Processes of plasma protein N-homocysteinylation in multiple sclerosis

Oxidative Stress Markers in Multiple Sclerosis

The pathogenesis of multiple sclerosis (MS) is not completely understood, but genetic factors, autoimmunity, inflammation, demyelination, and neurodegeneration seem to play a significant role. Data from analyses of central nervous system autopsy material from patients diagnosed with multiple sclerosis, as well as from studies in the main experimental model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE), suggest the possibility of a role of oxidative stress as well. In this narrative review, we summarize the main data from studies reported on oxidative stress markers in patients diagnosed with MS and in experimental models of MS (mainly EAE), and case-control association studies on the possible association of candidate genes related to oxidative stress with risk for MS. Most studies have shown an increase in markers of oxidative stress, a decrease in antioxidant substances, or both, with cerebrospinal fluid and serum/plasma malonyl-dialdehyde being the most reliable markers. This topic requires further prospective, multicenter studies with a long-term follow-up period involving a large number of patients with MS and controls.

Serum Homocysteine Level Is a Predictor of Relapse and Prognosis in Patients With First-Attack Neuromyelitis Optica Spectrum Disorders

Background: Many patients with neuromyelitis optica spectrum disorders (NMOSD) experience the adverse consequences of relapse and disability aggravation. Thus, it is necessary to identify sensitive and reliable biomarkers for early prognosis. This study investigated whether serum homocysteine (Hcy) level was associated with the risk of relapse or poor prognosis in first-attack NMOSD patients.

Methods: We enrolled 161 first-attack NMOSD patients in this retrospective study. We reviewed their medical records and evaluated their initial Expanded Disability Status Scale (EDSS). Clinical outcomes were measured by the final EDSS and the relapse rate. The association between Hcy levels and EDSS score at last follow-up was analyzed by binary logistic regression. The association between Hcy levels and relapse rate was assessed by Cox regression analysis. Receiver operating characteristic (ROC) curve analysis was used to predict the target value of Hcy reduction.

Results: Compared with the high Hcy group, the final EDSS score in the low Hcy group was significantly lower (median: 0.5 vs. 2.5, P < 0.001). The relapse rate differed significantly between these groups (30.6 vs. 50.0%, P = 0.023). Multivariate analysis showed that the initial EDSS score (odds ratio [OR] 3.03, 95% confidence interval [CI] 2.07–4.45, P < 0.001) and serum Hcy level (OR 1.13, 95%CI 1.04–1.22, P = 0.002) were significantly associated with poor prognosis in NMOSD patients. Additionally, multivariate analysis showed that serum Hcy level (hazard ratio 1.06, 95%CI 1.04–1.09, P < 0.001) was an independent predictor of the risk for relapse in NMOSD. The 12-month relapse rate of the high Hcy group was 34.8%, and 50% of high Hcy patients relapsed within 35 months after the first onset. A serum Hcy level exceeding 14.525 μmol/L indicated a high risk of relapse, with a sensitivity of 43.7%, specificity of 90.0%, and area under the ROC curve of 0.674 (95%CI 0.59–0.76, P < 0.001).

Conclusion: Serum Hcy level is an independent predictor of relapse and poor prognosis in first-attack NMOSD patients. Early monitoring and reduction of serum Hcy levels may be of great significance in the prevention of disease relapse and severe disability.

Paraoxonase Role in Human Neurodegenerative Diseases

The human body has biological redox systems capable of preventing or mitigating the damage caused by increased oxidative stress throughout life. One of them are the paraoxonase (PON) enzymes. The PONs genetic cluster is made up of three members (PON1, PON2, PON3) that share a structural homology, located adjacent to chromosome seven. The most studied enzyme is PON1, which is associated with high density lipoprotein (HDL), having paraoxonase, arylesterase and lactonase activities. Due to these characteristics, the enzyme PON1 has been associated with the development of neurodegenerative diseases. Here we update the knowledge about the association of PON enzymes and their polymorphisms and the development of multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD) and Parkinson's disease (PD).

Cladribine Treatment Improved Homocysteine Metabolism and Increased Total Serum Antioxidant Activity in Secondary Progressive Multiple Sclerosis Patients

Hyperhomocysteinemia plays a crucial role in the pathogenesis of many diseases of the central nervous system (CNS). The nervous system is particularly sensitive to high homocysteine (Hcy) level mainly due to its prooxidative and cytotoxic effects. Cladribine, a drug recently registered for the treatment of multiple sclerosis (MS), possesses additionally neuroprotective effects which are independent of its peripheral immunosuppressant action. Accumulating evidence suggests that oxidative stress and homocysteine thiolactone-mediated protein homocysteinylation play a causal role in MS. Both of these processes may be attenuated by paraoxonase 1 (PON1). Therefore, in the present study, we aimed to examine whether the beneficial effects of the drug in MS patients with a secondary progressive (SP) clinical course, treated with cladribine subcutaneously (s.c.), may be related to its ability to modify serum PON1 activity, Hcy concentration, and protein homocysteinylation, as well as to correct total antioxidant status. A total of 118 subjects were enrolled into the study: (1) patients with a SP type of MS, SP-MS (n = 40); (2) patients with a relapsing-remitting (RR) type of MS, RR-MS (n = 30); and (3) healthy people (n = 48). Patients with SP-MS were treated with cladribine. The drug was given in SP-SM patients s.c. six times every 6 weeks up to a total mean cumulative dose of 1.8 mg/kg. PON1 activity was assessed spectrophotometrically. The level of Hcy, homocysteine thiolactone (HTL) attached to plasma proteins (N-Hcy-protein), and antibodies against homocysteinylated proteins was assessed with an enzyme immunoassay. The total antioxidant activity of the serum was assessed with the ferric-reducing activity of plasma (FRAP) method. Basically, there was no difference in PON1 activity between untreated SP-MS, RR-MS, and control subjects. Serum Hcy was significantly higher in RR-MS patients (p < 0.001) and in SP-MS patients (p < 0.01) compared to the control group. The N-Hcy protein level was higher in RR-MS patients (p < 0.05) in comparison to the control group. Moreover, the elevated level of antibodies against homocysteinylated proteins was observed in the serum of patients with SP-MS. The total antioxidant capacity of serum was lower in MS patients vs. the control group (p < 0.001). After cladribine treatment, the activity of PON1 did not change in SP-MS patients, whereas cladribine treatment decreased the level of total Hcy (p < 0.05). Treatment with cladribine increased the total serum antioxidant activity in SP-MS patients (p < 0.01). The Expanded Disability Status Scale (EDSS) score did not change in SP-MS patients. Cladribine treatment in the SP-MS group attenuates hyperhomocysteinemia-induced protein homocysteinylation (n.s.). It also stabilises the neurological condition of SP-MS patients. The stabilisation of a neurological condition observed in SP-MS patients after cladribine treatment may be partially related to its ability to reduce elevated Hcy level and to improve serum antioxidant potential.

Serum levels of Homocysteine, Vitamin B12 and Folate in Patients with Multiple Sclerosis: an Updated Meta-Analysis

Background: Multiple sclerosis (MS) is a demyelinating and disabling inflammatory disease of the central nervous system. MS is triggered by complex environmental factors which mostly affect genetically the susceptible young people. Emerging data has suggested that changes of homocysteine (Hcy), Vitamin B12 and folate serum levels may be associated with MS. However, previous findings are not always consistent. Methods: In this study, we aimed to investigate the relationships between MS and Hcy, Vitamin B12 and folate with updated available data (until September, 2019). The diagnosis of MS was performed based on international criteria for the diagnosis of MS, including magnetic resonance imaging and cerebrospinal fluid tests. We searched the databases including PubMed, EMBASE, Cochrane Library and ScienceDirect. After data collection, separate analyses based on random-effect models were used to test for relationships between MS and Hcy, Vitamin B12 or folate blood levels. The effective sizes were estimated by the combined standardized mean difference (SMD) and associated 95% confidence interval (CI). Results: Based on the inclusion criteria, a total of 21 original studies with 1738 MS patients and 1424 controls were included in this study. There were 17 studies for measuring Hcy, 16 studies for measuring Vitamin B12 and 13 studies for measuring folate in patients with MS, respectively. Specifically, patients with MS had higher serum levels of Hcy (SMD: 0.64; 95% CI:0.33, 0.95; P <0.0001) compared with control groups. There were no significant differences of SMD for Vitamin B12 (SMD: -0.08; 95% CI: -0.35, 0.20; P=0.58) or folate (SMD: 0.07; 95% CI: -0.14, 0.28; P=0.52) between MS and controls. Subgroup analysis demonstrated that there was statistically significant difference for Hcy between relapsing-remitting MS (RRMS) patients and controls with a SMD of 0.67 (95% CI: 0.21, 1.13; P=0.004). However, no significant difference of Hcy serum levels between secondary progressive MS patients or primary progressive MS patients and controls was noted in this study. In addition, there was no significant difference of Hcy levels in females (SMD: 0.22; 95% CI: -0.16, 0.60; P=0.25) or males (SMD: 0.56; 95% CI: -0.13, 1.26; P=0.11) between MS patients and controls. Conclusions: Higher serum levels of Hcy were noted in patients with MS when compared with control groups. And the difference was especially significant between RRMS patients and controls. Hcy may play an important role in the pathogenesis of MS. Functional studies are required to assess the effects of Hcy on patients with MS at the molecular level.

Paraoxonases Activities and Polymorphisms in Elderly and Old-Age Diseases: An Overview

Aging is defined as the accumulation of progressive organ dysfunction. There is much evidence linking the involvement of oxidative stress in the pathogenesis of aging. With increasing age, susceptibility to the development of diseases related to lipid peroxidation and tissue injury increases, due to chronic inflammatory processes, and production of reactive oxygen species (ROS) and free radicals. The paraoxonase (PON) gene family is composed of three members (PON1, PON2, PON3) that share considerable structural homology and are located adjacently on chromosome 7 in humans. The most studied member product is PON1, a protein associated with high-density lipoprotein with paraoxonase/esterase activity. Nevertheless, all the three proteins prevent oxidative stress. The major aim of this review is to highlight the importance of the role of PON enzymes in the aging process, and in the development of the main diseases present in the elderly: cardiovascular disease, diabetes mellitus, neurodegenerative diseases, and cancer.

Cholesterol level correlate with disability score in patients with relapsing-remitting form of multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is an autoimmune disease characterised by demyelination. There are many environmental factors that can affect the progression of this disease. It is necessary to better understand the impact of these factors in MS pathogenesis and progression.

OBJECTIVE

Present study investigates the relationship of total cholesterol serum levels and other parameters contributing to cardiovascular risk - homocysteine and serum lipid parameters (triglycerides, HDL, LDL) - with the progression of MS (EDSS score).

METHODS

The study involved 169 patients diagnosed with MS. Total homocysteine levels were measured by high-performance liquid chromatography. Serum lipid parameters were measured with enzymatic kits.

RESULTS

There was no difference observed between homocysteine levels in MS patients and controls. Dyslipidaemia seems to be associated with MS progression, particularly in women with relapsing-remitting form of MS.

CONCLUSION

Positive correlation of total and LDL cholesterol with disability score in patients with relapsing-remitting form of MS suggests that lipid parameters could have a negative effect on the disease progression.

Serum paraoxonase 1 activity and protein N-homocysteinylation in primary human endometrial cancer

Paraoxonase 1 plays an important role in protection from oxidative stress and also decomposes homocysteine thiolactone, the toxic metabolite of homocysteine. A limited number of reports evaluated the role of paraoxonase 1 in women affected by female genital tract neoplasms, including endometrial cancer. This study aimed to analyze the paraoxonase activity in the group of endometrial cancer patients (n = 48) who underwent primary surgery and to compare the data available with a well-matched control group (n = 30). Due to the role of paraoxonase 1 in the metabolism of homocysteine (Hcy) thiolactone, the amount of Hcy-thiolactone as well as total serum Hcy concentrations was also measured. Serum paraoxonase 1 activity toward synthetic substrates, paraoxon and phenyl acetate, in the study group was significantly lower compared to the control one. The mean paraoxonase 1 activity toward homocysteine thiolactone tended to be lower in the endometrial cancer group but this difference was not significant. There was no relationship between endometrial cancer and Q192R polymorphism of PON1 assessed by the dual substrate method. No differences in paraoxonase 1 activity between endometrial cancer subgroups according to clinico-pathological features were detected. Total serum homocysteine and protein-bound homocysteine thiolactone did not differ between control and cancer groups. In conclusion, reduced paraoxonase 1 activity suggests diminished important antioxidant mechanisms during the development of primary endometrial cancers in humans. PON1 Q192R polymorphism is not associated with the risk of endometrial cancer. Despite lower paraoxonase 1 activity, homocysteine concentration, and protein N-homocysteinylation in endometrial cancers do not differ from matched controls.