title: Regulation of IgA Class Switch Recombination in Immunoglobulin A Nephropathy: Retinoic Acid Signaling and BATF.
abstract: Immunoglobulin (Ig) A nephropathy (IgAN) is the xFB01;nding of immune deposits predominantly containing polymeric IgA in the glomerular mesangium on renal biopsy. Increasing evidence suggested that retinoic acid (RA) signaling selectively induces IgA isotype switching and basic leucine zipper transcription factor, ATF-like (BATF) controls the global regulators of class switch recombination (CSR) in lymphocytes. Great effort has been paid to identify whether impaired immune regulation along the 'mucosa-bone marrow (BM) axis' play an important role in the pathogenesis of IgAN.
  
  
  
  The aim of the study was to investigate the expression of all-trans-RA (ATRA) and BATF, and to identify their impact on IgA CSR in IgAN patients and rat animal models. Blood samples and tonsillar tissue specimens were obtained from 22 patients with IgAN and 24 patients with chronic tonsillitis as control.
  
  
  
  Immunohistochemical, RT-PCR and western blotting examination revealed that RA signaling and BATF productions are activated in IgAN patients compared with controls. Lipopolysaccharide and α-hemolytic streptococcus stimulation upregulated RA receptor (RAR) and BATF expression, promote IgA CSR and ATRA productions in tonsil mononuclear cells. RAR alpha (RARα) or BATF siRNA decreases IgA expression. We also built IgAN rat models and found that RARα, BATF and activation-induced cytidine deaminase were upregulated in the peripheral blood, spleen and BM. With ATRA (500 μg/kg body weight) treatment for 8 weeks, IgA deposition on glomeruli and mesangial cells proliferation increased. It also revealed that ATRA activated BATF and IgA CSR in vivo.
  
  
  
  These data point toward the role of RA signaling together with BATF in IgA CSR of IgAN, and the data also support the notion that mucosal immunization with neoantigen results in impaired mucosal and systemic IgA responses.
authors.affiliation: Department of Nephrology, 2nd Xiangya Hospital, Central South University, Key Laboratory of Kidney Disease and Blood Purification in Hunan, Hunan, PR China.
authors.forename: Liyu
authors.initials: L
authors.lastname: He
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Peng
authors.forename: Yinyin
authors.initials: Y
authors.lastname: Chen
authors.forename: Guoyong
authors.initials: G
authors.lastname: Liu
authors.forename: Zhiwen
authors.initials: Z
authors.lastname: Liu
authors.forename: Jiefu
authors.initials: J
authors.lastname: Zhu
authors.forename: Yexin
authors.initials: Y
authors.lastname: Liu
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.forename: Yumei
authors.initials: Y
authors.lastname: Liang
authors.forename: Fuyou
authors.initials: F
authors.lastname: Liu
authors.forename: Lin
authors.initials: L
authors.lastname: Sun
authors.forename: Youming
authors.initials: Y
authors.lastname: Peng
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D050976:Basic-Leucine Zipper Transcription Factors / Q000097:blood*; D001853:Bone Marrow / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D005922:Glomerulonephritis, IGA / Q000276:immunology* / Q000378:metabolism*; D006801:Humans; D007070:Immunoglobulin A / Q000378:metabolism; D017578:Immunoglobulin Class Switching; D007678:Kidney Glomerulus / Q000378:metabolism; D008070:Lipopolysaccharides; D008297:Male; D050527:Mesangial Cells / Q000502:physiology; D008875:Middle Aged; D014066:Palatine Tonsil / Q000276:immunology / Q000378:metabolism*; D061251:Primary Cell Culture; D011897:Random Allocation; D017207:Rats, Sprague-Dawley; D000072482:Retinoic Acid Receptor alpha / Q000378:metabolism; D015398:Signal Transduction; D013154:Spleen / Q000378:metabolism; D014212:Tretinoin / Q000097:blood*; D055815:Young Adult
chemical_list: C099359:BATF protein, human; D050976:Basic-Leucine Zipper Transcription Factors; D007070:Immunoglobulin A; D008070:Lipopolysaccharides; D000072482:Retinoic Acid Receptor alpha; D014212:Tretinoin