Changes in laboratory markers of thrombotic risk early in the first trimester of pregnancy may be linked to an increase in estradiol and progesterone.

BACKGROUND: Pregnant women are at increased risk of venous thrombosis compared to non-pregnant women. Epidemiological and laboratory data suggest that hypercoagulability begins in the first trimester but it is unknown exactly how early in pregnancy this develops. The mechanisms that result in a prothrombotic state may involve oestrogens and progestogens. METHODS: Plasma samples were taken prior to conception and five times in early pregnancy, up to Day 59 gestation, from 22 women undergoing natural cycle in vitro fertilization, who subsequently gave birth at term following a normal pregnancy. Thrombin generation, free Protein S, Ddimer, Fibrinogen, factor VIII, estradiol and progesterone were measured. To counter inter-individual variability, the change in laboratory measurements between the pre-pregnant and pregnant state were measured over time. RESULTS: Peak thrombin, Endogenous Thrombin Potential, Velocity Index and fibrinogen significantly increased, and free Protein S significantly decreased, from pre-pregnancy levels, by 32 days gestation. Ddimer and VIII significantly increased from pre-pregnancy levels by 59 days gestation. Estradiol significantly increased by Day 32 gestation with a non-significant increase of 67% by Day 24 gestation. Progesterone significantly increased by Day 32 gestation. Almost all laboratory markers of thrombosis correlated significantly with estradiol and progesterone. CONCLUSION: Our work is the first to demonstrate that the prothrombotic state develops very early in the first trimester. Laboratory markers of hypercoagulability correlate significantly with estradiol and progesterone suggesting these are linked to the prothrombotic state of pregnancy. Clinicians should consider commencing thromboprophylaxis early in the first trimester in women at high thrombotic risk.

ß-cell specific T-lymphocyte response has a distinct inflammatory phenotype in children with Type 1 diabetes compared with adults.

AIM: To examine the hypothesis that the quality, magnitude and breadth of helper T-lymphocyte responses to ß cells differ in Type 1 diabetes according to diagnosis in childhood or adulthood. METHODS: We studied helper T-lymphocyte reactivity against ß-cell autoantigens by measuring production of the pro-inflammatory cytokine interferon-γ and the anti-inflammatory cytokine interleukin-10, using enzyme-linked immunospot assays in 61 people with Type 1 diabetes (within 3 months of diagnosis, positive for HLA DRB1*0301 and/or *0401), of whom 33 were children/adolescents, and a further 91 were unaffected siblings. RESULTS: Interferon-γ responses were significantly more frequent in children with Type 1 diabetes compared with adults (85 vs 61%; P = 0.04). Insulin and proinsulin peptides were preferentially targeted in children (P = 0.0001 and P = 0.04, respectively) and the breadth of the interferon-γ response was also greater, with 70% of children having an interferon-γ response to three or more peptides compared with 14% of adults (P < 0.0001). Islet ß-cell antigen-specific interleukin-10 responses were similar in children and adults in terms of frequency, breadth and magnitude, with the exception of responses to glutamic acid decarboxylase 65, which were significantly less frequent in adults. CONCLUSIONS: At diagnosis of Type 1 diabetes, pro-inflammatory autoreactivity is significantly more prevalent, focuses on a wider range of targets, and is more focused on insulin/proinsulin in children than adults. We interpret this as indicating a more aggressive immunological response in the younger age group that is especially characterized by loss of tolerance to proinsulin. These findings highlight the existence of age-related heterogeneity in Type 1 diabetes pathogenesis that could have relevance to the development of immune-based therapies.

Proinsulin multi-peptide immunotherapy induces antigen-specific regulatory T cells and limits autoimmunity in a humanized model.

Peptide immunotherapy (PIT) is a targeted therapeutic approach, involving administration of disease-associated peptides, with the aim of restoring antigen-specific immunological tolerance without generalized immunosuppression. In type 1 diabetes, proinsulin is a primary antigen targeted by the autoimmune response, and is therefore a strong candidate for exploitation via PIT in this setting. To elucidate the optimal conditions for proinsulin-based PIT and explore mechanisms of action, we developed a preclinical model of proinsulin autoimmunity in a humanized HLA-DRB1*0401 transgenic HLA-DR4 Tg mouse. Once proinsulin-specific tolerance is broken, HLA-DR4 Tg mice develop autoinflammatory responses, including proinsulin-specific T cell proliferation, interferon (IFN)-γ and autoantibody production. These are preventable and quenchable by pre- and post-induction treatment, respectively, using intradermal proinsulin-PIT injections. Intradermal proinsulin-PIT enhances proliferation of regulatory [forkhead box protein 3 (FoxP3(+))CD25(high) ] CD4 T cells, including those capable of proinsulin-specific regulation, suggesting this as its main mode of action. In contrast, peptide delivered intradermally on the surface of vitamin D3-modulated (tolerogenic) dendritic cells, controls autoimmunity in association with proinsulin-specific IL-10 production, but no change in regulatory CD4 T cells. These studies define a humanized, translational model for in vivo optimization of PIT to control autoimmunity in type 1 diabetes and indicate that dominant mechanisms of action differ according to mode of peptide delivery.

An investigation of the impact of the location and timing of antigen-specific T cell division on airways inflammation.

It is widely accepted that allergic asthma is orchestrated by T helper type 2 lymphocytes specific for inhaled allergen. However, it remains unclear where and when T cell activation and division occurs after allergen challenge, and whether these factors have a significant impact on airways inflammation. We therefore employed a CD4-T cell receptor transgenic adoptive transfer model in conjunction with laser scanning cytometry to characterize the location and timing of T cell division in asthma in vivo. Thus, for the first time we have directly assessed the division of antigen-specific T cells in situ. We found that accumulation of divided antigen-specific T cells in the lungs appeared to occur in two waves. The first very early wave was apparent before dividing T cells could be detected in the lymph node (LN) and coincided with neutrophil influx. The second wave of divided T cells accumulating in lung followed the appearance of these cells in LN and coincided with peak eosinophilia. Furthermore, accumulation of antigen-specific T cells in the draining LN and lung tissue, together with accompanying pathology, was reduced by intervention with the sphingosine 1-phosphate receptor agonist FTY720 2 days after challenge. These findings provide greater insight into the timing and location of antigen-specific T cell division in airways inflammation, indicate that distinct phases and locations of antigen presentation may be associated with different aspects of pathology and that therapeutics targeted against leukocyte migration may be useful in these conditions.