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

Mycobacterium tuberculosis upregulates coreceptors CCR5 and CXCR4 while HIV modulates CD14 favoring concurrent infection

Tuberculosis is the most frequent coinfection in humans infected with HIV-1, but little is known about mechanisms that favors coinfection. The aim of this work is to understand tuberculosis and HIV infections. We determined the pattern of expression of CD11c, CD14, CD40, CCR5, and CXCR4 and quantified IL-1beta, IL-6, IL-8, TNF-alpha, and RANTES in tuberculosis patients and HIV patients. Monocytes from healthy PPD+ volunteers (HP(+)V) stimulated with intracellular proteins (IP), lipids, and polysaccharides (PLS) from Mycobacterium tuberculosis down regulate CD11c expression (p < 0.05). On the contrary, CD14 expression was elevated in tuberculosis patients (p < 0.05) and HIV-infected patients (p > 0.05). CD14 expression was elevated on monocytes from HP(+)V stimulated with PLS and lipids (p < 0.05). CD40 low expression was found in tuberculosis patients and on monocytes from HP(+)V stimulated with lipids, but it was elevated in HIV-infected patients (p < 0.05). CXCR4 and CCR5 expression was high in pulmonary tuberculosis patients and low in HIV-infected patients (p < 0.05). Finally, CCR5+ monocytes from HP(+)V after stimulation with PLS and CXCR4+ lymphocytes were elevated after stimulation with IP (p < 0.05). In general, high levels of IL-1beta, IL-6, and TNF-alpha were found in all groups, but low levels of RANTES were found in pulmonary tuberculosis patients. In conclusion, the pulmonary tuberculosis patients have a microenvironment that facilitates the HIV infection through three possible mechanisms: (1) increasing the coreceptor for HIV entrance, (2) increasing proinflammatory cytokines, and (3) down-regulating RANTES. At the same time, HIV patients have a microenvironment that facilitates entry of M. tuberculosis into macrophages through CD14.

[The radiology of opportunistic pneumonias. I: Epidemiological, laboratory and clinical background]

In the guidelines of the German Society of Pneumology on diagnosis and therapy of opportunistic pneumonias, chest x-ray is listed as the basic diagnostic method in congenital and acquired immunodepression. In case of discrepancy between radiographic and the clinical findings or in cases of bilateral infiltrates, infection refractory to therapy or a difficult course in patients requiring artificial ventilation, a CT, or if necessary, ultrasound or MRI should be carried out. Cross-sectional imaging allows more precise assessment of the radiological pattern, estimation of the degree of severity (number of infiltrated segments) and detection of complications (pleural effusion, empyema, thorax wall infiltration). Clinical and laboratory parameters, bacteriological and serological examinations as well as information on the underlying immunocompromising factors must be taken into account in the differential diagnosis. The radiographic finding is an important diagnostic parameter which is used in the determination of the degree of severity of the pneumonia. The pattern of findings is one of rationales for the use of antibiotic therapy. In the first part of this contribution the epidemiological, laboratory and clinical background of the diagnosis of opportunistic pneumonias is discussed.

Pneumocystis cell wall beta-glucans stimulate alveolar epithelial cell chemokine generation through nuclear factor-kappaB-dependent mechanisms

Exuberant inflammatory responses are associated with respiratory failure during Pneumocystis pneumonia. Alveolar epithelial cells (AECs) promote Pneumocystis attachment and proliferation, but also contribute prominently to host cytokine-mediated inflammation during pneumonia. Recent investigations indicate that AECs produce macrophage inflammatory protein-2 (MIP-2) and tumor necrosis factor-alpha (TNF-alpha) following challenge with Pneumocystis carinii. Nuclear factor-kappaB (NF-kappaB) is a ubiquitous transcription factor critical for regulation of proinflammatory cytokine expression. Herein, we assess rat AEC NF-kappaB responses to challenge with a P. carinii beta-glucan cell wall component (PCBG). Prominent nuclear translocation of p65 NF-kappaB was demonstrated following PCBG challenge. NF-kappaB activation was in part mediated through Protein Kinase C (PKC) signaling pathways. PCBG challenge of AECs was also shown to induce MIP-2 and TNF-alpha mRNA production, a response that was ameliorated by NF-kappaB inhibition. MIP-2 protein expression was also dramatically increased by PCBG challenge, in a manner that was significantly attenuated by both PKC and NF-kappaB inhibition. The data further demonstrate that AEC chemokine responses were not mediated by the recently described dectin-1 receptor, but instead involved participation of cell surface lactosylceramide. These data support a significant role for AECs in host responses during Pneumocystis pneumonia, and further indicate that beta-glucan induces inflammatory cytokine production through NF-kappaB-dependent mechanisms.

Enhanced lung injury and delayed clearance of Pneumocystis carinii in surfactant protein A-deficient mice: attenuation of cytokine responses and reactive oxygen-nitrogen species

Surfactant protein A (SP-A), a member of the collectin family, selectively binds to Pneumocystis carinii and mediates interactions between pathogen and host alveolar macrophages in vitro. To test the hypothesis that mice lacking SP-A have delayed clearance of Pneumocystis organisms and enhanced lung injury, wild-type C57BL/6 (WT) and SP-A-deficient mice (SP-A(-/-)) with or without selective CD4(+)-T-cell depletion were intratracheally inoculated with Pneumocystis organisms. Four weeks later, CD4-depleted SP-A-deficient mice had developed a more severe Pneumocystis infection than CD4-depleted WT (P. carinii pneumonia [PCP] scores of 3 versus 2, respectively). Whereas all non-CD4-depleted WT mice were free of PCP, intact SP-A(-/-) mice also had evidence of increased organism burden. Pneumocystis infection in SP-A-deficient mice was associated histologically with enhanced peribronchial and/or perivascular cellularity (score of 4 versus 2, SP-A(-/-) versus C57BL/6 mice, respectively) and a corresponding increase in bronchoalveolar lavage (BAL) cell counts. Increases in SP-D content, gamma interferon, interleukin-4, interleukin-5, and tumor necrosis factor alpha in BAL fluid occurred but were attenuated in PCP-infected SP-A(-/-) mice compared to WT mice. There were increases in total BAL NO levels in both infected groups, but nitrite levels were higher in SP-A(-/-) mice, indicating a reduction in production of higher oxides of nitrogen that was also reflected in lower levels of 3-nitrotyrosine staining in the SP-A(-/-) group. We conclude that despite increases in inflammatory cells, SP-A-deficient mice infected with P. carinii exhibit an enhanced susceptibility to the organism and attenuated production of proinflammatory cytokines and reactive oxygen-nitrogen species. These data support the concept that SP-A is a local effector molecule in the lung host defense against P. carinii in vivo.

Intensive care in patients with HIV infection in the era of highly active antiretroviral therapy

STUDY OBJECTIVES

The use of highly active antiretroviral therapy (HAART) has dramatically improved morbidity and mortality in patients with HIV infection. The types of critical illness and their outcomes in HIV-infected patients in recent years is unknown.

DESIGN

We reviewed the medical records of all patients admitted to the Medical ICU of Beth Israel Medical Center, NY, from January to June 2001 and compared their characteristics with patients admitted to the same unit from November 1991 to October 1992.

RESULTS

Of 441 admissions in the first half of 2001, 63 admissions (14%) were in 53 HIV-seropositive patients. There were 65 admissions to the Medical ICU during the 1-year period spanning 1991 to 1992. Compared with the earlier period, the 2001 patients were more likely to be black (52% vs 26%, respectively; p < 0.01) and injection drug users (75% vs 48%, respectively; p < 0.01), and were less likely to be white (11% vs 23%, respectively; difference not significant) and homosexual men (6% vs 26%, respectively; p < 0.01). In 2001, patients were less likely to be admitted with respiratory failure (22% vs 54%, respectively; p < 0.01) and with Pneumocystis jiroveci pneumonia (formerly referred to as Pneumocystis carinii) [3% vs 34%, respectively; p < 0.001], and were more likely to be admitted with non-HIV-related diseases (67% vs 12%, respectively; p < 0.001). Overall survival was much higher in the later period (71% vs 49%, respectively; p < 0.01).

CONCLUSIONS

In the era of HAART, more patients with HIV infection were admitted to the ICU over a 12-month period than were 10 years previously. Patients were more likely to be injection drug users and were more likely to be admitted to the ICU because of non-HIV-associated conditions.

Different resistance mutations can be detected simultaneously in the blood and the lung of HIV-1 infected individuals on antiretroviral therapy

In this retrospective study, matched peripheral blood and lung samples from patients on antiretroviral therapy were studied in order to investigate whether differences in mutations associated with resistance to nucleoside analogues could be detected between the lung and blood. Discordant mutation patterns in the reverse transcriptase (RT) between plasma and cell free bronchoalveolar lavage fluid (BAL-fluid) HIV-1 genomic RNA was observed in five out of seven patients on nucleoside reverse transcriptase inhibitor (NRTI) monotherapy and six out of seven on combination therapy. In the cellular compartments, DNA recovered from peripheral blood mononuclear cells (PBMCs) and cells from BAL-cells discordant HIV-1 resistance genotypes were detected in 15 out of 44 matched samples. Differences in resistant genotypes between PBMCs and BAL-cells were most pronounced in patients receiving combination antiretroviral therapy. The pattern and number of mutations in RT associated with resistance differed in the BAL-cells compared to PBMCs in four out of 12 subjects not receiving antiretroviral therapy at the time of bronchoscopy, three from 14 patients on NRTI monotherapy, five out of nine on dual combination therapy and three out of nine on HAART. The differences in the detection of resistance mutations between blood and the lung suggest that the lung is a site of replication for HIV-1.

Lung cancer in patients with HIV infection: is it AIDS-related?

HIV-infected individuals have an increased risk of malignancy, especially non-Hodgkin's lymphoma and Kaposi's sarcoma. Recently, several workers have noted a raised prevalence of lung cancer in HIV-positive subjects. We describe the diagnosis and clinical course for four HIV-seropositive patients who presented with lung cancer. All of the patients were young and were heavy smokers. They were all on highly active antiretroviral therapy (HAART), although the adherence varied from poor to excellent. The CD4 cell counts of these patients ranged from 200 to 686 cells/microL and their viral loads ranged from undetectable to 29,000 HIV-1 RNA copies/mL. After initial diagnosis of HIV infection between 5 and 13 years previously, they all presented with advanced lung cancer, with a very short clinical course, and all four died within 2-9 months of diagnosis. A comparison of the incidence of lung cancer in patients with HIV infection at our centre with that in the general population suggests that there is an increased prevalence in the HIV-infected patients. We review the literature and discuss whether lung cancer in HIV infection is coincidental or related to the primary disease.

Pneumocystis pneumonia increases the susceptibility of mice to sublethal hyperoxia

Patients with Pneumocystis pneumonia often develop respiratory failure after entry into medical care, and one mechanism for this deterioration may be increased alveolar epithelial cell injury. In vitro, we previously demonstrated that Pneumocystis is not cytotoxic for alveolar epithelial cells. In vivo, however, infection with Pneumocystis could increase susceptibility to injury by stressors that, alone, would be sublethal. We examined transient exposure to hyperoxia as a prototypical stress that does cause mortality in normal mice. Mice were depleted of CD4+ T cells and inoculated intratracheally with Pneumocystis. Control mice were depleted of CD4+ T cells but did not receive Pneumocystis. After 4 weeks, mice were maintained in normoxia, were exposed to hyperoxia for 4 days, or were exposed to hyperoxia for 4 days followed by return to normoxia. CD4-depleted mice with Pneumocystis pneumonia demonstrated significant mortality after transient exposure to hyperoxia, while all uninfected control mice survived this stress. We determined that organism burdens were not different. However, infected mice exposed to hyperoxia and then returned to normoxia demonstrated significant increases in inflammatory cell accumulation and lung cell apoptosis. We conclude that Pneumocystis pneumonia leads to increased mortality following a normally sublethal hyperoxic insult, accompanied by alveolar epithelial cell injury and increased pulmonary inflammation.

T cell costimulatory molecule function determines susceptibility to infection with Pneumocystis carinii in mice

Loss of T cell number and function during HIV infection or secondary to pharmacologic immunosuppression renders individuals susceptible to opportunistic infections, including Pneumocystis carinii pneumonia. Because costimulatory receptors are critical for optimal T cell function, we hypothesized that these proteins would regulate susceptibility to opportunistic infections. We found that despite normal T cell numbers, mice deficient in the costimulatory molecules CD2 and CD28 spontaneously developed P. carinii pneumonia. In experiments using intratracheal injection of P. carinii organisms to induce infection, the loss of CD28 alone was sufficient to render mice susceptible to acute infection; however, the organism was eventually cleared. Examination of inflammatory responses to P. carinii revealed that mice deficient in both CD2 and CD28 accumulated CD8(+) T cells in their lungs in response to infection and demonstrated markedly reduced specific Ab titers. Analysis of cytokine profiles suggested that regulation of IL-10 and IL-15 may be important elements of the response to this pathogen. Thus, costimulatory molecule function is critical in determining the initial susceptibility to infection with P. carinii. Analysis of immunologic responses in these mice may provide important insights into the defects that render individuals susceptible to opportunistic infection, and provide opportunities for novel immunologically based therapies.