Abstract
Leprosy is a chronic granulomatous infection of skin and peripheral nerves caused by Mycobacterium leprae and is considered the main infectious cause of disability worldwide. Despite the several studies regarding leprosy, little is known about its effects on microvascular structure and function in vivo. Thus, we have aimed to compare skin capillary structure and functional density, cutaneous vasomotion (spontaneous oscillations of arteriolar diameter), which ensures optimal blood flow distribution to skin capillaries) and cutaneous microvascular blood flow and reactivity between ten men with lepromatous leprosy (without any other comorbidity) and ten age- and gender-matched healthy controls. Orthogonal polarization spectral imaging was used to evaluate skin capillary morphology and functional density and laser Doppler flowmetry to evaluate blood flow, vasomotion and spectral analysis of flowmotion (oscillations of blood flow generated by vasomotion) and microvascular reactivity, in response to iontophoresis of acetylcholine and sodium nitroprusside. The contribution of different frequency components of flowmotion (endothelial, neurogenic, myogenic, respiratory and cardiac) was not statistically different between groups. However, endothelial-dependent and -independent vasodilatations elicited by acetylcholine and sodium nitroprusside iontophoresis, respectively, were significantly reduced in lepromatous leprosy patients compared to controls, characterizing the existence of microvascular dysfunction. These patients also presented a significant increase in the number of capillaries with morphological abnormalities and in the diameters of the dermal papilla and capillary bulk when compared to controls. Our results suggest that lepromatous leprosy causes severe microvascular dysfunction and significant alterations in capillary structure. These structural and functional changes are probably induced by exposure of the microvascular bed to chronic inflammation evoked by the Mycobacterium leprae.
Highlights
Leprosy is a chronic granulomatous infection of skin and peripheral nerves caused by the Mycobacterium leprae [1]
Healthy participants and lepromatous leprosy (LL) patients did not have obesity or hypertension and there was no significant difference between groups in age, height, weight, body mass index (BMI) and systolic blood pressure (SBP)
All patients were normotensive, the diastolic blood pressure (DBP) in LL patients was statistically higher compared to controls
Summary
Leprosy is a chronic granulomatous infection of skin and peripheral nerves caused by the Mycobacterium leprae [1]. This obligatory intracellular pathogen causes nerve damage that affects sensory, motor and autonomic fibers resulting in disabilities and deformities [2,3]. In the last 50 years the prevalence of leprosy has reduced; the transmission still occurs and it remains an important public health problem worldwide [4]. Despite the several studies regarding leprosy epidemiology, immunological reactions, peripheral nerve infection and clinical features, little is known about its effects on the microcirculation in vivo. The microcirculation is the part of the vascular bed that encompasses vessels with diameters inferior to100 μm (arterioles, capillaries and venules), where delivery of oxygen and nutrients to tissues and removal of cellular waste as well as the control of peripheral vascular resistance occur [6,7]
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