Endometriosis, the ectopic growth of endometrial lesions, affects 10% of reproductive-aged women. Aberrant innate immune responses resulting in incomplete clearance of refluxed menstrual tissue in the pelvis have been implicated. The persistence or clearance of lesions appears to be governed by macrophages that exhibit either a pro-inflammatory (M1-like) or remodelling (M2-like) phenotype. microRNA-223 (miR-223) promotes M2-like macrophage activity and is elevated in ectopic endometrial tissue. We hypothesised that a miR-223 deficiency promotes M1-mediated inflammation, facilitating clearance of ectopic endometrium and that these cellular events would be reflected in a high-throughput RNA sequence analysis.
A menstrual model of endometriosis was established in miR-223 deficient mice by inoculating decidualised donor endometrial tissue subcutaneously into recipients. Lesions from miR-223-/- and miR-223+/+ mice were compared at days 7 (D7) and 14 (D14) –post inoculation (n=10-12/group). The Illumina Next-Seq500 platform was used in a RNA-seq analysis comparing un-inoculated donor endometrium, D7 and D14 lesions (n= 4/group). Differentially expressed gene (DEG) analyses (-0.5 < logFC < 0.5; FDR 0.1) were performed using R Studio and Qiagen IPA Software.
We found that miR-223-/- mice had significantly larger lesions, an early influx of F4/80+ macrophages, and cystic-like lesions by D14 compared to miR-233+/+ mice. RNA-seq comparison of D7 and D14 lesions identified 23 and 39 DEGs respectively; with DEGs associated with networks involved in phagosome maturation, iNOS and IL-4 signalling, indicating elevated M1 activity in miR-223-/-mice. Interestingly, when miR-223-/- and miR-233+/+ donor endometrium were compared, 646 DEG were identified with CSF1 and CXCL12 upregulated and FGFR1, CEBPB, and VEGFA downregulated in miR-223-/- endometrium. This suggests that signalling factors from donor endometrium may influence macrophage activity and subsequent lesion development in recipients.
This data demonstrates that miR-223 regulates macrophage activity, promoting endometriotic lesion development, and survival. Antagonism of miR-223 activity holds potential for future targeted therapeutics.