HIV-infected patients. We measured antibody avidity after influenza vaccination in HIV patients to assess vaccine efficacy.

METHODS

Two dosing strategies (Group1: single dose, n = 28. Group2: single dose plus booster, n = 36) with an AS03A-adjuvanted H1N12009 pandemic influenza vaccine (Arepanrix, GSK) were assessed in HIV patients. Serum hemagglutination inhibition (HAI) titers and antibody avidity reported as an avidity index (AI) were measured at days 21 and 42 and at 6 months.

RESULTS

Baseline HIV parameters were similar among all participants. Eighteen participants had measurable baseline HAI titers. In these subjects, AI was at ~9 at baseline and was not significantly increased by one or two vaccine doses. In those without detectable baseline antibodies, immunization induced modest antibody titers [Group1 HAI, 61 (26-144); Group2 HAI, 46 (28-76)] with high AI after one dose at day 21 [Group1 AI, 8.8 (7.3-10.7); Group2 AI, 8.9 (7.8-10.1)]. A second dose of vaccine generated significantly higher HAI titers at day 42 [Group1 HAI, 41 (18-90); Group2 HAI, 92 (64-132)] and persisted to 6 months [Group1 HAI, 9 (6-13); Group2 HAI, 19 (13-30)]. All subjects who produced detectable HAI titers after vaccination generated high antibody avidity (AI, 9-10), which persisted up to 6 months.

CONCLUSION

In participants initially seronegative, two doses of vaccine enabled a greater percentage of subjects to respond to the vaccine and elicited higher HAI titers. All subjects who produced detectable HAI titers also rapidly generated high AI in the short and long term. We demonstrate that high avidity antibodies can be achieved after vaccination and support a two-dose immunization strategy for HIV-positive subjects.

Clinical review: Respiratory failure in HIV-infected patients--a changing picture

Respiratory failure in HIV-infected patients is a relatively common presentation to ICU. The debate on ICU treatment of HIV-infected patients goes on despite an overall decline in mortality amongst these patients since the AIDS epidemic. Many intensive care physicians feel that ICU treatment of critically ill HIV patients is likely to be futile. This is mainly due to the unfavourable outcome of HIV patients with Pneumocystis jirovecii pneumonia who need mechanical ventilation. However, the changing spectrum of respiratory illness in HIV-infected patients and improved outcome from critical illness remain under-recognised. Also, the awareness of certain factors that can affect their outcome remains low. As there are important ethical and practical implications for intensive care clinicians while making decisions to provide ICU support to HIV-infected patients, a review of literature was undertaken. It is notable that the respiratory illnesses that are not directly related to underlying HIV disease are now commonly encountered in the highly active antiretroviral therapy (HAART) era. The overall incidence of P. jirovecii as a cause of respiratory failure has declined since the AIDS epidemic and sepsis including bacterial pneumonia has emerged as a frequent cause of hospital and ICU admission amongst HIV patients. The improved overall outcome of HIV patients needing ICU admission is related to advancement in general ICU care, including adoption of improved ventilation strategies. An awareness of respiratory illnesses in HIV-infected patients along with an appropriate diagnostic and treatment strategy may obviate the need for invasive ventilation and improve outcome further. HIV-infected patients presenting with respiratory failure will benefit from early admission to critical care for treatment and support. There is evidence to suggest that continuing or starting HAART in critically ill HIV patients is beneficial and hence should be considered after multidisciplinary discussion. As a very high percentage (up to 40%) of HIV patients are not known to be HIV infected at the time of ICU admission, the clinicians should keep a low threshold for requesting HIV testing for patients with recurrent pneumonia.

Abnormalities in host defense associated with HIV infection

The broad variety of pulmonary infections encountered in human immunodeficiency virus (HIV)-infected individuals demonstrates that the host defense network is impaired. An improved understanding of these events in the lung can lead to specific interventions aimed at restoration of deficient function. This review summarizes the pulmonary host defense deficits in HIV-infected individuals, focusing on lymphocytes, alveolar macrophages, and neutrophils.

Other HIV-associated pneumonias

The incidence, mortality, and epidemiology of human immunodeficiency virus (HIV)-associated pulmonary infections have changed as a result of effective antiretroviral and prophylaxis antimicrobial therapy. The clinical presentation, radiographic abnormalities, and treatment of pneumonia from various uncommon pathogens in patients with AIDS can be different from those in immunocompetent patients. Advances in invasive and noninvasive testing and molecular biological techniques have improved the diagnosis and prognosis of pulmonary infections in patients infected with HIV. This review focuses on pulmonary infections from nontuberculosis mycobacteria, cytomegalovirus, fungi (aspergillosis, cryptococcosis, endemic fungi), and parasites (toxoplasmosis), and uncommon bacterial pneumonia (nocardiosis, rhodococcosis) in these patients.

H1N1pdm09 adjuvanted vaccination in HIV-infected adults: a randomized trial of two single versus two double doses

Background

Since human immunodeficiency virus (HIV)-infected individuals are at increased risk of severe disease from pandemic influenza A (H1N1pdm09), vaccination was recommended as a prevention strategy. The aim of the present study was to evaluate the safety, immunogenicity and persistence of the immune response after vaccination against pandemic influenza A (H1N1pdm09) with an adjuvanted vaccine in human immunodeficiency virus (HIV)-infected adults using two single and two double doses.

Methodology/Principal Findings

Open label, randomized trial to evaluate the immune response following H1N1pdm09 vaccination in HIV-infected participants compared to HIV-negative controls (NCT01155037). HIV-infected participants were randomized to receive 2 single (3.75 µg hemagglutinin) or 2 double (7.5 µg hemagglutinin) doses of the vaccine, 21 days apart. Controls received one dose of the vaccine. The primary endpoint was seroconversion as measured by hemagglutination inhibition assay. Two hundred fifty six HIV-infected participants (129 and 127 randomized to single and double doses, respectively) and 71 HIV-negative controls were enrolled. Among HIV-infected participants, seroconversion increased from 46.7% and 51.7% after the first dose to 77.2% and 83.8% after the second dose of the vaccine using single and double doses, respectively. Participants aged >40 years showed higher seroconversion compared to younger participants. Seroconversion among HIV-infected women and those with nadir CD4<200 cells/mm³ was significantly higher with double doses. Persistence of protective antibodies six months after vaccination was achieved by 80% and 89.9% of the HIV-infected participants who received single and double doses, respectively.

Conclusions/Significance

Our results support the recommendation of two double doses of adjuvanted H1N1pdm09 vaccine for HIV-infected individuals, particularly women, and those aged >40 years or with nadir CD4<200 cells/mm³, to achieve antibody levels that are both higher and more sustained.

Trial Registration

ClinicalTrials.gov NCT01155037

Primary alveolar epithelial cell surface membrane microdomain function is required for Pneumocystis β-glucan-induced inflammatory responses

Intense lung inflammation characterizes respiratory failure associated with Pneumocystis pneumonia. Our laboratory has previously demonstrated that alveolar epithelial cells (AECs) elaborate inflammatory cytokines and chemokines in response to the Pneumocystis carinii cell wall constituent β-(1→3)-glucan (PCBG), and that these responses require lactosylceramide, a prominent glycosphingolipid constituent of certain cell membrane microdomains. The relevance of membrane microdomains, also termed plasma membrane lipid rafts, in cell signaling and macromolecule handling has been increasingly recognized in many biologic systems, but their role in P. carinii-induced inflammation is unknown. To investigate the mechanisms of microdomain-dependent P. carinii-induced inflammation, we challenged primary rat AECs with PCBG with or without pre-incubation with inhibitors of microdomain function. Glycosphingolipid and cholesterol rich microdomain inhibition resulted in significant attenuation of P. carinii-induced expression of TNF-α and the rodent C-X-C chemokine MIP-2, as well as their known inflammatory secondary signaling pathways. We have previously shown that protein kinase C (PKC) is activated by PCBG challenge and herein show that PKC localizes to AEC microdomains. We also demonstrate by conventional microscopy, fluorescence microscopy, confocal microscopy and spectrophotofluorimetry that AECs internalize fluorescently-labeled PCBG by microdomain-mediated mechanisms, and that anti-microdomain pretreatments prevent internalization. Taken together, these data suggest an important role for AEC microdomain function in PCBG-induced inflammatory responses. This offers a potential novel target for therapeutics for a condition that continues to exert unacceptable morbidity and mortality among immunocompromised populations.

Influenza and HIV: lessons from the 2009 H1N1 influenza pandemic

Influenza is a common respiratory disease in adults, including those infected with HIV. In the spring of 2009, a pandemic influenza A (H1N1) virus (pH1N1) emerged. In this article, we review the existing literature regarding pH1N1 virus infection in HIV-infected adults, which suggests that susceptibility to pH1N1 virus infection and severity of influenza illness are likely not increased in HIV-infected adults without advanced immunosuppression or comorbid conditions. The risk of influenza-related complications, however, may be increased in those with advanced immunosuppression or high-risk comorbid conditions. Prevention and treatment of high-risk comorbid conditions and annual influenza vaccination should continue to be part of HIV clinical care to help prevent influenza illness and complications. Additional information about pH1N1 vaccine immunogenicity and efficacy in HIV-infected patients would be useful to guide strategies to prevent influenza virus infection in this population.

A review of influenza vaccine immunogenicity and efficacy in HIV-infected adults

BACKGROUND

HIV-seropositive adults are at an increased risk for influenza infection. They also develop more severe influenza disease and are hyporesponsive to current influenza vaccinations.

METHODS

The authors examined findings from a systematic review of influenza vaccination in HIV-seropositive adults, and evaluated other relevant studies. A narrative overview of findings formulated to summarize the implications of currently available literature is presented. The primary goal of the present review is to assess the limitations of current evidence and to provide a framework for additional research.

RESULTS

There is a paucity of knowledge regarding the relative value of prophylactic influenza vaccination in HIV-positive adults compared with immunocompetent populations. There are shortcomings related to study methodology and temporal changes in the characteristics of patient baseline immune status, which limit the utility of this information to shape public health policy.

CONCLUSIONS

There is a pressing need to pursue methodologically rigorous studies that will increase knowledge related to improving the effectiveness of preventive influenza measures in this patient population.

Interactions between HIV infection and chronic obstructive pulmonary disease: Clinical and epidemiological aspects

Introduction

An association between HIV infection and chronic obstructive pulmonary disease (COPD) has been observed in several studies.

Objective and methods

we conducted a review of the literature linking HIV infection to COPD, focusing on clinical and epidemiological data published before and during widespread highly active antiretroviral therapy (HAART).

Results

Interactions between HIV infection and COPD appear to be influenced by multiple factors. In particular, the bronchopulmonary tract can be damaged by HIV infection, the immunodeficiency it induces, and the resulting increase in the risk of pulmonary infections. In addition, the prevalence of smoking and intravenous drug use is higher in HIV-infected populations, also increasing the risk of COPD. Before the advent of HAART, respiratory tract infections probably played a major role. Since the late 1990s and the widespread use of HAART, the frequency of opportunistic infections has fallen but new complications have emerged as life expectancy has increased.

Conclusion

given the high prevalence of smoking among HIV-infected patients, COPD may contribute significantly to morbidity and mortality in this setting.

Imaging lung manifestations of HIV/AIDS

Advances in our understanding of human immunodeficiency virus (HIV) infection have led to improved care and incremental increases in survival. However, the pulmonary manifestations of HIV/acquired immunodeficiency syndrome (AIDS) remain a major cause of morbidity and mortality. Respiratory complaints are not infrequent in patients who are HIV positive. The great majority of lung complications of HIV/AIDS are of infectious etiology but neoplasm, interstitial pneumonias, Kaposi sarcoma and lymphomas add significantly to patient morbidity and mortality. Imaging plays a vital role in the diagnosis and management of lung of complications associated with HIV. Accurate diagnosis is based on an understanding of the pathogenesis of the processes involved and their imaging findings. Imaging also plays an important role in selection of the most appropriate site for tissue sampling, staging of disease and follow-ups. We present images of lung manifestations of HIV/AIDS, describing the salient features and the differential diagnosis.

Influenza susceptibility, severity, and shedding in HIV-infected adults: a review of the literature

Influenza is a common cause of respiratory illness in adults infected with human immunodeficiency virus (HIV), but current knowledge about seasonal and 2009 H1N1 pandemic influenza A (H1N1pdm) virus infections in HIV-infected persons is limited. In this paper, we review the existing literature regarding influenza susceptibility, severity, and shedding in HIV-infected adults. Data show HIV infection does not significantly increase susceptibility to influenza. AIDS is associated with greater seasonal influenza-related morbidity and mortality, but the risk associated with HIV infection among those with less immune suppression is largely unknown. Immunologic compromise has been shown to increase the magnitude and duration of influenza virus shedding; however, these studies are limited within HIV-infected populations. With regards to H1N1pdm, data are even more limited. Reports raise concern of increased severity among HIV-infected persons, although this may be driven by other comorbid illnesses. Prospective studies are needed among HIV-infected persons to more definitively investigate influenza susceptibility, severity, and shedding.

Immunogenicity is not improved by increased antigen dose or booster dosing of seasonal influenza vaccine in a randomized trial of HIV infected adults

INTRODUCTION

The risk of poor vaccine immunogenicity and more severe influenza disease in HIV necessitate strategies to improve vaccine efficacy.

METHODS

A randomized, multi-centered, controlled, vaccine trial with three parallel groups was conducted at 12 CIHR Canadian HIV Trials Network sites. Three dosing strategies were used in HIV infected adults (18 to 60 years): two standard doses over 28 days, two double doses over 28 days and a single standard dose of influenza vaccine, administered prior to the 2008 influenza season. A trivalent killed split non-adjuvanted influenza vaccine (Fluviral™) was used. Serum hemagglutinin inhibition (HAI) activity for the three influenza strains in the vaccine was measured to assess immunogenicity.

RESULTS

297 of 298 participants received at least one injection. Baseline CD4 (median 470 cells/µL) and HIV RNA (76% of patients with viral load <50 copies/mL) were similar between groups. 89% were on HAART. The overall immunogenicity of influenza vaccine across time points and the three influenza strains assessed was poor (Range HAI ≥ 40 =  31-58%). Double dose plus double dose booster slightly increased the proportion achieving HAI titre doubling from baseline for A/Brisbane and B/Florida at weeks 4, 8 and 20 compared to standard vaccine dose. Increased immunogenicity with increased antigen dose and booster dosing was most apparent in participants with unsuppressed HIV RNA at baseline. None of 8 serious adverse events were thought to be immunization-related.

CONCLUSION

Even with increased antigen dose and booster dosing, non-adjuvanted influenza vaccine immunogenicity is poor in HIV infected individuals. Alternative influenza vaccines are required in this hyporesponsive population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00764998.

Undiagnosed AIDS in patients with progressive dyspnoea: an occupational risk for healthcare workers in Croatia

Pulmonary diseases are well documented and diverse in many patients with HIV in clinical stages 3 and 4. It is not unusual that these patients, most of whom do not know that they are already HIV-infected, are first examined and hospitalised by respiratory medicine specialists. While HIV-infection is relatively simple to diagnose if accompanied by advanced clinical manifestations and is regularly checked in patients with increased risk, this is not the case in low-risk patients, particularly in countries with low-level HIV epidemic and therefore low index of suspicion. Regular examination involves a series of tests, often including bronchoscopy with transbronchal lung biopsy in order to identify an interstitial lung disease and/or progressive dyspnoea. It is not uncommon that patients provide false or incomplete information about their lifestyle, which can mislead the clinician. At this point, HIV-infection is usually not suspected and healthcare workers may not strictly be following the safety principles which are otherwise applied when HIV-infection is known or suspect, although universal precautions are routine practice. At this point, the risk of exposure is the highest and HIV-transmission to healthcare workers is the most likely to occur. The cases presented here indicate that patients with progressive dyspnoea, which is typical of interstitial lung diseases, should undergo HIV-testing as a part of good clinical practice, even in a country with low-level HIV epidemic.

Prevalence and risk factors for unrecognized obstructive lung disease among urban drug users

Background

Obstructive lung disease (OLD) is frequently unrecognized and undertreated. Urban drug users are at higher risk for OLD due to race, behavioral, and socioeconomic characteristics, yet little data exist on prevalence and risk factors associated with unrecognized OLD in this population.

Objective

The objective of this study is to determine the prevalence of unrecognized OLD in an urban population and identify the characteristics associated with lack of physician-diagnosed OLD.

Design

Cross-sectional analysis from the Acquired Immunodeficiency Syndrome Linked to the Intravenous Experience (ALIVE) study, an observational study of current and former injection drug users in Baltimore, Maryland, USA.

Participants

All participants with spirometry-defined airflow obstruction were stratified by the presence or absence of physician diagnosis of OLD.

Main measures

Using cross-sectional demographic, clinical, and spirometric measurements, multivariable regression models were generated to identify factors independently associated with unrecognized OLD.

Key results

Of the 1083 participants evaluated in the ALIVE lung substudy, 176 (16.3%) met spirometric criteria for OLD. Of those, only 88 (50%) had a physician diagnosis of OLD. The prevalence of unrecognized OLD decreased as severity of airflow obstruction increased. Factors independently associated with unrecognized OLD were absence of respiratory symptoms (prevalence ratio [PR], 1.70; 95% confidence interval [CI]: 1.29–2.23; P < 0.01) and less severe dyspnea (PR, 0.83; 95% CI: 0.72–0.96, per point increase in dyspnea scale; P = 0.01). In the subset of human immunodeficiency virus (HIV)–infected participants, the use of antiretroviral therapy (ART) was independently associated with an increased prevalence of unrecognized OLD (PR, 1.93; 95% CI: 1.05–3.56; P = 0.03).

Conclusions

In a cohort of current and former urban drug users, OLD is substantially underrecognized and associated with lack of respiratory symptoms. Relying on the presence of respiratory symptoms as a trigger to perform spirometry may result in a substantial underdiagnosis of OLD in this population. HIV-infected individuals receiving ART are a population particularly vulnerable to unrecognized OLD.

Pneumocystis cell wall beta-glucan stimulates calcium-dependent signaling of IL-8 secretion by human airway epithelial cells

BACKGROUND

Respiratory failure secondary to alveolar inflammation during Pneumocystis pneumonia is a major cause of death in immunocompromised patients. Neutrophil infiltration in the lung of patients with Pneumocystis infection predicts severity of the infection and death. Several previous studies indicate that airway epithelial cells release the neutrophil chemoattractant proteins, MIP-2 (rodents) and IL-8 (humans), in response to Pneumocystis and purified Pneumocystis cell wall beta-glucans (PCBG) through the NF-kappaB-dependent pathway. However, little is known about the molecular mechanisms that are involved in the activation of airway epithelium cells by PCBG resulting in the secretion of IL-8.

METHOD

To address this, we have studied the activation of different calcium-dependent mitogen-activated protein kinases (MAPKs) in 1HAEo- cells, a human airway epithelial cell line.

RESULTS

Our data provide evidence that PCBG induces phosphorylation of the MAPKs, ERK, and p38, the activation of NF-kappaB and the subsequently secretion of IL-8 in a calcium-dependent manner. Further, we evaluated the role of glycosphingolipids as possible receptors for beta-glucans in human airway epithelial cells. Preincubation of the cells with D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) a potent inhibitor of the glycosphingolipids synthesis, prior to PCBG stimulation, significantly decreased IL-8 production.

CONCLUSION

These data indicate that PCBG activates calcium dependent MAPK signaling resulting in the release of IL-8 in a process that requires glycosphingolipid for optimal signaling.

Pulmonary infections in the HIV-infected patient in the era of highly active antiretroviral therapy: an update

The highly active antiretroviral therapy (HAART) era began in 1996 when the combination of multiple antiretroviral agents was found to improve outcomes in HIV-infected patients. HAART has made a tremendous impact on the progression of HIV and on the morbidity and mortality associated with its opportunistic infections. HIV-positive patients who respond to HAART have a decreased incidence of opportunistic infections. Studies have documented close to a 50% decline in the incidence of pneumocystis pneumonia and bacterial pneumonia with the use of antiretroviral therapy. Primary and secondary prophylaxis for pneumocystis pneumonia can be discontinued in patients who show a sustained response to antiretroviral therapy. Unique to the HAART era, immune reconstitution syndrome is characterized by a paradoxical deterioration of a preexisting infection that is temporally related to the recovery of the immune system. Recently, more and more patients are being admitted for non-AIDS related illnesses in the HAART era.

Viral pathogens including human metapneumovirus are the primary cause of febrile respiratory illness in HIV-infected adults receiving antiretroviral therapy

To determine the spectrum of pathogens causing acute febrile respiratory illness in human immunodeficiency virus (HIV)-infected adults, we re-analyzed data from a prospective surveillance study involving 50 outpatients (90% of whom received highly active antiretroviral therapy). Nasopharyngeal samples were tested for 23 respiratory viruses by multiplex reverse-transcriptase polymerase chain reaction (PCR) and for atypical bacteria by PCR. Sputum cultures and serological testing were performed. Viruses accounted for 64% of infections. After influenza (22 cases), human metapneumovirus infection (6 cases) was most common and was associated with bronchospasm. Bacterial infections occurred in 6 patients (3 of whom had concurrent viral infection). Over 80% of patients received antibiotics. Rapid testing to identify specific viral pathogens could aid in patient management and reduce unnecessary antibiotic exposure.

Bacterial pneumonia among HIV-infected patients: decreased risk after tobacco smoking cessation. ANRS CO3 Aquitaine Cohort, 2000-2007

BACKGROUND

Bacterial pneumonia is still a substantial cause of morbidity and mortality in HIV-infected patients in the era of combination Antiretroviral Therapy. The benefit of tobacco withdrawal on the risk of bacterial pneumonia has not been quantified in such populations, exposed to other important risk factors such as HIV-related immunodeficiency. Our objective was to estimate the effect of tobacco smoking withdrawal on the risk of bacterial pneumonia among HIV-infected individuals.

METHODOLOGY/PRINCIPAL FINDINGS

Patients of the ANRS CO3 Aquitaine Cohort with >or= two visits during 2000-2007 and without bacterial pneumonia at the first visit were included. Former smokers were patients who stopped smoking since >or= one year. We used Cox proportional hazards models adjusted on CD4+ lymphocytes (CD4), gender, age, HIV transmission category, antiretroviral therapy, cotrimoxazole prophylaxis, statin treatment, viral load and previous AIDS diagnosis. 135 cases of bacterial pneumonia were reported in 3336 patients, yielding an incidence of 12 per thousand patient-years. The adjusted hazard of bacterial pneumonia was lower in former smokers (Hazard Ratio (HR): 0.48; P = 0.02) and never smokers (HR: 0.50; P = 0.01) compared to current smokers. It was higher in patients with <200 CD4 cells/microL and in those with 200 to 349 CD4 cells/microL (HR: 2.98 and 1.98, respectively; both P<0.01), but not in those with 350 to 499 CD4 cells/microL (HR: 0.93; P = 0.79), compared to those with >or=500 CD4 cells/microL. The interaction between CD4 cell count and tobacco smoking status was not statistically significant.

CONCLUSIONS/SIGNIFICANCE

Smoking cessation dramatically reduces the risk of bacterial pneumonia, whatever the level of immunodeficiency. Smoking cessation interventions should become a key element of the clinical management of HIV-infected individuals.

Adenovirus vectors block human immunodeficiency virus-1 replication in human alveolar macrophages by inhibition of the long terminal repeat

Heterologous viruses may transactivate or suppress human immunodeficiency virus (HIV)-1 replication. An adenovirus type 5 gene transfer vector (Ad5) HIV-1 vaccine was recently evaluated in a clinical trial, without efficacy. In this context, it is relevant to ask what effect Ad vectors have on HIV-1 replication, particularly in cells that are part of the innate immune system. Infection of HIV-1-infected human alveolar macrophages (AMs) obtained from HIV-1(+) individuals with an Ad vector containing no transgene (AdNull) resulted in dose-responsive inhibition of endogenous HIV-1 replication. HIV-1 replication in normal AMs infected with HIV-1 in vitro was inhibited by AdNull with a similar dose response. Ad reduced AM HIV-1 replication up to 14 days after HIV-1 infection. Fully HIV-1-infected AMs were treated with 3'-azido-3'-deoxythymidine, after which Ad infection still inhibited HIV-1 replication, suggesting a postentry step was affected. Substantial HIV-1 DNA was still produced after Ad infection, as quantified by TaqMan real-time PCR, suggesting that the replication block occurred after reverse transcription. AdNull blocked HIV-1 long terminal repeat (LTR) transcription, as assessed by an vesicular stomatitis virus G protein pseudotyped HIV-1 LTR luciferase construct. The formation of HIV-1 DNA integrated into the host chromosome was not inhibited by Ad, as quantified by a two-step TaqMan real-time PCR assay, implying a postintegration block to HIV-1 replication. These data indicate that Ad vectors are inhibitory to HIV-1 replication in human AMs based, in part, on their ability to inhibit LTR-driven transcription.

IFN-gamma deficiency worsen Pneumocystis pneumonia with Th17 development in nude mice

Pneumocystis pneumonia (PCP) occurs frequently in patients with immunodeficiency syndromes, especially AIDS. In order to investigate the role of IFN-gamma on PCP, nude mice deficient in IFN-gamma (GKO nude) and their wild-type ones (WT nude) were infected with murine Pneumocystis. Nine weeks later they were sacrificed, and cytokines in BALF and lung histopathology were compared between them. Cyst burden was greater in GKO than in WT nude mice. Histopathology in the lung was severer and granulomatous lesions were observed more frequently in GKO nude mice. Levels of IL-17 were higher in BALF of GKO than in that of WT nude mice. Greater number of CD4(+) T cells from lungs of infected GKO nude mice produced IL-17 than those from WT ones. These results suggest that deficiency in IFN-gamma induces the differentiation of Th17 and that IL-17 is responsible for inflammatory response in PCP.

Etiologies and outcome of acute respiratory failure in HIV-infected patients

Objective

To assess the etiologies and outcome of acute respiratory failure (ARF) in HIV-infected patients over the first decade of combination antiretroviral therapy (ART) use.

Methods

Retrospective study of all HIV-infected patients (n = 147) admitted to a single intensive care unit (ICU) for ARF between 1996 and 2006.

Results

ARF revealed the diagnosis of HIV infection in 43 (29.2%) patients. Causes of ARF were bacterial pneumonia (n = 74), Pneumocystis jirovecii pneumonia (PCP, n = 52), other opportunistic infections (n = 19), and noninfectious pulmonary disease (n = 33); the distribution of causes did not change over the 10-year study period. Two or more causes were identified in 33 patients. The 43 patients on ART more frequently had bacterial pneumonia and less frequently had opportunistic infections (P = 0.02). Noninvasive ventilation was needed in 49 patients and endotracheal intubation in 42. Hospital mortality was 19.7%. Factors independently associated with mortality were mechanical ventilation [odds ratio (OR) = 8.48, P < 0.0001], vasopressor use (OR, 4.48; P = 0.03), time from hospital admission to ICU admission (OR, 1.05 per day; P = 0.01), and number of causes (OR, 3.19; P = 0.02). HIV-related variables (CD4 count, viral load, and ART) were not associated with mortality.

Conclusion

Bacterial pneumonia and PCP remain the leading causes of ARF in HIV-infected patients in the ART era. Hospital survival has improved, and depends on the extent of organ dysfunction rather than on HIV-related characteristics.

Pulmonary infections in HIV-positive children

Infection of the lungs and airways by viral, bacterial, fungal and protozoal agents, often producing atypical radiographic features, is common in children with human immunodeficiency virus (HIV) infection. Conventional chest radiography and chest CT remain the most useful imaging modalities for evaluation of the immunocompromised patient presenting with a suspected pulmonary infection. In this review the radiological features of acute lung infections in this population are discussed.

Immune reconstitution during Pneumocystis lung infection: disruption of surfactant component expression and function by S-nitrosylation

Pneumocystis pneumonia (PCP), the most common opportunistic pulmonary infection associated with HIV infection, is marked by impaired gas exchange and significant hypoxemia. Immune reconstitution disease (IRD) represents a syndrome of paradoxical respiratory failure in patients with active or recently treated PCP subjected to immune reconstitution. To model IRD, C57BL/6 mice were selectively depleted of CD4(+) T cells using mAb GK1.5. Following inoculation with Pneumocystis murina cysts, infection was allowed to progress for 2 wk, GK1.5 was withdrawn, and mice were followed for another 2 or 4 wk. Flow cytometry of spleen cells demonstrated recovery of CD4(+) cells to >65% of nondepleted controls. Lung tissue and bronchoalveolar lavage fluid harvested from IRD mice were analyzed in tandem with samples from CD4-depleted mice that manifested progressive PCP for 6 wks. Despite significantly decreased pathogen burdens, IRD mice had persistent parenchymal lung inflammation, increased bronchoalveolar lavage fluid cellularity, markedly impaired surfactant biophysical function, and decreased amounts of surfactant phospholipid and surfactant protein (SP)-B. Paradoxically, IRD mice also had substantial increases in the lung collectin SP-D, including significant amounts of an S-nitrosylated form. By native PAGE, formation of S-nitrosylated SP-D in vivo resulted in disruption of SP-D multimers. Bronchoalveolar lavage fluid from IRD mice selectively enhanced macrophage chemotaxis in vitro, an effect that was blocked by ascorbate treatment. We conclude that while PCP impairs pulmonary function and produces abnormalities in surfactant components and biophysics, these responses are exacerbated by IRD. This worsening of pulmonary inflammation, in response to persistent Pneumocystis Ags, is mediated by recruitment of effector cells modulated by S-nitrosylated SP-D.

Pneumocystis murina infection and cigarette smoke exposure interact to cause increased organism burden, development of airspace enlargement, and pulmonary inflammation in mice

Chronic obstructive pulmonary disease (COPD) is characterized by the presence of airflow obstruction and lung destruction with airspace enlargement. In addition to cigarette smoking, respiratory pathogens play a role in pathogenesis, but specific organisms are not always identified. Recent reports demonstrate associations between the detection of Pneumocystis jirovecii DNA in lung specimens or respiratory secretions and the presence of emphysema in COPD patients. Additionally, human immunodeficiency virus-infected individuals who smoke cigarettes develop early emphysema, but a role for P. jirovecii in pathogenesis remains speculative. We developed a new experimental model using immunocompetent mice to test the interaction of cigarette smoke exposure and environmentally acquired Pneumocystis murina infection in vivo. We hypothesized that cigarette smoke and P. murina would interact to cause increases in total lung capacity, airspace enlargement, and pulmonary inflammation. We found that exposure to cigarette smoke significantly increases the lung organism burden of P. murina. Pulmonary infection with P. murina, combined with cigarette smoke exposure, results in changes in pulmonary function and airspace enlargement characteristic of pulmonary emphysema. P. murina and cigarette smoke exposure interact to cause increased lung inflammatory cell accumulation. These findings establish a novel animal model system to explore the role of Pneumocystis species in the pathogenesis of COPD.

Minimal conjunctival limbal autograft for total limbal stem cell deficiency

PURPOSE

To report the results of one 60 degrees conjunctival limbal autograft (CLAU) combined with amniotic membrane (AM) transplantation for an eye with total limbal stem cell deficiency (LSCD).

METHODS

One eye of a patient with chronic total LSCD and symblepharon caused by chemical burn was subjected to symblepharon lysis, removal of pannus from corneal surface, AM transplantation to cover the conjunctival and corneal surfaces as a permanent graft, one 60 degrees CLAU to the superior limbal area, and insertion of ProKera as a temporary AM patch to cover the CLAU.

RESULTS

After surgery, corneal epithelialization over the AM was evident adjacent to the CLAU on day 6, progressed to pass the horizontal midline by day 11, and was completed by day 18. During a follow-up of 1 year, the corneal surface remained stable and smooth, and the stroma considerably regained clarity with regression of midstromal vascularization. The best-corrected visual acuity improved from 20/400 to 20/50. The conjunctival inflammation completely resolved, and the fornices were deep.

CONCLUSIONS

One 60 degrees CLAU combined with AM transplantation as both a permanent graft and a temporary patch can restore the entire corneal surface in an eye with total LSCD caused by chemical burn.

Th17 cells and mucosal host defense

Th17 cells are a new lineage of T-cells that are controlled by the transcription factor RORgammat and develop independent of GATA-3, T-bet, Stat 4 and Stat 6. Novel effector molecules produced by these cells include IL-17A, IL-17F, IL-22, and IL-26. IL-17RA binds IL-17A and IL-17F and is critical for host defense against extracellular planktonic bacteria by regulating chemokine gradients for neutrophil emigration into infected tissue sites as well as host granulopoiesis. Moreover, IL-17 and IL-22 regulate the production of antimicrobial proteins in mucosal epithelium. Although TGF-beta1 and IL-6 have been shown to be critical for development of Th17 cells from naive precursors, IL-23 is also important in regulating IL-17 release in mucosal tissues in response to infectious stimuli. Compared to Th1 cells, IL-23 and IL-17 show limited roles in controlling host defense against primary infections with intracellular bacteria such as Mycobacterium tuberculosis suggesting a predominate role of the Th17 lineage in host defense against extracellular pathogens. However, in the setting of chronic biofilm infections, as that occurs with cystic fibrosis or bronchiectasis, Th17 cells may be key contributors of tissue injury.

Influenzavirus infection is a primary cause of febrile respiratory illness in HIV-infected adults, despite vaccination

BACKGROUND

There are, to our knowledge, no prospective studies of respiratory tract infections in human immunodeficiency virus (HIV)-infected adults in the highly active antiretroviral therapy (HAART) era. We performed a surveillance study of outpatients who presented with fever and respiratory symptoms to examine the role of viral pathogens in these patients.

METHODS

Consecutive patients with a temperature of >38.0 degrees C and respiratory symptoms were recruited from a tertiary care HIV clinic during the period 2003-2006. Nasal pharyngeal samples were tested for influenzavirus A and B, respiratory syncytial virus, and human metapneumovirus using real-time multiplex polymerase chain reaction assays. Paired acute- and convalescent-phase serum samples were tested for respiratory viruses by complement fixation.

RESULTS

Fifty patients (90% of whom were receiving HAART) were included in the study (median CD4(+) T cell count, 325 cells/microL; median HIV RNA level, <50 copies/mL). A causative pathogen was identified in 25 patients (50%). Even though 76% of subjects had received influenza vaccine, viral infections were diagnosed in 21 patients (42%), as follows: influenza A, 10 patients; influenza B, 10; and parainfluenza virus type 3 infection, 1. Patients with and those without viral infection had similar demographic characteristics and HIV statuses. No patients with influenza and 23% of patients with other conditions had radiography-confirmed pneumonia (P=.07). Antibiotic prescriptions were common: 70% of patients received antibiotics. No patients with influenza required hospitalization, compared with 21% of other patients (P=.03).

CONCLUSIONS

Although illness was mild, influenza accounted for a large proportion of unscheduled visits to a health care provider for respiratory illness and was associated with unnecessary antibiotic prescriptions that may contribute to antimicrobial resistance. Vaccination alone was insufficient to prevent infection. Thus, specific identification and management of influenza should be performed in HIV-infected outpatients who present with fever and respiratory symptoms.

Critical care of immunocompromised patients: human immunodeficiency virus

OBJECTIVE

To describe critical illnesses that occur commonly in patients with human immunodeficiency virus (HIV) infection.

METHODS

We reviewed and summarized the literature on critical illness in HIV infection using a computerized MEDLINE search.

SUMMARY

In the last 10 yrs, our perception of HIV infection and acquired immune deficiency syndrome (AIDS) has changed from an almost uniformly fatal disease into a manageable chronic illness. Even patients with advanced immunosuppression may have prolonged survival, although usually with exacerbations and remissions, complicated by therapy-related toxicity and medical and psychiatric co-morbidity. The prevalence of opportunistic infections and the mortality have decreased considerably since early in the epidemic. The most common reason for intensive care unit admission in patients with AIDS is respiratory failure, but they are less likely to be admitted for Pneumocystis pneumonia and other HIV-associated opportunistic infections. HIV-infected persons are more likely to receive intensive care unit care for complications of end-stage liver disease and sepsis. Hepatitis C has emerged as a common cause of morbidity and mortality in patients with HIV infection. In addition, some develop life-threatening complications from antiretroviral drug toxicity and the immune reconstitution inflammatory syndrome.

HIV-AIDS in Minorities

HIV-AIDS has disproportionately affected minority populations in the United States. Significant disparities in case rates and mortality have been noted. This article reviews the magnitude of the problem and the many factors involved in the development and perpetuation of these disparities. Possible measures to help correct the problem are also reviewed.

The immunocompromised host: HIV infection

The variety of pulmonary infections encountered in HIV-infected individuals indicates that many components of the host defense network are impaired. In addition to depletion of CD4+ T cell numbers, HIV infection results in functional deficits in CD4+ T cells, CD8+ T cells, and natural killer cells. Although some components of macrophage defense are preserved, lack of activation signals from CD4+ T cells contributes to impaired defense by macrophages. There are few data examining the functional capabilities of neutrophils in the lung, but evidence from peripheral blood neutrophils indicates that defense by these cells is also impaired. An improved understanding of these events in the lung during HIV infection could lead to specific interventions aimed at restoration of deficient function.