Telomerase activity and apoptosis genes as parameters of lymphocyte aging in down syndrome patients

It is hypothesized that Down syndrome [DS] patients are associated with abnormalities of the immune system. Accordingly, this study was conducted to measure replicative aging and apoptosis in lymphocytes, which play an important role in the immune system, before and after being biostimulated with He:Ne laser. Replicative aging was measured in terms of telomerase activity, and ETS-2 gene relative expression. Apoptosis was measured in terms of DNA fragmentation and apoptosis genes [Fas, FasL and Bax] and antiapoptotic Bcl-2 protein. Results showed that Telomerase activity, ETS-2 mRNA expression, plasma DNA fragmentation, Fas and FasL were significantly higher among DS patients compared to controls: Telomerase activity [1.5 +/- 0.5 vs. 0.9 +/- 0.4, p < 0.001]; ETS2 mRNA expression [0.6 +/- 0.1 vs. 0.43 +/- 0.04,p < 0.0001]; plasma DNA fragmentation [0.45% +/- 0.12 vs. 0.2% +/- 0.1, p < 0.0001]; Fas protein [5.3 +/- 1.2 vs. 2.3 +/- 0.2, p < 0.0001]; FasL mRNA relative expression [0.37 +/- 0.05 vs. 0.24 +/- 0.01, p < 0.001]; Bax mRNA relative expression [0.9 +/- 0.1 vs. 0.5 +/- 0.1, p < 0.00001]. Bcl-2 protein was significantly low in DS patients compared to controls [8.6 +/- 1.3 vs. 10 +/- 2.1, p < 0.01]. He:Ne laser biostimulation applied to evaluate lymphocytes' response significantly increased the former parameters in DS patients compared to their level before irradiation, except for Bcl-2, which was significantly decreased. In conclusion: increased telomerase activity associated with increased activity and overexpression of ETS-2 on chromosome 21 in DS patients may contribute to the increased rate of early senescence in circulating lymphocytes, which consequently contributes to the abnormalities of the immune system observed in DS. Increased apoptosis is due to increased oxidative stress, which induces an increase in the apoptotic genes Bax, Fas and FasL accompanied by a decrease in the antiapoptotic gene Bcl-2

Assessment of immune function in down syndrome patients

In Down syndrome [DS], trisomy 21 leads to overexpression of gene coding for specific enzymes. This overexpression translates directly into biochemical aberrations that affect multiple interacting metabolic pathways which culminates in cellular dysfunction and contributes to the unique pathogenesis of DS. The aim of this study is to evaluate parameters of immune response in terms of cytokines [tumor necrosis factor-alpha [TNF-alpha] and interlukin-2 [IL-2]] together with the quantitative expression of cystathionine beta synthase [CBS], whose transsulfuration pathway generates cysteine and hydrogen sulfide [H[2]S]. H[2]S is known to boost host defense at physiological concentrations and to display cytotoxic activity at higher concentrations. Calcineurin activity [CAN] was also measured as its dysregulation has been shown to cause immune suppression. Subjects were 60 DS patients vs. 30 age and socioeconomic matching healthy controls. In their blood, the cytokines: TNF-alpha and IL-2, together with CBS and its by product H[2]S as well as CAN activity, were measured. Results showed that CBSmRNA relative expression [0.56 +/- .06 vs. 0.32 +/- .02], plasma H[2]S [72 +/- 8.5 vs. 50.8 +/- 4.1] and TNF-alpha [8.11 +/- .01 vs. 3.6 +/- 0.9] were significantly higher among DS patients compared to controls, while CAN [0.27 +/- 0.1 vs. 0.45 +/- 0.2 units], was significantly decreased in blood of DS patients compared to controls. IL-2 [36.4 +/- 2.6 vs. 37.4 +/- 0.9] showed no significant difference between DS patients and controls. Accordingly it can be concluded that excessive synthesis of multiple gene products derived from overexpression of the genes present on chromosome 21 may be the cause for decreased immunity in DS patients compared to controls

Indicators of apoptosis in Duchenne muscular dystrophy patients

Tissue sections of dystrophic muscle demonstrate apoptotic myonuclei in degenerating muscle fibers of Duchene muscle dystrophy [DMD] patients. The apoptosis cascade can be triggered by 2 main pathways, via an intrinsic, endogenous system such as the mitochondrial Bax/Bcl-2 or via an extrinsic system involving transmembrane receptors of the death receptor family Fas and Fas Ligand [FasL]. The present study is an attempt to demonstrate the levels of Fas and FasL and Bax/Bcl-2 in DMD pathogenesis. Subjects were 16 boys with DMD diagnosed clinically and at the molecular level versus 20 age and socioeconomic matching healthy boys. Plasma DNA fragmentation [0.38% +/- 0.12 vs. 0.2% +/- 0.15] and Fas [9.9 +/- 2.8 vs. 2 +/- 0.1, p < 0.001] together with FasL mRNA expression in circulating lymphocytes [0.47 +/- .09 vs. 0.24 +/- .04, p <0.001] were significantly increased in DMD patients compared to controls. There was a significant increase in Bax mRNA relative concentration [0.19 +/- 0.07 vs. 0.05 +/- 0.01, p <0.00001] accompanied by a significant decrease in Bcl-2 protein in circulating lymphocytes [6.4 +/- 1.6 vs l0 +/- 2.8, p <0.0001] both compared to controls. Indicate that apoptosis and its markers determined in blood of DMD patients can replace the invasive technique of tissue biopsy

Cytokines and growth factors in Duchene muscular dystrophy patients

Dystrophin deficiency associated with Duchene muscular dystrophy [DMD] results in chronic inflammation and severe skeletal muscle degeneration, where the extent of muscle fibrosis contributes to disease severity. The microenvironment of dystrophic muscles is associated with variation in levels of cytokine and growth factors. Most of the current researches test for such cytokines and growth factors in tissue biopsies, which is an invasive technique. Of the present study is to investigate whether cytokines and growth factors, as indicators of inflammatory response, can be detected in blood of DMD patients as non-invasive technique. Accordingly the cytokine tumor necrosis factor alpha [TNF TNF-alpha], as well as the growth factors basic fibroblast growth factor [bFGF] and vascular endothelial growth factor [VEGF] were measured in blood of 24 boys with DMD diagnosed clinically and at the molecular level versus 20 age matching healthy boys. Showed a significant increases in TNF-alpha [30.2 +/- 9.5 vs. 3.6 +/- 0.9 pg/ml] and bFGF [21.7 +/- 10.3 vs. 4.75 +/- 2.2 pg/ml.], while VEGF was significantly decreased [190 +/- 115 vs. 210 +/- 142 pg/ml] in blood of DMD patients compared to controls. Results provide further proof that inflammatory response is associated with DMD pathogenesis and favours the use of biomarkers in blood of such patients as a non invasive technique

Determination of candidate genes for Schistosomal fibrosis

The specific aims of this study are to characterize genetic patterns associated with schistosome-induced hepatic fibrosis and to link the development of hepatic fibrosis to polymorphic markers located near potential disease susceptibility genes. Approximately 70% of those age>11 in the community of Shamarka, in the Nile Delta were surveyed [n=2,038] for parasites and ultrasound evidence of fibrosis using the latest WHO criteria. The potential role of eleven regions containing genes that could be involved in the control of severe hepatic fibrosis was investigated by linkage analysis with the polymorphic markers. Segregation analysis was performed by the regressive logistic model. Tow - point LOD scores for various values of the recombination fraction [theta] were computed by means of the LINKAGE package and by the use of the major-gene model obtained from segregation analysis. A candidate gene search was carried out on 90 affected sibling pairs from 40 pedigrees in this community. From 2-4 single nucleotide polymorphisms [SNPs] were used per locus. Using the most conservative correction for multiple comparisons and the WHO ultrasound pattern, he INFGRI locus demonstrated a significant linkage for 1 of 4 SNPs [p=0.0014298]. The analysis further suggests that TGF beta 1 and the IL 13-4 region might also contribute to the development of fibrosis, but their scores did not reach significance after correction. The present work shows that severe fibrosis in subjects infected by S. mansoni is determined by a major locus that maps close to the IFN-gamma R1 gene. This finding opens that way to both the identification of the gene and the evaluation of its role in the determination of abnormal fibrosis of other etiological origins. Finally, our results will stimulate new strategies in drug and vaccine development