Low Alveolar Macrophage Function, Low IL-6, and High CD4 Cell Count Interaction in BALF of Severe Pneumonia Patients with Extubation Success

Abstract BackgroundUnderstanding the bronchoalveolar-lavage fluid immunopathology biomarker interactions can help clinicians decipher the pathophysiology of severe pneumonia and get better management for early extubation.ObjectivesThe objectives were to assess bronchoalveolar lavage fluid biomarker interactions of severely affected lung and their association in determining the early extubation success.MethodsIn this cross-sectional study, we consecutively evaluated 137 severe pneumonia patients. Patients who fulfilled inclusion criteria will undergo early bronchoscopy. The BALF was collected from the right and left lungs. Two Respirologist and Critical Illness consultants, plus one internist, determined the location for severely affected lung. Biomarker interactions in severely affected lung were analyzed. The primary outcome was the 19-days extubation.ResultsForty patients underwent bronchoscopy for BALF collection. The right lung was the predominant severely affected lung (28 patients). Eight patients survived and were successfully extubated within 19 days. There were significantly higher absolute CD4 + BALF cell counts (95% Confidence Interval = 9,24–49,50, p = 0,003) in the left lung and higher absolute CD4 + BALF cell counts (95% Confidence Interval = 9,00–29,75, p = 0,010) in the patients with extubation success and survived. Among all the patients with extubation success within 19 days, eight patients (100%) displayed the tendency of high CD4 levels (cutoff points median 16 cells/µL), low expression of alveolar macrophage function (cutoff points by ROC 756.5 MFI CD169), and low expression of IL-6 (cutoff points by ROC 369 pg/mg protein).ConclusionIn severely affected lung of severe pneumonia patients with early extubation success and survived, we found biomarker interactions marked by low alveolar macrophage function, low IL-6 levels, and high CD4 levels.Trial RegistrationThe study was registered at UMIN Clinical Trials Registry (UMIN-CTR) (registration number UMIN000046236), accessible at: https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000049197