Increased lymphatic elimination of interstitial hyaluronan during E. coli sepsis in sheep

The effect of septicemia on the elimination of hyaluronan (HA) from the lung interstitium was investigated in awake sheep with chronic lung lymph and thoracic duct fistulas. The result was compared with that after elevation of left atrial pressure (LAP). Lymph was sampled before and after a 20-min infusion of Escherichia coli (10(9) bacteria/kg body wt.), after elevation of LAP, or both. Infusion of E. coli caused an increased flux of HA in lung lymph and thoracic duct lymph. After an elevation of LAP, the HA flux in lung lymph was increased to a comparable extent. In animals subjected to an increase in LAP and subsequently to infusion of E. coli, no additive effect on HA flux was seen. The weight-average molecular weight of HA in lung lymph was increased both after sepsis and after elevation of LAP. The findings show that sepsis and elevated transvascular hydrostatic pressure result in increased mobilization of HA from the interstitium. This might partly explain the increased HA concentrations in plasma in clinical sepsis and may also lead to a change in the characteristics of the interstitial matrix in this condition.