We evaluated the prevalence of Helicobacter pylori infection and the association of H. pylori infection and/or nonsteroidal anti-inflammatory drug (NSAID) use with upper gastrointestinal (UGI) ulcers in a cohort of Japanese patients with rheumatoid arthritis (RA). Using the clinical database of the cohort of RA patients and the serum titers of H. pylori antibody, 1815 patients were analyzed. Clinical data were successfully collected for 1529 patients over 2 years, and the history of NSAID use and the occurrence of newly diagnosed UGI ulcer were ascertained by patient self-reports and confirmed by their medical records. A total of 871 patients (49.3%) were H. pylori antibody-positive. Rates of positivity for H. pylori in patients with and without NSAID use were 47.5% and 54.7%, respectively (odds ratio = 0.75, 95% confidence intervals [CI]: 0.58-0.96). The incidence of newly diagnosed UGI ulcer was 0% in the H. pylori-/NSAID- group, 1.24% in the H. pylori-/NSAID+ group, 1.06% in the H. pylori+/NSAID- group, and 3.46% in the H. pylori+/NSAID+ group. The odds ratios of H. pylori infection and NSAID for the occurrence of new UGI ulcers after adjusting for age and sex were 2.97 (95% CI: 1.19-7.38) and 4.31 (95% CI: 0.57-32.4), respectively. Although the prevalence of H. pylori antibody was low in patients with RA compared with that in healthy Japanese individuals, H. pylori infection was a significant risk factor for UGI ulcer in patients with RA.
A variety of myositis-specific autoantibodies (MSAs) have been detected in patients with dermatomyositis (DM). We analyzed MSAs in 20 cases with DM. Eleven of the 20 cases were positive. Out of those 11 cases, 3 were positive for antibodies against aminoacyl-tRNA synthetase and 3 had antibodies to anti-melanoma differentiation-associated gene 5 detected using an immunoprecipitation assay and/or a specific enzyme-linked immunosorbent assay. One case had anti-NXP-2 antibodies and 4 cases had anti-transcriptional intermediary factor 1 (TIF1)-α/γ antibodies detected by immunoprecipitation and Western blotting. Two of those 4 cases had antibodies for both TIF1-α and TIF1-γ, and the 2 other cases had antibodies for TIF1-γ alone. We report the 2 cases with antibodies for TIF1-γ only, who were young-adult females without an internal malignancy or interstitial pneumonia. Those 2 cases had clinically amyopathic DM. Among DM patients with antibodies against TIF1 family proteins, there seems to be a subgroup of young-adult cases who have clinically amyopathic DM and show good prognosis without malignancy.
The evolutionary loss of hepatic urate oxidase (uricase) has resulted in humans with elevated serum uric acid (urate). Uricase loss may have been beneficial to early primate survival. However, an elevated serum urate has predisposed man to hyperuricemia, a metabolic disturbance leading to gout, hypertension, and various cardiovascular diseases. Human serum urate levels are largely determined by urate reabsorption and secretion in the kidney. Renal urate reabsorption is controlled via two proximal tubular urate transporters: apical URAT1 (SLC22A12) and basolateral URATv1/GLUT9 (SLC2A9). In contrast, the molecular mechanism(s) for renal urate secretion remain unknown. In this report, we demonstrate that an orphan transporter hNPT4 (human sodium phosphate transporter 4; SLC17A3) was a multispecific organic anion efflux transporter expressed in the kidneys and liver. hNPT4 was localized at the apical side of renal tubules and functioned as a voltage-driven urate transporter. Furthermore, loop diuretics, such as furosemide and bumetanide, substantially interacted with hNPT4. Thus, this protein is likely to act as a common secretion route for both drugs and may play an important role in diuretics-induced hyperuricemia. The in vivo role of hNPT4 was suggested by two hyperuricemia patients with missense mutations in SLC17A3. These mutated versions of hNPT4 exhibited reduced urate efflux when they were expressed in Xenopus oocytes. Our findings will complete a model of urate secretion in the renal tubular cell, where intracellular urate taken up via OAT1 and/or OAT3 from the blood exits from the cell into the lumen via hNPT4.
