Diagnosis and management of idiopathic recurrent pregnancy loss (RPL): Current immune testing and immunomodulatory treatment practice in the United Kingdom.

Recurrent pregnancy loss (RPL) affects 1.9 % of couples. Despite the severe physical, psychological, and economic impact of RPL, miscarriage care provision remains highly heterogeneous. Due to the absence of strong scientific evidence, national and international guidelines on the diagnosis and treatment of this condition remain unclear and often contradictory. In the absence of identifiable RPL-associated risk factors, when the condition is termed "idiopathic", immunological tests and immunomodulatory treatments are sometimes suggested even though the contribution of aberrant immune activity to this condition remains undetermined. Through an online survey, distributed across the UK (37.7% response rate), a high variation in clinical practice was detected, with multiple RPL definitions utilized and different tests employed for potential risk factor identification. Immunological testing was found to be provided in 7.9 %(N = 3) of the included clinics. Moreover, multiple therapies, including immunomodulatory ones were utilized for the management of idiopathic RPL. These findings highlight a need for additional research on the implication of immune activity in this condition. The high variation between clinics regarding the tests employed for the diagnosis and management of idiopathic RPL also underlines the need for guidelines to direct clinical practice, taking into consideration both the patients' needs but also the strength of the available scientific evidence.

Understanding human immunity in idiopathic recurrent pregnancy loss.

Miscarriage, defined as the loss of a pregnancy before a viable gestation, affects 1 in 6 couples. Recurrent pregnancy loss (RPL), defined as two or more miscarriages, affects up to 1.9% of couples. The physical, psychological, and financial impact of miscarriage can be substantial. However, despite its multifactorial etiology, for up to 50% of couples a reason behind this condition cannot be identified, termed 'idiopathic RPL'. Much recent research has strived to understand this, with immune dysregulation being a source of particular interest. In this short review we summarize the current evidence on the complex role of the immune system both pre- and early post-conception in RPL. A key question is whether systemic peripheral blood markers, in particular natural killer cell and T cells, may be utilized to accurately predict and/ or diagnose those pregnancies at high risk of loss. Given the invasive nature of endometrial testing, identification of reliable peripheral immune biomarkers is particularly appealing. Clinical trials using potent immunomodulatory agents, including intravenous immunoglobulin, donor leukocyte immunization, and tumor necrosis factor (TNF)-α inhibitors, have been undertaken with the primary objective of preventing miscarriage in women with RPL. Standardisation of both diagnostic and prognostic immune cell testing assays is required to permit accurate identification of those women who may benefit from immunomodulation. Prompt clarification is required to meet the increasing expectation from couples and clinicians, as without these advancements women are at risk of exposure to potent immune-therapies and subsequent studies are at risk of failure, generating further controversy regarding the role of immune dysregulation in women with RPL. Through this review we highlight clear gaps in our current knowledge on immune activity in RPL.

Increased sensitivity of Treg cells from patients with PBC to low dose IL-12 drives their differentiation into IFN-γ secreting cells.

IL-12 is a pro-inflammatory cytokine that induces the production of interferon-γ (IFNγ) and favours the differentiation of T helper 1 (Th1) cells. In the presence of IL-12 human Treg cells acquire a Th1-like phenotype with reduced suppressive activity in vitro. Primary biliary cholangitis (PBC) is an autoimmune cholestatic liver disease characterised by high Th1 and Th17 infiltrating cells, reduced frequencies of Treg cells, and a genetic association with IL-12 signalling. Herein, we sought to evaluate the IL-12 signalling pathway in PBC pathology, by studying human samples from patients with PBC, alongside those with primary Sjögren's syndrome (pSS)(autoimmune disease with IL-12 signalling gene association), primary sclerosing cholangitis (PSC) (cholestatic liver disease without IL-12 gene association) and healthy individuals. Our data revealed that TLR stimulation of PBC (n = 17) and pSS monocytes (n = 6) resulted in significant induction of IL12A mRNA (p < 0.05, p < 0.01, respectively) compared to PSC monocytes (n = 13) and at similar levels to HC monocytes (n = 8). PSC monocytes expressed significantly less IL-12p70 (108 pg/ml, mean) and IL-23 (358 pg/ml) compared to HC (458 pg/ml and 951 pg/ml, respectively) (p < 0.01, p < 0.05). Treg cells from patients with PBC (n = 16) and pSS (n = 3) but not PSC (n = 10) and HC (n = 8) responded to low dose (10 ng/ml) IL-12 stimulation by significant upregulation of IFNγ (mean 277 and 254 pg/ml, respectively) compared to PSC and HC Treg cells (mean 22 and 77 pg/ml, respectively)(p < 0.05). This effect was mediated by the rapid and strong phosphorylation of STAT4 on Treg cells from patients with PBC and pSS (p < 0.05) but not PSC and HC. In the liver of patients with PBC (n = 7) a significantly higher proportion of IL-12Rß2+Tregs (16% on average) was detected (p < 0.05) compared to other liver disease controls (5%)(n = 18) which also showed ex vivo high IFNG and TBET expression. CONCLUSION: Our data show an increased sensitivity of PBC and pSS Treg cells to low dose IL-12 stimulation, providing ongoing support for the importance of the IL12-IL-12Rß2-STAT4 pathway on Treg cells in disease pathogenesis and potentially treatment.