Explainable Artificial Intelligence Helps in Understanding the Effect of Fibronectin on Survival of Sepsis.

Fibronectin (FN) plays an essential role in the host's response to infection. In previous studies, a significant decrease in the FN level was observed in sepsis; however, it has not been clearly elucidated how this parameter affects the patient's survival. To better understand the relationship between FN and survival, we utilized innovative approaches from the field of explainable machine learning, including local explanations (Break Down, Shapley Additive Values, Ceteris Paribus), to understand the contribution of FN to predicting individual patient survival. The methodology provides new opportunities to personalize informative predictions for patients. The results showed that the most important indicators for predicting survival in sepsis were INR, FN, age, and the APACHE II score. ROC curve analysis showed that the model's successful classification rate was 0.92, its sensitivity was 0.92, its positive predictive value was 0.76, and its accuracy was 0.79. To illustrate these possibilities, we have developed and shared a web-based risk calculator for exploring individual patient risk. The web application can be continuously updated with new data in order to further improve the model.

Fibronectin as a Marker of Disease Severity in Critically Ill COVID-19 Patients.

The SARS-CoV-2 virus alters the expression of genes for extracellular matrix proteins, including fibronectin. The aim of the study was to establish the relationship between different forms of fibronectin, such as plasma (pFN), cellular (EDA-FN), and proteolytic FN-fragments, and disease severity and mortality of critically ill patients treated in the intensive care unit. The levels of pFN, EDA-FN, and FN-fragments were measured in patients with a viral (N = 43, COVID-19) or bacterial (N = 41, sepsis) infection, using immunoblotting and ELISA. The level of EDA-FN, but not pFN, was related to the treatment outcome and was significantly higher in COVID-19 Non-survivors than in Survivors. Furthermore, EDA-FN levels correlated with APACHE II and SOFA scores. FN-fragments were detected in 95% of COVID-19 samples and the amount was significantly higher in Non-survivors than in Survivors. Interestingly, FN-fragments were present in only 56% of samples from patients with bacterial sepsis, with no significant differences between Non-survivors and Survivors. The new knowledge gained from our research will help to understand the differences in immune response depending on the etiology of the infection. Fibronectin is a potential biomarker that can be used in clinical settings to monitor the condition of COVID-19 patients and predict treatment outcomes.

Plasma and Cellular Forms of Fibronectin as Prognostic Markers in Sepsis.

BACKGROUND: There is a pressing need for specific prognostic markers that could be used to monitor the severity of sepsis. The aims of our study were to investigate changes in the expression of different molecular forms of fibronectin in sepsis and to assess their relationship to the clinical severity and mortality of patients. Material and Methods. Forms of fibronectin: plasma (pFN), cellular (EDA-FN), FN-fibrin complexes, and fibronectin fragments were analyzed in 71 sepsis patients (survivors and nonsurvivors) and in the control by ELISA and immunoblotting. RESULTS: The baseline pFN concentration of patients with sepsis was significantly lower than in the control (133.0 mg/L vs. 231.2 mg/L) (P < 0.001), and in nonsurvivors, it was lower than in survivors (106.0 mg/L vs. 152.8 mg/L) (P = 0.004). The baseline EDA-FN was significantly elevated in both sepsis groups (survivors: 6.7 mg/L; nonsurvivors: 9.4 mg/L) compared to the control (1.4 mg/L) (P < 0.001). It should be noted that among patients with more severe sepsis, the EDA-FN level was higher in nonsurvivors than in survivors. Furthermore, molecular FN-fibrin complexes as well as FN fragments occurred much more frequently in nonsurvivors than in survivors. CONCLUSION: The study showed that in sepsis, changes in plasmatic and cellular form of fibronectin were associated with the severity of sepsis and may be useful predictors of outcome.

Changes of plasma fibronectin and fibronectin-fibrin complexes in dams of stillborn dairy calves.

BACKGROUND: Fibronectin (FN) is a large (450-500 kDa), multidomain and multifunctional glycoprotein existing in mammalian tissues. Some fibronectin (FN) molecular forms might be involved in biological processes occurring within the perinatal period, such as tissue remodeling, coagulation, and repair. RESULTS: In this study fibronectin (FN) and fibrinogen (Fb) concentrations and FN-fibrin complexes occurrence and its relative amounts with increasing high molecular masses were respectively determined by ELISA, heat precipitation, and SDS-agarose-immunoblotting methods. Plasma samples from three groups of dams with: 1) singleton stillborn calf without or with negligible autolytic changes in internal organs (DSBn), 2) singleton stillborn calf with advanced autolytic changes in internal organs (DSBa), 3) singleton live-born control calf (DC), and 4) a group of cows during mid to late lactation (LC) were analyzed. Maternal plasma FN concentration in the DSBn and DSBa groups was significantly lower than in the LC group. The plasma samples of DSBa showed a significantly lower FN concentration than in the DC group. Plasma Fb concentration was significantly higher in the DSBa and DSBn, than in the LC group. FN immunoblotting of the cow plasma samples revealed, besides an FN-dimer band, the presence of supramolecular FN-fibrin bands corresponding to FN-fibrin complexes with increasing molecular masses: up to 5 bands from 750 kDa to 1900 kDa in the DSBn and DSBa plasma samples, two bands of 750 and 1000 kDa in the DC group, and only the smallest one of 750 kDa in the LC group. CONCLUSIONS: The observed low FN concentration and occurrence of supramolecular FN-fibrin complexes (1000 kDa and more) in the maternal plasma comparing to cows in lactation might have been associated with periparturient changes in tissues. The presence in maternal plasma of high-molecular FN-fibrin complexes (1300-1900 kDa) arouse the question if this is the consequence of calf perinatal mortality.

Time-dependent changes in extra-domain A-fibronectin concentration and relative amounts of fibronectin-fibrin complexes in plasma of patients with peripheral arterial disease after endovascular revascularisation.

Fibronectin (FN) may be involved in time- and stage-dependent and inter-related controlled processes of inflammation, coagulation, and wound healing accompanying peripheral arterial disease (PAD). In the present study, FN and FN-containing extra-domain A (EDA-FN), macromolecular FN-fibrin complexes, and FN monomer were analysed in the plasma of 142 PAD patients, including 37 patients with restenosis, for 37 months after revascularisation. FN concentration increased significantly in the plasma of PAD patients within 7 to 12 months after revascularisation, whereas the high concentration of EDA-FN was maintained up to 24 months, significantly higher in the group 7 to 12 months after revascularisation with recurrence of stenosis and lower in the PAD groups 1 to 3 months and 4 to 6 months after revascularisation with comorbid diabetes and ulceration, respectively. The relative amounts of FN-fibrin complexes up to 1600 kDa and FN monomer were significantly higher, within intervals of 4 to 24 months and 4 to 6 months after revascularisation, respectively. Moreover, the relative amounts of 750 to 1600 kDa FN-fibrin complexes within 13 to 24 months after revascularisation were higher in comparison with those in the group without restenosis. In conclusion, high levels of EDA-FN and FN-fibrin complexes could have potential diagnostic value in the management of PAD patients after revascularisation, predicting restenosis risk.

Analysis of Soluble Molecular Fibronectin-Fibrin Complexes and EDA-Fibronectin Concentration in Plasma of Patients with Atherosclerosis.

Atherosclerosis, a chronic vascular disease, leads to molecular events bound with interplaying processes of inflammation and coagulation. In the present study, fibronectin (FN), FN containing extra domain A (EDA-FN), frequency of occurrence, and relative amounts of soluble plasma FN-fibrin complexes were analyzed in 80 plasma samples of patients suspected of coronary artery disease based on clinical evaluation and changes in arteries found by computed tomographic coronary angiography. The study showed that in the plasma of the patients' group with high risk of coronary artery disease EDA-FN concentration was significantly higher (3.5 ± 2.5 mg/L; P < 0.025) and the molecular FN-fibrin complexes of 1000 kDa and higher occurred more often than in the groups of patients with mild risk of coronary artery disease and the normal age-matched. The increased level of EDA-FN and occurrence of FN-fibrin complexes could have a potential diagnostic value in the diagnosis and management of patients with coronary artery disease.

Occurrence of fibronectin-fibrin complexes in plasma of patients with multimorbidity due to the inflamm-aging phenomenon.

BACKGROUND: Multimorbidity is the co-occurrence of chronic diseases associated with low-grade chronic inflammation of connective tissue. AIM OF STUDY: Frequency of occurrence and relative amounts of fibronectin (FN) complexes with fibrin (FN-fibrin) and FN monomer were analyzed in 130 plasma samples of 18 to 94-year-old multimorbid patients in relation to concentrations of FN and extra domain A (EDA)-FN, and C-reactive protein (CRP) as well as to age, number of coexisting chronic diseases and presence of specified diseases. RESULTS: Immunoblotting revealed, besides FN dimer, the presence of FN monomer, and 750-, 1000-, and 1300-kDa FN-fibrin complexes in the multimorbid plasmas. The FN-fibrin complexes appeared more frequently and in higher relative amounts, but FN monomer less frequently and in a lower relative amount in the groups of elderly multimorbid patients, with a higher number of coexisting diseases and with dominance of cardiovascular diseases and osteoarthrosis, and with CRP concentration of 3-5mg/l. In contrast, the normal plasma contained only the FN-fibrin complex of 750 kDa in a lower relative amount, but with an increasing amount with normal aging. Moreover, FN concentration increased and EDA-FN decreased with the number of co-existing diseases and aging of patients, although both concentration values were lower than in the age-matched normal groups. FN concentration was the lowest in the exacerbation of a chronic disease and EDA-FN in the stable chronic disease groups. CONCLUSION: The alterations in plasma FN molecular status were associated with micro-inflammation and micro-coagulation, as well as multimorbidity of subjects and their physiological aging.

Occurrence of soluble supra-molecular FN-fibrin complexes in the plasma of children with recurrent respiratory infection.

OBJECTIVES: Fibronectin (FN) is able to bind fibrin and FN-fibrin complexes and is found in the plasma of some patients suffering from inflammatory disease. The present study was undertaken to determine whether soluble supra-molecular FN-fibrin complexes were present in the plasma of children with recurrent respiratory infections (RRI). DESIGN AND METHODS: The frequency of occurrence and relative amounts of the supra-molecular FN-fibrin forms, concentrations of immunoglobulins and numbers of natural killer cells (NK) were determined in the plasma of children with recurrent respiratory infections. The frequencies of these parameters were compared with their frequencies in the plasma of children with acute respiratory infections and plasma from healthy children. RESULTS: SDS-agarose immunoblotting of patients' plasma revealed the presence of several additional FN-fibrin bands, with decreasing electrophoretic mobilities and increasing molecular masses of 750 kDa, 1000 kDa, 1300 kDa, 1600 kDa and 1900 kDa. Such FN-fibrin complexes occurred with higher frequency and in larger amounts in the plasma of children with RRI and acute infection than they did in plasma from normal children. Moreover, bands above 1000 kDa were absent in most young healthy individuals. The occurrence of FN-fibrin complexes did not correlate with either immunoglobulin concentrations, or with the number of NK cells. CONCLUSIONS: The occurrence of plasma supra-molecular FN-fibrin complexes is associated with acute and recurrent respiratory infections of children.

Identification of soluble supramolecular FN-fibrin complexes in human plasma.

SDS-agarose FN immunoblotting of 257 normal and pathological human plasma samples revealed the ladder pattern of multiple plasma FN bands which corresponded to FN monomer and dimer, and 5 FN-fibrin bands with increasing molecular masses. The FN-fibrin bands of about 750 kDa, 1000 kDa, 1300 kDa, 1600 kDa, and 1900 kDa appeared more frequently and in significantly higher relative amounts in the pathological samples (P < 0.000) than in relatively healthy individuals. The revealing of high-molecular FN-fibrin complexes by SDS-agarose FN immunobloting might have the potential to become a laboratory biomarker of some diseases in which the coagulation system is triggered.

Molecular status of plasma fibronectin as an additional biomarker for assessment of Alzheimer's dementia risk.

BACKGROUND: Aberrant angiogenesis and senescence of the cerebrovascular system could initiate neurovascular events leading to neurovascular disorders. Fibronectin (FN) exerts a strong angiogenic influence on endothelial cells in the central nervous system. METHODS: In the present study the expression of the plasma fibronectin molecular forms in an Alzheimer patient group, compared with vascular dementia and age-matched control groups was analyzed by immunoblotting. RESULTS: FN in the plasma of the elderly individuals with and without dementia exists as a mixture of heterogeneous molecules with increasing molecular masses. Apart from the wide approximately 240-kDa and approximately 220-kDa FN bands, normally present in plasma, the high molecular FN forms having approximately 280 kDa and approximately 320 kDa appeared in the plasma of the Alzheimer dementia group more frequently and at the higher amounts than in the vascular dementia and age-matched nondemented groups. CONCLUSIONS: The plasma FN molecular status seems to be a molecular additional biomarker for assessment of dementia risk.

Presence of high-molecular-weight forms and domain alterations of fibronectin in pleural effusion of patients with lung cancer.

OBJECTIVES: Appearance of fibronectin (FN) molecular forms and alterations of domain expositions can be associated with lung cancer. DESIGN AND METHODS: The presence of the FN molecular forms and epitopes in its cell-binding, carboxyl-, and amino-terminal domains was determined in the plasma and pleural effusion of patients suffering from small- and non-small-cell lung cancer, and lung inflammation by immunoblotting and FN-ELISA. RESULTS: The 320-kDa and 280-kDa FN forms as well as FN fragments appeared in the pleural effusion and plasma of patients suffering from lung inflammation or cancer in significantly higher relative amounts in both lung cancer groups than in the inflammation. The domain concentrations were higher in the cancer and inflammatory plasma groups than those in the control group. The higher N-terminal epitope expression in pleural effusion than in plasma indicates different epitope accessibility for the monoclonal antibody. CONCLUSIONS: The molecular status of FN probably reflects the dynamic changes which occur in cancer and inflammatory tissue.

[Fibronectin as an active component of the extracellular matrix]. / Fibronektyna jako aktywny skladnik macierzy pozakomórkowej.

The extracellular matrix (ECM) is a highly dynamic, elastic, and multicomponent compact structure which fills the space between cells and provides a storage site for growth factors and cytokines. The ECM undergoes constant remodeling, most obviously during development, wound healing, and other repair processes. Fibronectin (FN), a multidomain and multifunctional glycoprotein, is one ECM components which plays not only a structural role, but also a functional one, regulating the cell-ECM interaction. This review focuses on fibrillogenesis. The current state of knowledge about the molecular mechanisms which initiate FN binding to the cell surface through central and N-terminal FN sequences is described. It appears that exciting and drastic changes in the FN molecule's conformation are associated with fibril formation. Globular dimeric FN binds with an integrin receptor on the cell surface. FN-bound alpha5beta1 integrins actively translocate from focal adhesions to fibrillar adhesions and this movement causes stretching of the FN molecule. FN thus becomes extended and fibrillar and dynamic tension forces seem to unmask the cryptic self-association and other sites implicated in FN-matrix assembly. This provides for the formation of a fibrillar matrix network anchoring cells and molecules essential for signal transduction within the tissue. Finally, the molecular process of provisional matrix formation during wound healing is considered. There are some suggestions that modified FN preparations could be applied in medicine, particularly in patients after ischemic injury.