The –A162G polymorphism of the PON1 gene and the risk of sporadic amyotrophic lateral sclerosis

Clinical perspective on oxidative stress in sporadic amyotrophic lateral sclerosis

Sporadic amyotrophic lateral sclerosis (ALS) is one of the most devastating neurological diseases; most patients die within 3 to 4 years after symptom onset. Oxidative stress is a disturbance in the pro-oxidative/antioxidative balance favoring the pro-oxidative state. Autopsy and laboratory studies in ALS indicate that oxidative stress plays a major role in motor neuron degeneration and astrocyte dysfunction. Oxidative stress biomarkers in cerebrospinal fluid, plasma, and urine are elevated, suggesting that abnormal oxidative stress is generated outside of the central nervous system. Our review indicates that agricultural chemicals, heavy metals, military service, professional sports, excessive physical exertion, chronic head trauma, and certain foods might be modestly associated with ALS risk, with a stronger association between risk and smoking. At the cellular level, these factors are all involved in generating oxidative stress. Experimental studies indicate that a combination of insults that induce modest oxidative stress can exert additive deleterious effects on motor neurons, suggesting that multiple exposures in real-world environments are important. As the disease progresses, nutritional deficiency, cachexia, psychological stress, and impending respiratory failure may further increase oxidative stress. Moreover, accumulating evidence suggests that ALS is possibly a systemic disease. Laboratory, pathologic, and epidemiologic evidence clearly supports the hypothesis that oxidative stress is central in the pathogenic process, particularly in genetically susceptive individuals. If we are to improve ALS treatment, well-designed biochemical and genetic epidemiological studies, combined with a multidisciplinary research approach, are needed and will provide knowledge crucial to our understanding of ALS etiology, pathophysiology, and prognosis.

Polymorphisms of paraoxonase 1 and 2 genes and the risk of multiple sclerosis in the Polish population

BACKGROUND AND PURPOSE

The aim of this study was to test the hypothesis that polymorphisms of the paraoxonase genes PON1 and PON2 may be associated with increased risk of developing multiple sclerosis (MS) in the Polish population.

MATERIAL AND METHODS

We studied the significance of the PON gene polymorphisms C311S, A162G, Q192R and L55M in 221 patients (including 145 women) with MS and in 661 healthy controls. In the MS population, mean Expanded Disability Status Scale score was 2.92, mean age was 36.8 years, and mean disease duration was 7.7 years. PON genotyping was determined using polymerase chain reaction and restriction enzyme digestion.

RESULTS

According to our results, the PON1 and PON2 genotypes distribution did not differ between the MS patients and the controls.

CONCLUSIONS

The polymorphisms of the PON genes studied are not related to increased risk of MS in the Polish population.

[The role of neurotrophic factors in regeneration of the nervous system]

Neurotrophic factors regulate survival, development, and function of nervous tissue. They act via two different classes of receptors and activation of various signaling pathways in the target cells. Illumination of their physiological role in the maintenance of central nervous system homeostasis as well as regeneration of damaged tissue have ignited expectations to heal neurodegenerative diseases, including amyotrophic late-ral sclerosis and Parkinson disease. Advances in pharmaco-therapy, gene therapy, and stem cell biology have enabled development of novel therapies with application of regenerating cell transplantation. In the foreseeable future, it may lead to the establishment of safe and effective ways of treatment of these severe and currently incurable diseases.

Paraoxonase gene polymorphism and the risk for Alzheimer's disease in the polish population

BACKGROUND

The relationship between different paraoxonase (PON) gene polymorphisms and the risk of Alzheimer's disease (AD) was studied several times and the results were controversial.

METHODS

We investigated the association of 4 single-nucleotide polymorphisms (SNPs) of the PON1 (M55L; Q192R; -161C/T) and the PON2 (C311S) genes that were shown to affect the risk of sporadic AD. We studied 360 Caucasian cases with late-onset AD and 354 nondemented controls.

RESULTS

No significant differences were observed between the studied PON SNPs and AD risk. The results did not change after stratification of the apolipoprotein E status. Meta-analyses of studies in Caucasians assessing the associations between the PON1 M55L, -161C/T and Q192R SNPs and the risk of AD were performed, and no associations were found.

CONCLUSION

Our results suggest that the studied PON1 and PON2 polymorphisms are not associated with late-onset AD.

Role of paraoxonase 1 (PON1) in organophosphate metabolism: implications in neurodegenerative diseases

Organophosphate pesticides are a class of compounds that are widely used in agricultural and rural areas. Paraoxonase 1 (PON1) is a phase-I enzyme that is involved in the hydrolysis of organophosphate esters. Environmental poisoning by organophosphate compounds has been the main driving force of previous research on PON1 enzymes. Recent discoveries in animal models have revealed the important role of the enzyme in lipid metabolism. However although PON1 function is well established in experimental models, the contribution of PON1 in neurodegenerative diseases remains unclear. In this minireview we summarize the involvement of PON1 genotypes in the occurrence of Parkinson's disease, Alzheimer's disease and amyotrophic lateral sclerosis. A brief overview of latest epidemiological studies, regarding the two most important PON1 coding region polymorphisms PON1-L55M and PON1-Q192R is presented. Positive and negative associations of PON1 with disease occurrence are reported. Notably the MM and RR alleles contribute a risk enhancing effect for the development of some neurodegenerative diseases, which may be explained by the reduced lipoprotein free radical scavenging activity that may give rise to neuronal damage, through distinct mechanism. Conflicting findings that fail to support this postulate may represent the human population ethnic heterogeneity, different sample size and environmental parameters affecting PON1 status. We conclude that further epidemiological studies are required in order to address the exact contribution of PON1 genome in combination with organophosphate exposure in populations with neurodegenerative diseases.