Blood-borne soluble protein antigen intensifies T cell activation in autoimmune CNS lesions and exacerbates clinical disease.

We explored the effect of i.v. soluble antigen on autoaggressive, myelin basic protein-specific effector T cells within their target organ during acute experimental autoimmune encephalomyelitis (EAE). Intravital two-photon imaging revealed that i.v. autoantigen reached the CNS and was taken up and processed by antigen-presenting cells within 30 min after injection. The exogenous autoantigen dramatically changed the motility and function of autoreactive effector T cells within the EAE lesions: T cells that had been cruising through the tissue slowed down and became tethered to local antigen-presenting cells within 1 h. One hour later, the effector T cells massively produced proinflammatory cytokines and up-regulated membranous activation markers. This strong activation of the T cells boosted CNS inflammation and aggravated clinical disease. Postactivated effector and resting memory T cells specific for a non-CNS antigen (ovalbumin) were recruited to EAE lesions and moved there without contacting antigen-presenting cells. These cells were similarly arrested and activated after i.v. infusion of ovalbumin, and they also exacerbated clinical disease. Our data are relevant for autoantigen-based therapies of autoimmune disorders. Further, the study indicates how brain unrelated antigens (microbial components) leaking into the chronically inflamed CNS through the bloodstream might trigger relapses in multiple sclerosis.

A new mtDNA mutation associated with a progressive encephalopathy and cytochrome c oxidase deficiency.

The authors describe a novel pathogenic G5540A transition in the mitochondrial transfer RNA (tRNA)Trp gene of a sporadic encephalomyopathy characterized by spinocerebellar ataxia. Clinical features also included neurosensorial deafness, peripheral neuropathy, and dementia. Biochemistry revealed a severe reduction of cytochrome c oxidase (COX) activity. Single-fiber PCR demonstrated higher levels of mutant genomes in COX-negative ragged red fibers than in normal fibers. These findings confirm that COX is more susceptible than other respiratory chain complexes to mutations in the mitochondrial tRNATrp gene.

Single-fiber PCR in MELAS(3243) patients: correlations between intratissue distribution and phenotypic expression of the mtDNA(A3243G) genotype.

We performed morphological, biochemical, and genetic studies, including single-fiber PCR (sf PCR), on muscle biopsies obtained from a mother and daughter with MELAS syndrome due to the A3243G transition of mitochondrial DNA (mtDNA). The severity of muscle involvement appeared quite distinct, in spite of the fact that both patients segregated similar mutant mtDNA levels on total muscle DNA. The daughter did not show any clinical muscle involvement: muscle biopsy revealed many ragged red fibers (RRFs) mostly positive for cytochrome-c oxidase (COX) activity. In contrast, her mother had developed a generalized myopathy without progressive external ophthalmoplegia (PEO), morphologically characterized by many COX-negative RRFs. Single-muscle fiber PCR demonstrated in both patients significantly higher percentages of wild-type mtDNA in normal fibers (daughter: 23.25 +/- 15.22; mother: 43.13 +/- 26.11) than in COX-positive RRFs (daughter: 11.25 +/- 5.22, P < 0.005; mother: 9.12 +/- 5.9, P < 0.001) and in COX-negative RRFs (daughter: 8.9 +/- 4.2, P < 0.001 mother: 4.8 +/- 2.8, P < 0.001). Wild-type mtDNA levels resulted higher also in COX-positive vs. COX-negative RRFs (daughter: P < 0.05; mother: P < 0.001). Our data confirm a direct correlation between A3243G levels and impairment of COX function at the single-muscle fiber level. Moreover, the evidence of a clinical myopathy in the patient with higher amounts of COX-negative RRFs bolsters the concept that a differential distribution of mutant mtDNAs at the cellular level may have effects on the clinical involvement of individual tissues. However, the occurrence of a similar morphological and biochemical muscle phenotype also in PEO(3243) patients suggests that other genetic factors involved in the interaction between mitochondrial and nuclear DNA, rather than the stochastic distribution of mtDNA genomes during embryogenesis, are primarily implicated in determining the various clinical expressions of the A3243G of mtDNA.

Cancer mortality in the Republic of San Marino.

San Marino is a small independent Republic encircled by Italy, with a population of approximately 20,000. It still maintains an ethnic profile favoured by a tendency to genetic segregation due to endogamy. Since 1908 detailed data have been kept on all deaths among residents also for those dying outside the country. In this study the mortality trends based on crude rates are reported for all neoplasms and for selected sites in the years 1908 to 1980, showing increased rates for all neoplasms and the highest rate for stomach cancer. Age-adjusted death rates were calculated for all neoplasms and for selected sites, by sex, in the years 1966 to 1980. Stomach cancer was the commonest cause of cancer death in San Marino and its age-adjusted death rate was the highest in the world. A sharp increase was also observed for respiratory tract and colorectal cancers in recent years.

Apoptosis and ROS detoxification enzymes correlate with cytochrome c oxidase deficiency in mitochondrial encephalomyopathies.

The aim of this work was to investigate in muscle the role of apoptosis and of oxidative stress in mitochondrial disorders with dysfunction of respiratory chain. In patients with cytochrome c oxidase deficiency (COX) we found a variable number of myofibers with apoptotic nuclei that matched with the level of enzymatic reduction and roughly correlated with muscle weakness. In parallel, a positive immunostaining for apoptosis-related proteins and Mn and Cu/Zn superoxide dismutase (SOD) were mostly localized in COX-negative fibers. Moreover, glutathione peroxidase activity was increased in muscles with high number of SOD-positive myofibers and prominent apoptotic features. No signs of apoptosis were observed in patients with deficiencies of complexes I and II and without muscle weakness. These data suggest that apoptosis along with increased ROS production, revealed by anti-oxidant enzymes overexpression, may play an important role in the pathophysiology of mitochondrial diseases associated with COX deficiency.