title: The 88-kDa Eales' protein in serum is a complex of haptoglobin, complement C3, and galectin-1 as identified by liquid chromatography coupled mass spectrometry.
abstract: Eales' disease (ED), an enigmatic inflammatory disease, affects peripheral retinal veins and thereby vision in males. This study was aimed at identifying and deciphering the role of a novel 88-kDa protein reported in the serum and vitreous of patients with ED.
  
  
  
  The purified 88-kDa protein was identified by UPLC coupled ESI-QTOF-MS. The identified proteins were quantified in the serum from 20 ED patients and controls (age and sex matched), respectively by ELISA. The interaction of these proteins was studied using co-immunoprecipitation, western blot, and MS analyses. N-glycosylation of protein was observed by MS and lectin blot.
  
  
  
  The 88-kDa protein was identified to be a complex of haptoglobin, complement C3, and galectin-1. ELISA results showed a 1.5-fold increase in levels of haptoglobin (p = 0.008), with level of complement C3 unaltered and 1.2-fold decreased serum galectin-1 levels (p = 0.003) in ED patients compared to controls. Co-immunoprecipitation illustrated the interaction between haptoglobin and complement C3. Reduced sialylation and increased β-1, 6-N-acetyl-glucosamine branched N-glycans were observed in haptoglobin of ED patients.
  
  
  
  The 88-kDa protein, a complex of haptoglobin, complement C3, and galectin-1, may play a potential role in ED pathogenesis while levels galectin-1 and haptoglobin may serve as potential biomarker of ED.
authors.affiliation: R. S. Mehta Jain Department of Biochemistry and Cell Biology, Vision Research Foundation, Sankara Nethralaya, Chennai, India.|Department of Biochemistry, Tamil Nadu Dr MGR Medical University, Chennai, India.
authors.forename: Saravanan
authors.initials: S
authors.lastname: Ramanujam
authors.affiliation: R. S. Mehta Jain Department of Biochemistry and Cell Biology, Vision Research Foundation, Sankara Nethralaya, Chennai, India.|Department of Biological Sciences, BITS, Pilani, Rajasthan, India.
authors.forename: Bharathselvi
authors.initials: B
authors.lastname: Muthuvel
authors.affiliation: Department of Uveitis, Medical Research Foundation, Sankara Nethralaya, Chennai, India.
authors.forename: Babu
authors.initials: B
authors.lastname: Aravind C
authors.affiliation: Department of Uveitis, Medical Research Foundation, Sankara Nethralaya, Chennai, India.
authors.forename: Jyothirmay
authors.initials: J
authors.lastname: Biswas
authors.affiliation: R. S. Mehta Jain Department of Biochemistry and Cell Biology, Vision Research Foundation, Sankara Nethralaya, Chennai, India.
authors.forename: N Sulochana
authors.initials: NS
authors.lastname: Konerirajapuram
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002851:Chromatography, High Pressure Liquid; D003176:Complement C3 / Q000032:analysis* / Q000378:metabolism; D030562:Databases, Protein; D004797:Enzyme-Linked Immunosorbent Assay; D037483:Galectin 1 / Q000097:blood* / Q000378:metabolism; D006242:Haptoglobins / Q000032:analysis* / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000378:metabolism / Q000473:pathology*; D031300:Retinal Vasculitis / Q000378:metabolism / Q000473:pathology*; D021241:Spectrometry, Mass, Electrospray Ionization; D055815:Young Adult
chemical_list: D003176:Complement C3; D037483:Galectin 1; D006242:Haptoglobins
keywords: Complement C3; Eales’ disease; Galectin-1; Haptoglobin; Mass spectrometry