Antibodies against cyclic citrullinated peptide and IgA rheumatoid factor predict the development of rheumatoid arthritis.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/art.11223

There is still an unresolved paradox with respect to the immunomodulating role of estrogens. On one side, we recognize inhibition of bone resorption and suppression of inflammation in several animal models of chronic inflammatory diseases. On the other hand, we realize the immunosupportive role of estrogens in trauma/sepsis and the proinflammatory effects in some chronic autoimmune diseases in humans. This review examines possible causes for this paradox. This review delineates how the effects of estrogens are dependent on criteria such as: 1) the immune stimulus (foreign antigens or autoantigens) and subsequent antigen-specific immune responses (e.g., T cell inhibited by estrogens vs. activation of B cell); 2) the cell types involved during different phases of the disease; 3) the target organ with its specific microenvironment; 4) timing of 17beta-estradiol administration in relation to the disease course (and the reproductive status of a woman); 5) the concentration of estrogens; 6) the variability in expression of estrogen receptor alpha and beta depending on the microenvironment and the cell type; and 7) intracellular metabolism of estrogens leading to important biologically active metabolites with quite different anti- and proinflammatory function. Also mentioned are systemic supersystems such as the hypothalamic-pituitary-adrenal axis, the sensory nervous system, and the sympathetic nervous system and how they are influenced by estrogens. This review reinforces the concept that estrogens have antiinflammatory but also proinflammatory roles depending on above-mentioned criteria. It also explains that a uniform concept as to the action of estrogens cannot be found for all inflammatory diseases due to the enormous variable responses of immune and repair systems.

/pdf/the-complex-role-of-estrogens-in-inflammation-29aw75ptuv.pdf

The complex role of estrogens in inflammation

Pregnancy constitutes a major challenge to the maternal immune system, as it has to tolerate the persistence of paternal alloantigen Although localized mechanisms contribute to fetal evasion from immune attack, maternal alloreactive lymphocytes persist We demonstrate here an alloantigen-independent, systemic expansion of the maternal CD25+ T cell pool during pregnancy and show that this population contains dominant regulatory T cell activity In addition to their function in suppressing autoimmune responses, maternal regulatory T cells suppressed an aggressive allogeneic response directed against the fetus Their absence led to a failure of gestation due to immunological rejection of the fetus

Regulatory T cells mediate maternal tolerance to the fetus.

Immunoglobulins are the major secretory products of the adaptive immune system. Each is characterized by a distinctive set of glycoforms that reflects the wide variation in the number, type, and location of their oligosaccharides. In a given physiological state, glycoform populations are reproducible; therefore, disease-associated alterations provide diagnostic biomarkers (e.g., for rheumatoid arthritis) and contribute to disease pathogenesis. The oligosaccharides provide important recognition epitopes that engage with lectins, endowing the immunoglobulins with an expanded functional repertoire. The sugars play specific structural roles, maintaining and modulating effector functions that are physiologically relevant and can be manipulated to optimize the properties of therapeutic antibodies. New molecular models of all the immunoglobulins are included to provide a basis for informed and critical discussion. The models were constructed by combining glycan sequencing data with oligosaccharide linkage and dynamics information from the Glycobiology Institute experimental database and protein structural data from "The Protein Data Bank."

The Impact of Glycosylation on the Biological Function and Structure of Human Immunoglobulins

The glycosylation of the circulating immunoglobulin-gamma (IgG) antibody molecules changes in rheumatoid arthritis The extent of the changes correlates with the disease severity and reverses in remission We demonstrate here that the alteration in glycosylation associated with rheumatoid arthritis can create a new mode for the interaction of IgG with complement through binding to the collagenous lectin mannose-binding protein (MBP) Rheumatoid arthritis is associated with a marked increases in IgG glycoforms that lack galactose (referred to as G0 glycoforms) in the Fc region of the molecule and that terminate in N-acetyl glucosamine (GlcNAc) We show, using nuclear magnetic resonance (NMR) and X-ray data, that these terminal GlcNAc residues become accessible for MBP binding We further demonstrate that multiple presentation of IgG-G0 glycoforms to MBP results in activation of the complement This suggests that a contribution to the chronic inflammation of the synovial membrane could arise from the localization of the IgG-G0 glycoforms in the affected joint and from resulting activation of complement

Glycosylation changes of IgG associated with rheumatoid arthritis can activate complement via the mannose-binding protein.

In addition to its well known effects on reproductive organs and lactation the pituitary hormone prolactin (PRL) also influences immune functions. The present investigation was performed in order to clarify the regulatory role of prolactin in autoimmune disease by using the collagen II arthritis model. Groups of virgin female DBA/1 mice were subjected to different short-term treatment protocols (5-10 days) with rat PRL and the drugs bromocriptine (inhibits prolactin secretion) and haloperidol (enhances prolactin secretion). Treatments were performed at different stages of disease development, and effects on clinical scores, anti-collagen II antibody titres as well as agalactosyl IgG levels were recorded. The effects of the treatment protocols on serum PRL levels were assessed by using a radioimmunoassay (RIA) system. Although the accumulated results of the present study indicate that PRL does not fulfil a major role in the regulation of collagen II arthritis, some interesting observations were made. High levels of PRL (PRL injections) made the arthritis worse only if treatment was performed during the induction stage of the disease. Bromocriptine treatment during the immunisation period did not significantly affect the course of arthritis, but treatment at later stages tended to cause exacerbation (significant at the onset period only). These results indicate that PRL has different effects during early and late stages of the development of collagen II-induced arthritis.

Increased levels of prolactin during, but not after, the immunisation with rat collagen ii enhances the course of arthritis in dba/1 mice

Pregnancy is known to influence the course of rheumatoid arthritis (RA) in women, as well as type II collagen-induced arthritis (CIA) in DBA/1 mice. A characteristic feature is the remission during gestation and the exacerbation of the diseases during the post-partum period. In the case of CIA in DBA 1 mice, two hormonal changes have been assumed to be critical for the induction of the post-partum flare: (i) the fall in steroid hormone levels from those present during pregnancy; and (ii) surges of prolactin (PRL) release at and after delivery. Our results show that treatment with oestradiol during a short period immediately after parturition protects the mouse from a post-partum flare of the disease, and that treatment with bromocriptine, a drug known to inhibit the endogenous PRL release, has a significant though less marked effect. Studies of lactating (i.e. animals with physiological stimulation of endogenous PRL release) and non-lactating arthritic mice revealed no clear-cut differences, indicating that PRL is of minor importance for the induction of the post-partum flare. Some steroids other than oestradiol, which may be implicated in the exacerbation of arthritis, namely progesterone and hydrocortisone, had no clinical effect. Analyses of agalactosyl IgG levels in mice with CIA, and anti-collagen II antibodies in sera collected at the end of the experiments revealed no significant differences between the oestradiol and the control groups. The successful oestradiol treatment of the mice indicates that the drop in endogenous oestradiol levels prior to delivery ends the oestrogen-mediated protection against arthritis during pregnancy.

Maintained pregnancy levels of oestrogen afford complete protection from post-partum exacerbation of collagen-induced arthritis.

Changes in IgG glycoform levels are associated with remission of arthritis during pregnancy.

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Increased levels of prolactin during, but not after, the immunisation with rat collagen ii enhances the course of arthritis in dba/1 mice

Maintained pregnancy levels of oestrogen afford complete protection from post-partum exacerbation of collagen-induced arthritis.

Changes in IgG glycoform levels are associated with remission of arthritis during pregnancy.