EC Gynaecology

The immune system profoundly shapes endometrial development, thickness, and receptivity through intricate interplay between immune cells, cytokines, and hormonal signals, which are vital for implantation and pregnancy.

Key immune cell populations-including uterine natural killer (uNK) cells, regulatory T cells, macrophages, and dendritic cells-undergo cyclic fluctuations tied to estrogen and progesterone levels, mediating vascular remodelling, immunological tolerance, and tissue repair essential for embryo acceptance.

Cytokines such as IL-6, IL-10, TGF-β, and TNF-α govern the critical balance between pro- and anti-inflammatory states, while growth factors like VEGF direct endometrial angiogenesis.

Hormonal regulation further modulates local immunity: estrogen and progesterone drive immune cell recruitment, polarisation, and cytokine production through both direct and indirect signalling.

Immune dysregulation, seen in thin endometrium or repeated implantation failure, typically manifests as an aberrant inflammatory milieu, compromised vascularisation, and disruption in complement system activity-culminating in impaired receptivity and reduced IVF success rates. Recent advances in immune profiling offer personalised diagnostic and therapeutic approaches, including targeted immunomodulation, cytokine, or complement therapies to restore a balanced, receptive endometrial environment and improve reproductive outcomes.

 Keywords: Immune System; Endometrial Development; IVF; Cytokine; Uterine Natural Killer (uNK) Cells

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