Aging Is Associated With Organ-Specific Alterations in the Level and Expression Pattern of von Willebrand Factor.

BACKGROUND: VWF (von Willebrand factor) is an endothelial-specific procoagulant protein with a major role in thrombosis. Aging is associated with increased circulating levels of VWF, which presents a risk factor for thrombus formation. METHODS: Circulating plasma, cellular protein, and mRNA levels of VWF were determined and compared in young and aged mice. Major organs were subjected to immunofluorescence analyses to determine the vascular pattern of VWF expression and the presence of platelet aggregates. An in vitro model of aging, using extended culture time of endothelial cells, was used to explore the mechanism of age-associated increased VWF levels. RESULTS: Increased circulating plasma levels of VWF with elevated levels of larger multimers, indicative of VWF functional activity, were observed in aged mice. VWF mRNA and cellular protein levels were significantly increased in the brains, lungs, and livers but not in the kidneys and hearts of aged mice. Higher proportion of small vessels in brains, lungs, and livers of aged mice exhibited VWF expression compared with young, and this was concomitant with increased platelet aggregate formation. Prolonged culture of endothelial cells resulted in increased cell senescence that correlated with increased VWF expression; VWF expression was specifically detected in senescent cultured endothelial cells and abolished in response to p53 knockdown. A significantly higher proportion of VWF expressing endothelial cells in vivo exhibited senescence markers SA-ß-Gal (senescence-associated ß-galactosidase) and p53 in aged mouse brains compared with that of the young. CONCLUSIONS: Aging elicits a heterogenic response in endothelial cells with regard to VWF expression, leading to organ-specific increase in VWF levels and alterations in vascular tree pattern of expression. This is concomitant with increased platelet aggregate formation. The age-associated increase in VWF expression may be modulated through the process of cell senescence, and p53 transcription factor contributes to its regulation.

Von Willebrand factor contribution to pathophysiology outside of von Willebrand disease.

VWF is a procoagulant protein that plays a central role in the initiation of platelets aggregate formation and thrombosis. While von Willebrand disease has long been known to result from qualitative and quantitative deficiencies of VWF, it is recently that contribution of elevated levels of VWF to various pathological conditions including thrombosis, inflammation, angiogenesis, and cancer metastasis has been appreciated. Here, we discuss contribution of elevated levels of VWF to various thrombotic and nonthrombotic pathological conditions.

Human parvovirus B19 infection in malignant and benign tissue specimens of different head and neck anatomical subsites.

BACKGROUND: The role of human parvovirus B19 (B19V) infection in malignant and benign lesions such as head and neck squamous cell carcinomas (HNSCCs) and oral mucocele lesions has not been established. Herein, we examined, for the first time, the presence of B19V in HNSCCs from Iranian subjects. METHODS: One hundred and eight HNSCC specimens were analyzed for the presence of B19V using nested polymerase chain reaction (nPCR) and TaqMan quantitative PCR assays. Immunohistochemistry procedures were performed to evaluate the expression of B19V VP1/VP2 proteins, p16INK4a, and NF-κB in tumor tissues and their adjacent non-tumor tissues. In addition, 40 oral mucocele, 30 oral buccal mucosa swabs, and 30 nasopharyngeal swabs obtained from healthy adults were analyzed as controls. RESULTS: B19V DNA was detected in 36.1% of HNSCCs. Further, 23.3% of HNSCC specimens showed immunoreactivity against B19V VP1/VP2 proteins. There was a significant difference in the frequency of B19V DNA-positive cases between the patient and control groups (p < 0.0001). Moreover, comparing tumoral tissues and their adjacent non-tumor tissues in terms of immunoreactivity against B19V structural proteins, a significant association was found between tumor tissues and B19V infection (p < 0.0001). Finally, investigating the simultaneous presence of B19V and high-risk human papillomaviruses (HPV) DNA, we found a significant association between these two viral infections in HNSCCs (p = 0.031). CONCLUSIONS: To sum up, B19V was frequently present in HNSCC tissues of Iranian patients but mostly absent in the adjacent non-tumor tissues as well as oral mucocele lesions, buccal, and nasopharyngeal swabs of healthy subjects. HPV possibly contributes to B19V persistence in HNSCC tissues. Additional research is required to investigate potential etiological or cofactor roles of B19V in the development of HNSCCs.

Age-Associated Increase in Thrombogenicity and Its Correlation with von Willebrand Factor.

Endothelial cells that cover the lumen of all blood vessels have the inherent capacity to express both pro and anticoagulant molecules. However, under normal physiological condition, they generally function to maintain a non-thrombogenic surface for unobstructed blood flow. In response to injury, certain stimuli, or as a result of dysfunction, endothelial cells release a highly adhesive procoagulant protein, von Willebrand factor (VWF), which plays a central role in formation of platelet aggregates and thrombus generation. Since VWF expression is highly restricted to endothelial cells, regulation of its levels is among the most important functions of endothelial cells for maintaining hemostasis. However, with aging, there is a significant increase in VWF levels, which is concomitant with a significant rise in thrombotic events. It is not yet clear why and how aging results in increased VWF levels. In this review, we have aimed to discuss the age-related increase in VWF, its potential mechanisms, and associated coagulopathies as probable consequences.

The frequency of high-risk human papillomavirus types, HPV16 lineages, and their relationship with p16INK4a and NF-κB expression in head and neck squamous cell carcinomas in Southwestern Iran.

High-risk human papillomaviruses (hr-HPVs) are the key risk factors implicated in the development of a significant proportion of head and neck squamous cell carcinomas (HNSCCs). We aimed to investigate the distribution of hr-HPV types and HPV16 lineages in a sample of patients with HNSCC and the possible association between HPV status and the expression of P16INK4A and NF-κB in Iranian HNSCC patients. We examined 108 formalin-fixed, paraffin-embedded (FFPE) histologically confirmed primary SCC tissue specimens of different head and neck anatomical sites. HPV types and HPV16 lineages were determined by nested PCR and overlapping nested PCR assays, respectively, followed by gene sequencing and phylogenetic analysis. The expression of p16INK4a and NF-κB was evaluated by immunohistochemistry. Twenty-five (23.1%) HNSCC tissue specimens were tested positive for HPV infection. The most prevalent HPV type was HPV-16, followed by HPV18 and HPV11. HPV16 variants belonged to the lineage A and lineage D which were further sorted into sublineages A1, A2, and D2. A significant association between HPV status and p16INK4a immunoreactivity was observed in more than 76% of the HPV-related HNSCCs (P < 0.0001). The overexpression of p16INK4a and cytoplasmic NF-κB was more common in low-grade HNSCC tumors. Our data highlights that HPV16, in particular the A2 sublineage, followed by A1 and D2 sublineages are the major agents associated with HNSCCs in Iran. Based on HPV16 predominance and its lineage distribution pattern, it seems that the prophylactic vaccines developed for cervical cancer prevention could also be applicable for the prevention of HPV-related HNSCCs in our population.

Enhancing Stability of Destabilized Green Fluorescent Protein Using Chimeric mRNA Containing Human Beta-Globin 5' and 3' Untranslated Regions.

BACKGROUND: In spite of recent progress in mRNA technologies and their potential applications for treatment of human diseases, problems such as the transient nature of mRNA limit the stability of gene up-regulation and, thus, potentially reduce mRNA efficiency for gene therapy. Using human ß-globin 5' and 3' untranslated regions (UTRs), this study aimed to develop the different chimeric constructs of mRNAs to increase the stability of destabilized green fluorescent protein (EGFPd2) in HEK 293 cells. METHODS: Purified human ß-globin (HBG) 5'-3'UTRs, and the coding sequence of destabilized green fluorescent protein (EGFPd2) were amplified separately and ligated to each other using SOEing PCR method in a different format. As controls, the original construct of EGFPd2 under the control of T7 promoter was used. Following in vitro transcription, HEK 293 cells were then transfected with several constructs and incubated at 37°C in a CO2 incubator. They were monitored under a fluorescence microscope every four hours for the first 24 hr, then every 12 hr afterwards. The resulting fluorescence was measured as a surrogate for translation efficiency and duration. RESULTS: By monitoring the HEK cells over 48 hr, cells transfected with mRNA with various HBG UTRs showed significantly different fluorescence intensity and stability in comparison with the pEGFPd2 prototype (control transcript) overtime. Overall, the images show that replacement of the 3' UTR end of the prototype vector pGFPd2 with the 3' end of ß-globin mRNA increases the half-life of the chimeric mRNA for more than 32 hr. CONCLUSION: This result indicates that ß-globin 3' UTR would definitely increase the half-life of mRNA and may help to decrease the mRNA therapeutic dosage in the treatment of diseases associated with mRNA therapy.

Endothelial cells of different organs exhibit heterogeneity in von Willebrand factor expression in response to hypoxia.

BACKGROUND AND AIMS: We have previously demonstrated that in response to hypoxia, von Willebrand factor (VWF) expression is upregulated in lung and heart endothelial cells both in vitro and in vivo, but not in kidney endothelial cells. The aim of our current study was to determine whether endothelial cells of different organs employ distinct molecular mechanisms to mediate VWF response to hypoxia. METHODS: We used cultured human primary lung, heart and kidney endothelial cells to determine the activation of endogenous VWF as well as exogenously expressed VWF promoter in response to hypoxia. Chromatin immunoprecipitation and siRNA knockdown analyses were used to determine the roles of VWF promoter associated transacting factors in mediating its hypoxia response. Platelet aggregates formations in vascular beds of mice were used as a marker for potential functional consequences of hypoxia-induced VWF upregulation in vivo. RESULTS: Our analyses demonstrated that while Yin Yang 1 (YY1) and specificity protein 1 (Sp1) participate in the hypoxia-induced upregulation of VWF specifically in lung endothelial cells, GATA6 mediates this process specifically in heart endothelial cells. In both cell types, the response to hypoxia involves the decreased association of the NFIB repressor with the VWF promoter, and the increased acetylation of the promoter-associated histone H4. In mice exposed to hypoxia, the upregulation of VWF expression was concomitant with the presence of thrombi in heart and lung, but not kidney vascular beds. CONCLUSIONS: Heart and lung endothelial cells demonstrated VWF upregulation in response to hypoxia, using distinct mechanisms, while this response was lacking in kidney endothelial cells.

Aspirin-mediated acetylation induces structural alteration and aggregation of bovine pancreatic insulin.

The simple aggregation of insulin under various chemical and physical stresses is still an important challenge for both pharmaceutical production and clinical formulation. In the storage form, this protein is subjected to various chemical modifications which alter its physicochemical and aggregation properties. Aspirin (acetylsalicylic acid) which is the most widely used medicine worldwide has been indicated to acetylate a large number of proteins both in vitro and in vivo. In this study, as insulin treated with aspirin at 37°C, a significant level of acetylation was observed by flourescamine and o-phthalaldehyde assay. Also, different spectroscopic techniques, gel electrophoresis, and microscopic assessment were applied to compare the structural variation and aggregation/fibrillation propensity among acetylated and non-acetylated insulin samples. The results of spectroscopic assessments elucidate that acetylation induces insulin unfolding which is accompanied with the exposure of protein hydrophobic patches, a transition from alpha-helix to beta-sheet and increased propensity of the protein for aggregation. The kinetic studies propose that acetylation increases aggregation rate of insulin under both thermal and chemical stresses. Also, gel electrophoresis and dynamic light scattering experiments suggest that acetylation induces insulin oligomerization. Additionally, the results of Thioflavin T fluorescence study, Congo red absorption assessment, and microscopic analysis suggest that acetylation with aspirin enhances the process of insulin fibrillation. Overall, the increased susceptibility of acetylated insulin for aggregation may reflect the fact that this type of modification has significant structural destabilizing effect which finally makes the protein more vulnerable for pathogenic aggregation/fibrillation.

Detection of Hepatitis E Virus Genotype 1 Among Blood Donors From Southwest of Iran.

BACKGROUND: Infection with hepatitis E virus (HEV) is endemic in developing countries and reveals significant regional differences. Several studies have reported virus transmission via blood transfusion. To date, however, no cases of HEV RNA detection in blood donors have been reported from Iran. OBJECTIVES: The aim of this study was to determine the presence of HEV RNA in plasma samples of blood donors referred to a blood transfusion center in Shiraz in the southwest of Iran. The HEV genotypes were also investigated using nucleotide sequencing. PATIENTS AND METHODS: Blood samples were collected from 700 blood donors who were referred to Fars blood transfusion organization from January to March 2014. Plasma samples were screened for the presence of HEV IgG and IgM antibodies by standard enzyme immunoassay. Samples seroreactive to anti-HEV were further tested for the presence of HEV RNA using nested polymerase chain reaction (PCR) with universal primers for detection of all four HEV genotypes. Positive PCR samples were then subjected to DNA sequencing for further analysis. RESULTS: Fifty (50, 7.1%) out of 700 plasma samples tested positive for anti-HEV antibodies. HEV RNA was detected in 7/50 (12%) of the antibody-positive samples, the majority of which were IgM positive. Sequence analysis of seven isolates of the HEV RNA ORF 2 gene region revealed > 80% similarity with genotype 1. CONCLUSIONS: The analysis indicates that the HEV isolated from blood donors in the southwest of Iran belongs to genotype 1. However, more samples from other geographic regions of Iran are needed to confirm these findings. Because transmission of HEV by administration of blood or blood components is likely to occur, it may be sensible to screen donor blood for HEV to eliminate transfusion-transmitted HEV infection when the recipient is immunocompromised.

Structural analysis and aggregation propensity of reduced and nonreduced glycated insulin adducts.

The milieu within pancreatic ß cells represents a favorable environment for glycation of insulin. Therefore, in this study, insulin samples were individually subjected to glycation under reducing and nonreducing conditions. As monitored by ortho-phthalaldehyde and fluorescamine assays, the reduced glycated insulin adduct demonstrates extensively higher level of glycation than the nonreduced glycated counterpart. Also, gel electrophoresis experiments suggest a significant impact of glycation under a reducing system on the level of insulin oligomerization. Furthermore, reduced and nonreduced glycated insulin adducts respectively exhibit full and partial resistance against dithiothreitol-induced aggregation. The results of thioflavin T and Congo red assays suggest the existence of a significant quantity of amyloid-like entities in the sample of reduced glycated insulin adduct. Both fluorescence and far-ultraviolet circular dichroism studies respectively suggest that the extents of unfolding and secondary structural alteration were closely correlated to the level of insulin glycation. Moreover, the surface tension of two glycated insulin adducts was inversely correlated to their glycation extents and to the quantity of exposed hydrophobic patches. Overall, the glucose-modified insulin molecules under reducing and nonreducing systems display different structural features having significant consequences on aggregation behaviors and surface tension properties. The particular structural constraints of glycated insulin may reduce the binding interaction of this hormone to its receptor which is important for both insulin function and clearance.

The enhancing effect of homocysteine thiolactone on insulin fibrillation and cytotoxicity of insulin fibril.

In the current study both structural alteration and fibrillation of insulin were studied in the presence of homocysteine thiolactone (HCTL). The spectroscopic studies revealed that HCTL increases rate of insulin unfolding, giving rise to the appearance of solvent-exposed hydrophobic regions and induces a transition from α-helix into predominantly ß-sheet structures. Thioflavin-T fluorescence studies revealed that HCTL markedly enhanced the quantity of insulin fibril formation in both agitating and non-agitating systems. Also gel electrophoresis results suggest that HCTL accelerates the process of formation of high molecular weight insulin aggregates. Moreover, insulin fibrils obtained in the presence of HCTL and those collected earlier in the pathway of insulin fibrillation displayed improved cytotoxicity against cancer cells. The enhancement of insulin fibril formation with elevated cytotoxic properties as occurred in the presence of HCTL, may suggest this homocysteine derivative as a possible contributing factor in the pathology of insulin fibrils.