Anti-prion activity of protein-bound polysaccharide K in prion-infected cells and animals

Protein-bound polysaccharide K (PSK) is a clinical immunotherapeutic agent that exhibits various biological activities, including anti-tumor and anti-microbial effects. In the present study, we report on the anti-prion activity of PSK. It inhibited the formation of protease-resistant abnormal prion protein in prion-infected cells without any apparent alterations in either the normal prion protein turnover or the autophagic function in the cells. Its anti-prion activity was predominantly composed of the high molecular weight component(s) of the protein portion of PSK. A single subcutaneous dose of PSK slightly but significantly prolonged the survival time of peritoneally prion-infected mice, but PSK-treated mice produced neutralizing antibodies against the anti-prion activity of PSK. These findings suggest that PSK is a new anti-prion substance that may be useful in elucidating the mechanism of prion replication, although the structure of the anti-prion component(s) of PSK requires further evaluation.     

Mineralocorticoid receptor activation: a major contributor to salt-induced renal injury and hypertension in young rats

Excessive salt intake is known to preferentially increase blood pressure (BP) and promote kidney damage in young, salt-sensitive hypertensive human and animal models. We have suggested that mineralocorticoid receptor (MR) activation plays a major role in kidney injury in young rats. BP and urinary protein were compared in young (3-wk-old) and adult (10-wk-old) uninephrectomized (UNx) Sprague-Dawley rats fed a high (8.0%)-salt diet for 4 wk. The effects of the MR blocker eplerenone on BP and renal injury were examined in the high-salt diet-fed young UNx rats. Renal expression of renin-angiotensin-aldosterone (RAA) system components and of inflammatory and oxidative stress markers was also measured. The effects of the angiotensin receptor blocker olmesartan with or without low-dose aldosterone infusion, the aldosterone synthase inhibitor FAD286, and the antioxidant tempol were also studied. Excessive salt intake induced greater hypertension and proteinuria in young rats than in adult rats. The kidneys of young salt-loaded rats showed marked histological injury, overexpression of RAA system components, and an increase in inflammatory and oxidative stress markers. These changes were markedly ameliorated by eplerenone treatment. Olmesartan also ameliorated salt-induced renal injury but failed to do so when combined with low-dose aldosterone infusion. FAD286 and tempol also markedly reduced urinary protein. UNx rats exposed to excessive salt at a young age showed severe hypertension and renal injury, likely primarily due to MR activation and secondarily due to angiotensin receptor activation, which may be mediated by inflammation and oxidative stress.     

Genetic diversity of the Japanese wood pigeon, Columba janthina, endemic to islands of East Asia, estimated by newly developed microsatellite markers

The Japanese wood pigeon Columba janthina is endemic to islands of East Asia and is listed as Near Threatened by the International Union for Conservation of Nature (IUCN). One subspecies, C. janthina nitens, in particular, is at the greatest risk of extinction due to its small population size. To reduce the extinction risk of C. janthina, it is important to understand the species' present genetic status and to develop an appropriate conservation plan based on genetic data. We developed seven new microsatellite markers for two subspecies of C. janthina: C. janthina janthina and C. janthina nitens. We also confirmed the cross-use of one microsatellite marker developed for Columba livia var. domestica. Seven loci were polymorphic in C. janthina janthina, while two loci were polymorphic in C. janthina nitens. Using the markers, we performed preliminary analysis of genetic diversity and genetic structure within each subspecies. The expected heterozygosity ranged from 0.00 to 0.64 in C. janthina janthina and from 0.00 to 0.08 in C. janthina nitens. Each subspecies and each population within C. janthina janthina had different allele frequencies. C. janthina nitens exhibited far lower genetic diversity than C. janthina janthina. Furthermore, C. janthina nitens appears to have experienced strong genetic drift from a common ancestral population, inferred by STRUCTURE analysis. The markers described here may be useful for investigating genetic diversity and genetic structure of C. janthina populations, and could be used to estimate appropriate evolutionary significant unit and to guide development of a captive breeding program based on genetic information.     

N-cadherin enhances APP dimerization at the extracellular domain and modulates Aβ production

Sequential processing of amyloid precursor protein (APP) by β- and γ-secretase leads to the generation of amyloid-β (Aβ) peptides, which plays a central role in Alzheimer's disease pathogenesis. APP is capable of forming a homodimer through its extracellular domain as well as transmembrane GXXXG motifs. A number of reports have shown that dimerization of APP modulates Aβ production. On the other hand, we have previously reported that N-cadherin-based synaptic contact is tightly linked to Aβ production. In the present report, we investigated the effect of N-cadherin expression on APP dimerization and metabolism. Here, we demonstrate that N-cadherin expression facilitates cis-dimerization of APP. Moreover, N-cadherin expression led to increased production of Aβ as well as soluble APPβ, indicating that β-secretase-mediated cleavage of APP is enhanced. Interestingly, N-cadherin expression affected neither dimerization of C99 nor Aβ production from C99, suggesting that the effect of N-cadherin on APP metabolism is mediated through APP extracellular domain. We confirmed that N-cadherin enhances APP dimerization by a novel luciferase-complementation assay, which could be a platform for drug screening on a high-throughput basis. Taken together, our results suggest that modulation of APP dimerization state could be one of mechanisms, which links synaptic contact and Aβ production.     

Tocilizumab,a Proposed Therapy for the Cachexia of Interleukin6-Expressing Lung Cancer

Background

We previously reported the role of IL-6 in a murine model of cancer cachexia and currently documented a patient in whom tocilizumab, anti-IL-6 receptor antibody, dramatically improved cachexia induced by IL-6 over-expressing lung cancer. Despite this potential to alleviate cancer cachexia, tocilizumab has not been approved for this clinical use. Therefore, preceding our planned clinical trial of tocilizumab, we designed the two studies described here to evaluate the levels of IL-6 in patients with lung cancer and the effect of tocilizumab in a murine model of human cancer cachexia.

Methods

First, we measured serum IL-6 levels in patients with lung cancer and analyzed its association with cachexia and survival. Next, we examined the effect of a rodent analog of tocilizumab (MR16-1) in the experimental cachexia model.

Results

Serum IL-6 levels were higher in patients with cachexia than those without cachexia. In patients with chemotherapy-resistant lung cancer, a high IL-6 serum level correlated strongly with survival, and the cut-off level for affecting their prognosis was 21 pg/mL. Meanwhile, transplantation of IL-6-expressing Lewis Lung Carcinoma cells caused cachexia in mice, which then received either MR16-1 or 0.9% saline. Tumor growth was similar in both groups; however, the MR16-1 group lost less weight, maintained better food and water intake and had milder cachectic features in blood. MR16-1 also prolonged the survival of LLC-IL6 transplanted mice (36.6 vs. 28.5 days, p = 0.016).

Conclusion

Our clinical and experimental studies revealed that serum IL-6 is a surrogate marker for evaluating cachexia and the prognosis of patients with chemotherapy resistant metastatic lung cancer and that tocilizumab has the potential of improving prognosis and ameliorating the cachexia that so devastates their quality of life. This outcome greatly encourages our clinical trials to evaluate the safety and efficacy of tocilizumab treatment for patients with increased serum IL-6.