SS-A/Ro (52kDa and 60kDa) and SS-B/La protein and mRNA expression in minor salivary glands from patients with Sjögrens syndrome. / Estudo da expressão dos auto-antígenos SS-A/Ro (polipeptídeos 52kda e 60kda) e SS-B/La (polipeptídeo 48kda) e de seus RNAs mensageiros em glândulas salivares menores de pacientes com síndrome de Sjögren.

AUTOR(ES)

Karin Spat Albino Barcellos Silveira

DATA DE PUBLICAÇÃO

2006

RESUMO

Purpose: The strong association between primary Sjögren syndrome (pSS) and autoantibodies to SS-A/Ro (52kDa and 60kDa) and SS-B/La may be indicative of a possible role for these autoantigens in the pathophysiology of the disease. The present study aimed to analyze protein and mRNA expression of SS-A/Ro and SS-B/La antigens in a preferential tissue target of pSS, i.e., minor salivary glands (MSGs). Methods: SS-A/Ro (60kDa &52kDa) and SS-B/La protein expression was studied by immunohistochemistry in MSG samples of 26 pSS patients and 16 control subjects. Analysis was carried out by two independent blinded observers according to the topography and intensity (semiquantitative score) of the staining. Total RNA extracted from MSG samples of 10 pSS patients and 7 control subjects was submitted to reverse transcription and quantified by Real Time PCR with primers specific to SS-A/Ro (60kDa &52kDa) and SS-B/La cDNA. Samples were normalized by ß-actin and GAPDH mRNA expression. Relative mRNA expression (2-ΔΔCT) was compared between pSS patients and control subjects. Results: In general the semiquantitative protein expression for the three autoantigens did not differ among pSS patients and control subjects, and was more prominent in the cytoplasm as compared to the nucleus in all cell types. However, SS-B/La protein had higher expression in the cytoplasm of ductal cells than in the cytoplasm of mucous acinar cells in pSS patients (p=0.013), while no significant difference was detected in the control group (p=0.704). SS-A/Ro 60kDa protein had higher expression in the cytoplasm of ductal cells than in the cytoplasm of serous acinar cells of pSS patients (p=0.006) but the same was not observed for controls (p=0.156). SS-A/Ro 52kDa protein topographic expression pattern was the same in patients and controls. SS-B/La mRNA expression was higher in samples from pSS patients (5.3265.107) than in controls (0.8561.255) (p=0.0311). The same was true for SS-A/Ro 60kDa mRNA expression (6.8667.868 vs 1.0451.329; p=0.0330). On the other hand, SS-A/Ro 52kDa mRNA expression showed a modest trend for higher expression in samples from pSS patients but the difference did not reach statistical significance (5.6164.885 vs 2.6484.223; p=0.0879). Samples with the highest histological inflammation score at MSG showed decreased expression of SS-A/Ro 60kDa, SS-A/Ro 52kDa and SS-B/La mRNAs. Conclusions: The increased SS-A/Ro 60kDa and SS-B/La mRNA expression in MSGs of pSS patients as well as the differential SS-A/Ro 60kDa and SS-B/La protein expression in ductal cells of MSGs in pSS patients suggest that these antigens are probably involved in triggering and maintaining the tissue-specific autoimmune response in pSS MSGs. The observed differential expression may contribute to the antigen-driven immune response and local autoantibody production in pSS.

ASSUNTO(S)

1. síndrome de sjögren . 2. glândulas salivares menores. 3. auto-antígenos. 4. auto-anticorpos. 5. ss-a/ro. 6. ss-b/la. 1. sjögrens syndrome. 2. minor salivary glands reumatologia

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