Mycobacterium leprae in neurons of the medulla oblongata and spinal cord in leprosy.

Peripheral neuropathy has been extensively studied in leprosy, a chronic disease caused by Mycobacterium leprae, but the central nervous system (CNS) is thought to be free from bacilli. Involvement of the CNS was explored in autopsy cases of clinically cured lepromatous leprosy (n = 67) and in non-leprosy cases (n = 15). Paraffin sections of the medulla oblongata and spinal cord were subjected to hematoxylin and eosin staining, Fite acid-fast staining, and anti-phenolic glycolipid-I (PGL-I) immunostaining. PGL-I-positive areas were microdissected from selected cases and nested polymerase chain reaction (PCR) targeting the M. leprae-specific repetitive sequence was performed. Of the 67 cases of leprosy, 44 (67%) had vacuolar changes of motor neurons either in medulla oblongata (nucleus ambiguous or hypoglossal nucleus) or spinal cord. Fite staining was negative, but PGL-I was positive in vacuolated areas. PCR revealed M. leprae-specific genomic DNA in 18 of 19 cases (95%) with vacuolated changes and 5 of 8 (63%) without vacuolated changes. All of above findings were negative in control cases. Terminal deoxynucleotidyl transferase dUTP nick-end labeling staining did not show a significant increase of apoptosis in the neurons. The PCR positivity had a significant correlation with PGL-I immunostaining (p < 0.05). The presence of vacuolar changes in the spinal cord was correlated with hand and feet deformity grades (p = 0.04). This study provides significant additional evidence to indicate that M. leprae is present in the CNS in a subset of patients. Further investigation is required to correlate this finding to motor dysfunction and silent neuropathy in leprosy.

Developmental changes in the fibre population of the optic nerve follow an avian/mammalian-like pattern in the turtle Mauremys leprosa.

The changes in the axon and growth cone numbers in the optic nerve of the freshwater turtle Mauremys leprosa were studied by electron microscopy from the embryonic day 14 (E14) to E80, when the animals normally hatch, and from the first postnatal day (P0) to adulthood (5 years on). At E16, the first axons appeared in the optic nerve and were added slowly until E21. From E21, the fibre number increased rapidly, peaking at E34 (570,000 fibres). Thereafter, the axon number decreased sharply, and from E47 declined steadily until reaching the mature number (about 330,000). These observations indicated that during development of the retina there was an overproduction and later elimination of retinal ganglion cells. Growth cones were first observed in the optic nerve at as early as E16. Their number increased rapidly until E21 and continued to be high through E23 and E26. After E26, the number declined steeply and by E40 the optic nerve was devoid of growth cones. These results indicated that differentiation of the retinal ganglion cells occurred during the first half of the embryonic life. To examine the correlation between the loss of the fibres from the optic nerve and loss of the parent retinal ganglion cells, retinal sections were processed with the TUNEL technique. Apoptotic nuclei were detected in the ganglion cell layer throughout the period of loss of the optic fibres. Our results showed that the time course of the numbers of the fibres in the developing turtle optic nerve was similar to those found in birds and mammals.

TUNEL and limited immunophenotypic analyses of apoptosis in paucibacillary and multibacillary leprosy lesions.

Some mycobacterial infections, such as tuberculosis, are characterized by apoptosis of infected or by-stander mononuclear immune cells. For localized (paucibacillary, PB) and disseminated (multibacillary, MB) leprosy, characterized by polarized Th1-like vs. Th2-like immune responses, respectively, little is known about lesional apoptosis. We analyzed sections of paraffin-embedded, untreated leprosy lesions from 21 patients by an indirect immunofluorescent terminal deoxynucleotide-transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL) assay. Some TUNEL (+) PB sections were then reacted with phycoerythrin-conjugated (red) antibodies against T cells, monocytes, or antigen-presenting (Langerhans) cells. TUNEL (+) bodies were detected in 9 of 16 PB lesions (56%) and in 1 of 5 MB lesions (20%). Some TUNEL (+) bodies in PB disease were CD3+ (T cell), as well as CD4+ (T-helper) or CD8+ (T-cytotoxic). Apoptosis characterizes PB and MB leprosy lesions and may be more frequent in PB disease. In PB disease, some TUNEL (+) bodies may derive from T cells.

Rifampicin attenuates brain damage in focal ischemia.

Rifampicin is an antibacterial agent that is widely used in tuberculosis and leprosy therapy. Interestingly, some experimental studies indicate that rifampicin acts as a hydroxyl radical scavenger and a glucocorticoid receptor activator. In this study, the neuroprotective effect of rifampicin was evaluated after transient and permanent focal cerebral ischemia. Anaesthetized male C57BL/6j mice were submitted to permanent or transient thread occlusion of the middle cerebral artery (MCA). Reperfusion in transient ischemia was initiated 30 min later by thread retraction. Rifampicin or vehicle were applied intraperitoneally before permanent or immediately after 30 min of transient ischemia. Later, 24 h after permanent or transient ischemia, animals were re-anesthetized and decapitated. Brain injury was evaluated by triphenyltetrazolium chloride staining (TTC), terminal transferase biotinylated-dUTP nick end labeling (TUNEL) and cresyl violet staining. A 20-mg/kg sample of rifampicin showed a significant neuroprotection after cerebral ischemia. The number of TUNEL-positive cells in the striatum, where disseminated tissue injury was observed, was also reduced by application of rifampicin as compared with vehicle-treated animals. The present report shows that administration of rifampicin efficiently reduces brain injury after permanent and transient focal cerebral ischemia in mice.