Targeting Pathological Amyloid Aggregates with Conformation-Sensitive Antibodies

2020 ◽  
Vol 17 (8) ◽  
pp. 722-734
Author(s):  
Alessandra Bigi ◽  
Gilda Loffredo ◽  
Roberta Cascella ◽  
Cristina Cecchi
Keyword(s):  
Senile Plaques ◽  
Neuronal Cells ◽  
Cytotoxic Effects ◽  
Specificity And Sensitivity ◽  
Amyloid Aggregates ◽  
Culture Models ◽  
Therapeutic Tools

Background: The pathogenesis of Alzheimer's disease (AD) is not directly caused by the presence of senile plaques but rather by the detrimental effects exerted on neuronal cells by toxic soluble oligomers. Such species are formed early during the aggregation process of the Aβ1-42 peptide or can be released from mature fibrils. Nowadays, efficient tools for an early diagnosis, as well as pharmaceutical treatments targeting the harmful agents in samples of AD patients, are still missing. Objective: By integrating in vitro immunochemical assay with in vivo neuronal models of toxicity, we aim to understand and target the principles that drive toxicity in AD. Methods: We evaluated the specificity and sensitivity of A11 and OC conformational antibodies to target a range of pathologically relevant amyloid conformers and rescue their cytotoxic effects in neuronal culture models using a number of cellular readouts. Results: We demonstrated the peculiar ability of conformational antibodies to label pathologically relevant Aβ1-42 oligomers and fibrils and to prevent their detrimental effects on neuronal cells. Conclusion: Our results substantially improve our knowledge on the role of toxic assemblies in neurodegenerative diseases, thus suggesting new and more effective diagnostic and therapeutic tools for AD.

scholarly journals Role of NADase in Virulence in Experimental Invasive Group A Streptococcal Infection

2005 ◽  
Vol 73 (10) ◽  
pp. 6562-6566 ◽  
Author(s):  
Angela L. Bricker ◽  
Vincent J. Carey ◽  
Michael R. Wessels
Keyword(s):  
Human Infection ◽  
Host Animal ◽  
Cytotoxic Effects ◽  
Invasive Group ◽  
Streptolysin O ◽  
Group A ◽  
Wild Type Parent

ABSTRACT Group A streptococci (GAS) produce several exoproteins that are thought to contribute to the pathogenesis of human infection. Two such proteins, streptolysin O (SLO) and NAD+-glycohydrolase (NADase), have been shown to interact functionally as a compound signaling toxin. When GAS are bound to the surface of epithelial cells in vitro, SLO forms pores in the cell membrane and delivers NADase to the epithelial cell cytoplasm. In vitro, intoxication of keratinocytes with NADase is associated with cytotoxic effects and induction of apoptosis; however, the importance of NADase during infection of an animal host has not been established. We employed isogenic GAS mutants to assess the contribution of NADase activity to GAS virulence in vivo using mouse models of invasive soft-tissue infection and septicemia. In both models, mutant GAS that lacked NADase activity were significantly attenuated for virulence compared with the isogenic wild-type parent, confirming an important role for NADase in the infection of a host animal. A double mutant lacking SLO and NADase activity had an intermediate virulence phenotype, consistent with the hypothesis that SLO evokes a protective innate immune response. We conclude that NADase and SLO together enhance GAS virulence in vivo.

Are all granzymes cytotoxic in vivo?

2014 ◽  
Vol 395 (2) ◽  
pp. 181-202 ◽  
Author(s):  
Lars T. Joeckel ◽  
Phillip I. Bird
Keyword(s):  
Serine Proteases ◽  
Ex Vivo ◽  
Cytotoxic Lymphocytes ◽  
Cytotoxic Effects ◽  
Knock Out ◽  
Granzyme A ◽  
Knock Out Mice

Abstract Granzymes are serine proteases mainly found in cytotoxic lymphocytes. The most-studied member of this group is granzyme B, which is a potent cytotoxin that has set the paradigm that all granzymes are cyototoxic. In the last 5 years, this paradigm has become controversial. On one hand, there is a plethora of sometimes contradictory publications showing mainly caspase-independent cytotoxic effects of granzyme A and the so-called orphan granzymes in vitro. On the other hand, there are increasing numbers of reports of granzymes failing to induce cell death in vitro unless very high (potentially supra-physiological) concentrations are used. Furthermore, experiments with granzyme A or granzyme M knock-out mice reveal little or no deficit in their cytotoxic lymphocytes’ killing ability ex vivo, but indicate impairment in the inflammatory response. These findings of non-cytotoxic effects of granzymes challenge dogma, and thus require alternative or additional explanations to be developed of the role of granzymes in defeating pathogens. Here we review evidence for granzyme cytotoxicity, give an overview of their non-cytotoxic functions, and suggest technical improvements for future investigations.

Ganoderma lucidum Polysaccharides: Immunomodulation and Potential Anti-Tumor Activities

2011 ◽  
Vol 39 (01) ◽  
pp. 15-27 ◽  
Author(s):  
Zengtao Xu ◽  
Xiuping Chen ◽  
Zhangfeng Zhong ◽  
Lidian Chen ◽  
Yitao Wang
Keyword(s):  
Ganoderma Lucidum ◽  
Tumor Therapy ◽  
White Rot ◽  
In Vivo Studies ◽  
White Rot Fungus ◽  
Bioactive Substances ◽  
Cytotoxic Effects

Ganoderma lucidum (G. lucidum), a basidiomycete white rot fungus, has long been prescribed to prevent and treat various human diseases, particularly in China, Japan, and Korea. Several classes of bioactive substances have been isolated and identified from G. lucidum, such as triterpenoids, polysaccharides, nucleosides, sterols, and alkaloids, among others. This paper examines the potential role of G. lucidum polysaccharide (GLPS) in tumor therapy and the possible mechanisms involved. Both in vitro and in vivo studies suggested that the anti-tumor activities of GLPS are mediated by its immunomodulatory, anti-angiogenic, and cytotoxic effects. GLPS affects immune cells and immune-related cells including B lymphocytes, T lymphocytes, dendritic cells, macrophages, and natural killer cells. In addition, recent data also suggest that GLPS suppresses tumorigenesis or inhibits tumor growth through direct cytotoxic effect and anti-angiogenic actions. However, many questions still need to be answered before both G. lucidum and GLPS can be widely accepted and used as anti-tumor agents.

scholarly journals The Human NUP58 Nucleoporin Can Form Amyloids In Vitro and In Vivo

Biomedicines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1451
Author(s):  
Lavrentii G. Danilov ◽  
Svetlana E. Moskalenko ◽  
Andrew G. Matveenko ◽  
Xenia V. Sukhanova ◽  
Mikhail V. Belousov ◽  
...  
Keyword(s):  
Phase Separation ◽  
Disulfide Bonds ◽  
Amyloid Fibrils ◽  
Bioinformatic Analysis ◽  
Amyloid Formation ◽  
Amyloid Aggregates ◽  
Protease Treatment

Amyloids are fibrillar protein aggregates with a cross-β structure and unusual features, including high resistance to detergent or protease treatment. More than two hundred different proteins with amyloid or amyloid-like properties are already known. Several examples of nucleoporins (e.g., yeast Nup49, Nup100, Nup116, and human NUP153) are supposed to form amyloid fibrils. In this study, we demonstrated an ability of the human NUP58 nucleoporin to form amyloid aggregates in vivo and in vitro. Moreover, we found two forms of NUP58 aggregates: oligomers and polymers stabilized by disulfide bonds. Bioinformatic analysis revealed that all known orthologs of this protein are potential amyloids which possess several regions with conserved ability to aggregation. The biological role of nucleoporin amyloid formation is debatable. We suggest that it is a rather abnormal process, which is characteristic for many proteins implicated in phase separation.

Abstract 270: Role of the Mitochondrial Iron in Cardiomyoblast Survival and Maturation of Cytosolic Fe/S Proteins.

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Anita Thakur ◽  
Marina Bayeva ◽  
Hossein Ardehali
Keyword(s):  
Cell Death ◽  
Iron Accumulation ◽  
Iron Chelators ◽  
Inner Mitochondrial Membrane ◽  
Cytotoxic Effects ◽  
Mitochondrial Iron ◽  
S Proteins

ATP-binding cassette (ABC)-B8 is an ABC half transporter that resides in the inner mitochondrial membrane. We previously showed that ABCB8 has a role in mitochondrial iron export, and that a reduction in ABCB8 both in vitro and in vivo results in mitochondrial iron accumulation, increased reactive oxygen species (ROS) and cell death, and decreased activity of cytosolic Fe/S proteins. However, it is not known whether the cytotoxic effects of ABCB8 knockdown are due to mitochondrial iron accumulation or decreased cytosolic Fe/S protein or other processes. Furthermore, the link between mitochondrial iron and the activity of cytosolic Fe/S proteins is uncharacterized. Here, we studied whether a reduction in mitochondrial iron can reverse the effects of ABCB8 knockdown on cell survival, ROS production and the activity of Fe/S proteins. We altered the mitochondrial iron using various iron chelators and by decreasing the levels of mitochondrial iron importer, mitoferrin-2 (MFRN2). The increase in mitochondrial iron and ROS levels associated with ABCB8 knockdown was significantly reversed by iron chelators and with MFRN-2 knockdown. Furthermore, cell death was also reversed with iron chelators and MFRN-2 knockdown, suggesting that the cytotoxic effects of ABCB8 knockdown is due to mitochondrial iron accumulation. We then studied the effects of iron chelators on cytosolic Fe/S proteins. Iron chelators reversed the defect in cytosolic Fe/S proteins that is associated with ABCB8 knockdown in cell culture or knockout in mice. However, antioxidants and knockdown of MFRN-2 failed to have similar effects. These results indicated that the defect in the maturation of cytosolic Fe/S proteins due to mitochondrial iron accumulation can be reversed by chelating mitochondrial iron, and is independent of the associated oxidative stress. Thus, mitochondrial iron levels are likely sensed in the cytoplasm and determine the maturation of cytosolic Fe/S proteins. Altogether, these studies provide insights into the role of mitochondrial iron in the cytotoxic effects of ABCB8 knockdown, and suggest that mitochondrial iron is sensed in the cytoplasm and influences the maturation of cytosolic Fe/S proteins.

The Role of Polyphenols in the Modulation of Plasma Non-Enzymatic Antioxidant Capacity (NEAC)

2012 ◽  
Vol 82 (3) ◽  
pp. 228-232 ◽  
Author(s):  
Mauro Serafini ◽  
Giuseppa Morabito
Keyword(s):  
Antioxidant Capacity ◽  
Dietary Intervention ◽  
Ex Vivo ◽  
The Body ◽  
Dietary Polyphenols ◽  
Enzymatic Antioxidant ◽  
Endogenous Antioxidant

Dietary polyphenols have been shown to scavenge free radicals, modulating cellular redox transcription factors in different in vitro and ex vivo models. Dietary intervention studies have shown that consumption of plant foods modulates plasma Non-Enzymatic Antioxidant Capacity (NEAC), a biomarker of the endogenous antioxidant network, in human subjects. However, the identification of the molecules responsible for this effect are yet to be obtained and evidences of an antioxidant in vivo action of polyphenols are conflicting. There is a clear discrepancy between polyphenols (PP) concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the endogenous antioxidant network. This work will discuss the role of polyphenols from galenic preparation, food extracts, and selected dietary sources as modulators of plasma NEAC in humans.

Anti-obesity role of Aster glehni extract: in vivo and in vitro effects

Planta Medica ◽  
2012 ◽  
Vol 78 (11) ◽  
Author(s):  
HM Lee ◽  
TG Ahn ◽  
CW Kim ◽  
HJ An
Keyword(s):  
In Vitro Effects

A Molecular Approach to Immunoscintigraphy: A Study of the T-Antigen Conformation on the Surface of Tumors

1987 ◽  
Vol 26 (01) ◽  
pp. 1-6 ◽  
Author(s):  
S. Selvaraj ◽  
M. R. Suresh ◽  
G. McLean ◽  
D. Willans ◽  
C. Turner ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Tumor Cell ◽  
T Antigen ◽  
Human Carcinomas ◽  
Animal Tumor ◽  
Synthetic Antigens

The role of glycoconjugates in tumor cell differentiation has been well documented. We have examined the expression of the two anomers of the Thomsen-Friedenreich antigen on the surface of human, canine and murine tumor cell membranes both in vitro and in vivo. This has been accomplished through the synthesis of the disaccharide terminal residues in both a and ß configuration. Both entities were used to generate murine monoclonal antibodies which recognized the carbohydrate determinants. The determination of fine specificities of these antibodies was effected by means of cellular uptake, immunohistopathology and immunoscintigraphy. Examination of pathological specimens of human and canine tumor tissue indicated that the expressed antigen was in the β configuration. More than 89% of all human carcinomas tested expressed the antigen in the above anomeric form. The combination of synthetic antigens and monoclonal antibodies raised specifically against them provide us with invaluable tools for the study of tumor marker expression in humans and their respective animal tumor models.

THYROID STIMULATORS AND THYROID STIMULATION

1971 ◽  
Vol 66 (3) ◽  
pp. 558-576 ◽  
Author(s):  
Gerald Burke
Keyword(s):  
Regulatory System ◽  
Control Site ◽  
Thyroid Cell ◽  
Primary Control ◽  
Physico Chemical ◽  
Site Of Action ◽  
Long Acting

ABSTRACT A long-acting thyroid stimulator (LATS), distinct from pituitary thyrotrophin (TSH), is found in the serum of some patients with Graves' disease. Despite the marked physico-chemical and immunologic differences between the two stimulators, both in vivo and in vitro studies indicate that LATS and TSH act on the same thyroidal site(s) and that such stimulation does not require penetration of the thyroid cell. Although resorption of colloid and secretion of thyroid hormone are early responses to both TSH and LATS, available evidence reveals no basic metabolic pathway which must be activated by these hormones in order for iodination reactions to occur. Cyclic 3′, 5′-AMP appears to mediate TSH and LATS effects on iodination reactions but the role of this compound in activating thyroidal intermediary metabolism is less clear. Based on the evidence reviewed herein, it is suggested that the primary site of action of thyroid stimulators is at the cell membrane and that beyond the(se) primary control site(s), there exists a multifaceted regulatory system for thyroid hormonogenesis and cell growth.

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