Systemic and local airways inflammatory response to endotoxin.

Endotoxin can be detected in house dust. Numerous studies have revealed that endotoxin exposure is a risk factor in increasing airway obstructive manifestations, both in occupational and domestic environments. In humans, inhalation of pure endotoxin induces systemic symptoms and a change in bronchial non-specific responsiveness, related with changes in blood and sputum inflammatory markers. However, some recent work suggests that, prior to airway disease development, endotoxin may have an atopy-protective effect. In particular, indoor endotoxin exposure in early life may protect against allergen sensitisation by enhancing type-1 immunity. Finally, since large variations between human immune responses to endotoxin have been reported, genetic mutations could alter the mechanisms of endotoxin recognition and contribute to the risk of atopy.