Linked production of antibodies to mammalian DNA and to human polyomavirus large T antigen: footprints of a common molecular and cellular process?

OBJECTIVE: To test whether the presence of antibodies to human polyomavirus large T antigen, a viral DNA-binding protein essential for productive polyomavirus replication, correlates with the presence of antibodies to single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), or the autologous TATA-binding protein (TBP). METHODS: Sera from patients with various diagnosed or suspected autoimmune syndromes were analyzed for the presence of antibodies to T antigen, DNA, or TATA-binding protein, and correlations were determined. Rheumatoid factor (RF) was studied as a control antibody. RESULTS: A highly significant correlation between antibodies to T antigen and antibodies to ssDNA or TATA-binding protein, but not between anti-T antigen antibodies and RF, was found in all patient groups. Of all sera that were positive for antibodies to dsDNA, 62% were positive for antibodies to T antigen (P<0.03). CONCLUSION: A non-self DNA-binding protein such as human polyomavirus large T antigen may render DNA immunogenic upon binding to nucleosomes when expressed in vivo. This is indicated by the strong correlation between antibodies to T antigen and antibodies to DNA or TBP and is consistent with a hapten-carrier model. This model implies cognate antigen-selective interaction of T antigen-specific T helper cells and DNA-specific B cells or B cells specific for other components of nucleosomes, consistent with the results of previous experiments.     

Function of the hemochromatosis protein HFE： Lessons from animal models

Hereditary hemochromatosis （HH） is caused by chronic hyperabsorption of dietary iron. Progressive accumulation of excess iron within tissue parenchymal cells may lead to severe organ damage. The most prevalent type of HH is linked to mutations in the HFE gene, encoding an atypical major histocompatibility complex class I molecule. Shortly after its discovery in 1996, the hemochromatosis protein HFE was shown to physically interact with transferrin receptor 1 （TfR1） and impair the uptake of transferrin-bound iron in cells. However, these findings provided no clue why HFE mutations associate with systemic iron overload. It was later established that all forms of HH result from misregulation of hepcidin expression. This liverderived circulating peptide hormone controls iron efflux from duodenal enterocytes and reticuloendothelial macrophages by promoting the degradation of the iron exporter ferroportin. Recent studies with animal models of HH uncover a crucial role of HFE as a hepatocyte iron sensor and upstream regulator of hepcidin. Thus, hepatocyte HFE is indispensable for signaling to hepcidin, presumably as a constituent of a larger ironsensing complex. A working model postulates that the signaling activity of HFE is silenced when the protein is bound to TfR1. An increase in the iron saturation of plasma transferrin leads to displacement of TfR1 from HFE and assembly of the putative iron-sensing complex. In this way, iron uptake by the hepatocyte is translated into upregulation of hepcidin, reinforcing the concept that the liver is the major regulatory site for systemic iron homeostasis, and not merely an iron storage depot.     

Near-infrared fluorescence molecular imaging of amyloid beta species and monitoring therapy in animal models of Alzheimer’s disease

Near-infrared fluorescence (NIRF) molecular imaging has been widely applied to monitoring therapy of cancer and other diseases in preclinical studies; however, this technology has not been applied successfully to monitoring therapy for Alzheimer’s disease (AD). Although several NIRF probes for detecting amyloid beta (Aβ) species of AD have been reported, none of these probes has been used to monitor changes of Aβs during therapy. In this article, we demonstrated that CRANAD-3, a curcumin analog, is capable of detecting both soluble and insoluble Aβ species. In vivo imaging showed that the NIRF signal of CRANAD-3 from 4-mo-old transgenic AD (APP/PS1) mice was 2.29-fold higher than that from age-matched wild-type mice, indicating that CRANAD-3 is capable of detecting early molecular pathology. To verify the feasibility of CRANAD-3 for monitoring therapy, we first used the fast Aβ-lowering drug LY2811376, a well-characterized beta-amyloid cleaving enzyme-1 inhibitor, to treat APP/PS1 mice. Imaging data suggested that CRANAD-3 could monitor the decrease in Aβs after drug treatment. To validate the imaging capacity of CRANAD-3 further, we used it to monitor the therapeutic effect of CRANAD-17, a curcumin analog for inhibition of Aβ cross-linking. The imaging data indicated that the fluorescence signal in the CRANAD-17–treated group was significantly lower than that in the control group, and the result correlated with ELISA analysis of brain extraction and Aβ plaque counting. It was the first time, to our knowledge, that NIRF was used to monitor AD therapy, and we believe that our imaging technology has the potential to have a high impact on AD drug development.Alzheimer’s disease (AD) has been considered incurable, because none of the clinically tested drugs have shown significant effectiveness (1–4). Therefore, seeking effective therapeutics and imaging probes capable of assisting drug development is highly desirable. The amyloid hypothesis, in which various Aβ species are believed to be neurotoxic and one of the leading causes of AD, has been considered controversial in recent years because of the failures of amyloid beta (Aβ)-based drug development (1, 3, 5–8). However, no compelling data can prove that this hypothesis is wrong (2, 5), and no other theories indicate a clear path for AD drug development (4). Thus the amyloid hypothesis is still an important framework for AD drug development (1–5, 9–14). Additionally, Kim and colleagues (15) recently reported that a 3D cell-culture model of human neural cells could recapture AD pathology. In this study, their finding that the accumulation of Aβs could drive tau pathology provided strong support for the amyloid hypothesis (15).It is well known that Aβ species, including soluble monomers, dimers, oligomers, and insoluble fibrils/aggregates and plaques, play a central role in the neuropathology of AD (2, 5). Initially, it was thought that insoluble deposits/plaques formed by the Aβ peptides in an AD brain cause neurodegeneration. However, studies have shown that soluble dimeric and oligomeric Aβ species are more neurotoxic than insoluble deposits (16–21). Furthermore, it has been shown that soluble and insoluble species coexist during disease progression. The initial stage of pathology is represented by an excessive accumulation of Aβ monomers resulting from imbalanced Aβ clearance (22, 23). The early predominance of soluble species gradually shifts with the progression of AD to a majority of insoluble species (24, 25). Therefore imaging probes capable of detecting both soluble and insoluble Aβs are needed to monitor the full spectrum of amyloidosis pathology in AD.Thus far, three Aβ PET tracers have been approved by the Food and Drug Administration (FDA) for clinical applications. However, they are not approved for positive diagnosis of AD; rather, they are recommended for excluding the likelihood of AD. The fundamental limitation of these three tracers and others under development is that they bind primarily to insoluble Aβs, not the more toxic soluble Aβs (26–32). Clearly, work remains to be done in developing imaging probes based on Aβs, and imaging probes capable of diagnosing AD positively are undeniably needed.Numerous agents reportedly are capable of inhibiting the generation and aggregation of Aβs in vitro; however, only few have been tested in vivo. Partially, this lack of testing arises from the lack of reliable imaging methods that can monitor the agents’ therapeutic effectiveness in vivo. PET tracers, such as ¹¹C-Pittsburgh compound B (¹¹C-PiB) and ¹⁸F-AV-45, recently have been adapted to evaluate the efficacy of experimental AD drugs in clinical trials (33). However, they are rarely used to monitor drug treatment in small animals (30–32), likely because of the insensitivity of the tracers for Aβ species [particularly for soluble species (34–36)], complicated experimental procedures and data analysis in small animals, the high cost of PET probe synthesis and scanning, and the use of radioactive material. Therefore, a great demand for imaging agents that could be used in preclinical drug development to monitor therapeutic effectiveness in small animals remains unmet.Because of its low cost, simple operation, and easy data analysis, near infrared fluorescence (NIRF) imaging is generally more suitable than PET imaging for animal studies. Several NIRF probes for insoluble Aβs have been reported (37–45). It has been almost 10 y since the first report of NIRF imaging of Aβs by Hintersteiner et al. in 2005 (41). However, to the best of our knowledge, successful application of NIRF probes for monitoring therapeutic efficacy has not yet been reported. Our group recently has designed asymmetrical CRANAD-58 to match the hydrophobic (LVFF) and hydrophilic (HHQK) segments of Aβ peptides and demonstrated its applicability for the detection of both insoluble and soluble Aβs in vitro and in vivo (46). In this report, CRANAD-3 was designed to enhance the interaction with Aβs by replacing the phenyl rings of curcumin with pyridyls to introduce potential hydrogen bonds. Additionally, we demonstrated, for the first time to our knowledge, that the curcumin analog CRANAD-3 could be used as an NIRF imaging probe to monitor the Aβ-lowering effectiveness of therapeutics.     

Inflammatory bowel diseases: From the mystical to the cellular and now the molecular

It is of interest in an era of increasing biomedical sophistication to recall that a relatively short time ago, early in the 20th century, 'simple' ulcerative colitis was an obscure 'medical curiosity' emerging slowly from an unknown past. Crohn's     

How to evaluate plaque vulnerability in animal models of atherosclerosis?

Prevention of heart attack and stroke depends on detection of vulnerable plaques and development of plaque-stabilizing therapies. In turn, progress in diagnostics and treatment is contingent on our understanding of molecular mechanisms of plaque vulnerability. Animal models are essential for testing mechanistic hypotheses in a controlled manner. Currently, there is no single, golden standard animal model of a vulnerable plaque. However, the whole range of experimental approaches is readily available. It includes traditional models of atherosclerosis combined with new 'vulnerability endpoints', as well as several models featuring spontaneous or induced plaque rupture/thrombosis. This review summarizes current literature on the animal models of vulnerable atherosclerotic plaques.     

Genetics and experimental models of crystal-induced arthritis. Lessons learned from mice and men: is it crystal clear?

PURPOSE OF REVIEW: We examine the major genes in mice and humans involved in the pathogenesis of monosodium urate, calcium pyrophosphate dihydrate and hydroxyapatite crystal-induced arthritis. RECENT FINDINGS: Several genetic causes of renal disease associated with hyperuricemia and gout provide insight into genes involved in renal urate handling. Mutations or polymorphisms in exons 4 and 5 and intron 4 of urate transporter 1 may be independent genetic markers of hyperuricemia and gout. Genetic analysis supports the role of ANKH mutations in calcium pyrophosphate dihydrate-induced arthritis. ANKH gain-of-function mutations were confirmed by functional studies; however, the crystals formed in ATD5 cells were basic calcium phosphate, not calcium pyrophosphate dihydrate, underlying the significance of chondrocyte differentiation state and the factors regulating normal and pathological mineralization. Animal models have implicated a general model of crystal-induced inflammation involving innate immunity through the NALP3 (Natch domain, leucine-rich repeat, and PYD-containing protein 3) inflammasome signaling through the interleukin-1 receptor and its signaling protein myeloid differentiation primary response protein 88. SUMMARY: Genetic analysis has elucidated genes responsible for crystal formation and animal models have unveiled mechanisms in the development of crystal-induced arthritis. Future studies will hasten understanding of the pathology of crystal-induced arthritis and provide new therapies.     

Anthracycline-induced cardiotoxicity and renin-angiotensin-aldosterone system—from molecular mechanisms to therapeutic applications

Heart Failure Reviews - Few millions of new cancer cases are diagnosed worldwide every year. Due to significant progress in understanding cancer biology and developing new therapies, the mortality...     

Oxidative stress in phenylketonuria—evidence from human studies and animal models,and possible implications for redox signaling

Metabolic Brain Disease - Phenylketonuria (PKU) is one of the commonest inborn error of amino acid metabolism. Before mass neonatal screening was possible, and the success of introducing diet...     

The molecular and cellular mechanisms of itch and the involvement of TRP channels in the peripheral sensory nervous system and skin

Itch is an unpleasant cutaneous sensation that can arise following insect bites, exposure to plant ingredients, and some diseases. Itch can also have idiopathic causes. Itch sensations are thought to protect against external insults and toxic substances. Although itch is not directly lethal, chronic and long lasting itch in certain diseases can worsen quality of life. Therefore, the mechanisms responsible for chronic itch require careful investigation. There is a significant amount of basic research concerning itch, and the effect of various itch mediators on primary sensory neurons have been studied. Interestingly, many mediators of itch involve signaling related to transient receptor potential (TRP) channels. TRP channels, especially thermosensitive TRP channels, are expressed by primary sensory neurons and skin keratinocytes, which receive multimodal stimuli, including those that cause itch sensations. Here we review the molecular and cellular mechanisms of itch and the involvement of TRP channels in mediating itch sensations.     

Helicobacter pylori eradication to prevent gastric cancer： underlying molecular and cellular mechanisms

Numerous cellular and molecular events have been described in development of gastric cancer. In this article, we overviewed roles of Helicobacter pylori (H pylori) infection on some of the important events in gastric car-cinogenesis and discussed whether these cellular and molecular events are reversible after cure of the infection. There are several bacterial components affecting gastric epithelial kinetics and promotion of gastric carci-nogenesis. The bacterium also increases risks of genetic instability and mutations due to NO and other reactive oxygen species. Epigenetic silencing of tumor suppressor genes such as RUNX3 may alter the frequency of phe-notype change of gastric glands to those with intestinal metaplasia. Host factors such as increased expression of growth factors, cytokines and COX-2 have been also reported in non-cancerous tissue in H py/ori-positive subjects. It is noteworthy that most of the above phenomena are reversed after the cure of the infection. However, some of them including overexpression of COX-2 continue to exist and may increase risks for carcinogenesis in metaplastic or dysplastic mucosa even after successful H pylori eradication. Thus, H pylori eradication may not completely abolish the risk for gastric carcinogenesis. Efficiency of the cure of the infection in suppressing gastric cancer depends on the timing and the target population, and warrant further investigation.     

Microglial autophagy is impaired by prolonged exposure to β-amyloid peptides: evidence from experimental models and Alzheimer’s disease patients

GeroScience - Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by the presence of misfolded proteins, amyloid-β (Aβ) aggregates, and...     

Cystic echinococcosis of the liver and lung treated by radiofrequency thermal ablation： An ex-vivo pilot experimental study in animal models

AIM： To evaluate radiofrequency thermal ablation （RTA） for treatment of cystic echinococcosis in animal models （explanted organs）.
METHODS： Infected livers and lungs from slaughtered animals, 10 bovine and two ovine, were collected. Cysts were photographed, and their volume, cyst content, germinal layer adhesion status, wall calcification and presence of daughter or adjacent cysts were evaluated by ultrasound. Some cysts were treated with RTA at 150 W, 80℃, 7 min. Temperature was monitored inside and outside the cyst. A second needle was placed inside the cyst for pressure stabilization. After treatment, all cysts were sectioned and examined by histology. Cysts were defined as alive if a preserved germinal layer at histology was evident, and as successfully treated if the germinal layer was necrotic.
RESULTS： The subjects of the study were 17 cysts （nine hepatic and eight pulmonary）, who were treated with RTA. Pathology showed 100% success rate in both hepatic （919） and lung cysts （8/8）; immediate volume reduction of at least 65%; layer of host tissue necrosis outside the cyst, with average extension of 0.64 cm for liver and 1.57 cm for lung; and endocyst attached to the pericystium both in hepatic and lung cysts with small and focal de novo endocyst detachment in just 3/9 hepatic cysts.
CONCLUSION： RTA appears to be very effective in killing hydatid cysts of explanted liver and lung. Bile duct and bronchial wall necrosis, persistence of endocyst attached to pericystium, should help avoid or greatly decrease in v/vo post-treatment fistula occurrence and consequent overlapping complications that are common after surgery or percutaneous aspiration, injection and reaspiration. In vivo studies are required to confirm and validate this new therapeutic approach.     

Inflammatory bowel diseases： From the mystical to the cellular and now the molecular

It is of interest in an era of increasing biomedical sophistication to recall that a relatively short time ago, early in the 20th century, ‘simple‘ ulcerative colitis was an obscure ‘medicalcuriosity‘ emerging slowly from an unknown past. Crohn‘s disease was yet unidentified as a separate entity although careful review of the IBD literature documented its early presence, masquerading as‘intestinal tuberculosis‘. Into the 1930s, the etiology and pathogenesis of ulcerative colitis and Crohn‘s disease were unknown, and investigative hypotheses were scarce. Therapeutic resources were limited and treatment was primitive. At a time of limited biomedical knowledge and minimal clinical awareness, unsubstantiated views prevailed, including‘vague reactions to foods‘ (sugar,margarine, corn flakes), deficiency of a ‘protective factor‘in pig intestine, and psychiatric disease.