A new sight for paraquat poisoning from immunology.

Paraquat (methyl viologen, PQ) is highly toxic to humans. Pulmonary fibrosis is the most common cause of death after PQ poisoning. However, no effective therapy is available. The current treatment dilemma and pathology suggest that we should reconsider how to treat the poisoning using other methods, such as immunization. Some clues indicate that immune mechanisms may play important roles in the pathology of PQ poisoning. We implemented a simple experiment to test the hypothesis that activated innate immunity was involved in acute lung injury induced by PQ. Six rats were randomly distributed to two groups: PQ poisoning group and Immunosuppression group (cyclophosphamide pretreatment). Forty-eight hours after PQ administration, rats were anesthetized. The right lungs were excised for histopathology. The experimental results confirmed that in the set of immune deficiency, the inflammatory response in Immunosuppression group could not be effectively triggered so the lung pathology was much better than PQ poisoning group. The immunopathogenic mechanism of PQ poisoning may be essentially a sterile inflammation triggered and amplified by damage-associated molecular patterns (DAMPs). If the hypothesis is established, it may change the therapeutic regimen of PQ poisoning and the prognosis of patients.