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Abstract: PO2233

Expression of Immunoglobulin G in Human Proximal Tubule Epithelial Cell and Its Role in Epithelial Mesenchymal Transformation

Session Information

Category: Pathology and Lab Medicine

  • 1601 Pathology and Lab Medicine: Basic

Authors

  • Deng, Zhenling, Peking University Third Hospital, Beijing, China
  • Wang, Song, Peking University Third Hospital, Beijing, China
  • Wang, Yue, Peking University Third Hospital, Beijing, China
Background

Our previous studies showed that human mesangial cells and podocytes can synthesize and secrete IgA and IgG respectively, participating in cell viability and adhesion. Proximal tubular epithelial cells (PTECs) mediate transcytosis of IgG through neonatal Fc receptor (FcRn). Whether PTECs express IgG has not been reported. The aim of this study was to explore whether PTECs express immunoglobulins

Methods

Kidney cortical tissues were obtained far from the tumor of patients undergoing nephrectomy as a result of renal carcinoma. Immunohistochemical (IHC) staining was used to assay the IgG expression in PTECs. Single PTECs were sorted by FACS from the cell suspension of the cortexes. 10×Genomics and nested PCR combined with Sanger sequencing were used to detect the transcripts and repertoires of Igs in single PTECs. An immortalized PTEC cell line (HK-2) was used to detect Igs protein expression and potential roles in tubular epithelial mesenchymal transformation.

Results

IHC showed positive staining of IgG but not other Igs in PTECs of kidney cortex. High throughput single cell RNA sequencing by 10×Genomics only detected Ig γ transcripts in few PTECs without V(D)J rearrangements. Nested PCR amplified Ig γ transcripts in 82% (91/111) manually picked single PTECs. Sanger sequencing showed that PTEC-derived Ig γ variable region displayed classic VHDJH rearrangements but predominant VH1-24/DH2-15/JH4 sequence, biased VH1 usage and less diversity than B cells derived IgG. Western blot and immunofluorescence staining demonstrated Ig γ (including Ig γ4), Ig κ and Ig λ in HK-2. RP215, which specifically recognizes non-B cell-derived Ig γ, can identify the Ig γ in HK-2. The Ig γ was upregulated by TGF-β1 and accompanied by the up-regulation of α-smooth muscle actin and the down-regulation of E-cadherin. In addition, the transcripts of recombination activating gene 1/2 (RAG1/2, essential for V(D)J rearrangement) and activation-induced cytidine deaminase (AID, essential for class switch recombination) were detected in HK-2.

Conclusion

Our study suggests that PTECs can express IgG in a similar way as B cells. TGF-β1 can upregulate the expression of IgG in PTECs. PTEC-derived IgG may be involved in tubular epithelial mesenchymal transformation and interstitial fibrosis.

Funding

  • Government Support - Non-U.S.