Navigation Links
Intestinal cell defense mechanism against bacteria

FRANKFURT. Salmonella is widely prevalent in the animal kingdom. The reason we do not suffer from severe intestinal infections very often is due to our body's defence system, which manages to digest invading bacteria. This is why, generally speaking, a healthy human being will only fall ill if he consumes more than 100.000 salmonella bacteria via a contaminated food source, such as eggs or meat. An international team of researchers, led by Prof. Ivan Dikic from the Goethe University in Frankfurt has now found out how body cells recognise salmonella and render it harmless. Understanding this process at a molecular level is crucial in identifying new targets for treatment. Tropical and sub-tropical countries in particular, where various sub-species of salmonella are common, are experiencing a rapid increase in resistance to antibiotics, with children at greatest risk.

Salmonella infection begins with bacteria entering the epithelial cells of the intestinal mucosa. To prevent them multiplying there, special cell organelles, called autophagosomes are activated. These encircle the invaders and then become absorbed in other organelles lysosomes that contain certain special digestive enzymes, which break down the bacteria into their constituent parts. But how exactly do the autophagosomes recognise salmonella? Prof. Ivan Dikic and his research group at the Biochemistry Institute II have now shed light on this mechanism.

As reported in a current article in the scientific journal "Science", the salmonella are marked as 'waste material' by the molecule ubiquitin. In order for the autophagosomes to become active, the marked bacteria have to bind to another molecule LC3 on the autophagosomal membrane. Here, the protein optineurin plays a key role, linking the marked Salmonella to the autophagosmal LC3, thereby setting off a process of selective autophagy. But optineurin becomes active as a link only after being chemically modified by an enzyme, (in this case it is phosphorylated by the protein kinase TBK1). "We suspect that phosphorylation acts as a regulated switch to trigger selective autophagy of bacteria but might also prove significant in other cargoes like protein aggregates or damaged mitochondria" explains Prof. Ivan Dikic, underlining the importance of these findings. It is thought that impaired autophagy processes may be implicated in, among other things, the development of cancer as well as neurodegenerative diseases.

In the area of infectious diseases, these findings are particularly relevant in view of the fact that gastrointestinal disease caused by Salmonella enterica has rapidly increased since the mid-1980s. In Germany, approx. 30,000 cases were reported to the health authorities in 1985, but by 2005 the figure has risen to 52,000. Worldwide, 94 million people fall ill each year with acute gastroenteritis, and 155,000 of these die. Typhoid, a disease also caused by Salmonella, affects 16 million people annually and mortality rates reach 200,000, with children in particular falling victim to the disease. Bacteria are becoming increasingly resistant to antibiotics so that the potential for treating disease is limited. Chloramphenicol, a formerly popular broad-spectrum antibiotic, is now ineffective, and even Fluoroquinolones, currently a commonly prescribed antibiotic, is proving inadequate in fighting bacteria. As co-author Prof. Dirk Bumann from the Biozentrum at Basel University puts it: "There is a pressing need to find new forms of treatment for infectious diseases. A better understanding of how the body's own defence mechanism makes use of autophagy will certainly help."


Contact: Prof. Ivan Dikic
Goethe University Frankfurt

Related medicine news :

1. Protein Appears Key to Intestinal Balance
2. ReportsandReports : The Gastrointestinal Market Outlook to 2014: Market Dynamics, Competitive Landscape, Emerging Therapies
3. Feedback loop explains inflammatory effect on intestinal lining
4. A new endoscopic technique for gastrointestinal perforations: the over-the-scope-clip
5. Factors increasing the risk of atrophic gastritis and intestinal metaplasia
6. The effect of dietary supplements, acids and animal protein on gastrointestinal disorders
7. Suppressing activity of common intestinal bacteria reduces tumor growth
8. Motorcycle Cancer Risk and ELF EMF Radiation Invasion of Gastrointestinal Melatonin
9. What affects the gastrointestinal symptoms in peritoneal dialysis patients?
10. Optimal surgical procedure for duodenal gastrointestinal stromal tumors
11. New studies highlight obesitys impact on gastrointestinal health
Post Your Comments:
Related Image:
Intestinal cell defense mechanism against bacteria
(Date:10/13/2017)... ... October 13, 2017 , ... Lori R. Somekh, founder of ... ElderCounsel, a national organization of elder law and special needs planning attorneys. “Membership in ... It also provides a forum to network with elder law attorneys nationwide,” said Somekh. ...
(Date:10/13/2017)... NJ (PRWEB) , ... October 13, 2017 , ... Global ... at scenic Alexandria Park in Milford, NJ. This free event, sponsored by Global ... physical activity. The fun run is geared towards children of all ages; it ...
(Date:10/13/2017)... (PRWEB) , ... October 13, 2017 , ... “America On ... Christian identity. “America On The Brink” is the creation of published author, William ... several great-grandchildren. As a WWII veteran, he spent thirty years in the Navy. ...
(Date:10/12/2017)... ... 2017 , ... IsoComforter, Inc. ( ), one of the ... new design of the shoulder pad. The shoulder pad provides optimal support and ... pain while using cold therapy. By utilizing ice and water that is circulated from ...
(Date:10/12/2017)... ... ... HMP , a leader in healthcare events and education, today announced that ... for ‘Best B-to-B Healthcare Website.’ Winners were announced during the Eddie & Ozzie Awards ... recognizes editorial and design excellence across a range of sectors. This year’s program included ...
Breaking Medicine News(10 mins):
(Date:10/4/2017)... , Oct. 4, 2017  South Korean-based healthcare ... CPR training aide "cprCUBE" on Kickstarter. The device will ... during cardiac arrests with better efficiency compared to the ... offers real-time feedback on efficacy of the compression for ... campaign has a goal to raise $5,000. ...
(Date:10/2/2017)... -- AllianceRx Walgreens Prime, the combined central specialty pharmacy and ... manager Prime Therapeutics LLC (Prime), today officially began the ... of new signage at its headquarters in ... few other company-owned facilities across the country. This also ... whom will begin to see the AllianceRx Walgreens Prime ...
(Date:9/27/2017)... , Sept. 27, 2017  Commended for their devotion to ... awards. Ranked as number one in the South Florida Business ... in Inc. 5000 yearly list, the national specialty pharmacy has ... Armando Bardisa will soon be honored by SFBJ as ... Set to receive his award in October, ...
Breaking Medicine Technology: