Dissecting the miRNome of psoriatic keratinocytes

Purpose: The purpose of this study was to identify the miRNome of keratinocytes in psoriasis Method: We performed next-generation sequencing for small RNAs from the RNA samples obtained from keratinocytes from psoriasis lesional, non-lesional and healthy skin. Next, we removed adapters and the low quality tags from the sequencing data and clean reads were mapped and aligned to known miRNAs sequences (miRBase 21). Novel miRNA transcripts were predicted based on the length (22-25 nucleotide) and secondary structure (precursor analysis) using MIREAP and mapped to the human genome. Data were normalized (transcripts per million, TPM) and analysed using Bioconductor-EdgeR. Group comparisons (lesional vs. healthy, lesional vs. non lesional and non-lesional vs. healthy) were performed. MiRNAs with <10% FDR, fold change >1.4 (1 TPM at least in one of the groups and expressed in half of the samples in any group) were considered statistically significant. Results: Robust expression of 411 known and 30 novel miRNAs (TPM > 1 in >50% of the samples in at least one of the groups) was detected in our samples. Using EdgeR we identified 104 miRNAs with significantly altered level (fold change > 1.4, FDR < 0.1) between healthy and psoriatic keratinocytes (P vs H). While, pair-wise comparison of miRNA expression in keratinocytes from non-lesional and lesional psoriasis skin (P vs. N) identified 87 deregulated miRNAs. Comparison of the miRNome of keratinocytes from non-lesional skin of psoriasis patients to healthy keratinocytes (N vs. H) identified 7 differentially expressed miRNAs. Conclusion: Here, for the first time we show the keratinocyte miRNome in psoriasis which may serve as the basis for future functional studies of miRNAs deregulated in keratinocytes in psoriasis. Keratinocytes were sorted from epidermal cell population of healthy, psoriasis lesional and non-lesional skin and small RNA sequencing was performed.