BACKGROUNDPsoriasis is a common immune-mediated chronic inflammatory disease of the
skin and joints, affecting 1-3% of the population. It is generally accepted
that the pathogenesis of psoriasis involves accumulation of effector T-cells
within lymph nodes and their subsequent migration into the skin through the
blood system. Here we provide evidence that psoriatic plaque itself may
serve as a source of inflammatory T-cells.OBJECTIVEWe examined the intradermal proliferation of T-cells and the number of
effector/memory (CD45RO+) T-cells in the skin of psoriatic patients at
different periods of the disease.METHODSSkin samples were obtained from 41 patients with progressive psoriatic
lesions; 18 of these patients also donated skin specimens during the
remission of the disease. The control group consisted of 16 healthy
subjects. Ki-67 immunohistochemical staining was applied to detect
proliferating cells, CD3ε served as a T-cell marker, and CD45RA and
CD45RO antibodies were utilized to discriminate between naive and
effector/memory T-cells, respectively.RESULTSProgressive psoriatic lesions demonstrated Ki67 staining both in
keratinocytes and in the CD3ε+ cells of dermal infiltrate. Median
count of CD45RO+ cells per microscopic field was 15 in healthy controls, 59
in patients in remission and 208 in progressive psoriatic plaques. The
observed differences demonstrated high level of statistical
significance.STUDY LIMITATIONSLimited number of analyzed patients.CONCLUSIONProgressive phase of psoriasis is characterized by intradermal proliferation
of T-cells. Spots of regressed psoriatic lesions contain high number of
CD45RO+ cells, which are likely to render an immunological memory.
The IL12B gene encodes protein р40 being a common subunit of interleukin-12 and interleukin-23 playing an important
part in the pathogenesis of psoriasis. The IL12B gene has polymorphism rs12188300, which can be associated with the
risk of psoriasis development. The goal of the study was to assess the distribution of alleles of polymorphism rs12188300
in psoriatic patients in the Northwestern region of Russia. Genotyping was carried out using the real-time allele-specific
polymerase chain reaction. An increased occurrence of a rare allele T in psoriatic patients as compared to healthy people
was observed (OR = 1.96, р = 0.0007). The occurrence of the rare allele T in patients with psoriatic arthritis was higher
than in the control group (OR = 3.49, р = 0.005). These results suggest that rs12188300 polymorphism of the IL12B gene
is a new genetic marker of psoriasis and psoriatic arthritis.
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