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End-stage renal disease (ESRD) is a condition accompanied by increased inflammation, oxidative stress, risk of cardiovascular complications, and coagulopathies. The structure of fibrinogen and characteristics of fibrin from plasma samples of ESRD patients on peritoneal dialysis (PD) was investigated. Fibrinogen from ESRD patients had a higher degree of carbonylation than fibrinogen from healthy individuals. The Aα chain was the most susceptible to oxidation, followed by the Bβ chain, whereas the γ-chain was the most resistant to oxidation. Spectrofluorimetric analysis suggested a higher extent of modification of amino acid side chains in fibrinogen from ESRD patients. The tertiary structure of fibrinogen was more affected than its secondary structure. The kinetics (time and rate) of fibrinogen coagulation did not differ between the tested groups. Fibrin prepared from the isolated fibrinogen had a similar structure in both groups. Our results confirm that oxidation and structural alterations of fibrinogen occur in ESRD patients on PD, although these modifications produce no direct effect on the fibrin formation. Taking into account that some patients suffer from bleeding, whereas others develop thrombotic complications, further research on this subject is required to identify other components and processes that contribute to the outcome.

The primary role of insulin-like growth factor binding proteins (IGFBPs) is to regulate availability of IGFs for interacting with receptors, but IGFBPs perform IGF-independent actions as well. The availability and activity of IGFBPs in the circulation is influenced primarily by their concentration and structural modifications, but possibly also by interaction with major plasma proteins such as transferrin, alpha-2-macroglobulin (α2M), and fibrinogen. Four types of circulating IGFBP complexes were examined in this study by immuno- and ligand-binding assays in adults of different age. The amounts of IGFBP-3/transferrin and IGFBP-1/fibrinogen complexes were similar in middle- and old-aged persons, whereas the amounts of IGFBP-1 (or -2)/α2M monomer complexes were lower in the old-aged group and negatively correlated with total IGFBP-1 (or -2) amounts in blood. In contrast to IGFBP-1, IGFBP-2 was present in significantly greater quantities in complexes with α2M dimer than α2M monomer in older individuals. IGFBP complexes did not bind 125 I-labeled IGF-I in amounts detectable by ligand blotting. According to the results of this study, the quantities of IGFBP-1 and IGFBP-2, which interact with α2M, are age-dependent and, in the case of complexes with α2M monomer, they are negatively correlated with the total circulating levels of these two IGFBPs.

Fibrinogen is a plasma glycoprotein and one of the principle participants in blood coagulation. It interacts with many proteins during formation of a blood clot, including insulin-like growth factors (IGFs) and their binding proteins (IGFBP). Fibrinogen complexes were found as minor fractions in fibrinogen preparations independently of the coagulation process, and their presence influences the kinetics of polymerization. The idea of this work was to investigate whether fibrinogen in human plasma interacts with IGFBPs independently of the tissue injury or coagulation process. The results have shown that fibrinogen forms complexes with IGFBP-1 under physiological conditions. Several experimental approaches have confirmed that complexes are co-isolated with fibrinogen from plasma, they are relatively stable, and they appear as a general feature of human plasma. Several other experiments excluded the possibility that alpha-2 macroglobulin/IGFBP-1 complexes or IGFBP-1 oligomers contributed to IGFBP-1 immunoreactivity. The role of fibrinogen/IGFBP-1 complexes is still unknown. Further investigation in individuals expressing both impaired glucose control and coagulopathy could contribute to identification and understanding of their possible physiological role.