title: Intracellular tubulo-reticular structures of peripheral blood mononuclear cells as an ultra-structural marker of disease activity in systemic lupus erythematosus: a pilot study.
abstract: OBJECTIVE
  Under physiological stress, the membranes of organelles undergo conformational change to tubulo-reticular structures (TRS) for gaining survival advantage. We aim to explore whether TRS formation in the peripheral blood mononuclear cells (PBMCs) of patients with systemic lupus erythematosus (SLE) correlates with more active disease where physiological stress prevails.
  
  
  METHODS
  To mimic the intracellular impact of interferon-alpha (IFN-α) on lymphocytes, human B-lymphocyte cell line was stimulated by recombinant IFN-α in concentrations of 100, 1000 and 10 000 IU/mL for 72 h. TRS within the lymphocytes was then quantified by transmission electron microscopy (TEM). Upon confirming TRS formation under IFN-α influence, PBMCs of lupus patients were isolated, fixed and quantified for TRS under TEM. The frequency of TRS in lupus PBMCs was compared with that of healthy controls and correlated with the clinical SLE disease activity index (SLEDAI).
  
  
  RESULTS
  After 72 h, an increase in TRS frequency was observed in a dose-response fashion when the human B-lymphocyte cell line was stimulated by increasing concentrations of IFN-α. In lupus patients, their PBMCs had a significantly higher TRS frequency than healthy controls (P = 0.037). The frequency of TRS was positively associated with the SLEDAI (Spearman ρ = 0.632, P = 0.012), which remained statistically significant after adjustment for daily prednisolone dose (Pearson r = 0.747, P = 0.002).
  
  
  CONCLUSIONS
  While the clinical significance of TRS formation in lupus PBMCs deserves further investigation, these preliminary findings suggest a significant relationship between the disease severity of SLE and intracellular physiological stress. These results underscore the potential of TRS in PBMCs as an ultra-structural disease activity biomarker of SLE.
authors.affiliation: Division of Rheumatology, Department of Medicine, University Medicine Cluster, Singapore City, Singapore.
authors.forename: Anselm
authors.initials: A
authors.lastname: Mak
authors.forename: Zakaria A M
authors.initials: ZA
authors.lastname: Almsherqi
authors.forename: Ya-Wei
authors.initials: YW
authors.lastname: Lai
authors.forename: Alicia A-C
authors.initials: AA
authors.lastname: Cheak
authors.forename: Yuru
authors.initials: Y
authors.lastname: Deng
mesh_terms: D000328:Adult; D001402:B-Lymphocytes / Q000187:drug effects / Q000648:ultrastructure; D016022:Case-Control Studies; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D016898:Interferon-alpha / Q000494:pharmacology; D007425:Intracellular Membranes / Q000187:drug effects / Q000648:ultrastructure*; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000648:ultrastructure*; D008180:Lupus Erythematosus, Systemic / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D008297:Male; D046529:Microscopy, Electron, Transmission; D015388:Organelles / Q000187:drug effects / Q000648:ultrastructure*; D010865:Pilot Projects; D013312:Stress, Physiological; D013997:Time Factors
chemical_list: D016898:Interferon-alpha
keywords: cubic membranes; disease activity; lupus; stress; tubulo-reticular