Short report: Cyclooxygenase 2 expression in vessels and nerves in reversal reaction leprosy

Tissue expression of cyclooxygenase (COX)2, an inducible enzyme synthesizing eicosanoids in inflammation, was studied in reversal reaction (RR) leprosy in comparison with nonreactionary leprosy. COX2 was consistently expressed in cells of the mononuclear-macrophage lineage across the leprosy spectrum. Only in RR, the following two additional sites showed COX2 expression in the dermis and subcutis: 1) microvessels and 2) nerve bundles and isolated nerve fibers. The same sites also express vascular endothelial growth factor (VEGF). This is in keeping with experimental models relating VEGF to COX2 expression, with VEGF enhancing prostaglandin production through COX2 stimulation and prostaglandin synthase expression. We postulate that selective COX2 inhibitors, which are currently used in several inflammatory conditions, could be considered for RR treatment to reduce acute symptoms caused by tissue edema and possibly prevent long-term nerve damage, the main complication of RR.

Untreated lepromatous leprosy: histopathological findings in cutaneous blood vessels

Skin biopsies from 100 patients with untreated lepromatous leprosy from Malaysia, India, Africa, and South America were examined with particular regard to pathological changes in intima, media, or adventitia of blood vessels and to the presence of leprosy bacilli in these layers. Bacilli were found in capillaries, venules, or arterioles in all cases, and in many instances they were present in endothelial lining cells or smooth muscle in large masses (globi). In several cases, solid-staining bacilli in endothelial lining cells were especially prominent. The findings are discussed in relation to a) the continuous bacteremia of lepromatous leprosy, b) the role of endothelial cells in phagocytosis, c) smooth muscle cells of the media as a site in which bacilli may persist, and d) the transmission of human leprosy by biting arthropods.