Pathogenesis of some neurological immune ultrastructural and morphometrical observations on rat thymus

Abstract

Numerous studies on neuro-immuno-modulation indicate that the thymus is involved in many neurological diseases, including experimental allergic encephalomyelitis (EAE). Twenty Lewis rats were induced for EAE. At X, XII, XX and XXX days post-inoculation the animals were killed, and the thymus was recovered and harvested. Specimens of thymus were submitted to morphological light microscopy analysis (1% toluidine blue) and ultra-structural analysis (transmission electron microscopy). Significant morphometric data were collected by examining the images quantitatively and by statistically analysing the values. Our results show that the microenvironment of the thymus is severally involved in acute EAE. Thymocytes and reticular epithelial cells show many changes which are closely related to the pathogenesis of EAE. In particular we observed: (1) inside the cell an increase in intra-cytoplasmic vacuoles, and changes in the thickness of the nuclear membrane, mitochondria, rough endoplasmic reticulum, cellular inter-digitations and cellular electron-density; (2) outside the cell an increase in pericellular translucent halo, intercellular spaces, intercellular contacts and apoptotic and necrotic figures. The evidence of a thymic role in MS may suggest the intriguing therapeutic concept of thymectomy in the management of this neurological disease.

Cognitive performance and the thymus among HIV-infected subjects receiving HAART

“…Findings from these studies reveal that both alcohol and HIV may increase oxidative stress in the brain and produce pro-inflammatory and TH2 interleukins (Meyerhoff 2001). These results are of relevance to our findings, as the thymus regulates a number of the interleukins and thymic hormones, which have been demonstrated to reduce damage induced by oxidative stress in the CNS (Fabris et al 1988; Song and Bao 1991; Saito et al 1994; Zhang et al 1994; Wang and Spitzer 1997; Spangelo 1995; Antoniou et al 1997; Turrini et al 1998; Savino and Dardenne 2000; Nishiyama 2001; Morale et al 2003; Cavalloti et al 2005). …”

“…These findings are of particular relevance to our study, as neuropsychological disturbances associated with HIV-1 infection are consistent with dysfunction of frontal-subcortical circuitry (Meyerhoff 2001). Cytokines, prolactin, and thymosins are some of many candidates for the role of messengers mediating thymus induction of cognitive and psychobehavioral disorders (Fabris et al 1988; Song and Bao 1991; Saito et al 1994; Zhang et al 1994; Spangelo 1995; Antoniou et al 1997; Wang and Spitzer 1997; Turrini et al 1998; Savino and Dardenne 2000; Nishiyama 2001; Morale et al 2003; Cavalloti et al 2005). These findings confirm that our results have solid physiopathological reasons and represent more than a fortuitous association.…”

“…The immune system and central nervous system (CNS), once considered completely independent, have been demonstrated to be closely linked (Dalakas et al 1986; Fabris et al 1988; Spangelo 1995; Antoniou et al 1997; Turrini et al 1998; Savino and Dardenne 2000; Nishiyama 2001; Morale et al 2003; Cavalloti et al 2005; Fleming et al 2005). Bidirectional communication between the brain and the thymus has been described in numerous studies, in association with cytokines, hormones, growth factors, and neurotransmitters (Fabris et al 1988; Antoniou et al 1997; Morale et al 2003; Cavalloti et al 2005). These factors enable the thymus, which plays a critical role during highly active antiretroviral therapy (HAART) reconstitution, to act at sites distant from it, and it influences the ontogenesis and function of both the immune system and CNS.…”

Thymic Alterations in GM2 Gangliosidoses Model Mice

“…6A, B, 7). High expression of CXCL13 has been found previously in many autoimmune diseases, such as myasthenia gravis [31], multiple sclerosis [33], and in a model mouse of SLE [26], and is considered to be associated with autoantibody production. We have shown also in our previous study that a significant elevation of serum antibody levels occurs in the terminal stages of Hexb −/− FcRγ +/+ mice of more than 14 weeks of age [10].…”

“…In our present study, we observed a dramatic involution of the thymus in 15 week old Hexb −/− FcRγ +/+ mouse. The thymus plays a crucial role in immune system homeostasis, and thymic abnormalities have been previously reported in many autoimmune diseases, such as myasthenia gravis [31], systemic sclerosis [32], in a mouse model of systemic lupus erythematosus [24], and multiple sclerosis [33]. Since autoimmunity is found also in SD, the contribution of thymus abnormalities to the pathogenesis of this disease seems plausible.…”