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Plasma fibronectin concentration in animal models of sepsis and endotoxemia
Abstract:
Plasma fibronectin is a nonspecific opsonin which mediates phagocytosis of particulate matter by macrophages. Fibronectin depletion results in depression of reticuloendothelial system phagocytic function. This may potentiate microvascular embolization and sludging in critical illness. It has been hypothesized that sepsis is a major cause of fibronectin depletion. To explore this hypothesis, plasma fibronectin concentrations were measured in rats with intraabdominal abscesses and in rabbits subjected to the generalized Shwartzman reaction (spaced doses of endotoxin). In both groups of animals there was a significant increase (P less than 0.05) rather than decrease in fibronectin concentrations at times when sepsis and disseminated intravascular coagulation were manifest. This study does not support the hypothesized relationship between sepsis and fibronectin depletion. Until the kinetics of fibronectin production and utilization are further delineated, caution must be exercised in the interpretation of immunoreactive plasma fibronectin levels.
Insights
This study investigated the link between sepsis and fibronectin depletion. Contrary to the hypothesis, sepsis in animal models led to increased plasma fibronectin levels, not depletion.
Area of Science:
- Immunology
- Critical Care Medicine
- Pathophysiology
Background:
- Plasma fibronectin acts as an opsonin, mediating macrophage phagocytosis and supporting reticuloendothelial system function.
- Fibronectin depletion is hypothesized to contribute to microvascular issues like embolization and sludging in critical illness.
- Sepsis is suspected as a primary driver of fibronectin depletion in critically ill patients.
Purpose of the Study:
- To investigate the relationship between sepsis and plasma fibronectin concentrations.
- To determine if sepsis causes fibronectin depletion as hypothesized.
Main Methods:
- Plasma fibronectin levels were measured in rats with induced intraabdominal abscesses.
- Plasma fibronectin levels were measured in rabbits undergoing the generalized Shwartzman reaction (endotoxin administration).
- Measurements were taken during periods of manifest sepsis and disseminated intravascular coagulation.
Main Results:
- In both animal models, plasma fibronectin concentrations significantly increased (P < 0.05) during sepsis.
- The study observed an elevation, not a decrease, in fibronectin levels when sepsis and DIC were present.
- These findings do not support the hypothesis that sepsis causes fibronectin depletion.
Conclusions:
- The study does not support the hypothesis linking sepsis to fibronectin depletion.
- Elevated plasma fibronectin levels were observed during sepsis in animal models.
- Further research into fibronectin kinetics is needed for accurate interpretation of plasma fibronectin levels.