PD08-01: B-cell clonotype in patients with Interstitial Cystitis/Bladder Pain Syndrome presenting with Hunner lesions

Inna Tabansky, Mahasset, NY, Min Liu, New Haven, CT, Robert Moldwin, Manhasset, NY, Souhel Najjar, New York, NY, Derin Keskin, Boston, MA, Vishaan Nursey, Manhasset, NY, Johannes Yeh, Cold Spring Harbor, NY, Vladimir Brusic, Ningbo, China, People's Republic of, Guanglan Zhang, Boston, MA, Joel N.H. Stern*, Hempstead, NY

Introduction: Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS) is an inflammatory disorder of the bladder urothelium, but the immune pathophysiology is unknown. A subset of patients with IC/BPS present with Hunner lesions, which are defined areas of inflammation on the bladder wall. It has been previously proposed that Hunner lesions are enriched in B and T cells, suggesting that IC/BPS may have an autoimmune component. However, it is possible that B-cell enrichment in the Hunner lesions is caused by general inflammatory processes. To identify immune cell subtypes that may contribute to Hunner lesions, we performed single-cell analysis of B- and T-cell receptors in lesion biopsies.

Methods: Two millimeter bladder biopsy tissue sample isolated from a Hunner lesioned area and another biopsy was taken 5 cm from the Hunner lesion. Single cell quality control (QC) was performed to include cells only with more than 0.8 unique molecular identifiers (UMIs) per gene and less than 0.3 mitochondrial ratio (number of UMIs assigned to mitochondrial genes over total number of UMIs per cell). P-values were calculated using Bonferroni (default) and Benjamini–Hochberg correction. T cell receptor (TCR) and B cell receptor (BCR) clonotypes were annotated and grouped by Cell Ranger. Sequences are read out using barcoded Illumina primers. The resulting sequences are identified through alignment to the international ImMunoGeneTics information system® (IMGT) database.

Results: Here, we distinguished between these hypotheses by using single cell sequencing to identify B-cell clonotypes in the Hunner lesion bladder. This B-cell clonotype is shared in two patients with IC/BPS. The B cell clone was CD19+. Such a finding is highly unlikely to occur by chance, and it is strong evidence that B cells in the patient’s bladders are reacting against a specific antigen.

Conclusions: We reported the identification of a common B cell clone in two patients with IC/BPS and Hunner lesions. In addition, we observed multiple immune cell subtypes, including T cells, monocytes and various subtypes of B cells within the bladder. These finding strongly indicates that the B cells in the bladder of these patients are reacting to a specific antigen and the inflammation observed is likely due to this specific immune response. Our results are consistent with previous data that indicate infiltration of B cells into the Hunner lesions. We did not observe any overlapping T cell clones or other overlapping B cell clones in the IC/BPS samples that we analyze. The overlapping B cell clonotype was present in multiple cells. All of these observations indicate that the clone is unlikely to have arisen by cross-contamination between samples. Future studies can identify the antibody produced by this B cell clonotype, the antigen that it targets, and how prevalent it is in patients with IC/BPS.

Source of Funding: I.T. ,V.N., and J.N.H.S. was supported by the H.F. Langbert Research Fund.