Background The aim of this study was to determine the prevalence and extent of amyloid A deposition on different tissue structures in various organs of rheumatoid arthritis (RA) and psoriatic arthritis (PsA) patients.

Methods AAa was detected in 34 (21.1%) (females: 29, average age: 64.3 years, range: 83–32, onset of RA: 48.6, average disease duration: 15.7 years; males: 5, average age: 51.2 years at death, range: 88–19, onset of RA: 41.3, average disease duration: 14.8 years) of 161 RA, and in 2 (16%) female: 2, average age: 57.5 years, range: 63–52, onset of PsA: 47.5, average disease duration: 11.0 years) of 12 PsA patients.

RA and PsA were diagnosed clinically according to the criteria of the American College of Rheumatology (ACR) [1,2].

Amyloid deposits on different tissue structures [arteriole, small artery, medium size artery, venule, small vein, medium size vein, interstitial collagen fiber, reticulin fiber (collagen IV), basal laminas, nerve, renal glomerulus] of 6 organs [heart, lungs, liver, kidney, skin and brain] were determined histologically. The extent of amyloid A deposits was evaluated by semi-quantitative, visual estimation on a 0 to 3 plus scale, based on the number of involved tissue structures per light microscopic field [3].

The prevalence and extent of amyloid A deposits on different tissue structures were compared by Student (Welch) t-probe.

Results The average prevalence (in %) and the average extent of amyloid A deposits (absolute value) on different tissue structures of analyzed 6 organs in RA and PsA patients are summarized in Table.

Conclusions The difference between average prevalence (p<0.388) and average amount (p<0.444) of amyloid A deposits/structures in RA and PsA patients was not significant.

The prevalence and extent of amyloiod A deposits on different tissue structures of analyzed organs changed parallel in RA or PsA patients except for collagen IV and interstitial collagen.

The reverse prevalence and extent of amyloid A deposits on collagen IV and interstitial collagen fibers between RA or PsA patients may be due to structural (qualitative) changes of collagen IV resulting in its increased affinity of amyloid A in PsA patients. Qualitative change of collagens in systemic sclerosis patients has been demonstrated [4].

References

1. Arnett FC et al: Arthritis Rheum. 1988; 31(3):315–24. PMID: 3358796.

2. Helliwell PS, Taylor WJ: Classification and diagnostic criteria for psoriatic arthritis. Ann Rheum Dis 2005;64:ii3-ii8 doi:10.1136/ard.2004.032318.

3. Bély M, Apáthy Άgnes: Clinical pathology of rheumatoid arthritis. 1–440 pp. Akadémiai Kiadό, Budapest 2012 http://www.akkrt.hu.

4. Istok R et al: Pyridinoline in fibrotized tissues of patients with systemic sclerosis. Annals Rheum Dis 1999; 58(Suppl. 1):192.

References

Disclosure of Interest None declared