Somatotropin and somatostatin effects on vitamin K-dependent plasma coagulation factors

The haemostatic system in acromegaly: a single-centre case-control study

PURPOSE

Although the mortality from acromegaly is due in most cases to an increased cardiovascular risk, no study has globally evaluated the haemostatic balance in acromegaly to ascertain the presence of hypercoagulability. We endeavoured to assess the overall coagulation profile in patients with acromegaly using both traditional and global coagulation assays.

METHODS

Consecutive outpatients with a diagnosis of acromegaly were enrolled and matched with healthy subjects. Whole blood thromboelastometry and impedance aggregometry, procoagulant, anticoagulant and fibrinolytic factors, as well as thrombin-generation assay and circulating endothelium-derived microvesicles were measured.

RESULTS

Forty patients (M/F 14/26, median age 59 years) with either new diagnosis (naïve, 14 cases) or treated acromegaly (26 cases) were enrolled in this study. Median time from diagnosis was 11 years. Levels of factor VIII and fibrinogen were significantly higher in acromegalic patients vs. controls (p = 0.029 and < 0.003, respectively). Overall, thromboelastometry parameters showed a faster coagulation formation with a more stable clot. Acromegaly patients showed significantly higher endogenous thrombin potential [ETP] and thrombin peak compared to controls (p = 0.016 and p < 0.001, respectively). ETP remained significantly higher (p < 0.001) when thrombomodulin was added. Endothelial-derived microvesicles were significantly higher in acromegaly patients than controls (52 [40.5-67] MVs/µL and 30 [18-80] MVs/µL, p = 0.03). Patients with untreated (naïve) acromegaly showed significantly reduced ETP with and without thrombomodulin vs. patients with treated acromegaly (p = 0.01).

CONCLUSION

Hypercoagulability in acromegaly is mainly due to higher levels of fibrinogen, factor VIII and thrombin generation, and appears to be more linked to the chronic phase of the disease.

Comprehensive Map and Functional Annotation of Human Pituitary and Thyroid Proteome

Knowledge about human tissue proteome will provide insights into health organ physiology. To construct a comprehensive data set of human pituitary and thyroid proteins, post-mortem pituitaries and thyroids from 10 normal individuals were used. The pooled samples were prepared using two methods. One part of the sample was processed using 14 high-abundance proteins immunoaffinity column. The other part was directly subjected to digestion. Finally, a total of 7596 proteins in pituitary and 5602 proteins in thyroid with high confidence were identified, with 6623 and 4368 quantified, respectively. A total of 5781 of pituitary and 3178 of thyroid proteins have not been previously reported in the normal pituitary and thyroid proteome. Comparison of pituitary and thyroid proteome indicated that thyroid prefers to be involved in nerve system regeneration and metabolic regulation, while pituitary mainly performs functions of signal transduction and cancer modulation. Our results, for the first time, comprehensively profiled and functionally annotated the largest high-confidence data set of proteome of two important endocrine glands, pituitary and thyroid, which is important for further studies on biomarker identification and molecular mechanisms of pituitary and thyroid disorders. The mapping results can be freely downloaded at http://www.urimarker.com/pituitary/ and http://www.urimarker.com/thyroid/ . The raw data are available via ProteomeXchange with identifier PXD006471.

Protein C and protein S changes in GH-deficient adults on r-HGH replacement therapy: correlations with PAI-1 and t-PA plasma levels

BACKGROUND

In the rat liver, growth hormone (GH) affects the synthesis of vitamin-K-dependent factors, including Protein C (prot.C) and protein S (prot.S), two natural anticoagulants that prevent hypercoagulable states. Adults with GH deficiency (GHD) are at risk of thrombotic events. High circulating levels of PAI-1 and t-PA, that reflect hypercoagulable states, may contribute to such risk. In GHD adults on replacement therapy with recombinant human GH (r-HGH), %Δ PAI-1 and %Δ t-PA are related to %Δ insulin changes.

OBJECTIVES

To evaluate changes in vitamin-K-dependent factors in GHD on r-HGH replacement.

METHODS

In 60 GHD adults, to relate plasma levels of vitamin-K-dependent factors with those of PAI-1, t-PA and insulin before and after 6-month (6-mo) replacement therapy with r-HGH.

RESULTS

After 6-mo r-HGH replacement, %Δ insulin enhancements occurred in 36/60 subjects. PAI-1, t-PA, Prot.C, Prot.S and FVIIact did not change in them. In the 24/40 subjects that experienced %Δ insulin reductions, Prot.C (p=0.025), Prot.S (p=0.031) and FVIIact (p=0.049) decreased significantly. PAI-1 (p=0.019) and t-PA antigen (p=0.009) behaved similarly. In a multivariate analysis, %∆ PAI-1 (β=0.436, p<0.01) was the strongest predictor of %∆ prot.S, wheras %∆ t-PA (β=0.385, p<0.008) and %∆ insulin (β=0.429, p<0.004) were the strongest predictors of %∆ prot.C. In all cases, regardless of %Δ insulin changes, FII, FVII Ag and FIX levels did not change from baseline.

CONCLUSIONS

In GHD adults on r-HGH replacement, changes in vitamin-K-dependent factors reflect a subtle adaptation of the natural anticoagulant system to PAI-1 and t-PA changes, via the response of insulin to r-HGH.

Sex differences in thrombosis in mice are mediated by sex-specific growth hormone secretion patterns

Sex differences in thrombosis are well described, but their underlying mechanism(s) are not completely understood. Coagulation proteins are synthesized in the liver, and liver gene expression is sex specific and depends on sex differences in growth hormone (GH) secretion--males secrete GH in a pulsatile fashion, while females secrete GH continuously. Accordingly, we tested the hypothesis that sex-specific GH secretion patterns cause sex differences in thrombosis. Male mice were more susceptible to thrombosis than females in the thromboplastin-induced pulmonary embolism model and showed shorter clotting times ex vivo. GH-deficient little (lit) mice were protected from thrombosis, and pulsatile GH given to lit mice restored the male clotting phenotype. Moreover, pulsatile GH administration resulted in a male clotting phenotype in control female mice, while continuous GH caused a female clotting phenotype in control male mice. Expression of the coagulation inhibitors Proc, Serpinc1, Serpind1, and Serpina5 were strongly modulated by sex-specific GH patterns, and GH modulated resistance to activated protein C. These results reveal what we believe to be a novel mechanism whereby sex-specific GH patterns mediate sex differences in thrombosis through coordinated changes in the expression of coagulation inhibitor genes in the liver.