Fever - Pyrogen Pathophysiology



EXOGENOUS PYROGEN

 • Bacteria: Lipopolysaccharide components, peptidoglycans and muramyl peptide derivatives, Toxins

 • Virus: Double stranded RNA

 • Fungi: Mannan and glucan components



Exogenous Pyrogen 

	→ Stimulate immune cells (neutrophils, monocytes/macrophages)

	→ Synthesis of proinflammatory mediators (endogenous pyrogen) TNF, IL-1, IFN, IL-6



ENDOGENOUS PYROGEN - Transport to brain vasculature via:

 • Active transport across blood-brain barrier

 • Passive transport through fenestrated capillaries in the circumventricular organs



CNS - Endogenous Pyrogen

	→ Induce synthesis of Prostaglandins (PGE2)

	→ PGE2 stimulates cAMP in the hypothalamus

	→ Elevates thermoregulatory set point

	→ Heat conservation, Heat production

	→ Fever



#Fever #Pathophysiology #Pyrogen