Role of estrogen signaling in fibroblastic reticular cells for innate and adaptive immune responses in antigen-induced arthritis

• Women are more prone to develop rheumatoid arthritis, with peak incidence occurring around menopause. Estrogen has major effects on the immune system and is protective against arthritis. We have previously shown that treatment with estrogen inhibits inflammation and joint destruction in murine models of arthritis, although the mechanisms involved remain unclear. Fibroblastic reticular cells (FRCs) are specialized stromal cells that generate the three-dimensional structure of lymph nodes (LNs). FRCs are vital for coordinating immune responses from within LNs and are characterized by the expression of the chemokine CCL19, which attracts immune cells. The aim of this study was to determine whether the influence of estrogen on innate and adaptive immune cells in arthritis is mediated by estrogen signaling in FRCs. Conditional knockout mice lacking estrogen receptor alpha (ER alpha) in CCL19-expressing cells (Ccl19-CreER alpha fl/fl) were generated and tested. Ccl19-CreER alpha fl/fl mice and littermate controls were ovariectomized, treated with vehicle or estradiol and subjected to the 28-day-long antigen-induced arthritis model to enable analyses of differentiated T- and B-cell populations and innate cells in LNs by flow cytometry. The results reveal that while the response to estradiol treatment in numbers of FRCs per LN is significantly reduced in mice lacking ER alpha in FRCs, estrogen does not inhibit joint inflammation or markedly affect immune responses in this arthritis model. Thus, this study validates the Ccl19-CreER alpha fl/fl strain for studying estrogen signaling in FRCs within inflammatory diseases, although the chosen arthritis model is deemed unsuitable for addressing this question. This study investigated the influence of signaling through estrogen receptor alpha (ER alpha) in fibroblastic reticular cells (FRCs) on innate and adaptive immune responses using a mouse model where ER alpha was conditionally deleted in CCL19-expressing cells. The results reveal that the deletion of ER alpha in FRCs does not affect the FRC phenotype or LN architecture at steady state while the response of FRCs to estrogen treatment during experimental arthritis is significantly reduced in the conditional knock-out mice. However, ER alpha signaling via FRCs does not inhibit joint inflammation or markedly affect immune responses in the antigen-induced arthritis model. image

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Reumatologi och inflammation (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Rheumatology and Autoimmunity (hsv//eng)

Keyword

Antigen-induced arthritis

estrogen

estrogen receptor alpha

fibroblastic reticular cells

lymph node

inflammation

Publication and Content Type

ref (subject category)

art (subject category)