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Abstract Pulmonary fibrosis may be a secondary effect of other diseases called interstitial lung diseases (ILD), which also be called interstitial pulmonary fibrosis. ILDs are a group of diseases affecting the interstitium of the lung and progress to pulmonary fibrosis. The most common cause of ILD is idiopathic pulmonary fibrosis which has poor prognosis and median survival rate 3-5 years. Biomarkers are defined as cellular, biochemical or molecular alterations that are measurable in biological media such as human tissues, cells or fluids. Biomarkers are potentially useful along the whole spectrum of the disease and their use in medicine lies in their ability to detect disease and support diagnosis and therapeutic decisions. There are many lung peripheral biologic markers in interstitial pulmonary fibrosis. The most studied and interesting are SP-A, SP-D and KL-6, the mean serum concentration in healthy volunteers is 48 ng /ml for SP-A and 116ng /ml for SP-D. The highest ever reported serum SP-D concentration in idiopathic pulmonary fibrosis patient is 1800 ng/ ml. The median serum concentration of KL-6 in healthy volunteers is 306 U/ ml, the highest increase in serum KL-6 was described in patients with ARDS with mean values above 2000U/ml. Activated alveolar macrophages can release cytokines, growth factors, extracellular matrix proteins and tissue inhibitors of metalloproteases contributing to alveolar injury and aberrant lung repair occurring in idiopathic pulmonary fibrosis. Many cytokines play an important role in pathogenesis of idiopathic pulmonary fibrosis especially IL-4, IL-13 and TGFβ each of these cytokines can exhibit significant pro fibrotic activity acting through the recruitment, activation and proliferation of fibroblasts, macrophages and myofibroblast. Diagnosis of interstitial pulmonary fibrosis is based on HRCT and histopathological criteria. Combination of several biomarkers may be a promising direction of research but at present cannot replace conventional diagnostic procedures. Serum concentration of SP-A increase in UIP than NSIP, BAL concentration of SP-D in patients with UIP lower than NSIP. So, SP-A and SP-D are useful for discriminating UIP from other types of interstitial pneumonias. Serum concentration of KL-6 increase in patient with active interstitial pneumonia than those with inactive interstitial pneumonia, KL-6 increase with deterioration of interstitial pneumonia while decrease when interstitial pneumonia treatment was successful. Biomarkers have a significant role in prognosis of interstitial pulmonary fibrosis, concentration of SP-D 460ng /ml appears to be the optimal cut off level to discriminate survival after 1 year. CCL-18 concentration was strongly predictive of mortality as cut off level 150 ng /ml the best indicator of survival in patients with idiopathic pulmonary fibrosis.There is no treatment approved for idiopathic pulmonary fibrosis and there is a great effort to find definitive treatment for IPF and the aim of the treatment is slowing or preventing progression of this chronic illness.Conclusion: Interstitial pulmonary fibrosis is a chronic disease and the most common cause is idiopathic pulmonary fibrosis which progress to pulmonary fibrosis with poor prognosis and median survival rate 3-5 years. No therapy has been proved to prolong survival. So, lung transplantation seems to be the only option. |