Mycobacterial trehalose 6,6'-dimycolate induced vascular occlusion is accompanied by subendothelial inflammation.

Mycobacterium tuberculosis (MTB) is a pathogen that infects and kills millions yearly. The mycobacterium's cell wall glycolipid trehalose 6,6'-dimycolate (TDM) has been used historically to model MTB induced inflammation and granuloma formation. Alterations to the model can significantly influence the induced pathology. One such method incorporates intraperitoneal pre-exposure, after which the intravenous injection of TDM generates pathological damage effectively mimicking the hypercoagulation, thrombus formation, and tissue remodeling apparent in lungs of infected individuals. The purpose of these experiments is to examine the histological inflammation involved in the TDM mouse model that induces development of the hemorrhagic response. TDM induced lungs of C57BL/6 mice to undergo granulomatous inflammation. Further histological examination of the peak response demonstrated tissue remodeling consistent with hypercoagulation. The observed vascular occlusion indicates that obstruction likely occurs due to subendothelial localized activity leading to restriction of blood vessel lumens. Trichrome staining revealed that associated damage in the hypercoagulation model is consistent with intra endothelial cell accumulation of innate cells, bordered by collagen deposition in the underlying parenchyma. Overall, the hypercoagulation model represents a comparative pathological instrument for understanding mechanisms underlying development of hemorrhage and vascular occlusion seen during MTB infection.

Mycobacterial glycolipid cord factor trehalose 6,6'-dimycolate causes a decrease in serum cortisol during the granulomatous response.

Serum cortisol levels were evaluated in mice following intravenous administration of purified mycobacterial glycolipid trehalose 6,6'-dimycolate (TDM). C57BL/6 mice develop lung granulomas in response to TDM, while A/J mice are deficient in this process. Administration of TDM to C57BL/6 mice led to a rapid reduction in serum cortisol, concurrent with initiation of the granulomatous response and cytokine and chemokine mRNA induction. Cortisol levels were lowest on day 5 after TDM administration, but there was significant production of IL-6, TNF-alpha and IL-1beta messages. Granuloma formation and full immune responsiveness to TDM were only apparent upon a sufficient decrease in levels of systemic cortisol. Treatment of the C57BL/6 mice with hydrocortisone abolished inflammatory responses. Histologically nonresponding A/J mice exhibited higher constitutive serum cortisol and demonstrated different kinetics of cortisol reduction upon administration of TDM. A/J mice demonstrated hyperplastic morphology in the suprarenal gland with a high degree of vacuolization in the medullary region and activation of cells in the zona fasciculata and zona reticularis. The A/J mice were dysregulated with respect to cytokine responses thought to be necessary during granuloma formation. The high constitutive serum cortisol in the A/J mice may therefore contribute to pulmonary immunoresponsiveness and the establishment of an environment counterproductive to the initiation of granulomatous responses. The identification of a mycobacterial glycolipid able to influence serum cortisol levels is unique and is discussed in relation to immunopathology during tuberculosis disease.

Measurement of serum monocyte chemoattractant protein-1 and its clinical application for estimating the activity of granuloma formation in sarcoidosis.

BACKGROUND AND AIM OF THE WORK: The role of monocyte chemoattractant protein-1 (MCP-1) in bronchoalveolar lavage fluids from sarcoidosis patients was previously reported. To study the role of MCP-1, we evaluated the serum MCP-1 and its clinical significance in sarcoidosis. METHODS: The serum MCP-1 level was measured in 47 patients with sarcoidosis and 10 normal healthy controls with the use of an enzyme-linked immunosorbent assay. The localization and mRNA expression of MCP-1 in sarcoid lymph nodes were evaluated by an immunohistochemical method using an anti-MCP-1 monoclonal antibody and an in situ hybridization technique to determine the cellular source(s) of MCP-1. RESULTS: Serum MCP-1 levels were significantly elevated in the sarcoidosis patients compared with the healthy controls (698.3 +/- 101.9 vs. less than 39 pg/ml, p < 0.001). A comparison of the patients' serum MCP-1 levels among standard radiographic stages revealed that the serum MCP-1 was significantly higher in early stages: stage 0 vs. III, and stage I vs. II. In addition, the serum MCP-1 levels were significantly correlated with the serum angiotensin converting enzyme levels (r = 0.539, p = 0.0006). MCP-1 expression was detected in macrophages peripheral to the epithelioid granuloma in sarcoid lymph nodes, by both immunohistochemistry and in situ hybridization. CONCLUSIONS: These data suggest that MCP-1 may be expressed by the macrophages in the granuloma throughout the body, and that the measurement of serum MCP-1 levels may have clinical value as an indicator in estimating the activity of granuloma formation throughout the body in sarcoidosis.