Barbara P. Barna

Interferon-β impairs induction of HLA-DR antigen expression in cultured adult human astrocytes☆

We studied the effect of interferons on the expression of class II histocompatibility (HLA-DR) antigens by cultured adult human astrocytes. Cultures were derived from brain tissue resected for surgical treatment of intractable epilepsy. Cultured astrocytes did not spontaneously display HLA-DR antigen as determined by immunocytochemistry and flow cytometry with antibody to HLA-DR. Astrocytes cultured for 72 h with recombinant or natural interferon-gamma (IFN gamma) demonstrated a dose-dependent increase in HLA-DR expression with optimal stimulation by 100 U/ml IFN gamma. HLA-DR expression was not detectable in astrocytes cultured with IFN gamma for less then 48 h, and peak HLA-DR expression (over 80% of cells) was seen at 120 h of culture. Optimal HLA-DR expression required continuous presence of IFN gamma. Exposure of astrocytes to recombinant or natural interferon-beta (IFN beta) did not induce HLA-DR and pretreatment of astrocytes with IFN beta or interferon-alpha (IFN alpha) significantly inhibited subsequent induction of HLA-DR expression by IFN gamma. These observations suggest that interferons may function in regulating human astrocyte HLA-DR expression within the central nervous system.

Granulomatous disease associated with pulmonary deposition of titanium.

A patient presented with granulomatous lung disease associated with the pulmonary deposition of various metallic particles. To evaluate the relation between the metallic dust and the granulomatous process, lymphocyte transformation tests to aluminium sulphate, titanium chloride, beryllium sulphate, and nickel sulphate were performed. A lymphocyte proliferative response to titanium chloride was observed on two separate occasions; no responses to the other metals were shown. These results are consistent with hypersensitivity to titanium, and suggest, in this individual, a possible aetiological role between the inhalation of titanium and a granulomatous disease process.

Activation of alveolar macrophage TNF and MCP-1 expression in vivo by a synthetic peptide of C-reactive protein.

Administration of multilamellar vesicles (MLV) encapsulating a synthetic peptide (RS‐83277) derived from human C‐reactive protein (CRP) augments anti‐tumor activity of murine alveolar macrophages and reduces established pulmonary metastases of experimental tumors. To explore mechanisms involved in these phenomena, we investigated cytokine and integrin (CD11b) expression of bronchoalveolar lavage (BAL)‐derived alveolar macrophages in control (blank MLV) and RS‐83277‐MLV‐treated C57B1 mice. Alveolar macrophage production of tumor necrosis factor α (TNF‐α) and monocyte chemoattractant bioactivity increased at 48 h after treatment with RS‐83277‐MLV but not control MLV. Chemoattractant activity was neutralized by antibody to monocyte chemoattractant protein‐1 (MCP‐1), but not irrelevant immunoglobulin G (IgG). Changes were reflected by augmented TNF‐α and MCP‐1 mRNA levels in pulmonary tissue and enhanced CD11b expression on mononuclear leukocytes derived from total lung tissue, but not on BAL‐derived alveolar macrophages. Results suggest that RS‐83277‐MLV treatment is associated with activation of alveolar macrophage TNF‐α and MCP‐1 production and up‐regulation of adhesion molecules on pulmonary mononuclear leukocytes but not on alveolar macrophages.

Elevated MicroRNA-33 in Sarcoidosis and a Carbon Nanotube Model of Chronic Granulomatous Disease

We established a murine model of multiwall carbon nanotube (MWCNT)-induced chronic granulomatous disease, which resembles human sarcoidosis pathology. At 60 days after oropharyngeal MWCNT instillation, bronchoalveolar lavage (BAL) cells from wild-type mice exhibit an M1 phenotype with elevated proinflammatory cytokines and reduced peroxisome proliferator-activated receptor γ (PPARγ)-characteristics also present in human sarcoidosis. Based upon MWCNT-associated PPARγ deficiency, we hypothesized that the PPARγ target gene, ATP-binding cassette (ABC) G1, a lipid transporter with antiinflammatory properties, might also be repressed. Results after MWCNT instillation indicated significantly repressed ABCG1, but, surprisingly, lipid transporter ABCA1 was also repressed, suggesting a possible second pathway. Exploration of potential regulators revealed that microRNA (miR)-33, a lipid transporter regulator, was strikingly elevated (13.9 fold) in BAL cells from MWCNT-instilled mice but not sham control mice. Elevated miR-33 was also detected in murine granulomatous lung tissue. In vitro studies confirmed that lentivirus-miR-33 overexpression repressed both ABCA1 and ABCG1 (but not PPARγ) in cultured murine alveolar macrophages. BAL cells of patients with sarcoidosis also displayed elevated miR-33 together with reduced ABCA1 and ABCG1 messenger RNA and protein compared with healthy control subjects. Moreover, miR-33 was elevated within sarcoidosis granulomatous tissue. The findings suggest that alveolar macrophage miR-33 is up-regulated by proinflammatory cytokines and may perpetuate chronic inflammatory granulomatous disease by repressing antiinflammatory functions of ABCA1 and ABCG1 lipid transporters. The results also suggest two possible pathways for transporter dysregulation in granulomatous disease-one associated with intrinsic PPARγ status and the other with miR-33 up-regulation triggered by environmental challenges, such as MWCNT.

Exposure to a Mycobacterial Antigen, ESAT-6, Exacerbates Granulomatous and Fibrotic Changes in a Multiwall Carbon Nanotube Model of Chronic Pulmonary Disease

Recent studies suggest additive effects of environmental pollutants and microbial antigens on respiratory disease. We established a granuloma model in which instilled multiwall carbon nanotubes (MWCNT) elicit granulomatous pathology. We hypothesized that mycobacterial antigen ESAT-6, a T cell activator associated with tuberculosis and sarcoidosis, might alter pathology. Wild-type C57Bl/6 mice received MWCNT with or without ESAT-6 peptide. Controls received vehicle (surfactant-PBS) or ESAT-6 alone. Mice were evaluated 60 days later for granulomas, fibrosis, and bronchoalveolar lavage (BAL) cell expression of inflammatory mediators (CCL2, MMP-12, and Osteopontin). Results indicated increased granulomas, fibrosis, and inflammatory mediators in mice receiving the combination of MWCNT+ESAT-6 compared to MWCNT or vehicle alone. ESAT-6 alone showed no significant effect on these pathological endpoints. However, CD3 (+) lymphocyte infiltration of lung tissue increased with MWCNT+ESAT-6 versus MWCNT alone. Findings suggest that concurrent exposure to microbial antigen and MWCNT exacerbates chronic pulmonary disease.