Amyloidosis in Whipple's Arthritis

Infections and AA amyloidosis: An overview

BACKGROUND

Amyloidoses are a heterogeneous group of systemic diseases characterised by extracellular accumulation of insoluble amyloid fibrils derived from unfolded proteins. Inflammatory (AA) amyloidosis can complicate various inflammatory disorders that are associated with a sustained acute phase response and serum amyloid A (SAA) protein overproduction. Chronic infections were the first recognised cause of amyloidoses. However, with the better management of underlying diseases, the frequency of AA amyloidosis is decreasing.

PURPOSE

The aim of this overview was to discuss the several infections associated with AA amyloidosis and the relative frequency of infections as aetiological factors.

METHODS

A search of the literature was performed using the PubMed database using the MeSH terms "Amyloidosis" and "Infections," from inception to December 31st, 2019. Articles written in other languages than English or French were excluded.

RESULTS

The frequency of AA amyloidosis secondary to infections decreased from more than 50% to less than 20% after the 2000s, with a parallel increase in the frequency of AA amyloidosis secondary to inflammatory diseases and to an unknown cause.

CONCLUSION

Whereas new antibiotics have been developed and sanitary conditions are better, infections still represent 5%-30% of the causes of AA amyloidosis, including in developed countries. These data argue for better screening of chronic infections to prevent AA amyloidosis and the development of new strategies to manage recurrent infections.

Whipple's disease

Whipple's disease is a chronic systemic bacterial infection that predominantly affects middle-aged men. Antimicrobial therapy is curative. The causative agent has been identified as Tropheryma whippelii. A PCR-based diagnostic test is now available and is particularly useful in patients with early-stage or atypical disease. The test can detect bacterial nucleic acids in tissues and body fluids, including joint fluid. Studies using this test found no evidence that T. whippelii may be a common cause of unexplained seronegative oligoarthritis or polyarthritis. Further work is needed to identify the patient subsets most likely to benefit from T. whippelii PCR testing in joint specimens. Isolation of the organism has been achieved recently. This will probably allow development of a serological test, which may facilitate the diagnosis. Weight loss and diarrhea are the most common symptoms of Whipple's disease. Joint manifestations antedate the intestinal complaints in three-fourths of patients, the mean interval being 6 years. In most patients, duodenal and jejunal biopsy specimens contain macrophages filled with PAS-stained granules corresponding to bacteria. Nevertheless, some patients have no intestinal symptoms, and a few have normal intestinal histological findings. Before the onset of intestinal symptoms, several clinical patterns should suggest Whipple's disease. Unexplained, chronic, seronegative oligoarthritis or polyarthritis affecting the large limb joints is the most common presentation. A characteristic feature is the intermittent occurrence of the joint manifestations, at least early in the disease. Other patterns are destructive polyarthritis and spondyloarthropathy. The major advances made recently in techniques for detecting and isolating the causative agent may show that Whipple's disease is more common and has a broader clinical spectrum than was previously thought. Another hope is that the diagnosis will be made earlier, before the development of potentially fatal systemic complications.

Whipple disease and arthritis

Whipple disease is a chronic, multisystem, curable, bacterial infection that usually affects middle-aged men and has a wide range of clinical manifestations. The most common symptoms are weight loss and diarrhea, preceded in three quarters of cases by arthritis for a mean of 6 years. In most patients, periodic acid-Schiff staining of proximal small bowel biopsy specimens reveals inclusions within the macrophages, corresponding to bacterial structures. However, patients with various manifestations of the disease may have no gastrointestinal symptoms and negative jejunum biopsy results. Before the onset of gastrointestinal symptoms, a strong index of clinical suspicion is the key to diagnosis. The classic setting is long-term, unexplained, seronegative oligoarthritis or polyarthritis with a palindromic or relapsing course, although chronic destructive polyarthritis and spondyloarthropathy have been repeatedly reported. Identification of the Whipple bacterium, Tropheryma whippelii, has led to the development of polymerase chain reaction as a diagnostic tool in patients in the early stages of the disease or with atypical Whipple disease. This technique can be used to detect the bacterium in many tissues and fluids, including synovial tissue and fluid. The recent cultivation of the Whipple bacillus should lead to the development of serologic tests, further facilitating diagnosis. These recent major advances may show that the infection is more frequent than previously suspected and may expand the clinical spectrum of the disease. It may also allow earlier diagnosis, thereby preventing the development of the severe systemic and sometimes fatal forms of the disease.

Antibiotic treatment and relapse in Whipple's disease. Long-term follow-up of 88 patients

Reports of clinical relapse occurring after apparently successful antibiotic treatment of Whipple's disease prompted this review of long-term follow-up of treated patients. Follow-up of at least 1 yr after completion of treatment or 2 yr after diagnosis was obtained on 88 patients with documented Whipple's disease by a review of the medical literature, correspondence with the authors as needed, and questionnaires mailed to academic gastroenterology programs in the United States. Relapse was defined on the basis of morphology (preferably) or clinically, or both. Thirty-one patients relapsed, 6 of whom relapsed twice. Fifty-seven patients did not relapse. The mean time to relapse was 4.2 yr. The mean follow-up period of patients who did not relapse was 8.2 yr. The type and number of relapses were as follows: clinical, 16; central nervous system, 13; arthralgia, 5; gastrointestinal, 1; and cardiac, 2. The clinical, arthralgia, and gastrointestinal relapses were evenly distributed between early relapses (occurring less than 2 yr after diagnosis) and late relapses (occurring greater than 2 yr after diagnosis). All cardiac and central nervous system relapses were late. Twenty-one of 49 patients treated with tetracycline alone relapsed. Two relapses were reported in 15 patients treated with penicillin and streptomycin followed by tetracycline. Three relapses developed in 8 patients treated with penicillin alone. Five of the 16 patients treated with other regimens relapsed. Nine of the 13 patients with central nervous system relapse had been initially treated with tetracycline, 2 were treated with penicillin, and 2 were treated with combinations of antibiotics. Results of treatment of central nervous system relapse were poor in 10 of the 11 patients for whom details were available. Results of treatment of non-central-nervous-system relapse were excellent in 19 of 20 patients. It is concluded that tetracycline alone, or penicillin alone, is not adequate initial therapy for Whipple's disease and that central nervous system relapse is resistant to antibiotic therapy. The authors recommend parenteral penicillin and streptomycin followed by 1 yr of oral trimethoprim-sulfamethoxazole therapy or oral trimethoprim-sulfamethoxazole alone for 1 yr as initial therapy for Whipple's disease. Relapse should be defined by demonstration of recurrence of bacilli whenever possible.

Ultrastructure of synovial changes in rheumatoid disease and in seronegative inflammatory arthropathies

Synovial tissue has been examined by electron microscopy from patients suffering from either sero-positive or sero-negative inflammatory arthropathies to allow direct comparison of the ultrastructural changes found in these groups and to confirm and extend observations previously made in a smaller group of sero-negative arthropathies. Both groups have been compared with material from healthy controls. The sero-positive group comprised 13 cases of 'definite' or 'classical' rheumatoid arthritis. The sero-negative group consisted of 9 cases of arthritis secondary to Crohn's disease (3); Reiter's syndrome (2); Whipple's disease (1); Behcet's disease (1); Wegener's granulomatosis (1) and ankylosing spondylitis (1). The control tissue was obtained from 6 non-arthritic subjects undergoing surgery for non-inflammatory conditions. Confirmation was obtained of changes previously reported in subcellular organelles, especially in synovial B cells, in all forms of inflammatory arthritis as compared with controls. Attention is now drawn to other intracellular changes in B cells and intermediate cells which included: a marked increase of intermediate filaments and microfilaments: and proliferation of pinocytotic vesicles and rough endoplasmic reticulum. These changes were often accompanied by the presence, in the immediate environment of these cells, of extracellular microfibrillary masses but little or no accumulation of intermediate filaments. It was confirmed that synovial A cells were reduced in number but showed changes suggestive of increased phagocytic activity and also exhibited proliferation of cytoskeletal elements. Differences in these structural changes between sero-positive and sero-negative arthritis were of degree rather than of kind and no 'specific' or diagnostic differences were observed between the various forms of seronegative athropathies. The possible significance of the structural changes observed is discussed.