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Background: Plasma hyaluronan concentrations are increased during sepsis but underlying mechanisms leading to high plasma hyaluronan concentration are poorly understood. In this study we evaluate the roles of plasma hyaluronan, effective plasma hyaluronidase (HYAL) activity and its endogenous plasma inhibition in clinical and experimental sepsis. We specifically hypothesized that plasma HYAL acts as endothelial glycocalyx shedding enzyme, sheddase. Methods: Plasma hyaluronan, effective HYAL activity and HYAL inhibition were measured in healthy volunteers (n = 20), in patients with septic shock (n = 17, day 1 and day 4), in patients with acute pancreatitis (n = 7, day 1 and day 4) and in anesthetized and mechanically ventilated pigs (n = 16). Sixteen pigs were allocated (unblinded, open label) into three groups: Sepsis-1 with infusion of live Escherichia coli (E. coli) 1 x 10(8) CFU/h of 12 h (n = 5), Sepsis-2 with infusion of E. coli 1 x 10(8) CFU/h of 6 h followed by 1 x 10(9) CFU/h of the remaining 6 h (n = 5) or Control with no E. coli infusion (n = 6). Results: In experimental E. coli porcine sepsis and in time controls, plasma hyaluronan increases with concomitant decrease in effective plasma HYAL activity and increase of endogenous HYAL inhibition. Plasma hyaluronan increased in patients with septic shock but not in acute pancreatitis. Effective plasma HYAL was lower in septic shock and acute pancreatitis as compared to healthy volunteers, while plasma HYAL inhibition was only increased in septic shock. Conclusion: Elevated plasma hyaluronan levels coincided with a concomitant decrease in effective plasma HYAL activity and increase of endogenous plasma HYAL inhibition both in experimental and clinical sepsis. In acute pancreatitis, effective plasma HYAL activity was decreased which was not associated with increased plasma hyaluronan concentrations or endogenous HYAL inhibition. The results suggest that plasma HYAL does not act as sheddase in sepsis or pancreatitis.

While fluid resuscitation is fundamental in the treatment of sepsis-induced tissue hypo-perfusion, a sustained positive fluid balance is associated with excess mortality. Hyaluronan, an endogenous glycosaminoglycan with high affinity to water, has not been tested previously as adjuvant to fluid resuscitation in sepsis.

In a prospective, parallel-grouped, blinded model of porcine peritonitis-sepsis, we randomized animals to intervention with adjuvant hyaluronan (add-on to standard therapy) (n=8) or 0.9% saline (n=8). After the onset of hemodynamic instability the animals received an initial bolus of 0.1 % hyaluronan 1 mg/kg/10 min or placebo (0.9% saline) followed by a continuous infusion of 0.1% hyaluronan (1 mg/kg/h) or saline during the experiment. We hypothesized that the administration of hyaluronan would reduce the volume of fluid administered (aiming at stroke volume variation <13%) and/or attenuate the inflammatory reaction.

Total volumes of intravenous fluids infused were 17.5 ± 11 ml/kg/h vs. 19.0 ± 7 ml/kg/h in intervention and control groups, respectively (p = 0.442). Plasma IL-6 increased to 2450 (1420 – 6890) pg/ml and 3690 (1410 – 11960) pg/ml (18 hours of resuscitation) in the intervention and control groups (NS). The intervention counteracted the increase in proportion of fragmented hyaluronan associated with peritonitis-sepsis alone (mean peak elution fraction (18 hours of resuscitation) control group: 17.9 ± 0.6 vs. intervention group: 16.8 ± 0.9 (p = 0.031).

In conclusion, hyaluronan did not reduce the volume needed for fluid resuscitation or decrease the inflammatory reaction, even though it counterbalanced the peritonitis induced shift towards increased proportion of fragmented hyaluronan.

Sepsis is a condition with high morbidity and mortality. Prompt recognition and initiation of treatment is essential. Despite forming an integral part of sepsis management, fluid resuscitation may also lead to volume overload, which in turn is associated with increased mortality. The optimal fluid strategy in sepsis resuscitation is yet to be defined. Hyaluronan, an endogenous glycosaminoglycan with high affinity to water is an important constituent of the endothelial glycocalyx. We hypothesized that exogenously administered hyaluronan would counteract intravascular volume depletion and contribute to endothelial glycocalyx integrity in a fluid restrictive model of peritonitis. In a prospective, blinded model of porcine peritonitis sepsis, we randomized animals to intervention with hyaluronan (n = 8) or 0.9% saline (n = 8). The animals received an infusion of 0.1% hyaluronan 6 ml/kg/h, or the same volume of saline, during the first 2 h of peritonitis. Stroke volume variation and hemoconcentration were comparable in the two groups throughout the experiment. Cardiac output was higher in the intervention group during the infusion of hyaluronan (3.2 ± 0.5 l/min in intervention group vs 2.7 ± 0.2 l/min in the control group) (p = 0.039). The increase in lactate was more pronounced in the intervention group (3.2 ± 1.0 mmol/l in the intervention group and 1.7 ± 0.7 mmol/l in the control group) at the end of the experiment (p < 0.001). Concentrations of surrogate markers of glycocalyx damage; syndecan 1 (0.6 ± 0.2 ng/ml vs 0.5 ± 0.2 ng/ml, p = 0.292), heparan sulphate (1.23 ± 0.2 vs 1.4 ± 0.3 ng/ml, p = 0.211) and vascular adhesion protein 1 (7.0 ± 4.1 vs 8.2 ± 2.3 ng/ml, p = 0.492) were comparable in the two groups at the end of the experiment. In conclusion, hyaluronan did not counteract intravascular volume depletion in early peritonitis sepsis. However, this finding is hampered by the short observation period and a beneficial effect of HMW-HA in peritonitis sepsis cannot be discarded based on the results of the present study.

Background: Sepsis is a critical condition characterized by a dysregulated immune response to infection. As sepsis develops to septic shock, its most severe form, morbidity and mortality increases. Hyaluronan is a key component of the extracellular matrix and the endothelial glycocalyx. In sepsis, plasma hyaluronan concentrations are increased and correlate with disease severity. In this study we aimed to explore and compare the proteomic profiles of hyaluronan-associated proteins in patients with the dysregulated immune response of septic shock and the sterile inflammation of acute alcohol-related pancreatitis.

Methods: The present study involved proteomic analysis of patients with septic shock (n = 13), pancreatitis (n = 8), and healthy controls (n = 8). LC-MS/MS was conducted for peptide analysis. Hyaluronan-associated proteins were identified using the UniProt REST API, followed by functional and pathway enrichment analyses with GOATOOLS and GSEApy. Statistical analyses, including ANOVA and post hoc tests, were performed using Python and SPSS, with significance set at p < 0.05.

Results: From a total sum of 663 detected unique plasma proteins, 15 were identified as hyaluronan-related proteins. Plasma levels of 11/15 proteins separated septic shock from pancreatitis in a statistically significant manner. Between the groups differences were apparent on day 1 (8 proteins in septic shock versus 3 in pancreatitis) and day 4 (6 proteins in septic shock versus 3 in pancreatitis) relative to controls. Functional enrichment analysis revealed associations with extracellular matrix organization, proteolytic enzyme regulation, and hyaluronan metabolism. Notably, members of the inter-alpha-inhibitor family demonstrated distinct patterns, with ITIH3 levels increasing and ITIH1, ITIH2, and ITIH4 levels decreasing in septic shock compared to controls. Additionally, plasma hyaluronidase inhibition correlated positively with ITIH3 levels.

Conclusion: The present study explored the role of hyaluronan-related proteins in septic shock pathophysiology, revealing potential dysregulation associated with sepsis severity. The decrease in ITIH1, ITIH2 and ITIH4, as compared to the increase in ITIH3, suggest a complex alteration in the protein balance of the I alpha I-family in sepsis. Overall, the altered proteomic profile of hyaluronan-related proteins as reflected by the GO terms indicates a complex dysregulation not only in hyaluronan metabolism and extracellular matrix, but also in the regulation of several proteolytic enzymes. Future studies on this area are warranted.