The following is a summary of “Possible microRNA-based mechanism underlying relationship between chronic spontaneous urticaria and Blastocystis,” published in the December 2022 issue of Experimental Parasitology by Örsten, et al.

Extraintestinal clinical symptoms, such as urticaria etiology, have been linked to Blastocystis spp. This study aimed to compare the microRNA (miRNA) expression patterns of people with Chronic Spontaneous Urticaria (CSU) who had been infected with Blastocystis spp. with those without CSU who had not been infected. Furthermore, cellular pathways identified as being altered by Blastocystis spp. About 20 patients with a CSU diagnosis were included in the trial and randomly assigned to one of 2 categories based on the presence of Blastocystis spp. In addition, 6 healthy volunteers were included in the analysis. 

Using the miScript miRNA PCR Array Human miRBase Profiler, researchers analyzed the expression levels of 372 human-derived miRNAs in serum samples from CSU patients and healthy controls. Blastocystis-positive (BP)-CSU patients had lower levels of expression of 3 miRNAs (hsa-miR-3183, hsa-miR-4469, and hsa-miR-5191) than Blastocystis-negative (BN)-CSU patients (p<0.05). Also, the miRNA expression profiles of 6 healthy people (3 with Blastocystis and 3 without) were looked at. It was found that the expressions of 7 miRNAs (hsa-miR-4661-5p, hsa-miR-4666a-5p, hsa-miR-4803, hsa-miR-5587-5p, hsa-miR-4500, hsa-mi Most down-regulated miRNAs in BP-CSU patients affect cell adhesion molecules (CAMs) and signaling pathways. 

Because of this, the presence of Blastocystis spp. may affect the clinical presentation of urticaria by causing an immune system that isn’t working right. Blastocystis spp. may also affect the TGF- signaling pathway by changing miRNAs, laying the groundwork for CSU to develop in healthy people. Therefore, this is the first publication to demonstrate that Blastocystis spp. affects the expression profile of miRNAs. More research on miRNAs is required to understand the molecular mechanisms at play in the interaction between Blastocystis spp. and CSU.