Yuko Furusho

Novel Therapy for Atherosclerosis Using Recombinant Immunotoxin Against Folate Receptor β-Expressing Macrophages.

Background Folate receptor β (FRβ) is induced during macrophage activation. A recombinant immunotoxin consisting of the truncated Pseudomonas exotoxin A (PE38) conjugated to an anti-FRβ antibody (anti–FRβ-PE38) has been reported to kill activated macrophages in inflammatory diseases. To elucidate the effect of an immunotoxin targeting FRβ on atherosclerosis, we determined the presence of FRβ-expressing macrophages in atherosclerotic lesions and administered the FRβ immunotoxin in apolipoprotein E–deficient mice. Methods and Results The FRβ-expressing macrophages were observed in atherosclerotic lesions of apolipoprotein E–deficient mice. At 15 or 35 weeks of age, the apolipoprotein E–deficient mice were divided into 3 groups and were intravenously administered 0.1 mg/kg of anti–FRβ-PE38 (immunotoxin group), 0.1 mg/kg of PE38 (toxin group), or 0.1 mL of saline (control group) every 3 days, for a total of 5 times for each age group. The mice were analyzed at 21 or 41 weeks of age. Treatment with the immunotoxin resulted in 31% and 22% reductions in atherosclerotic lesions of the 21- and 41-week-old mice, respectively (P<0.05). Administration of immunotoxin reduced the numbers of FRβ- and tumor necrosis factor-α–expressing macrophages, reduced cell proliferation, and increased the number of apoptotic cells (P<0.05). Real-time polymerase chain reaction demonstrated that the expression of FRβ and tumor necrosis factor-α mRNA was significantly decreased in the immunotoxin group (P<0.05). Conclusions These results suggest that FRβ-expressing macrophages exist in the atherosclerotic lesions of apolipoprotein E–deficient mice and that FRβ immunotoxin administration reduces the progression of atherosclerotic lesions in younger and older individuals. The recombinant FRβ immunotoxin targeting activated macrophages could provide a novel therapeutic tool for atherosclerosis. (J Am Heart Assoc. 2012;1:e003079 doi: 10.1161/JAHA.112.003079.)

Comparative study of therapeutic effects of short- and long-acting loop diuretics in outpatients with chronic heart failure (COLD-CHF).

BACKGROUND Loop diuretics have two different classes with different duration of activity: short-acting such as furosemide (duration of activity, 6h) and long-acting such as azosemide (duration of activity, 10-12h). We conducted a multicenter, randomized, controlled trial in order to compare the therapeutic effects of azosemide, a long-acting loop diuretic, and furosemide, a short-acting one, on neurohumoral factors and cardiac function in outpatients with chronic heart failure (CHF). METHODS We enrolled 98 patients with CHF who were receiving furosemide and an angiotensin-converting enzyme inhibitor, and they were randomly divided into furosemide (n=49) and azosemide (n=49) groups. The furosemide group continued furosemide at the same dosage, and the azosemide group switched from furosemide to azosemide. At baseline and after 3 months, we measured body weight, and levels of brain natriuretic peptide (BNP), atrial natriuretic peptide (ANP), norepinephrine, active renin, creatinine, blood urea nitrogen, sodium, potassium, and hematocrit. Chest X-ray and echocardiography were also performed. RESULTS Body weight and plasma levels of BNP and ANP significantly decreased after 3 months in the azosemide group compared to the furosemide group. There were no significant differences in changes of levels of creatinine, blood urea nitrogen, sodium, potassium, hematocrit, norepinephrine, and active renin after 3 months between the furosemide and azosemide groups. Echocardiography and chest X-ray did not demonstrate significant differences between the two groups. CONCLUSIONS Long-acting azosemide is suggested to be useful for the improvement of neurohumoral factors compared with short-acting furosemide in patients with CHF.

Production of a High-affinity Monoclonal Antibody Reactive with Folate Receptors Alpha and Beta

Folate receptors α (FRα) and β (FRβ) are two isoforms of the cell surface glycoprotein that binds folate. The expression of FRα is rare in normal cells and elevated in cancer cells. Thus, FRα-based tumor-targeted therapy has been a focus area of laboratory research and clinical trials. Recently, it was shown that a significant fraction of tumor-associated macrophages expresses FRβ and that these cells can enhance tumor growth. Although FRα and FRβ share 70% identity in their deduced amino acid sequence, a monoclonal antibody (MAb) reactive with both receptors has not been developed. A MAb that can target both FRα-expressing cancer cells and FRβ-expressing tumor-associated macrophages may provide a more potent therapeutic tool for cancer than individual anti-FRα or anti-FRβ MAbs. In this study, we developed a MAb that recognizes both FRα and FRβ (anti-FRαβ). The anti-FRαβ specifically stained trophoblasts and macrophages from human placenta, synovial macrophages from rheumatoid arthritis patient, liver macrophages from cynomolgus monkey and common marmoset, and cancer cells and tumor-associated macrophages from ovary and lung carcinomas. Surface plasmon resonance showed that the anti-FRαβ bound to soluble forms of the FRα and FRβ proteins with high affinity (KD=6.26×10(-9) M and 4.33×10(-9) M, respectively). In vitro functional analysis of the anti-FRαβ showed that this MAb mediates complement-dependent cytotoxicity, antibody-dependent cellular cytotoxicity, and antibody-dependent cellular phagocytosis of FRα-expressing and FRβ-expressing cell lines. The anti-FRαβ MAb is a promising therapeutic candidate for cancers in which macrophages promote tumor progression.