Tag: Probiodrug

Company News: Neurodegeneration in Alzheimer’s Disease: The crucial role of QC

Probiodrug provides further insights into the onset of AD in The Journal of Neuroscience

Probiodrug AG (Probiodrug), a biotech company developing novel products for the treatment of neurodegenerative and inflammatory disorders, today announced the publication of data providing key insights into the onset and development of Alzheimer’s disease (AD) in the Journal of Neuroscience (http://redir.ec/jneurosci).

AD is characterized by deposition of amyloid-β (Aβ) plaques in the brain. However, quantitative relationship between plaque deposition and severity of cognitive decline in the affected individuals is still elusive. Often, elderly people carry a large amyloid burden without any signs of cognitive impairments, and many animal models of AD also develop the characteristic hallmarks, such as plaques, but do not demonstrate the cognitive defects and loss of neurons typical of the human disease.

Several years ago, Probiodrug developed the hypothesis that the missing link between Aβ load and prevalence of AD is a certain modification of Aβ, in which the Aβ molecule carries a pyroglutamate residue (pGlu) at its N-terminus. This pGlu-Aβ is neurotoxic and develops a strong tendency to aggregate and to seed aggregation of further pGlu-Aβ as well as unmodified Aβ. The modification of glutamic acid to a pGlu-residue is catalyzed by the so-called QC enzyme (glutaminyl cyclase).

In this week’s The Journal of Neuroscience* Probiodrug researchers (and their collaborators from Friedrich Alexander University, Erlangen, the German Center of Neurodegenerative Diseases, Magdeburg, the Leibniz Institute for Neurobiology, Magdeburg, the Paul Flechsig Institute for Brain Research, Leipzig, and the University of Tennessee, Knoxville/ USA) now describe the generation and characterization of a novel animal model that solely expresses N-truncated human Aβ, which in turn is modified by QC to pGlu-Aβ. As a result, these animals which express the toxic species 1000fold less than other models do with Aβ not only have the typical pathological changes, but also neuronal loss and cognitive impairments.

”We now have animal models that represent the full spectrum of pathological and behavioral changes in AD without overexpressing the Aβ peptides. In addition, we could once again clearly demonstrate that the activity of QC enzymes is starting the chain of events that ultimately leads to the debilitating disease, which already affects millions of people world-wide. The results in this study also demonstrate that lowering the QC-dependent formation of pGlu-Aβ reduces the amount of neurotoxic aggregations, and further strengthens the hypothesis that inhibition of QC is a promising new treatment strategy for AD” commented Hans Ulrich Demuth, CSO of Probiodrug.

*doi:10.1523/JNEUROSCI.2172-11.2011

Food for Thought: Weekly Wrap-Up

Joachim Müller-Jung in Frankfurter Allgemeines Zeitung (FAZ) this week deals with the ethic implications of non-invasive prenatal diagnosis, describing that a huge number of tests based on fetal DNA entering the mother’s blood stream is ready to enter the market. His recommendation is to start an immediate discussion about which tests should be applied and which ones should not.

Ulrich Bahnsen in Die ZEIT interviews Norbert Donner-Banzhoff, Professor at the University of Marburg’s Department of General Practice, Preventive and Rehabilitative Medicine. Donner-Banzhoff conducted a study published in the Canadian Medical Association Journal CMAJ investigating the influence of pharmaceutical advertising on the drug recommendations made in articles in 11 German journals that focus on medical education. Donner-Banzhoff and his team come to the conclusion that journals financed by advertisement from the pharma industry and given away for free almost exclusively recommended the use of specified drugs, whereas journals financed entirely with subscription fees tended to recommend against the use of the same drugs. In the interview, Donner-Banzhoff suggests that a lot of articles published in the free journals have been written by ghost writers and/or members of the pharmaceutical industry.

Matthew Herper in Forbes this week deals with the latest setback in developing drugs to treat Alzheimer’s Disease (AD). He features the failure of Eli Lilly’s semagacest in a Phase III trial in more than 2,600 patients with mild-to-moderate AD. According to an interim analysis, patients receiving the drug, a gamma secretase blocker, worsened to a statistically significant greater degree than those treated with placebo. In addition, the drug was associated with an increased risk of skin cancer. Herper concludes that there is something fundamentally wrong with current hypotheses on the onset of AD and that the failure of the drug may set AD drug development back by many years (see also akampioneer’s recent comment on Probiodrug’s AD hypothesis).

While William Pentland, also in Forbes, reports a potential biofuel breakthrough in producing isobutanol directly from cellulose by using a microbe thriving in decaying grass, Josh Wolfe, co-founder and managing partner of Lux Capital Management, in Forbes states it is time to realize that investing in biofuels may be foolish. He states that while it is hyped as biotech 2.0, there is in fact a fundamental difference to biotech 1.0 which is often overlooked. While biotech 1.0 drugs and molecules can be protected by IP, biofuels cannot. In addition, the marginal cost of producing IP-protected molecules is really low once you did the discovery and first synthesis work (as compared to your margins) – so you can make big profits. Biofuel molecules however have to compete from the onset with the generic fuels already on the market. Biofuel is a commodity, he states, and instead of going back to an agrarian-based economy we should focus on materials and processing based on high energy density, such as uranium.

Donald G. McNeil jr in The New York Times reports on a panel of independent experts from 24 countries that reviewed the handling of the swine flu by the World Health Organization (WHO) in 2009. The draft report – “posted in an obscure corner of the W.H.O.’s Web site” – criticizes the WHO’s “needlessly complex” definition of a pandemic, its inability to deploy 78 million doses donated by rich nations for use in poor ones and its “clumsy communications”.

Colin Barras in New Scientist writes about the origin of cancer and features recent contributions by astrobiologists. While many researchers think that cancer is triggered by a malfunction of the genes trying to control replication which needs to be limited in multicellular organisms, some astrobiologists think a tumor is switching back to some forms of basic cellular cooperation found in the earliest ancestors of multicellular organisms. The distinction is far from being academic: if cancer is some sort of “living fossil” revived it would have only a limited set of survival strategies. In contrast, contemporary medicine regards a tumor as independently evolving cells with nearly unlimited evolutionary potential to escape treatment strategies. The hypothesis explains the co-ordinated survival strategies of cancer, such as angiogenesis and metastasis, and will be further tested soon by genetic profiling.

 

Food for Thought: Probiodrug’s Alzheimer Hypothesis Independently Confirmed

Two decades ago, it was discovered by the founders of German biotech company Probiodrug that the so-called amyloid beta peptides (Aβ) forming the notorious plaques in the brain of Alzheimer’s Disease (AD) patients are not a homogeneous species. While it was known that there are variants in length (from 36 to 43 amino acids), the Probiodrug researchers discovered that there also are pyroglutamated variants (pGlu-Aβ) of the peptides. However, little was known about their origin and biological role. This has changed significantly over the last years, and Probiodrug has pioneered this research.

At this year’s 10th International Conference on Alzheimer’s and Parkinson’s Diseases (AD/PD 2011), taking place in Barcelona/Spain from March 9 to 13, more than two dozen posters and presentations provide further insights into the mechanisms and consequences of pGlu-Aβ formation, and there is overwhelming evidence that pGlu-Aβ is key to understanding Alzheimer’s Disease and to developing novel treatments. Abstracts can be found here.

The findings can be summarized as follows:

1.    Amyloid plaques alone correlate poorly with the severity of AD.

2.    The presence of pGluAβ in plaques, however, does correlate with disease severity in both sporadic and familial AD.

3.    Antibodies recognizing oligomeric forms of pGluAβ bind to plaques in the brains of familial AD patients.

4.    pGluAβ is elevated 8.5-fold in AD brains compared to controls.

5.    pGluAβ forms the center of plaques, with full-length Aβ at the periphery, suggesting that pyroglutamate forms Aβ seed deposits.

6.    pGluAβ is a form of Aβ that aggregates faster than conventional full-length Aβ, is more neurotoxoc and – being protected against degradation – much more stable.

7.    pGluAβ is formed by the enzyme glutaminyl cyclase (QC) at the N-terminus of Aβ by cyclizing a glutamate residue.

8.    Expression of QC is increased in the brain of AD patients.

9.    Mice engineered to express human QC show highly increased levels of pGluAβ as well as motor and memory problems.

10. QC not only produces pGluAβ, but also promotes inflammation by acting on monocyte chemoattractant protein (MCP-1, also known as CCL2), making a pyroglutamate derivative that is stable and resists proteases.

11. Mixtures of pGluAβ and conventional Aβ42 are 10- to 50-fold more deadly to neurons than either peptide alone.

12. Toxicity of these Aβ mixtures depends on the presence of tau, suggesting that tau acts downstream of Aβ.

Novel insights to the hypothesis presented on this year’s AD/PD 2011 include the discovery that QC enzymes are also responsible for the activation of several pro-inflammatory chemokines in the brain by introducing a pGlu-residue. As this residue confers resistance to proteolytic degradation, overexpression or -activity of QC may be involved in turning inflammatory processes into a chronic state of neuroinflammation, which often is observed in CNS diseases.

Another abstract describes a novel ELISA test for the reliable determination of Aβ in biological fluids as well as a novel antibody detecting the biologically active form of an inflammatory biomarker. The ELISA test allows for a clear discrimination between controls showing normal aging and individuals affected by Alzheimer’s Disease in prodromal or demented stages.

 

Company News: Probiodrug to Host Alzheimer Symposium

Despite considerable efforts to find a cure, Alzheimer’s disease  (AD) at present cannot be treated adequately, as there is no therapy available to significantly slow down disease progression, halt the disease or prevent it.
During the past years, researchers from the German-based biotech company Probiodrug have generated a compelling body of evidence that a particular variant of the notorious A beta peptide, which clumps together in the brain of AD patients to the typical plaques, is the major culprit. This variant is formed through a hitherto unknown reaction of a brain enzyme called glutaminyl cyclase (QC) and carries a pyroglutamic residue at its N-terminus. This renders it much more neurotoxic than the unmodified A-beta and also significantly reduces its solubility so that it starts aggregating.
Today, this hypothesis  is not an outsider opinion any more. On Monday, November 22, well-known Alzheimer researchers from Germany (Christian Haass, Stephan v. Hörsten, Marcus Fändrich, Thomas Bayer, Steffen Roßner, and Stephan Schilling), the U.S. (Cynthia Lemere, Lennart Mucke, Steve Jacobsen), Austria (Reinhold Schmidt), and Japan (Takaomi Saido) will meet at Probiodrug´s Halle (Saale) headquarter to provide the latest findings in the light of this hypothesis and to discuss novel therapeutic strategies. One of the approaches pursued by Probiodrug is inhibiting the formation of the toxic A-beta variant by small molecule inhibitors of the QC enzyme.
The public symposium entitled “Neurodegenerative Disorders During Aging – Contemporary Research and New Therapies” will take place on Weinberg Campus in Halle (Saale) on Monday, November 22, 2010, from 10am to 3pm. The detailed program can be found on Probiodrug‘s website.

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