Takemasa Matsuda

Selective expression of folate receptor β and its possible role in methotrexate transport in synovial macrophages from patients with rheumatoid arthritis

OBJECTIVE To investigate the expression of folate receptors (FR) and reduced folate carrier (RFC) and determine their relevance to methotrexate (MTX) transport in synovial mononuclear cells (SMC) from patients with rheumatoid arthritis (RA). METHODS Levels of FR and RFC messenger RNA (mRNA) were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) in SMC from RA patients and peripheral blood mononuclear cells from healthy donors. Expression of FR-beta mRNA and protein was determined by Northern blot and Western blot analyses in RA SMC and monocyte/macrophage-lineage cells. FR-beta expression and folic acid binding capacity on the cell surface were examined by flow cytometric analysis and 3H-folic acid binding analysis. Studies of the inhibition of 3H-MTX uptake in the presence of unlabeled folic acid were performed to investigate the uptake of MTX through FR in RA SMC. RESULTS RT-PCR, Northern blot, and Western blot analyses showed that FR-beta mRNA and protein were expressed selectively in activated monocytes and CD14+ RA SMC. These cells exhibited folic acid binding capacity. Furthermore, the FR-beta protein was shown to have folic acid binding capacity. Uptake of 3H-MTX through RA SMC was significantly inhibited in the presence of unlabeled folic acid. CONCLUSION These results demonstrate that FR-beta expression is selectively elevated in RA synovial macrophages and suggest that MTX is transported through FR-beta in RA synovial macrophages. The findings suggest that folate antagonists with higher affinity for FR-beta would be useful in the treatment of RA.

Leflunomide-induced interstitial lung disease: prevalence and risk factors in Japanese patients with rheumatoid arthritis

OBJECTIVES The possible link between LEF and interstitial lung disease (ILD) has evoked increasing concern. The aim of the present study was to elucidate the prevalence and risk factors for newly developed and/or exacerbated ILD, based on post-marketing surveillance data, in which all RA patients receiving LEF were pre-registered and monitored for 24 weeks in Japan. METHODS We analysed data from a cohort of 5054 RA patients who were prescribed LEF since its launch in September 2003 in Japan. Multivariable logistic analysis was performed to identify the risk factors for newly developed and/or exacerbation of ILD. RESULTS Sixty-one (1.2%) of 5054 RA patients who received LEF were reported to have development and/or exacerbation of ILD as an adverse drug reaction to LEF, judged by the attending physicians. Multivariable logistic regression analysis identified pre-existing ILD [odds ratio (OR) 8.17; 95% CI 4.63, 14.4], cigarette smoking (3.12; 95% CI 1.73, 5.60), a low body weight (<40 kg vs >50 kg) (2.91; 95% CI 1.15, 7.37) and the use of a loading dose (3.97; 95% CI 1.22, 12.9) as independent risk factors for LEF-induced ILD. CONCLUSIONS Pre-existing ILD was the most important risk factor for LEF-induced ILD. We suggest that LEF should not be prescribed for RA patients complicated with ILD.

Factors associated with fatal outcome of leflunomide-induced lung injury in Japanese patients with rheumatoid arthritis

OBJECTIVE To elucidate the factors associated with poor prognosis of LEF-induced lung injury in patients with RA. METHODS The background and clinical and laboratory features of LEF-induced lung injury were examined and compared between patients who died of and who recovered from it. RESULTS Among 22 patients who developed LEF-induced lung injury, 9 died of and 13 recovered from it. The patients who died tended to have pre-existing interstitial pneumonia (8/9 vs 6/13, P = 0.07). The loading and maintenance doses, serum concentration of the LEF metabolite A771726 and administration period did not differ between the groups. Patients who died had more frequently hypoxaemia of <60 Torr and mechanical ventilation, and had a high serum CRP level (19.3 +/- 9.4 vs 10.1 +/- 8.1 mg/dl, P = 0.03) and a low albumin level (2.7 +/- 0.6 vs 3.3 +/- 0.5 g/dl, P = 0.03) at the lung injury onset. The peripheral blood lymphocyte count decreased in both groups at the lung injury onset, and it remained low until fatal outcome, in contrast to a re-increase upon recovery (406 +/- 394 vs 1203 +/- 399/microl, P = 0.006). The main histopathological finding in two autopsied patients was diffuse alveolar damage, in contrast to the alveolitis observed in a biopsied patient who recovered. CONCLUSIONS Pre-existing interstitial pneumonia, extremely high serum CRP and low albumin levels, severe hypoxaemia and mechanical ventilation indicated poor prognosis. Peripheral blood lymphocytopenia developed in association with lung injury, and a sustained low lymphocyte count indicated a fatal outcome.

α1Acid glycoprotein expression in human leukocytes: Possible correlation between α1-acid glycoprotein and inflammatory cytokines in rheumatoid arthritis

Abstractα-Acid glycoprotein is an acute-phase reactant that becomes markedly elevated in serum during inflammation and has an immunosuppressive effect on lymphocyte fonctions. Patients with collagen diseases had significant increases ofα1-acid glycoprotein in their serum and on the surface of peripheral leukocytes compared with controls. The levels from patients with rheumatoid arthritis were higher than those from patients with systemic lupus erythematosus, mixed connective tissue disease, and Behçets disease. In patients with rheumatoid arthritis, the value of serumα1-acid glycoprotein correlated with disease activity. Among leukocyte subpopulations, monocytes showed more α1-acid glycoprotein on their surface than polymorphonuclear leukocytes; and lymphocytes. The cell surface expression ofα1-acid glycoprotein on cultured monocytes surface peaked after 48 h. Interleukin-1β and tumor necrosis factor-α stimulated the production of α1-acid glycoprotein RNA message in peripheral blood mononuclear cells over 18–24 h during cell culture. The results show that serumα1-acid glycoprotein reflects systemic disease activity in rheumatoid arthritis. Furthermore, monocytes may serve as a source of production ofα1-acid glycoprotein.

Comparative evaluation of KL-6 and surfactant protein D as serum markers for interstitial pneumonia associated with collagen diseases

Abstract We evaluated the usefulness of serum levels of KL-6 and surfactant protein D (SP-D) as markers of interstitial pneumonia (IP) associated with collagen diseases in 115 patients. KL-6 and SP-D levels in patients with IP (n = 38) were significantly higher than those in patients without IP (n = 77). Moreover, KL-6 and SP-D levels in patients with active IP (n = 8) were significantly higher than those in patients with inactive IP (n = 30). Both KL-6 and SP-D proved useful for the diagnosis of IP associated with collagen diseases and for the evaluation of disease activity. We classified IP into three groups according to the extent of the lesion on computed tomographs of the chest. There was a significant difference among three groups in serum levels of KL-6, but not in serum levels of SP-D. KL-6 proved to be useful as an indicator of the extent of the IP lesions. We monitored changes in KL-6 and SP-D levels in seven of eight patients with active IP. Chronological changes of serum KL-6 and SP-D in patients with active IP were different. In fatal cases in particular, serum levels of SP-D decreased at the terminal stage of IP while levels of KL-6 continued to increase.