Circulating Neutrophils Exhibit an Altered Immune Response in Chronic LUTS: An Image-Based Deep Learning Analysis.

introduction and hypothesisChronic lower urinary tract symptoms (LUTS) are characterised by persistent symptoms and elevated urinary leukocyte counts. Much evidence supports an infective aetiology in chronic LUTS, often coined chronic UTI, due to the poor performance of current gold standard tests to detect refractory forms of infection. Hence, we hypothesised that neutrophils from chronic LUTS patients may exhibit an aberrant response which prevents complete disease resolution.

methodsFreshly isolated circulating neutrophils from seven healthy women (control neutrophils) and four patients (patient neutrophils) were stimulated with commensal E. coli or pathogenic E. coli in artificial urine or pooled urine from controls (control urine) and patients (patient urine). Live imaging was performed at 37 °C for 15 h. Image sequences were analysed to assess neutrophil viability counts, morphometrics, cell activity and bacterial growth.

resultsNeutrophils from both cohorts were able to recognise a commensal E. coli from a pathogenic strain, with cell death occurring faster when stimulated with the latter. However, when stimulated with the same bacterial strain in control urine, patient neutrophils showed a higher level of activity and a delayed rate of death. Without bacterial stimulation, patient neutrophils died faster in patient urine. The delayed response and the shorter survival without bacteria exhibited by patient neutrophils may have implications in chronic LUTS patients, where their neutrophils are unable to effectively clear bacteria or survive for an adequate duration to exert their functions.

conclusionsTemporal differences in neutrophil response towards bacteria and dysregulation in neutrophil maturation or activation may lead to symptom persistence in chronic LUTS.