Nobuko Iizuka

Proteomic Surveillance of Autoantigens in Relapsing Polychondritis

Relapsing polychondritis (RP) is a systemic inflammatory disease, in which autoimmunity to cartilage‐related components is thought to be involved in its pathogenesis. However, the autoimmune profile in RP has not been studied fully. We therefore investigated autoantibodies/autoantigens in RP comprehensively, by 2‐dimensional electrophoresis (2DE), subsequent western blotting (WB) and mass spectrometry, using cell‐extracted proteins as the antigen source. As a result, we detected 15 autoantigens on 2DE‐WB, and further identified five of them. On average, one RP serum recognized approximately 8 out of the 15 autoantigens. Frequencies of the autoantibodies to the 5 identified antigens of tubulin alpha ubiquitous/6, vimentin, alpha enolase, calreticulin, and colligin‐1/‐2 were 91%, 46%, 36%, 82%, and 36%, respectively. ELISA using recombinant proteins for them revealed that frequencies of the autoantibodies to tubulin alpha ubiquitous, vimentin, alpha enolase, calreticulin, and colligin‐1 were 36%, 64%, 46%, 27%, and 18%, respectively. Our data demonstrated that the autoimmune reaction was not restricted to cartilage‐related components, rather a variety of autoimmune responses occurred in patients with RP, which may be involved in the pathophysiology of RP. In addition, the proteomic approach using cell‐extracted proteins would be a powerful way to investigate autoantigens.

Identification of autoantigens specific for systemic lupus erythematosus with central nervous system involvement

Using proteomic analysis, we identified candidate autoantigens specific for central nervous system (CNS) involvement in systemic lupus erythematosus (SLE). Proteins, extracted from cultured human neuroblastoma cells, were separated both by SDS-PAGE (1-DE) and two-dimensional electrophoresis (2-DE), and transferred to membranes. Western blot analysis was performed using serum samples from 30 SLE patients with CNS involvement (CNS-Lupus) and from 30 SLE patients without CNS involvement (non-CNS-SLE). The detected autoantigens were identified using MALDI-TOF/TOF MS. On the 1-DE Western blot, we detected 32 antigenic bands in the serum samples from the CNS-Lupus patients. Among them, four bands were detected significantly more frequently in the CNS-Lupus patients than in the non-CNS-SLE patients. Three bands were detected in four or more of the CNS-Lupus patients but in only one or none of the non-CNS-SLE patients. We thus selected these seven bands for the next investigations. Next, we detected protein spots corresponding to the selected seven bands by 2-DE Western blot and identified four proteins. They are peroxiredoxin-4, ubiquitin carboxyl-terminal hydrolase isozyme L1, splicing factor arginine/serine-rich 3, and histone H2A type 1. These four candidate autoantigens for the anti-neuronal cell antibodies would be a useful marker for CNS-Lupus.

Reversible focal neurological deficits in systemic lupus erythematosus: Report of 2 cases and review of the literature

We report two cases presenting focal neurological deficits with high intensity lesions in fluid attenuated inversion recovery (FLAIR) images on brain magnetic resonance imaging (MRI), which almost completely improved by corticosteroid therapy. Marked elevation of cerebrospinal fluid IL-6 was also noted when these patients showed neurological deficits. As far as we explored, there have been thirteen published case reports of systemic lupus erythematosus patients with reversible focal neurological deficits. The neurological symptoms varied from case to case, but could be attributed to the lesions on MRI scans. The completely reversible feature of neurological manifestations as well as MRI findings on corticosteroid therapy is distinct from any other disorder, including cerebrovascular disease and demyelinating syndrome, in the 1999 American College of Rheumatology nomenclature. Therefore, we propose that reversible focal neurological deficits should be added to the 1999 nomenclature and classification and case definitions.

Henoch-Schönlein pupura complicated by perforation of the gallbladder

Henoch-Schönlein purpura is a systemic vasculitis of small vessels characterized by purpura, arthralgias, glomerulonephritis and gastrointestinal involvements which can cause intestinal perforation. A 75-year-old man with renal dysfunction and palpable purpura (petechiae) of which dermal specimen showed leukocytoclastic vasculitis was diagnosed as Henoch-Schönlein purpura. Corticosteroid and cyclosporine were effective, but subsequently he developed pneumocystis pneumonia. After he improved by treatment with trimethoprim-sulfamethoxazole, he presented sudden abdominal pain, caused by perforation of the gallbladder. Histological analysis revealed infiltration of inflammatory cells with bleeding in the gallbladder wall at the site of perforation. It is suggested that inflammatory disruption of capillary walls might lead to the perforation of the gallbladder.

Effects of methotrexate and salazosulfapyridine on protein profiles of exosomes derived from a human synovial sarcoma cell line of SW982.

To elucidate effects of salazosulfapyridine (SASP) and methotrexate (MTX), major anti‐rheumatic drugs, on exosomes derived from SW982 of a human synovial sarcoma cell line.

Roles of serum fibrinogen α chain‐derived peptides in Alzheimer's disease

To find a blood biomarker and disease‐related peptides in Alzheimers disease (AD), we comprehensively detected serum peptides.

Autoantigenicity of carbonic anhydrase 1 in patients with abdominal aortic aneurysm, revealed by proteomic surveillance

Abdominal aortic aneurysm (AAA) is sometimes detected in patients with atherosclerosis. One of the histological characteristics of AAA walls is infiltration of inflammatory cells, in which autoimmunity may be involved. Thereby, we here surveyed autoantigens in AAA walls by proteomics. Specifically, we separated proteins extracted from AAA wall samples by 2-dimensional electrophoresis and detected candidate autoantigens by western blotting. One of the detected candidates was carbonic anhydrase 1 (CA1). ELISA confirmed that the autoantibodies to CA1 were detected more frequently in AAA patients (n=13) than in healthy donors (n=25) (p=0.03). Interestingly, some serum samples from the AAA patients reacted to CA1 of the AAA walls stronger than to CA1 of peripheral blood mononuclear cells from healthy donors. Our data indicate that CA1 in the AAA walls would be modified to express neo-epitope(s) and that the autoimmunity to CA1 may be involved in the pathogenesis of AAA.

Effects of sulfasalazine and tofacitinib on the protein profile of articular chondrocytes

Abstract Objective. Sulfasalazine (SSZ) and tofacitinib are effective for treating rheumatoid arthritis, however, their effects on chondrocytes have not been fully understood. We here tried to elucidate their effects on chondrocyte proteins. Methods. We treated chondrocytes from five osteoarthritis patients with IL-1β, IL-1β+ SSZ, IL-1β+ tofacitinib, SSZ alone, and tofacitinib alone. Then, we compared protein profiles of the chondrocytes using two-dimensional differential gel electrophoresis. Further, we identified altered proteins by mass spectrometry. Results. Out of 892 detected protein spots, the IL-1β stimulation changed intensity of 43 spots more than 1.3-fold or less than 1/1.3-fold significantly. SSZ suppressed the IL-1β-induced intensity alteration in 16 (37%) out of the 43 protein spots. Tofacitinib suppressed the IL-1β-induced alteration in 4 (9.3%) out of the 43 spots. The production of AMP deaminase 2 and procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2 were increased by IL-1β and the increase was suppressed by SSZ and by tofacitinib. SSZ alone altered intensity of 273 (31%) out of the 852 spots significantly, whereas tofacitinib alone altered intensity of only 24 (2.7%) out of them. Conclusion. SSZ and, to lesser extent, tofacitinib suppress the effects of IL-1β on the protein profiles of chondrocytes. Our data would promote understanding of effects of the drugs on chondrocytes.

Proteomic Analysis of Whole Glomeruli in Patients with IgA Nephropathy Using Microsieving

Background: To promote understanding of immunoglobulin A nephropathy (IgAN) pathophysiology, we tried to elucidate glomerular protein profiles in IgAN, using microsieving that we established recently to isolate glomeruli from renal biopsy samples and proteomic approaches. Methods: Glomeruli were isolated from renal biopsy samples of patients with IgAN (n = 5) and with minimal change nephrotic syndrome (MCNS; n = 5) using microsieving. Proteins extracted from the isolated glomeruli were separated by 2-dimensional differential gel electrophoresis (2D-DIGE). Proteins with different amounts between the two groups were identified by mass spectrometry. One of the identified proteins, α-actinin-4 (ACTN4), was further analyzed by Western blotting, RT-polymerase chain reaction (PCR), and immunohistochemistry. Results: By 2D-DIGE, 72 out of the detected 1,170 protein spots showed significantly different intensity between the two groups (p < 0.05). Thirty-four out of the 72 protein spots showed more than 1.5-fold or less than 1/1.5-fold intensity, out of which 16 protein spots were successfully identified. No microbial protein was identified. ACTN4 molecules with a low molecular weight of approximately 77 kDa were found to increase in the IgAN group. Lack of an N-terminal part of ACTN4 was demonstrated by Western blotting. No defect of mRNA for ACTN4 was evidenced by RT-PCR. Predominant existence of ACTN4 in capillary walls of glomeruli of IgAN patients was demonstrated by immunohistochemistry in glomerular sections of patients with IgAN. Conclusion: Use of microsieving enabled us to biochemically analyze glomerular proteins in renal biopsy samples from patients with glomerular diseases. With this method, we demonstrated skewed glomerular protein profiles in IgAN.

Comparative proteomic analysis of neutrophils from patients with microscopic polyangiitis and granulomatosis with polyangiitis

UNLABELLED Both microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) belong to ANCA-associated vasculitis (AAV), in which neutrophils play a key role in their pathology. In this study, in order to discriminate between MPA and GPA, protein profiles of peripheral blood polymorphonuclear cells (PMNs) of 11 MPA patients and 9 GPA patients and 10 healthy controls (HC) were analyzed by 2D-DIGE. In all the 864 spots detected, intensity of 55 spots was significantly different (p<0.05) among the three groups by ANOVA. 31 out of the 55 spots were identified by mass spectrometry. Orthogonal partial-least-squares-discriminate analysis revealed that the abundance profile of the protein spots discriminated the AAV group from the HC group, and the MPA group from the GPA group completely. 13 protein spots were considered as biomarker candidates to distinguish between MPA and GPA. In those, spots whose intensity was higher in MPA than in GPA included actin with various pI values, while a considerable part of spots whose intensity was higher in GPA were proteins related with the activity of neutrophils. Among the candidate proteins, ROC analysis showed that a combination of neutrophil gelatinase-associated lipocalin and a-kinase anchor protein 7 isoforms beta had a high diagnostic potential. BIOLOGICAL SIGNIFICANCE In this study, protein profiles of polymorphonuclear cells (PMNs) of microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) patients and healthy controls (HC) were investigated by 2D-DIGE, and MS analysis. As a result, we found that the protein profiles of PMNs were useful for distinguishing between patients (MPA and GPA) and HC, and between patients with MPA and patients with GPA. Especially, we found that the 13 protein spots that consisted of 10 proteins considerably contributed to the discrimination between MPA and GPA. This is the first to demonstrate that protein profiles of PMNs are different among MPA, GPA and healthy control. The 10 proteins we identified in this study would be new biomarkers for the diagnosis of the diseases, and may be reflect the pathology difference between MPA and GPA.