In some tissues, such as the lung and the liver, the absence of MMP-8 and the attendant initial reduction in neutrophil influx and reduced chemokine activation can be protective, as has been observed in models of ventilator-induced injury in the lung (15), bleomycin-induced lung fibrosis (14), and TNFα-induced lethal hepatitis (44). This evidence concerns the gene TNF and pulmonary fibrosis.