The association of lipopolysaccharide and inflammatory markers with severe dengue infection

Background Although serum lipopolysaccharide (LPS) was shown to associate with development of severe dengue, the reasons for high LPS and its subsequent involvement in disease pathogenesis are not known. Methods: We assessed LPS, lipopolysaccharide binding protein (LBP), CRP, IL-18, procalcitonin in patients with acute dengue fever (DF=129) and dengue haemorrhagic fever (DHF=64) and correlated these observations with the presence of comorbid illnesses, concurrent bacteraemia and clinical disease severity. Results: LPS levels were significantly (p=0.01) higher in patients with DHF, compared to those with DF. 45 (70%) of those with DHF and 63 (49%) of those with DF had detectable LPS and therefore, presence of LPS was significantly associated with DHF (p=0.005, OR=2.48, 95% CI: 1.29 to 4.64). Those with metabolic diseases, 22/29 (75.9%) and those with atopic diseases 17/22 (77.3%) were significantly more likely to have detectable LPS (p=0.025, OR=2.9, 95% CI- 1.17 to 7.59) and (p=0.039, OR=3.06, 95% CI-1.07 to 7.81) respectively, than others. LPS, LBP and CRP levels were high at the febrile phase, before onset of plasma leakage and reduced towards to the critical phase. The CRP levels were significantly higher (p=0.03) in early illness (≤3 days of illness) in those who progressed to develop DHF when compared to those who developed DF. Those who had detectable serum LPS also had a significantly higher CRP (p=0.01). Although there was no difference in procalcitonin (PCT) levels in patients with DF and DHF, the PCT levels were significantly higher in those who had detectable serum LPS (p=0.02). Conclusions: LPS levels were higher in patients with DHF and associated with high levels of other inflammatory markers. Since LPS levels were highest during early infection and were significantly more likely to be present in those with comorbid illnesses, the possible role of LPS in disease pathogenesis, should be further investigated.