Breaking News
October 20, 2018 - New approach to understanding cancers will accelerate development of better treatments
October 20, 2018 - LJI and UC San Diego awarded $ 4.5 million as part of NCI’s Cancer Moonshot initiative
October 20, 2018 - School-based HPV vaccination did not increase risky sexual behaviors among adolescent girls
October 20, 2018 - Eye discovery to pave way for more successful corneal transplants
October 20, 2018 - New analysis examines the importance of location in the opioid crisis
October 20, 2018 - Green filters increase reading speed for children with dyslexia
October 19, 2018 - Bariatric Sx Cuts Macrovascular Complications in Obesity, T2DM
October 19, 2018 - Better assessments for early age-related macular degeneration
October 19, 2018 - Visible and valued: Stanford Medicine’s first-ever LGBTQ+ Forum | News Center
October 19, 2018 - Understanding of metal-free enzymes used by bacteria could lead to new effective antibiotics
October 19, 2018 - Beckman Coulter Life Sciences announces new research-focused website
October 19, 2018 - Study finds link between refined soluble fibers, gut microbiota and liver cancer
October 19, 2018 - Social media reduces risk of depression among seniors with pain
October 19, 2018 - Newly developed synthetic DNA molecule may one day be used as ‘vaccine’ for prostate cancer
October 19, 2018 - Preoperative weight loss may not provide health benefits after surgery
October 19, 2018 - U.S. Birth Rates Continue to Drop as Age of New Moms Rises
October 19, 2018 - New technology can keep an eye on babies’ movements in the womb
October 19, 2018 - Juul e-cigarettes pose addiction risk for young users | News Center
October 19, 2018 - Gene sequencing reveals crucial molecular aspects of Trypanosoma brucei
October 19, 2018 - New DNA vaccine strategy protects mice against lethal challenge by multiple H3N2 viruses
October 19, 2018 - Study shows close link between cytokine interleukin-1ß and obesity-promoted colon cancer
October 19, 2018 - Muscle mass plays a critical role in health, shows research
October 19, 2018 - Study finds undiagnosed prediabetes in many infertile men
October 19, 2018 - The Current issue of “The view from here” is concerned with Nanotherapeutic strategies
October 19, 2018 - Delay in replacing the Pap smear with HPV screening is costing lives
October 19, 2018 - Physicians battle pediatric diseases of ear, nose, throat in Zimbabwe | News Center
October 19, 2018 - Researchers investigate why some cancers affect only young women
October 19, 2018 - Drugmakers funnel millions to lawmakers; a few dozen get $100,000-plus
October 19, 2018 - Unselfish people tend to have more children and receive higher salaries
October 19, 2018 - New findings reveal potential cellular players in tumor microenvironment
October 19, 2018 - Human brain cell transplant offers insights into neurological conditions
October 19, 2018 - Parental education associated with increased family health care spending
October 19, 2018 - New statistical method estimates long- and short-term risk of recurrence of breast cancer in US women
October 19, 2018 - Father’s exposure to nicotine may cause cognitive deficits in descendants
October 19, 2018 - Could we prevent Alzheimer’s disease by treating herpes?
October 19, 2018 - Nurse-led care can be more successful in managing gout
October 19, 2018 - Trump administration, pharma exchange verbal volleys on drug-price transparency
October 19, 2018 - Duke researchers find way to detect blood doping in athletes
October 19, 2018 - Many primary care doctors are still prescribing sedative drugs for older adults
October 19, 2018 - Finger length can predict sexuality in women say researchers
October 19, 2018 - Study finds differences in side-effects experienced by male and female OG cancer patients
October 19, 2018 - Dysfunction of single gene leads to miscarriages
October 19, 2018 - Few Seniors Who Self-Harm Referred for Mental Health Care
October 19, 2018 - Don’t sweat the sweet stuff
October 19, 2018 - URMC researchers discover new approach to deliver therapeutics to the brain
October 19, 2018 - Speech Pathology Australia raises awareness about Developmental Language Disorder
October 19, 2018 - Middlemen suppliers can increase drug prices and hospital bills, say Johns Hopkins researchers
October 19, 2018 - Survey finds high prevalence of HTLV-1 infection among teens and adults in Gabon
October 19, 2018 - Bliss funds research to find whether parental touch can help alleviate pain in premature infants
October 19, 2018 - Human neurons employ highly compartmentalized signaling, study shows
October 19, 2018 - Ultromics expands multiple clinical trials for coronary heart disease to the U.S.
October 19, 2018 - $11 million NIH grant for Clemson University helps launch new center for musculoskeletal research
October 19, 2018 - A new approach identified to control Zika virus, dengue fever
October 19, 2018 - Head Blows Without Concussion May Not Damage Brain, Study Claims
October 19, 2018 - US opioid use not declined, despite focus on abuse and awareness of risk
October 19, 2018 - Next-generation RNA sequencing technology sheds new light on human mitochondrial diseases
October 19, 2018 - UT Southwestern biochemist receives 2019 Breakthrough Prize in Life Sciences for innate immunity discovery
October 19, 2018 - The immune system also plays a key role in day-to-day function of healthy organs
October 19, 2018 - New tool may reveal how the brain structure impacts brain activity, human behavior
October 19, 2018 - Trump Administration announces ‘Winning on Reducing Food Waste’ initiative
October 19, 2018 - For-profit nursing home residents more likely to experience health issues caused by substandard care
October 19, 2018 - Incidence of stroke has risen steadily among marijuana users, show studies
October 19, 2018 - Conceptual framework proposed to examine role of exercise in multiple sclerosis
October 19, 2018 - Near infrared spectroscopy technique for accurate evaluation of chondral injuries
October 19, 2018 - Scientists receive $5.1 million grant to develop stem cell-based therapy for blinding retinal conditions
October 19, 2018 - Shorter physician encounters associated with antibiotic prescribing
October 19, 2018 - In the Spotlight: Enjoying research and exploring opportunities
October 19, 2018 - Physical activity lowers cardiovascular mortality risk in frail older adults
October 19, 2018 - New imaging tool helps visualize how sound-induced vibrations travel through the ear
October 19, 2018 - Key insights into the application, production of bioactive materials
October 19, 2018 - New urea sorbent could speed up the development of wearable artificial kidney
October 19, 2018 - Intensive care patients’ muscles less able to use fats for energy
October 19, 2018 - FDA Advisory Committee Recommends Approval of Dsuvia for the Treatment of Moderate-to-Severe Acute Pain
October 19, 2018 - 48,XXXY syndrome – Genetics Home Reference
October 19, 2018 - Physical exercise improves the elimination of toxic proteins from muscles
October 19, 2018 - How a new system improved wait times for Stanford kidney transplant patients
October 19, 2018 - Nutrition has bigger positive impact on bone mass and strength than exercise
October 19, 2018 - Study finds lack of progress in media representation of nurses over last 20 years
October 19, 2018 - Many people have trouble understanding differences between OCD and OCPD
October 19, 2018 - New family planning app found to be as effective as modern methods

Researchers catch killer cells red-handed in the act of microbial murder

image_pdfDownload PDFimage_print

Immune cells called “killer cells” target bacteria invading the body’s cells, but how do they do this so effectively? Bacteria can quickly evolve resistance against antibiotics, yet it seems they have not so readily been able to evade killer cells. This has caused researchers to become interested in finding out the exact mechanism that killer cells use to destroy bacterial invaders.

Although one way that killer cells can trigger bacterial death is by inflicting oxidative damage, it has not yet been at all understood how killer cells destroy bacteria in environments without oxygen.

Now, for the first time, researchers have caught killer cells red-handed in the act of microbial murder, observing them as they systematically killed three strains of microbes: E. coli and the bacteria responsible for causing Listeria infection and tuberculosis. The process inflicts bacterial cell death regardless of whether the environment contains oxygen or not.

Their findings, published in Cell, reveal that killer cells act methodically, shooting deadly enzymes into bacteria to “program” a complete internal breakdown and cell death.

The researchers, from Boston Children’s Hospital, the Wistar Institute and the University of Michigan (U-M), used an equally systematic approach to make the discovery.

“We took three bacteria that are very different — and to see which proteins were destroyed by killer cells — we measured their protein levels before, during and after they were attacked,” says Judy Lieberman, MD, PhD, of Boston Children’s Program in Cellular and Molecular Medicine (PCMM), who is co-senior author on the study.

Proteins are critical to life because they direct the use of nutrients and production of cellular machinery that bacteria need to survive.

“Each strain of bacteria has about 3,000 proteins and we saw that — in all three bacterial species — about five to 10 percent of those proteins were slashed by the killer cells’ death-inducing enzyme, called granzyme B,” Lieberman says. “If you made a list of the proteins that bacteria absolutely needed to survive, it would be a small list — interestingly, this seems to be identical to granzyme B’s hit list.”

Deadlier than antibiotics

To deliver the fatal blow of granzyme B, killer cells seek out surface markers on the body’s cell surfaces that might indicate a bacterial invader has taken up residence inside the cell. Killer cells then latch onto the infected cell and use an enzyme to create a small pore in the cell’s surface, through which they inject granzyme B. Once granzyme B gets into the cell, it passes into the invading bacterium and essentially destroys critical proteins for cell survival as well as its ribosomes, the pieces of bacteria’s cellular machinery that actually make proteins.

“The bacteria’s ribosomes fall apart and stop functioning,” says Lieberman, also a professor of pediatrics at Harvard Medical School.

It’s as if the bacteria’s internal factory of life not only loses the blueprints for the parts it needs to make, but also suffers a catastrophic mechanical failure of its assembly line.

“By discovering the bacterial proteins that killer cells ‘take out,’ we have identified potential therapeutic targets that could pave the way for a new class of antimicrobial drugs,” Lieberman suggests.

“We have a huge crisis of antibiotic resistance right now in that most drugs that treat diseases like tuberculosis or listeria, or pathogens like E.coli, are not effective,” said Sriram Chandrasekaran, PhD, co-senior author of the study from U-M, in a press release. “So, there is a huge need for figuring out how the immune system does its work. We hope to design a drug that goes after bacteria in a similar way.”

Importantly, no matter how many times the researchers exposed the bacteria to granzyme B, the bacteria did not develop resistance to its fatal attack. It’s possible that the only way bacteria can survive is to camouflage themselves so that killer cells cannot “see” them and shoot granzyme B into them.

Lieberman is now searching for the specific mechanisms by which bacteria might evade killer cells. She’s also investigating how similar “death pathways” take effect in fungi and parasites, such as those that cause malaria.

Source:

https://vector.childrenshospital.org/2017/11/bacteria-microbial-murder-mystery/

Tagged with:

About author

Related Articles