Slower rescue of ER homeostasis by the unfolded protein response pathway associated with common variable immunodeficiency.
Common variable immunodeficiency (CVID) is a primary immunodeficiency characterized by hypogammaglobulinemia and recurrent infections. Herein we addressed the role of unfolded protein response (UPR) in the pathogenesis of the disease. Augmented unspliced X-box binding protein 1 (XBP-1) mRNA concurrent with co-localization of IgM and BiP/GRP78 were found in one CVID patient. At confocal microscopy analysis this patient's cells were enlarged and failed to present the typical surface distribution of IgM, which accumulated within an abnormally expanded endoplasmic reticulum. Sequencing did not reveal any mutation on XBP-1, neither on IRE-1alpha that could potentially prevent the splicing to occur. Analysis of spliced XBP-1, IRE-1alpha and BiP messages after LPS or Brefeldin A treatment showed that, unlike healthy controls that respond to these endoplasmic reticulum (ER) stressors by presenting waves of transcription of these three genes, this patient's cells presented lower rates of transcription, not reaching the same level of response of healthy subjects even after 48 h of ER stress. Treatment with DMSO rescued IgM and IgG secretion as well as the expression of spliced XBP-1. Our findings associate diminished splicing of XBP-1 mRNA with accumulation of IgM within the ER and lower rates of chaperone transcription, therefore providing a mechanism to explain the observed hypogammaglobulinemia.
Kuribayashi
Juliana S
JS
Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, Avenida Professor Lineu Prestes 1730, São Paulo, Brazil.
Bombardieri
Cíntia R
CR
Baracho
Gisele V
GV
Aliberti
Júlio
J
Machado
Fabiana S
FS
Kalil
Jorge
J
Guilherme
Luiza
L
Kokron
Cristina M
CM
Rizzo
Luiz V
LV
de Camargo
Maristela M
MM
D000328:Adult; D001402:B-Lymphocytes / Q000187:drug effects / Q000473:pathology; D020126:Brefeldin A / Q000494:pharmacology; D017074:Common Variable Immunodeficiency / Q000276:immunology*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000276:immunology*; D000091342:Endoplasmic Reticulum Chaperone BiP; D005260:Female; D006706:Homeostasis / Q000187:drug effects / Q000276:immunology*; D006801:Humans; D007962:Leukocytes / Q000187:drug effects / Q000276:immunology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D017510:Protein Folding
D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D008070:Lipopolysaccharides; D020126:Brefeldin A; D004121:Dimethyl Sulfoxide