#2324 Do urinary tract infections trigger chronic inflammation in the kidney allograft? Interleukin 17 levels in the urine of kidney recipients
Authors: Wojciuk Bartosz , Zioło Anna , Birger Radosław , Sarna Angela , Grygorcewicz Bartłomiej , Pierzyńska Klaudia , Dołęgowska Barbara , Ciechanowski Kazimierz , Wojciechowska-Koszko Iwona 
Published: May 2024

Abstract

Background and Aims
Urinary tract infections (UTI) represent the most common complication following kidney transplantation. Their role in triggering immune phenomena in kidney allograft remains unclear. Interleukin 17 (IL17) represents the significant branch in antimicrobial immunity. At the same time IL17 has been found associated with autoimmune inflammatory disorders. The triggering role of infections in autoimmunity as well as the similarities between autoimmunity and post-transplant immunity have been postulated. The aim of the study was to analyze the levels of urine IL 17A levels in relation to prior UTI history and the timeframe after the last UTI episode.

Method
The group of 91 kidney recipients who received kidney transplantation between 2016 and 2019 was analyzed. The set of 233 urine samples (109 from females and 124 from males) obtained within first 24 months post-transplant was investigated, among these 144 samples from the patients with no previous UTI history and 89 samples from the patients with previous UTI history (1-22 months after the last episode, average 6.7 ± SD 5.7). Furthermore, 18 samples obtained at the time of an UTI episode and 29 samples from healthy controls were included. Urine IL 17A levels were measured with Human IL 17 ELISA Kit (Sigma Aldrich) and urine IL/creatinine concentrations ratio was calculated for each value. Szapiro-Wilk test was used to assess data distribution, Kruskal-Wallis test was used to assess the differences between independent groups and two proportions Z test was used to compare the groups compositions.

Results
Interleukin 17A appeared detectable in 105 out of the 233 investigated samples (45%), with significantly higher frequency in samples from the recipients with previous UTI history (p = 0.02). The difference was not significant in the group who underwent recurrent UTI episodes vs. these after a single UTI episode. Among the samples in which IL 17A was detected, the period between the last UTI episode and sample collection was divided into three timeframes: 1-3 months, 4-12 months and 12-24 months. Urine IL17A levels appeared significantly higher independently in each timeframe post-UTI when compared to the samples from the recipients without UTI history and controls (p = 0.0001). Fig. 1 It was apparent within the whole group but also in males and females separately. Further, urine IL17A levels were significantly higher in males 1-3 months after the last UTI episode than in females in the analogous period (p = 0.001).

Conclusion
Interleukin 17A was more frequently detected in urine samples from kidney recipients with previous UTI history. UTI history impacted IL17A urine levels in the analyzed kidney recipients. Within the first 24 months post-transplant, these were higher in the recipients with UTI history prior to the sample collection and it was independent on the timeframe between the last UTI episode and the sample collection. The factors other than UTI history which influence urine IL17A detectability are not fully recognized and remain under investigation.