Identification of interleukin-7 as a candidate disease mediator in spondylarthritis

OBJECTIVE

Understanding of the molecular pathophysiology of spondylarthritis (SpA) remains largely elusive. This is related both to the complexity of the disease (axial versus peripheral disease, inflammation versus tissue remodeling) and to the difficulty in obtaining samples from primary disease sites. This study was undertaken to explore a gene expression approach for identifying novel candidate mediators of SpA.

METHODS

Sacroiliac joint fluid aspirates from 3 SpA patients with active sacroiliitis were studied by microarray analysis. The expression of selected candidate molecules in peripheral synovitis was confirmed by reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay.

RESULTS

Microarray analysis identified 4 sacroiliitis gene clusters, containing a total of 47 messenger RNA (mRNA) transcripts. Two clusters contained genes expressed in all sacroiliitis samples, corresponding to both known and unsuspected candidate mediators of SpA pathology. These included proinflammatory molecules as well as molecules involved in tissue remodeling, such as transforming growth factor beta2. Of the novel candidate genes selected for confirmation, interleukin-7 (IL-7) mRNA expression was higher in SpA peripheral synovial fluid and synovial tissue samples than in osteoarthritis samples, and similar to expression in rheumatoid arthritis (RA) samples. At the protein level, synovial fluid IL-7 levels were even higher in SpA than in RA, despite lower levels of tumor necrosis factor alpha and IL-1beta.

CONCLUSION

In the present study, both known and unsuspected candidate mediators of SpA pathogenesis were identified, including IL-7. The specific overexpression of IL-7 at sites of peripheral synovitis in SpA suggests that further functional investigations of the role of this cytokine in SpA pathogenesis are warranted.

Purification and biochemical characterization of a laccase from the aquatic fungus Myrioconium sp. UHH 1-13-18-4 and molecular analysis of the laccase-encoding gene

Myrioconium sp. strain UHH 1-13-18-4 is an ascomycete anamorph isolated from the river Saale, Central Germany. An extracellular, monomeric, and glycosylated laccase with a molecular mass of 72.7 kDa as determined by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry and an isoelectric point below 2.8 was purified from CuSO(4) and vanillic acid amended liquid fungal cultures grown in malt extract medium. The catalytic efficiencies (k(cat)/K(m)) for the oxidation of syringaldazine, 2,6-dimethoxyphenol, and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonate) were 67.3, 46.9, and 28.2 s(-1) mM(-1), respectively, with K(m) values of 4.2, 67.8, and 104.9 microM. After pre-incubation at different pH values and temperatures for 1 h, more than 80% of the initial laccase activity was retained between pH 4 to 6 and 15 degrees C. The laccase-encoding gene was identified and sequenced at both the genomic and complementary DNA (cDNA) level, and corresponding structural characteristics and putative regulatory elements of the promoter region are reported. The identification of two tryptic peptides of the purified enzyme by mass spectrometry confirmed the identity of the functional laccase protein with the translated genomic sequence of the Myrioconium sp. laccase. Myrioconium sp. laccase shows the highest degree of identity with laccases from ascomycetes belonging to the family Sclerotiniaceae, order Helotiales.

Bildgebende Verfahren in der Frühdiagnostik rheumatischer Veränderungen der Hände

PURPOSE

Besides the use of conventional x-rays in the diagnostic work-up of initial changes in patients suffering from rheumatoid arthritis (RA), 3-phase bone scintigraphy (3P-Sz) is as well established as magnetic resonance imaging (MRI). The aim of this study was to compare the diagnostic value of ultrasound of the hands with proven methods such as conventional x-rays, low-field MRI and 3P-Sz.

METHODS

A total of 30 patients were studied using a 1 day protocol with ultrasound, 3P-Sz, MRI and x-ray of the hands. Images were visually assessed by two blinded nuclear medicine physicians and radiologists and classified as RA typical and non-RA typical changes. All methods were compared to the summarized findings interpreted by a rheumatologist after 2 years.

RESULTS

Of the 30 patients, 19 presented with clinical symptoms of initial changes due to rheumatoid arthritis. Ultrasound revealed 14/19 patients with the correct diagnosis. Conventional x-rays indicated 11/19 patients, while 3P-Sz (100%) and low-field MRI (95%) showed high sensitivity. It was possible to differentiate between inflammation and inconspicuous findings.

CONCLUSIONS

An experienced examiner can use ultrasound effectively for the initial diagnosis of RA. Based on its low cost, ultrasound is a valid alternative to conventional x-rays.

Rationalizing molecular analysis of field-collected roots for assessing diversity of arbuscular mycorrhizal fungi: to pool, or not to pool, that is the question

For rationalizing molecular analysis of field-collected roots in diversity studies on arbuscular mycorrhiza, we compared three different approaches. After DNA extraction from 50 root samples of Plantago lanceolata grown on monoculture plots at a former arable field site, (1) DNAs were amplified separately by nested PCR and each amplicon was cloned separately; (2) DNAs were amplified separately by nested PCR, 1 mul of each amplicon was pooled, and a single cloning was made from the resulting amplicons mix; and (3) DNAs were pooled and the single amplicon derived from the nested PCR was cloned. Based on these three different methods, 109 nuclear ribosomal internal transcribed spacer sequences were obtained. Methods 1 and 2 enabled the detection of almost similar levels of arbuscular mycorrhizal fungal diversity. However, method 1 was expensive and time-consuming as much more cloning had to be done. Method 3 was completely biased by preferential amplification of nontarget organisms, which were only detected in low frequencies by the other methods.

Bildgebende Verfahren in der Rheumatologie: Bildgebung bei der Psoriasisarthritis (PsA)

Conventional radiography is still the standard method of imaging in PsA since it displays many joints at the same time, thereby allowing different types of joint involvement to be recognized. Moreover, thanks to the high resolution of radiography, bony changes in a single joint are depicted in a brilliant way. Several features of psoriatic arthritis allow the distinction from rheumatoid arthritis, including the frequent involvement of the distal interphalangeal joints, asymmetry of joint involvement, axial involvement of finger joints, oligoarticular involvement; however, symmetric polyarthritis is also possible. At the level of the single joint, there are signs of severe destructive changes potentially leading to mutilation and at the same time signs of periostal bone proliferation and ankylosis may be present. Bony proliferation and/or osteolysis are not restricted to the joint region but can affect also the total phalanx with bone apposition or concentric osteolysis which may lead to a complete disappearance of phalanxes. For purposes of quantification of radiographic changes scoring methods are used that were originally developed for rheumatoid arthritis. So far, there is only one validated scoring method that was specifically designed for PsA and that takes into account both features of PsA, damage as well as proliferation of bone. In contrast to conventional radiography, MRI and sonography are able to visualize inflammatory processes within the soft tissue (joint capsules, tendon sheaths, tendon insertions, etc.), allowing an estimation of disease activity. Scintigraphy is nonspecific and can only be used to detect clinically silent inflammatory spots. The relatively frequent spinal (axial) involvement is similar to that seen in ankylosing spondylitis. However, unilateral sacroiliitis, asymmetry of syndesmophytes and development of parsyndesmophytes may distinguish PsA from ankylosing spondylitis. While conventional radiography demonstrates the bony consequences of inflammation in the spine, MRI also shows the active inflammatory changes in sacroiliacal joints and vertebrae.

[Imaging procedures in rheumatology. Differential diagnosis using various imaging procedures in rheumatoid arthritis (RA)]

Conventional radiography, ultrasonography (US), magnetic resonance imaging (MRI), computed tomography, and scintigraphy are imaging techniques in use for rheumatoid arthritis (RA). Conventional radiography of the hands and the forefeet should be performed every 6 to 12 months in the first two years, and every 12 to 24 months after two years, in search of erosions. If radiography fails to detect erosions, radiography using a second plane should be done. US or MRI may be used to detect earlier erosions if therapeutic consequences exist. In severe RA, radiography of the cervical spine in the neutral position and with inclination should be performed every 3 to 4 years. MRI should be done, if the distance between atlas and dens is >4 mm. Scintigraphy is indicated if arthralgia occurs in many joints. US may detect or exclude inflammatory changes if arthralgia occurs in a few joints. Single symptomatic joints may be assessed by US to differentiate pathologies. Radiography aids in establishing a differential diagnosis, e. g., to detect osteoarthritis. MRI is indicated if the radiography or US is equivocal. It is indicated to diagnose osteonecrosis or meniscal lesions. Arthrocenthesis may be done without imaging or under radiographic or sonographic guidance.

Association of anti-cyclic citrullinated peptide antibodies, anti-citrullin antibodies, and IgM and IgA rheumatoid factors with serological parameters of disease activity in rheumatoid arthritis

We evaluated the association of anti-cyclic citrullinated peptide (CCP) antibody titers with serological markers of disease activity. We also compared three different anti-CCP antibody ELISAs with an anti-citrullin ELISA and the IgM and the IgA rheumatoid factor (RF) in their performance of discriminating between rheumatoid arthritis (RA) and other rheumatic diseases. Sera from 333 consecutive patients of the Rheumaeinheit der Medizinischen Poliklinik Munchen, an outpatient clinic for rheumatic diseases, were collected and tested. Anti-CCP antibodies were assayed with three different commercially available ELISAs. Antifilaggrin antibodies were tested with a commercially available ELISA using in vitro deiminated recombinant rat filaggrin. IgA-RF was analyzed with an ELISA, whereas IgM-RF was measured by latex-enhanced turbidimetry. Rheumatoid arthritis (RA) was diagnosed in 87 patients according to the revised classification criteria of the American College of Rheumatology (ACR), probable RA was diagnosed in 23 patients in an early phase not (yet) fulfilling the ACR criteria, and 223 patients had other rheumatic diseases. Differences in sensitivity and specificity were calculated using McNemar's test. A measure of agreement (kappa statistic) was used to examine whether the tests tended to identify the same patients as positive or negative. Correlations between CCP titers and other tests were analyzed by Spearman nonparametric rank correlation. No significant differences in sensitivity and specificity were found between the tested CCP assays (80.0-80.9% and 97.3-98.1%, respectively). All three CCP tests were slightly but not significantly more sensitive and specific than the anti-citrullin assay (77% and 92%, respectively), comparably sensitive but significantly more specific compared with the IgM-RF (86% and 82%, respectively), and significantly more sensitive but comparably specific compared with the IgA-RF (63% and 94.4%, respectively) in detecting the patients with RA. There was no significant correlation between anti-CCP, anti-citrullin, or IgM-RF or IgA-RF antibody titers and C-reactive protein, erythrocyte sedimentation rate, or white blood cell count. A weak but significant linear correlation was found between anti-CCP titers and IgM-RF titers (r = 0.2, P = 0.03). We could not find a significant difference between the three tested anti-CCP assays and the anti-citrullin test in terms of sensitivity and specificity. Compared with the IgM-RF, all the anti-CCP assays were superior in specificity and comparable in sensitivity. Compared with the IgA-RF, they were more sensitive and comparably specific in the discrimination of patients with RA from other rheumatic diseases. No correlation of any tested autoantibody titer with serological parameters of inflammation was found.