Lymphoid interstitial pneumonitis in pediatric AIDS. Natural history of the disease

Relationship of cell bearing EBER and p24 antigens in biopsy-proven lymphocytic interstitial pneumonia in HIV-1 subtype E infected children

Lymphocytic interstitial pneumonia (LIP) is an uncommon histopathologic entity characterized by infiltration of the interstitium and alveolar spaces of the lung by lymphocytes and other lymphoid elements. An increased incidence of LIP has been seen in the pediatric population, especially in children with acquired immune deficiency syndrome. Our previous study supports the notion that Langerhans cells (LCs) are reservoirs for Epstein-Barr virus (EBV) in lungs of human immunodeficiency virus (HIV) subtype E-infected pediatric LIP. To further understand the pathogenesis of LIP, we studied the relationship between EBV, the suggested causative agent of LIP and HIV-1 capsid protein p24, which play an important role in the interaction with host proteins during HIV-1 adsorption, membrane fusion, and entry in surgical lung biopsy-proven LIP from 9 vertically HIV subtype E-infected pediatric patients. The dominant microscopic feature of LIP demonstrated widespread widening of alveolar septum by mononuclear inflammatory cell infiltrate, mainly composed of mature lymphocytes and plasma cells surrounding airways and expanding to the lung interstitium. EBV-encoded RNA (EBER) in situ hybridization (ISH) and p24 immunohistochemistry, performed on formalin-fixed, paraffin-embedded tissue from open lung biopsy specimens, revealed positive intranuclear EBER signals and intracytoplasmic immunostains for p24 core protein in all 9 LIP cases. By combining ISH and immunohistochemistry, these results suggest that (i) EBV/p24-carrying cells are likely involved in the development of LIP, either directly or indirectly; (ii) LCs and related dendritic cells are the main reservoir of both EBV and HIV subtype E in pediatric LIP and possibly LCs may play an important role in the recruitment of inflammatory cell infiltrates, especially T cells into these tissues; (iii) coexpression of EBV/p24 in bronchioalveolar epithelium supports the hypothesis that these cells serve as a reactivation source for both viruses to achieve greater quantities in alveolar septum and interstitium around bronchioles. These results indicate a strong association between the presence of HIV core protein p24 and expression of EBV RNA transcripts (EBER). Interactions between LCs and related dendritic cells together with T cells are important for effective HIV and EBV replications. The coexpression of both viruses could be related to the evolution of pediatric LIP in HIV subtype E infection.

Cell reservoirs of the Epstein-Barr virus in biopsy-proven lymphocytic interstitial pneumonitis in HIV-1 subtype E infected children: identification by combined in situ hybridization and immunohistochemistry

Lymphoid interstitial pneumonitis (LIP), a frequent pulmonary complication in human immune deficiency virus (HIV)-infected pediatric patients, is characterized histologically by marked infiltration of lymphoid cells. Several theories have been suggested that LIP may be caused by Epstein-Barr virus (EBV). To identify the reservoir of EBV and pathogenesis of lymphoid infiltrates in HIV subtype E infected pediatric LIP, we examined the distribution and expression of EBV in the inflammatory cell recruitment in surgical lung biopsy-proven LIP from 9 vertically HIV subtype E-infected pediatric patients. The dominant microscopic feature of LIP demonstrated widespread widening of alveolar septum by mononuclear inflammatory cell infiltrate mainly composed of mature lymphocytes and plasma cells surrounding airways and expanding to the lung interstitium. EBV-encoded RNA (EBER) in situ hybridization, performed from paraffin-embedded lung tissues, revealed positive intranuclear signals in all 9 LIP cases. Interestingly, combined immunohistochemical and in situ hybridization analyses in 6 out of 9 LIP cases revealed 30% to 50% of the Langerhans and related dendritic cells were infected with EBV, whereas <30% of the T and B cells were infected with EBV. These results suggested that a chronic antigenic stimulus of EBV played important roles in the pathogenesis of LIP in these patients. This supports the notion that Langerhans cells (LCs) are more readily infected with EBV, indicating that LCs are reservoirs for EBV in lungs of HIV subtype E-infected pediatric LIP. And possibly LCs may play an important role in the recruitment of inflammatory cell infiltrates, especially T cells into these tissues. In addition, HIV may provide a milieu or microenvironment for the evolution of LIP, which represent an immunologic response to EBV infection. Interactions between LCs and related dendritic cells together with T cells are important for effective HIV and EBV replications.

Epstein-Barr virus (EBV) gene expression in interstitial pneumonitis in Brazilian human immunodeficiency virus-1-infected children: is EBV associated or not?

To gain further knowledge on the subject we evaluated Epstein-Barr virus (EBV) gene expression and TCD4+, TCD8+, and B lymphocyte counts in lung tissue samples from 20 human immunodeficiency virus (HIV)-infected children with chronic lung disease. Twenty HIV-1 infected children with chronic pulmonary disease underwent open lung biopsy to define the diagnosis. Histological section of this material was submitted to nonisotopic in situ hybridization (ISH) using EBV-encoded RNA (EBER) 1/2 probes and TCD4+, TCD8+, and CD20+ B-cell counts by immunohistochemistry. The histology of 16 out of the 20 children (median age 53.5 months) proved to be examples of pulmonary lymphoid hyperplasia/lymphoid interstitial pneumonitis (PLH/LIP) complex, 13 of which were EBER positive, but no significant association was found (Fisher exact test P = 0.439). Four patients had non-LIP diseases (3, nonspecific interstitial pneumonia; 1, diffuse advanced alveolar damage), two being EBER negative. Nineteen children showed a predominant T-CD8+ cell response (CD4+/CD8+ <1) in lung tissue. The mean TCD4+ and theTCD4/TCD8 ratio in lung tissue were significantly higher in the sections with PLH/LIP complex, but without significant difference between EBER positive and EBER negative samples. EBV gene expression was detected in the majority of the lung samples but without significant association with PLH/LIP complex or with TCD4+, TCD8+, B cells and the TCD4+/TCD8+ ratio. Regarding the pattern of lung disease in HIV-1 infected children, associated or not to EBV, the findings are of importance concerning the possible role of EBV in the pathogenesis of PLH/LIP.

Chronic lung disease in human immunodeficiency virus (HIV) infected children

The development of chronic lung disease is common in HIV-infected children. The spectrum of chronic HIV-associated lung disease includes lymphocytic interstitial pneumonia (LIP), chronic infections, immune reconstitution inflammatory syndrome (IRIS), bronchiectasis, malignancies, and interstitial pneumonitis. Chronic lung disease may result from recurrent or persistent pneumonia due to bacterial, mycobacterial, viral, fungal or mixed infections. In high tuberculosis (TB) prevalence areas, M. tuberculosis is an important cause of chronic respiratory illness. With increasing availability of highly active antiretroviral therapy (HAART) for children in developing countries, a rise in the incidence of IRIS due to mycobacterial or other infections is being reported. Diagnosis of chronic lung disease is based on chronic symptoms and persistent chest X-ray changes but definitive diagnosis can be difficult as clinical and radiological findings may be non-specific. Distinguishing LIP from miliary TB remains a difficult challenge in HIV-infected children living in high TB prevalence areas. Treatment includes therapy for specific infections, pulmonary clearance techniques, corticosteroids for children with LIP who are hypoxic or who have airway compression from tuberculous nodes and HAART. Children who are taking TB therapy and HAART need adjustments in their drug regimes to minimize drug interactions and ensure efficacy. Preventative strategies include immunization, chemoprophylaxis, and micronutrient supplementation. Early use of HAART may prevent the development of chronic lung disease.

Improvement of symptomatic human immunodeficiency virus-related lymphoid interstitial pneumonia in patients receiving highly active antiretroviral therapy

To analyze the impact of highly active antiretroviral therapy on lymphoid interstitial pneumonia (LIP), we reviewed the medical files of 5 human immunodeficiency virus (HIV)-infected patients in whom LIP was diagnosed during 1996-2001 who had never previously received antiretroviral treatment. Patients were mildly immunosuppressed at the time of diagnosis of LIP but had high plasma HIV loads and marked circulating and pulmonary CD8 hyperlymphocytosis. All patients improved clinically, radiologically, and functionally; improvement was accompanied by a drastic reduction in the virus load and an increase in the CD4 lymphocyte count.