Structural and functional changes in the microcirculation of lepromatous leprosy patients - Observation using orthogonal polarization spectral imaging and laser Doppler flowmetry iontophoresis

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.

Tuberculoid leprosy: An in vivo microvascular evaluation of cutaneous lesions

“…In other words, microvascular function in TT skin lesions was preserved. Using the same technique, our group demonstrated that LL (the other polar form of Leprosy) caused a significant impairment of endothelial dependent and independent vasodilatations, which evidence an expressive microvascular dysfunction in these patients [22]. Ultrastructural studies of skin biopsies of LL patients revealed endothelial infection by M. leprae [6,34].…”

“…Decreased blood perfusion was also reported by our group in the other polar form of leprosy. In this recent study Treu and coworkers [22], using orthogonal polarization spectral imaging (OPS), showed that LL patients have a significant lower functional capillary density (number of perfused capillaries/mm 2 ) in their skin compared to healthy controls. In addition to functional capillary density, estimated by PVD, SDF allows the evaluation of FHI, which is the difference between the highest MFI and the lowest MFI divided by the mean MFI.…”

“…Endothelium-dependent and -independent vasodilatations were evaluated by LDF combined to iontophoresis of ACh and SNP, respectively. This protocol was adapted from [18,22], since we needed to perform iontophoresis of ACh and SNP exactly at the same sites (surface of the skin lesion or the surface of control skin in the contralateral limb). In general, different sites were used for ACh and SNP iontophoresis.…”

Structural aspects of lesional and non-lesional skin microbiota reveal key community changes in leprosy patients from India

“…This leads to development of anesthetic skin patch and peripheral nerve thickening [27][28][29] . The skin lesions thus developed due to nerve damage and loss of sensory perception has gross micro-vascular dysfunction and significant alterations in blood capillary network and these changes are attributed to inflammation 30 . Such altered blood flow may result in altered hydration levels of skin that changes in resident microbial community structure.…”

Heart Failure in a Patient with Leprosy

“…7 Treu et al showed lepromatous leprosy causes severe microvascular dysfunction and significant alterations in capillary structure. 8 Since microvascular dysfunction is a systemic process that occurs similarly in the entire body, 9 it is possible to consider that the impairment of microvascular function observed in the skin microvasculature also occurs in the coronary microcirculation, which results in heart failure.…”