Increased frequencies of cochlin-specific T cells in patients with autoimmune sensorineural hearing loss

Autoimmune sensorineural hearing loss (ASNHL) is the most common cause of sudden hearing loss in adults. Although autoimmune etiopathogenic events have long been suspected in ASNHL, inner ear-specific Ags capable of targeting T cell autoreactivity have not been identified in ASNHL. In this study, we show by ELISPOT analysis that compared with normal hearing age- and sex-matched control subjects, ASNHL patients have significantly higher frequencies of circulating T cells producing either IFN-gamma (p = 0.0001) or IL-5 (p = 0.03) in response to recombinant human cochlin, the most abundant inner ear protein. In some patients, cochlin responsiveness involved both CD4+ and CD8+ T cells whereas other patients showed cochlin responsiveness confined to CD8+ T cells. ASNHL patients also showed significantly elevated cochlin-specific serum Ab titers compared with both normal hearing age- and sex-matched control subjects and patients with noise- and/or age-related hearing loss (p < 0.05 at all dilutions tested through 1/2048). Our study is the first to show T cell responsiveness to an inner ear-specific protein in ASNHL patients, and implicates cochlin as a prominent target Ag for mediating autoimmune inner ear inflammation and hearing loss.     

Persistent and high levels of Hes1 expression regulate boundary formation in the developing central nervous system

The developing central nervous system is partitioned into compartments by boundary cells, which have different properties than compartment cells, such as forming neuron-free zones, proliferating more slowly and acting as organizing centers. We now report that in mice the bHLH factor Hes1 is persistently expressed at high levels by boundary cells but at variable levels by non-boundary cells. Expression levels of Hes1 display an inverse correlation to those of the proneural bHLH factor Mash1, suggesting that downregulation of Hes1 leads to upregulation of Mash1 in non-boundary regions, whereas persistent and high Hes1 expression constitutively represses Mash1 in boundary regions. In agreement with this notion, in the absence of Hes1 and its related genes Hes3 and Hes5, proneural bHLH genes are ectopically expressed in boundaries, resulting in ectopic neurogenesis and disruption of the organizing centers. Conversely, persistent Hes1 expression in neural progenitors prepared from compartment regions blocks neurogenesis and reduces cell proliferation rates. These results indicate that the mode of Hes1 expression is different between boundary and non-boundary cells, and that persistent and high levels of Hes1 expression constitutively repress proneural bHLH gene expression and reduce cell proliferation rates, thereby forming boundaries that act as the organizing centers.     

NSAID activated gene (NAG-1), a modulator of tumorigenesis

The NSAID activated gene (NAG-1), a member of the TGF-beta superfamily, is involved in tumor progression and development. The over-expression of NAG-1 in cancer cells results in growth arrest and increase in apoptosis, suggesting that NAG-1 has anti-tumorigenic activity. This conclusion is further supported by results of experiments with transgenic mice that ubiquitously express human NAG-1. These transgenic mice are resistant to the development of intestinal tumors following treatment with azoxymethane or by introduction of a mutant APC gene. In contrast, other data suggest a pro-tumorigenic role for NAG-1, for example, high expression of NAG-1 is frequently observed in tumors. NAG-1 may be like other members of the TGF-beta superfamily, acting as a tumor suppressor in the early stages, but acting pro-tumorigenic at the later stages of tumor progression. The expression of NAG-1 can be increased by treatment with drugs and chemicals documented to prevent tumor formation and development. Most notable is the increase in NAG-1 expression by the inhibitors of cyclooxygenases that prevent human colorectal cancer development. The regulation of NAG-1 is complex, but these agents act through either p53 or EGR-1 related pathways. In addition, an increase in NAG-1 is observed in inhibition of the AKT/GSK-3beta pathway, suggesting NAG-1 alters cell survival. Thus, NAG-1 expression is regulated by tumor suppressor pathways and appears to modulate tumor progression.     

Changes in gene expression contribute to cancer prevention by COX inhibitors

Non-steroidal anti-inflammatory drugs (NSAIDs) are used primarily for the treatment of inflammatory diseases. However, certain NSAIDs also have a chemopreventive effect on the development of human colorectal and other cancers. NSAIDs inhibit cyclooxygenase-1 (COX-1) and/or cyclooxygenase-2 (COX-2) activity and considerable evidence supports a role for prostaglandins in cancer development. However, the chemopreventive effect of NSAIDs on colorectal and other cancers appears also to be partially independent of COX activity. COX inhibitors also alter the expression of a number of genes that influence cancer development. One such gene is NAG-1 (NSAID-Activated Gene), a critical gene regulated by a number of COX inhibitors and chemopreventive chemicals. Therefore, this article will discuss the evidence supporting the conclusion that the chemo-preventive activity of COX inhibitors is mediated, in part, by altered gene expression with an emphasis on NAG-1 studies. This review may also provide new insights into how chemicals and environmental factors influence cancer development. In view of the cardiovascular and gastrointestinal toxic side effects of COX-2 inhibitors and non-selective COX inhibitors, respectively, the results presented here may provide the basis for the development of a new family of anti-tumorigenic compounds acting independent of COX inhibition.     

Tick-Borne Rickettsial Pathogens in Ticks and Small Mammals in Korea

In order to investigate the prevalence of tick-borne infectious agents among ticks, ticks comprising five species from two genera (Hemaphysalis spp. and Ixodes spp.) were screened using molecular techniques. Ticks (3,135) were collected from small wild-caught mammals or by dragging/flagging in the Republic of Korea (ROK) and were pooled into a total of 1,638 samples (1 to 27 ticks per pool). From the 1,638 tick samples, species-specific fragments of Anaplasma phagocytophilum (1 sample), Anaplasma platys (52 samples), Ehrlichia chaffeensis (29 samples), Ehrlichia ewingii (2 samples), Ehrlichia canis (18 samples), and Rickettsia rickettsii (28 samples) were amplified by PCR assay. Twenty-one pooled and individual tick samples had mixed infections of two (15 samples) or three (6 samples) pathogens. In addition, 424 spleen samples from small captured mammals (389 rodents, 33 insectivores, and 2 weasels) were screened for selected zoonotic pathogens. Species-specific DNA fragments of A. phagocytophilum (110 samples), A. platys (68 samples), E. chaffeensis (8 samples), E. ewingii (26 samples), E. canis (51 samples), and Rickettsia sp. (22 samples) were amplified by PCR assay. One hundred thirty small mammals had single infections, while 4, 14, and 21 striped field mice (Apodemus agrarius) had mixed infections of four, three, and two pathogens, respectively. Phylogenetic analysis based on nucleotide sequence comparison also revealed that Korean strains of E. chaffeensis clustered closely with those from China and the United States, while the Rickettsia (rOmpA) sequences clustered within a clade together with a Chinese strain. These results suggest that these agents should be considered in differential diagnosis while examining cases of acute febrile illnesses in humans as well as animals in the ROK.     

cAMP elevating agents suppress secretory phospholipase A(2)-induced matrix metalloproteinase-2 activation

Phospholipase A2 proteins are major regulators of the arachidonic acid cascade and are involved in various cellular responses. Previously, we reported that group IB PLA2 proteins stimulate MMP-2 activation and subsequent cell migration. Here, we describe a novel mechanism whereby sPLA2-induced proMMP-2 activation is regulated by intracellular cAMP in HT1080 cells, although sPLA2 itself had no effect on the regulation of cAMP levels. Exogenous dibutyryl cAMP (a cAMP analogue) strongly inhibited proMMP-2 activation, and cAMP elevating agents, namely, cholera toxin (a Gs activator) and forskolin (an adenylyl cyclase activator), abrogated basal and sPLA2-induced proMMP-2 activation. We also found that the down-regulation of TIMP-2 expression and extracellular signal-regulated kinase (ERK)1/2 activation by sPLA2 were blocked by increasing the intracellular cAMP level. Taken together, our data indicate that sPLA2-induced proMMP-2 activation is influenced by intracellular cAMP levels via the modulations of TIMP-2 expression and ERK1/2 activation.     

Classification methods for the development of genomic signatures from high-dimensional data

Personalized medicine is defined by the use of genomic signatures of patients to assign effective therapies. We present Classification by Ensembles from Random Partitions (CERP) for class prediction and apply CERP to genomic data on leukemia patients and to genomic data with several clinical variables on breast cancer patients. CERP performs consistently well compared to the other classification algorithms. The predictive accuracy can be improved by adding some relevant clinical/histopathological measurements to the genomic data.     

SUMO-specific protease SUSP4 positively regulates p53 by promoting Mdm2 self-ubiquitination

The p53 tumour suppressor has a key role in the control of cell growth and differentiation, and in the maintenance of genome integrity. p53 is kept labile under normal conditions, but in response to stresses, such as DNA damage, it accumulates in the nucleus for induction of cell-cycle arrest, DNA repair or apoptosis. Mdm2 is an ubiquitin ligase that promotes p53 ubiquitination and degradation. Mdm2 is also self-ubiquitinated and degraded. Here, we identified a novel cascade for the increase in p53 level in response to DNA damage. A new SUMO-specific protease, SUSP4, removed SUMO-1 from Mdm2 and this desumoylation led to promotion of Mdm2 self-ubiquitination, resulting in p53 stabilization. Moreover, SUSP4 competed with p53 for binding to Mdm2, also resulting in p53 stabilization. Overexpression of SUSP4 inhibited cell growth, whereas knockdown of susp4 by RNA interference (RNAi) promoted of cell growth. UV damage induced SUSP4 expression, leading to an increase in p53 levels in parallel with a decrease in Mdm2 levels. These findings establish a new mechanism for the elevation of cellular p53 levels in response to UV damage.     

Feasibility of supercritical CO₂ treatment for controlling biofouling in the reverse osmosis process

Physical cleaning and/or chemical cleaning have been generally used to control biofouling in the reverse osmosis (RO) process. However, conventional membrane cleaning methods to control biofouling are limited due to the generation of by-products and the potential for damage to the RO membranes. In this study, supercritical carbon dioxide (SC CO(2)) treatment, an environmentally friendly technique, was introduced to control biofouling in the RO process. SC CO(2) (100 bar at 35°C) treatment was performed after biofouling was induced on a commercial RO membrane using Pseudomonas aeruginosa PA01 GFP as a model bacterial strain. P. aeruginosa PA01 GFP biofilm cells were reduced on the RO membrane by >8 log within 30 min, and the permeate flux was sufficiently recovered in a laboratory-scale RO membrane system without any significant damage to the RO membrane. These results suggest that SC CO(2) treatment is a promising alternative membrane cleaning technique for biofouling in the RO process.