Lipid profile and its relationship to Oxidant and Antioxidant status in Psoriatic Arthritis

The aim of this present study was to evaluate the oxidative stress and dyslipidemia in patients with psoriatic arthritis.A 50 known psoriatic arthritis cases and 50 age and sex matched healthy controls were included in this study. In all the subjects, lipid profile and levels of lipid peroxidation as malondialdehyde, antioxidant enzymes like glutathione peroxidase, superoxide dismutase, Vitamin A, E &C were estimated.The levels of lipid profile were found to be significantly altered in the patient group. Levels of malondialdehyde were significantly increased (p<0.001), whereas the glutathione peroxidase, superoxide dismutase, Vitamin A, C & E were significantly decreased (p<0.001) in patients with psoriatic arthritis when compared to the controls.


Introduction
Approximately 5% to 10% of the 3 million people who have psoriasis develop psoriatic arthritis. Psoriatic arthritis affects men and women equally and usually begins between ages 30 and 50. Psoriasis can develop before or after the arthritis, but psoriasis develops first in about 75% of cases. A person may begin to get morning joint stiffness before the arthritis is recognized. People who have psoriasis that involves the nails, especially nail pitting, are much more likely to develop arthritis than those without this problem (50% versus 10%).The cause of psoriatic arthritis is unknown. There is some evidence that infection or trauma can play a role in the development of the disease up to 40% of people with psoriatic arthritis have a family history of skin or joint disease. Certain genes seem to be involved in certain types of psoriatic arthritis; the gene HLA-B27 has been associated with psoriatic spondylitis.
Increased or prolonged free radical action can overwhelm ROS defense mechanisms, contributing to the development of cutaneous diseases and disorders. 1 Psoriatic arthritis is a common chronic and recurrent inflammatory skin and joint disorder 2 that has been associated with abnormal plasma lipid metabolism and high frequency of cardiovascular events. 3 This prevalence seems to be related to the severity of psoriatic arthritis, as it occurs more frequently in patients presenting large areas of the body affected with psoriasis lesions. Though dyslipidemia is known to occur, less is known about its status and association with oxidative stress in patients of psoriatic arthritis. Malondialdehyde (MDA), is a marker of oxidative stress, glutathione peroxidase (GPX), superoxide dismutase (SOD), Vitamin C, A & E play an important role in the protection of cell membranes against oxidative damage and may be used as indicators of anti-oxidative status. Hence, this study was carried out to evaluate the oxidative stress and dyslipidemia in patients with psoriatic arthritis.

Material and Methods
A case control study was carried out in Department of Biochemistry and Medicine at DSMCH, Perambalur. Fifty patients of psoriatic arthritis with a mean age of 40 ±10 were included in the study. Fifty age and sex matched normal healthy controls with a mean age of 41 ±09 were selected as controls. The patients were diagnosed by Auspitz sign, clinical features of psoriatic erythema, itching, thickening and scaling of the skin. All the patients being treated only with topical agents, Vitamin D analogues, Dithanol have been included in the study. Patients with any chronic inflammatory disease, diabetes mellitus, renal disorders, ischemic heart disease (IHD), hypothyroidism, obstructive liver disease, any other skin disorder were excluded from the study. All the patients of systemic drug therapy of beta blockers, thiazides, retinoids and lipid lowering agents were also excluded from the study.
A 5 ml of venous blood samples was collected in EDTA bottle and plain bulb from patients with psoriatic arthritis and normal healthy individuals and were estimated for lipid profile, lipid peroxidation and antioxidant enzymes-glutathione peroxidase, superoxide dismutase, Vitamin A, C and E. Serum total cholesterol, triglyceride and HDL-cholesterol were measured by an enzymatic kit. LDL cholesterol was calculated using Friedwalds formula.

Statistical methods
Statistical analysis was done using Salstat statistical software. Descriptive statistics like mean and standard deviation were calculated using the software. The results are shown as Mean ± SD in table-1 and table-2. The non-parametric equivalent to parametric unpaired t-test, Mann-Whitney U test was used to compare the mean between case and control at 95% level of confidence interval.

Results
Total cholesterol, VLDL, HDL, LDL-cholesterol and triglycerides levels were statistically significantly increased in patients of psoriatic arthritis than controls (p<0.001) as shown in our table one.  Table 2 depicts the levels of MDA (p<0.001) which were significantly elevated in psoriatic patients as compared to normal healthy controls. The levels of GPx and SOD antioxidants were significantly decreased (p<0.001) in psoriatic patients as compared to normal healthy controls ( Table 2).

Discussion
Psoriatic arthritis is a chronic inflammatory skin disorder with joint involvement characterized by pathological skin lesions due to various exogenous and endogenous factors and is associated with a number of biochemical and immunological disturbances and considered to be an autoimmune disorder, initiated by the overactive skin innate immune system. A complex network of cytokines and chemokines mediates the pathological reaction in chronic nature of psoriasis. 6 Though conflicting reports are available regarding the serum lipid values in psoriasis 3,7,8,10 , the potential role of lipid abnormality in psoriatic arthritis patients has been discussed. High levels of total cholesterol, triglycerides, VLDL, and LDL-cholesterol in patients of psoriatic arthritis were seen as shown in our table-I. Thus, psoriatic arthritis is a risk factor for hyperlipidemia and its possible subsequent squeal such as obstructive vascular disease can-not be excluded. The free radicals induced oxidation of polyunsaturated fatty acids results in the formation of lipid per-oxidation products such as MDA. Our study showed an increase in the level of MDA in psoriatic arthritis patients when compared to the normal controls (p<0.001) as shown in our table-2. This shows an increased oxidative stress in psoriatic arthritis patients. Similarly our study showed that the lipid profile parameters like total cholesterol, LDL, VLDL and triglycerides were statistically significantly increased in psoriatic arthritis patients when compared to the normal controls (p<0.001) as shown in our table-2.
IJBR (2014) 05 (04) www.ssjournals.com Superoxide dismutase, an antioxidant enzyme, catalyzes the dismutation of superoxide into the less harmful molecules, oxygen and hydrogen peroxide. Our study showed a decrease in the levels of antioxidant enzyme SOD in psoriatic arthritis patients when compared to the normal controls (p<0.001) as shown in our table-2. The decrease in the levels of antioxidant SOD in patients of psoriatic arthritis is probably to counter act the stress caused by oxidation.
Cells contain enzymes GPx which change the hydro peroxide group to the much less toxic hydroxyl moiety. Furthermore our study also showed that the level of GPx was statistically significantly decreased in patients with psoriatic arthritis as compared with the healthy controls (p<0.001) as shown in our table-2. Selenium being an integral part of the enzyme GPx, reduction in the enzyme activity leads to the accumulation of hydroxyl radicals in inflamed tissue.
Finally our study showed a statistically significantly decrease in antioxidant vitamins like vitamin E, vitamin A and water soluble vitamin C in psoriatic arthritis patients when compared to the normal controls (p<0.001) as shown in our table-2.
Finally our study results showed an increased oxidative stress and decreased antioxidants in patients with psoriatic arthritis as compared with the healthy controls respectively. In conclusion, hyperlipidemia along with increase in lipid peroxidation and decrease in antioxidants levels are a feature of psoriatic arthritis. Inactivating the effects of free radicals and stabilization of the cell membranes in order to prevent new epidermal destruction could be achieved by antioxidant supplementation.