Abstract:Objective: To explore the prognostic value of chemokine CCL2 (C-C motif) and gap score in bronchoalveolar lavage fluid (BALF) in the real world.Methods: 35 patients with IPF hospitalized in Gulou Hospital Affiliated to Medical College of Nanjing University from January 2017 to December 2019 were analyzed retrospectively. At the same time, 10 outpatients with chronic cough (CC) but no other lung diseases or other organ diseases were collected. The differences of gender, age, forced vital capacity (FVC), diffusion capacity for carbon monoxide (DLCO) (except CC group) and blood gas analysis between the two groups were compared. At the same time, the concentrations of CCL2 in serum and BALF were detected, and the differences of CCL2 between different gap groups were analyzed The difference of survival time and the correlation between CCL2 and gap score. Results: compared with the control group, the oxygenation index and FVC% in IPF group decreased (P < 0.05), and CCL2 in serum and BALF increased (P < 0.05). Compared with the control group, there was no difference in lymphocytes, neutrophils and macrophages in BALF in IPF group. In terms of correlation, CCL2 was negatively correlated with FVC% (r = -0.488, P < 0.01) and DLCO% (r = -0.581, P < 0.01) in BALF, but there was no strong correlation between CCL2 and FVC% (r = -0.088, P = 0.617) and DLCO% (r = -0.178, P = 0.320) in serum, and receiver operating characteristic curve (ROC) The curve shows that when the level of CCL2 in BALF is greater than or equal to 363.74pg/ml, the mortality of patients increases. Then, according to the gap score for the staging of IPF patients, the results show that the level of CCL2 in serum has no difference in IPF group (phase I, II and III), but in BALF, except that there is no significant difference in CCL2 level between phase I and control group, phase III and control group, IPF group (phase I, II and III) The levels of CCL2 were significantly different between the two groups (P < 0.05). In pulmonary function, FVC% and DLCO% in stage II and III were significantly lower than those in stage I (P < 0.05), and there was little difference in FVC% and DLCO% between stage II and III. further survival analysis showed that the survival time of stage II and III patients was significantly lower than that of stage I patients (P < 0.05) , but there was no significant difference in survival between stage II and stage III. it was found that there was a strong positive correlation between CCL2 and gap score in BALF (r = 0.847, P < 0.01).Conclusion: This study further verified that CCL2 and gap scores in BALF can predict the prognosis of IPF. At the same time, it was the first time to explore the difference of CCL2 level in BALF in different gap stages, and there is a strong correlation between CCL2 and gap scores in BALF.