Elimination of eosinophils using anti-IL-5 receptor alpha antibodies effectively suppresses IL-33-mediated pulmonary arterial hypertrophy.

Interleukin (IL)-5 is a critical regulator of eosinophils and a therapeutic target for asthma. The administration of anti-IL-5 or anti-IL-5 receptor (IL-5R) antibodies has been shown to reduce eosinophil counts and ameliorate asthmatic symptoms in studies on animal models of allergy as well as in human clinical trials. In order to explore other potential clinical uses of IL-5R antibodies, we used an animal model of IL-33-mediated pulmonary arterial hypertrophy. We first generated chimeric monoclonal antibodies against the mouse IL-5 receptor α chain (IL-5Rα), which comprised an Fc region from human IgG1 and a Fab region from a previously established anti-mouse IL-5Rα monoclonal antibody. To investigate the role of antibody-dependent cell-mediated cytotoxicity (ADCC), chimeric antibodies that lacked ADCC were prepared. These antibodies recognized IL-5Rα to the same extent as the ADCC-sufficient antibodies. Administration of chimeric antibodies with ADCC resulted in the elimination of eosinophils from the lung and thus suppressed the development of arterial hypertrophy. This effect was attenuated in mice treated with antibodies lacking ADCC. Taken together, the results of this study provided a potential use for anti-IL-5Rα antibodies in the treatment of arterial hypertrophy, which leads to pulmonary hypertension.

Inhibition of G0/G1 Switch 2 Ameliorates Renal Inflammation in Chronic Kidney Disease.

Chronic kidney disease (CKD) is a global health problem, and novel therapies to treat CKD are urgently needed. Here, we show that inhibition of G0/G1 switch 2 (G0s2) ameliorates renal inflammation in a mouse model of CKD. Renal expression of chemokine (C-C motif) ligand 2 (Ccl2) was increased in response to p65 activation in the kidneys of wild-type 5/6 nephrectomy (5/6Nx) mice. Moreover, 5/6Nx Clk/Clk mice, which carry homozygous mutations in the gene encoding circadian locomotor output cycles kaput (CLOCK), did not exhibit aggravation of apoptosis or induction of F4/80-positive cells. The renal expression of G0s2 in wild-type 5/6Nx mice was important for the transactivation of Ccl2 by p65. These pathologies were ameliorated by G0s2 knockdown. Furthermore, a novel small-molecule inhibitor of G0s2 expression was identified by high-throughput chemical screening, and the inhibitor suppressed renal inflammation in 5/6Nx mice. These findings indicated that G0s2 inhibitors may have applications in the treatment of CKD.

Alterations of Hepatic Metabolism in Chronic Kidney Disease via D-box-binding Protein Aggravate the Renal Dysfunction.

Chronic kidney disease (CKD) is associated with an increase in serum retinol; however, the underlying mechanisms of this disorder are poorly characterized. Here, we found that the alteration of hepatic metabolism induced the accumulation of serum retinol in 5/6 nephrectomy (5/6Nx) mice. The liver is the major organ responsible for retinol metabolism; accordingly, microarray analysis revealed that the hepatic expression of most CYP genes was changed in 5/6Nx mice. In addition, D-box-binding protein (DBP), which controls the expression of several CYP genes, was significantly decreased in these mice. Cyp3a11 and Cyp26a1, encoding key proteins in retinol metabolism, showed the greatest decrease in expression in 5/6Nx mice, a process mediated by the decreased expression of DBP. Furthermore, an increase of plasma transforming growth factor-ß1 (TGF-ß1) in 5/6Nx mice led to the decreased expression of the Dbp gene. Consistent with these findings, the alterations of retinol metabolism and renal dysfunction in 5/6Nx mice were ameliorated by administration of an anti-TGF-ß1 antibody. We also show that the accumulation of serum retinol induced renal apoptosis in 5/6Nx mice fed a normal diet, whereas renal dysfunction was reduced in mice fed a retinol-free diet. These findings indicate that constitutive Dbp expression plays an important role in mediating hepatic dysfunction under CKD. Thus, the aggravation of renal dysfunction in patients with CKD might be prevented by a recovery of hepatic function, potentially through therapies targeting DBP and retinol.

24-hour rhythm of aquaporin-3 function in the epidermis is regulated by molecular clocks.

Aquaporin 3 (AQP3) is located in the basal layer of the epidermis and regulates biological functions of skin such as water content and trans-epidermal water loss. A recent study showed that the biological function of skin exhibits a 24-hour rhythm, but the molecular mechanism of the variation remains poorly understood. Here we show that mice mutated in the core clock component CLOCK (Clk/Clk) show decreased stratum corneum hydration. An extensive search for the underlying cause led us to identify AQP3 as a new regulator to control the 24-hour variation in biological functions of skin. In mouse epidermis of wild-type mice, mAqp3 exhibits circadian rhythms; however, these are significantly decreased in Clk/Clk. Luciferase reporter gene analysis revealed that transcription of mAqp3 is activated by D-site-binding protein, a clock gene. A human homolog, hAQP3, also exhibited significant oscillation in human keratinocyte (HaCaT) cells synchronized with medium containing 50% serum, and this rhythm was regulated by the endogenous CLOCK/BMAL1 heterodimer. These data indicate that although the molecular mechanisms underlying the rhythmic expression of mAqp3 and hAQP3 are different, clock genes are involved in time-dependent skin hydration. Our current findings provide a molecular link between the circadian clock and AQP3 function in mouse dorsal skin and HaCaT cells.