Psoriasis is a chronic, inflammatory skin disease, with strong genetic background. miRNAs represent a promising class of small, noncoding RNA molecules that function to regulate gene expression. Aberrant expression of miRNAs is involved in the pathogenesis of many diseases.
miRNAs research in psoriasis is still relatively new and little is known about their contribution in psoriasis and about their relation to the treatment response.
This work aimed to investigate the association between a functional SNP of rs2910164 in miR-146a and the risk of psoriasis, to correlate the skin expression levels of pre-miRNA 146a in psoriasis patients before and after PUVA therapy and to investigate the association between the skin expression levels of pre-miRNA 146a and the response to treatment in different genotypes, in Benha University Hospital.
This study was conducted during the period from January 2015 to December 2016 on forty patients and twenty healthy controls matched for age and sex with patients, attending Outpatient Dermatology and Andrology Clinic, Benha University Hospital.
The forty patients were classified as follows:
• Group 1: including 40 patients with psoriasis vulgaris not receiving any treatment.
• Group 2: including the same 40 patients with psoriasis vulgaris after receiving treatment with PUVA therapy for 3 months.
This group was furtherly classified into:
- Group 2a: including 26 patients who showed response to treatment.
- Group 2b: including 14 patients who did not show response to treatment.
All participants were subjected to:
a- Full history taking:
1. Personal history (name, age, sex).
2. History of the present illness (onset, course and duration of the disease and treatment).
3. Family history of similar conditions.
b- Clinical examination: Poriasis Area and Severity Index (PASI), body mass index, and response to treatment which was evaluated by reduction in PASI score by ≥70%.
Blood samples were collected and polymorphism in miR-146a gene were detected using PCR- restriction fragment length polymorphism (PCR-RFLP), Skin specimens were taken and the expression levels of pre-miRNA 146a were measured by quantitative real-time PCR before and 3 months after treatment with PUVA therapy.
The results of the current study showed that:
- The frequencies of the CC, CG and GG genotypes for the miR-146a polymorphism were 45 %, 30 % and 25 %, respectively among the cases, and 40%, 40% and 20 %, respectively among control group.
- Compared with the wild miR-146a rs2910164 CC genotype, there was no significant association between combined rs2910164 variant genotypes (CG + GG) and risk of psoriasis.
- There were significant differences in the proportion of different single nucleotide polymorphism between males and females (P= 0.01), while there were no significant differences as regards age, BMI or family history.
- There were no significant differences among patients with different genotypes as regards the onset, course or PASI score.
- As regards the skin expression levels of pre-miRNA 146a, there were significant differences in the levels of pre-miRNA 146a between patients and control group (P