Mannose-binding lectin deficiency and miscarriages in rheumatoid arthritis

Reproductive Effect by Rheumatoid Arthritis and Related Autoantibodies

Rheumatoid arthritis (RA) is a common inflammatory arthritis in women. The effects of RA on the reproductive system are usually overlooked, as RA is not diagnosed until later in reproductive age. Whether RA itself or its related rheumatoid antibodies have an impact on female reproductive function has long been a thought-provoking issue. In brief, relevant epidemiological evidence has shown that women affected by RA are more likely to have coexisting reproductive disorders, including infertility, endometriosis, and premature ovarian insufficiency (POI), or to subsequently develop them. Furthermore, linkage between RA and pregnancy loss (PL) as well as polycystic ovary syndrome (PCOS) is also well known, albeit controversial in available evidence. RA and reproductive disorders appear to share a similar inflammatory immune response and genetic background. The stress experienced by patients with RA may affect their reproductive choices to some extent. Notably, few studies have explored the impact of rheumatoid antibodies such as rheumatoid factors (RFs) and anti-citrullinated protein antibodies (ACPAs) on reproductive disorders. Although it has been mentioned that the rate of RF and/or ACPA positivity is higher in women with a history of PL and POI, the clinical relevance of this relationship and underlying mechanisms still need to be further clarified.

Serum Levels of Collectins Are Sustained During Pregnancy: Surfactant Protein D Levels Are Dysregulated Prior to Missed Abortion

About 15% of pregnant women undergo missed abortion (MA), wherein women do not experience cramping and vaginal bleeding. Dysregulation of the immune molecules and steroid hormones contribute to early pregnancy loss. Collectins- surfactant protein A (SP-A), surfactant protein D (SP-D), and mannose-binding lectin (MBL) are a group of innate immune molecules regulated by the steroid hormones. Reduced levels of SP-A and SP-D during the early gestation exhibited a significant association with the severe early onset preeclampsia. In order to determine the serum profile of collectins throughout the normal pregnancy and explore their predictive potential during the 8-12 weeks of gestation for MA, we examined a prospective cohort of pregnant women (n = 221). The serum levels of SP-A and SP-D were significantly downregulated in the normal pregnant women in all the three trimesters (n = 30) compared with the non-pregnant women (n = 20) and were not significantly different across the three trimesters. Fourteen of the women from the cohort underwent MA during the 14-20 weeks of gestation and exhibited a significant downregulation in the serum levels of SP-D during 8-12 weeks of gestation. A significant inhibition of the HTR-8/SVneo cell proliferation and migration in the presence of a recombinant fragment of human SP-D suggested the relevance of SP-D in placental development. We report here that the serum levels of SP-A, SP-D, and MBL are consistently maintained during pregnancy in the Indian cohort. Dysregulated serum levels of SP-D and P4/E2 ratio during the early first trimester may predict occurrence of MA.

Complement, infection, and autoimmunity

PURPOSE OF REVIEW

Complement system dysfunction in terms of upregulation, downregulation, or dysregulation can create an imbalance of both host defense and inflammatory response leading to autoimmunity. In this review, we aimed at describing the role of complement system in host defense to inflection and in autoimmunity starting from the evidence from primary and secondary complement system deficiencies.

RECENT FINDINGS

Complement system has a determinant role in defense against infections: deficiencies of complement components are associated with increased susceptibility to infections. Primary complement system deficiencies are rare disorders that predispose to both infections and autoimmune diseases. Secondary complement system deficiencies are the result of the complement system activation with consumption. Complement system role in enhancing risk of infective diseases in secondary deficiencies has been demonstrated in patients affected by systemic autoimmune disorders, mainly systemic lupus erythematosus and vasculitis.

SUMMARY

The relationship between the complement system and autoimmunity appears paradoxical as both the deficiency and the activation contribute to inducing autoimmune diseases. In these conditions, the presence of complement deposition in affected tissues, decreased levels of complement proteins, and high levels of complement activation fragments in the blood and vessels have been documented.