Interleukin-23, a novel marker in the diagnosis of psoriasis

Abstract               Background: In psoriasis, local and systemic cytokines regulation contributes an important role in pathogenesis. Serum IL-23 levels was notably raised in active psoriasis patients, indicating their role in disease pathogenesis and negatively associated with extent of the disorder. Aim: To estimate and assess whether IL-23 is a key specific factor in pathogenesis of psoriasis. Material and Methods: In this case control study, a total of 90 individuals were included and divided into -Group I (Cases): 45 newly diagnosed cases of psoriasis and Group II (Controls): 45 Non-psoriatic healthy individuals with no family history of psoriasis. IL-23 was estimated by ELISA using Sincere kit. Results: The mean value of IL-23 level in controls was 61.47 and for cases 62.26. In the mean value of controls and cases, there was only a little elevation in cases, which was statistically insignificant. Conclusion: In present study, insignificant relationship was found between cases and controls in IL-23 values. This could be due to the study population was selected from low socioeconomic status people, have been relatively associated with elevated levels of inflammatory markers due to their lifestyle.

Key Word: Psoriasis, Non-Psoriatic Individuals, Interleukin-23, Low Socioeconomic Status

INTRODUCTION

Psoriasis is a common, chronic, mutilating, inflammatory, and proliferative condition of the skin. In psoriasis both genetic and environmental influences have a crucial role.¹To understand the pattern of psoriasis, many studies are done recently. This recent progression shows that the local and systemic cytokines regulation contributes an important role in pathogenesis.² It was hypothesized that it is an immune mediated disorder with cutaneous and systemic over expression of a number of proinflammatory cytokines; most predominantly type-1 cytokines for example IL-2, IL-6, IL-8, IL-12, IFN-gamma and TNF-alpha. After the detection of IL-23, this conclusion was challenged and then experimental and clinical facts put the center of attention on the IL-23/Th17 axis in psoriasis.³ The diagnosis of psoriasis is usually based on the presence of typical skin lesions. And rarely the biopsy is needed.⁴ Serum IL-10 and IL-23 levels were notably raised in active psoriasis patients, indicates their role in disease pathogenesis and IL-23 negatively associated with extent of the disorder.⁵In present study, an attempt was made to assess the IL-23 levels in early psoriatic cases.

MATERIAL AND METHODS

In this case control study, a total of 90 individuals were included and divided into -

Group I(Cases): 45 newly diagnosed cases of psoriasis and

Group II (Controls): 45 Non-psoriatic healthy individuals with no family history of psoriasis.

Inclusion criteria

• Newly diagnosed psoriatic patients in the age group of 21- 60 years.

The diagnosis of psoriasis was confirmed in all cases by Dermatologist based on established clinical criteria.

Exclusion criteria

• Psoriatic patients on treatment.
• Other type of skin diseases like atopic dermatitis.
• Other inflammatory and autoimmune diseases like DM, HT, CAD, and Bone diseases.
• Immunosuppression, malignancies, autoimmune/genetic/metabolic/ rheumatic diseases and bacterial, viral, or fungal infections up to 4 weeks.

Estimation of Interleukin-23: 3ml of venous blood was drawn in a plain serum vacutainer tube under sterile conditions after fulfilling the selection criteria, from the anticubital vein with explicit informed consent. Keep the samples in a serum separator tube for 2 hours at room temperature to clot. Serum was separated by centrifugation at approximately 2000-3000rpm for 15-20min and aliquoted, into an eppendorf, and immediately frozen at -20⁰C and keeps it in storage until processed. Interleukin-23 was estimated by Enzyme Linked Immuno Sorbent Assay using Sincere kit. Catalogue no: E13651016 (type II), 96T

Principle: The kit assay IL-23 level in serum, use purified human IL-23 antibody to coat microtiter plate wells, make solid-phase antibody, then add samples to wells, combined human IL-23 antibody which with HRP labeled, become antibody-antigen-enzyme-antibody complex, after washing completely, add TMB substrate solution, TMB substrate become blue color, at HRP enzyme-catalyzed, reaction is terminated by the addition of a sulphuric acid solution and the color change(yellow) is measured spectrophotometrically at a wavelength of 450 nm. The concentrations of human IL-23 in the samples were determined by comparing the O.D of the samples to the standard curve.

RESULTS

The age match between the cases and controls was insignificant (p value=0.088). There were no significant differences in male/female ratio between the patients and controls with p value 0.063. (p>0.05).

Table 1: Characteristics of study population

The mean value of IL-23 level in controls was 61.47 and for cases 62.26. In the mean value of controls and cases, there was only a little elevation in cases, but did not show any significance in p values (p=0.883; p> 0.05) which clearly shows the non-significant relationship among the two groups.

Table 2: Comparison between controls and cases.

The mean value of controls and cases did not show any significant difference in the IL-23 titers. The P value was 0.898 which was > 0.05 clearly show their significant relationship among the two groups.

DISCUSSION

For the past 15 years from its discovery in 2000, IL-23 has promptly established as a key contributor and a probable therapeutic object in psoriasis than just a pro-inflammatory cytokine.³ Recently why IL-23 gets this much importance because, it is released in the early onset of disease and its level in serum is inversely related to disease duration as per Alobaidi et al study.⁴ It is suggested by Fotiadou C et al study in which, there is the possible crucial role of IL-23 and IL-17A in the early stages of the disease and activity of psoriasis.⁶Based on Sara Brenner study, therapies involved against the target IL-23 is showing early success in the treatment of plaque type psoriasis vulgaris.⁷As per Meglio et al study, IL-23 was revealed has a major role in autoimmunity. They quoted that in the past 3 years major advances in genetics, immunopathology and clinical findings of psoriasis, we can understand the fundamental role of the IL-23/Th17 axis.³Stritesky et al study supports the above statement that is; IL-23 sustains the population of IL-17 secreting T cells, noted as Th-17 cell expansion or survival. Results of this study imply that IL-23 is a maintenance factor for the Th17 phenotype.⁸ As per Michalak-Stoma study, even though both IL-12 and IL-23 were present in psoriasis, IL-23, rather than IL-12, was vital during the pathogenesis of psoriasis. IL-23 is overexpressed in psoriatic skin. IL-23 is overproduced by dermal keratinocytes, dentritic cells and in lesional psoriatic skin.⁹ The selected cases with psoriasis in our study were who had not undergone any previous local or systemic treatment. The patients were diagnosed clinically and selected for study as per Dermatologist opinion. The control group was included the healthy, non-psoriatic volunteers with no family history of psoriasis. Both cases and controls had no history, or clinically any findings or routine laboratory findings consist with, abnormal renal or function, or parasitic and any other infection. The mean value of controls and cases did not show any significant difference inthe IL-23 titers. The P value was 0.883. These results of our study may be due to the sample collection from the hospital where, mostly they belonged to low socioeconomic group. So, there is an alteration in inflammatory markers range in controls also as per Annemarie Koster et al, their study analyzed the relationship between socioeconomic state and several markers of inflammation from a large sample of community-dwelling adults. The result is low socioeconomic status has been related to higher levels of inflammatory markers. This is moreover, as inflammation is essence of a biological response of the immune system and it is associated with increased morbidity and mortality across the age span, including in old age.¹⁰ As per Paalani et al study, Inflammatory based risk for health problems may vary according to ethnicity and other demographic factors. Exercise, diet and body mass like factors also show influence in the levels of inflammatory markers.¹¹In our study there was an insignificant association between both controls and cases because of both the groups belonged to low socioeconomic status.

CONCLUSION

Several studies put forward the fact, that psoriasis is by the Th17 cell–mediated disease which was driven by IL-23. There is an increase in IL-23 values in cases when compare with controls as per many other studied. But in this study there is an insignificant relationship between cases and controls in IL-23 values. This couldbe due to the study population was selected from low socioeconomic state people, have been relatively associated with elevated levels of inflammatory markers due to their lifestyle or may be many patients are going without treatment due to unawareness of the disease.

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