MicroRNA for treating cancer and asthma

A microRNA that regulates inflammation shows promise as a treatment for inflammatory diseases such as asthma and cancer. The microRNA, known as miR-223, is highly expressed in blood cells that cause inflammation (neutrophils). When they're working correctly, those blood cells protect the body against infections, but sometimes they damage host tissue instead of microbes, causing chronic inflammation and disease.

To uncover the link between miR-223 and inflammation, a Purdue University research team created a zebrafish totally deficient of miR-223. Then they cut off a small chunk of its fin. "The inflammation was really robust," said Qing Deng, a professor of biological sciences at Purdue and corresponding author of the paper. "Neutrophils accumulated at the wound and they just kept coming. This is consistent with the literature, but we wanted to understand why."

Extensive gene expression analysis led them to pathway NF-kB, a protein complex found in nearly all animal cell types that regulates inflammation and cell proliferation. Heightened activation of this pathway is the cause of increased inflammation, although it's limited to the deeper, or basal, layer of the epithelium. This means any therapeutics would need to reach the basal layer to work.

The same pathway plays an important role in human bronchial epithelial cells, which are critical in the development of asthma, according to the study. MiR-223 suppresses the pathway, which means supplementing it to epithelial cells could help control inflammatory disease.
            haleplushearty.blogspot.com

Roles of bacteria in colon cancer

Patients with an inherited form of colon cancer harbor two bacterial species that lead to development of the disease, and the same species have been found in people who develop a sporadic form of colon cancer, a study led by a Johns Hopkins Bloomberg~Kimmel Institute for Cancer Immunotherapy research team finds.

A second study by the same researchers shows a possible mechanism behind how one of these species spurs a specific type of immune response, promoting-instead of inhibiting the formation of malignant tumors. Together, these findings could lead to new ways to more effectively screen for and ultimately prevent colon cancer.

The Science findings describe a process in which these bacteria invade the protective mucus layer of the colon and collude to create a microenvironment-complete with nutrients and everything the bacteria need to survive that induces chronic inflammation and subsequent DNA damage that supports tumor formation.

These findings suggest a change in the standard of care for people who carry both types of bacteria. "More frequent colon cancer screening than the currently recommended once every 10 years should be considered," says Drew Pardoll, M.D., Ph.D., director of the Bloomberg~Kimmel Institute for Cancer Immunotherapy. Ultimately, once better understood, administering drugs or vaccines to prevent colonization of the bacteria in the colon, and potentially even probiotics to chase the bugs from the colon, are preventive measures that could be explored to interrupt the cancer-promoting process.

These new findings shows that particular strains of bacteria can invade the colon mucus in some patients who get colon cancer but who have no inherited predisposition for the disease. Unlike most bacteria, which do not make it past the colon's protective mucus layer, these communities of bacteria that invade the mucus form a sticky biofilm right next to the colon epithelial cells that line the colon, where colon cancer usually originates.

About 5 percent of colon cancers are caused by a hereditary syndrome called familial adenomatous polyposis (FAP), in which an inherited mutation launches a series of genetic changes that develop over time and eventually prompt the epithelial cells to turn malignant. However, it was unclear whether ETBF or other bacteria played a role in the progression to colon cancer in FAP patients.

To investigate the relationship between the bacteria-caused biofilms and cancer formation, researchers examined colon tissue removed from six FAP patients. Tests showed patchy sections of biofilms distributed along the colon's length in about 70 percent of the patients. The researchers used gene probes to identify the particular bacterial species and found that the biofilms consisted mainly of two types, Bacteroides fragilis and Escherichia coli, a surprising finding since the colon contains at least 500 different types of bacteria.

Tests on 25 additional colon samples from FAP patients showed that the B. fragilis strain was a subtype, called ETBF, which makes a toxin that triggers certain oncogenic, or cancer-promoting, pathways in colon epithelial cells and causes colon inflammation. The E. coli strain produced a substance called colibactin (synthesized by a set of genes in the bacterial genome called the PKS island), which causes DNA mutations.

FAP is a devastating disease that ultimately results in surgical removal of the colon, a Currently, using colonoscopy to monitor for the formation of precancerous tumors, called polyps, is the standard of care. Using a mouse model of colon cancer, the researchers found that animals whose colons were colonized with just one of these species developed few or no tumors. However, when their colons were colonized with both species simultaneously, they developed many tumors, suggesting a synergy between the two types of bacteria.

An earlier study suggested a unique type of immune response producing an inflammatory protein called IL-17-was key to ETBF-induced tumor formation. In order to prove the importance of IL-17 in the cancer-promoting effects of the bacterial combination, they used a mouse model in which the IL-17 gene was genetically deleted so it could not make IL-17, and colonized the mice with both ETBF and PKS+E. coli. Unlike animals that readily made IL-17, the genetically altered mice didn't form colon tumors, confirming the importance of this protein in bacterial-driven colon cancer.

However, in addition to IL-17, the studies showed that ETBF digested the mucus layer, enabling the PKS+ E. coli to adhere in larger numbers to the colon mucosa where together the bacteria induced increased DNA damage, a step preceding the gene mutations that underlie colon tumor formation. The complementary findings in Cell Host & Microbe demonstrate how ETBF's toxin prompts colon cancer to develop. Using a different mouse model of colon cancer, the researchers colonized the animals' colons with ETBF and then performed a series of tests to monitor the resulting cellular and molecular changes.

Their results revealed that ETBF's toxin spurs a cascade of events that promote colon inflammation that feeds back to act on the colon epithelial cells. First, the toxin triggers colon immune cells to produce IL-17. This inflammatory molecule then acts directly on the colon epithelial cells to trigger activation of a protein complex involved in promoting further inflammation, known as NFkappaB. NFkappaB in turn induces the colon epithelial cells to produce several signaling molecules that recruit more immune cells, called myeloid cells, to the colon.

These immune cells are involved in the inflammatory response and are known to support tumor growth. This process culminates in tumors forming in the colon. Additional experiments showed that a protein known as STAT3, which was previously shown to play a role in regulating cancer and inflammatory genes, is also necessary for tumor formation.
            haleplushearty.blogspot.com

How intestine repairs itself

Researchers at Baylor College of Medicine, Johns Hopkins University School of Medicine and the University of California, San Francisco have gained new insights into how the small intestine, one of the fastest renewing tissues in the human body, repairs itself after injury caused by intestinal rotavirus infection. Their findings have led them to propose that, contrary to the current thinking, how the intestine repairs itself seems to depend on the type of damage, and they found that triggers that were previously thought to be unimportant are actually essential for repairing virus-caused injury.

They studied different damage model, damage caused by rotavirus, a common small intestinal viral infection that affects young children. Repair and turnover of the epithelium, the most external cellular layer of the small intestine responsible for absorption of nutrients and other functions, depend on the intestinal stem cells, regardless of the cause of the damage. There are two types of intestinal stem cells: CBCs (crypt-based columnar cells) and reserve intestinal stem cells. The type of injuries studied until now damages the highly proliferative CBCs, and when these stem cells are destroyed, the reserve intestinal stem cells respond to restore the damage. The response to injury caused by rotavirus, however, is different.

Rotavirus is an infection and has a very specific damage pattern, the virus specifically infects epithelial cells, but not the stem cells. The first finding refers to the type of stem cell involved in the repair of the epithelial cells damaged by the virus. Previous studies had shown that when CBC stem cells are damaged, the reserve stem cells come to their rescue leading the reconstitution of the damaged epithelium. When rotavirus damages the epithelium, but not the stem cells,  the CBCs, not the reserve stem cells, are the primary cell type involved in the restoration of the intestinal epithelium.

 CBCs were not considered important for the repair of intestinal epithelium, but the results show that they are crucial for injury repair after rotavirus-induced epithelial cell damage in contrast to previous studies supporting the reserve intestinal stem cells as the cell type involved in epithelial restitution. The second finding refers to the source of the signaling molecules-called WNTs that trigger the growth and activation of stem cells leading to injury repair. Scientists have described two sources of WNT molecules, epithelial cells and mesenchymal cells. Epithelial WNT molecules were essential to signal the stem cells to repair the damage caused by rotavirus infection.
          haleplushearty.blogspot.com

Antibiotics may reduce the ability of immune cells

Antibiotics normally act in concert with an organism's immune system to eliminate an infection. However, the drugs can have broad side effects, including eliminating "good" bacteria in the course of fighting off a pathogen. Researchers has shown that antibiotics can also reduce the ability of mouse immune cells to kill bacteria, and that changes to the biochemical environment directly elicited by treatment can protect the bacterial pathogen.

Different types of antibiotics can damage mitochondria in mice and in human epithelial cells, and that bacterial susceptibility to drugs can be affected by small molecules, called metabolites, released by cells as intermediates of their metabolic reactions. Antibiotic treatment might further alter the infection microenvironment in ways that impact bacteria and immune cells.

To investigate, the team treated mice infected by Escherichia coli bacteria with a commonly used antibiotic called ciprofloxacin, administered through the animals' drinking water at concentrations relative to what a human would receive, and quantified the biochemical changes. The researchers found that the antibiotic treatment elicited systemic changes in metabolites-not by influencing the microbiome, but by acting directly on the mouse tissues.

On further investigation, the team determined that metabolites released by mouse cells made E. coli more resistant to ciprofloxacin. Antibiotic exposure also impaired immune function by inhibiting respiratory activity in immune cells: Macrophages treated with ciprofloxacin were less able to engulf and kill E. coli bacteria.
The results highlight the potential of antibiotics to modulate the immune system, and reveal the importance of the metabolic microenvironment in resolving an infection.
          haleplushearty.blogspot.com

MicroRNA regulates movements of tumour cells

Cancer cells can reactivate a cellular process that is an essential part of embryonic development. This allows them to leave the primary tumor, penetrate the surrounding tissue and form metastases in peripheral organs.

During an embryo's development, epithelial cells can break away from the cell cluster, modify their cell type-specific properties, and migrate into other regions to form the desired structures. This process is known as an epithelial–mesenchymal transition EMT is reversible and can also proceed in the direction from mesenchymal cells to epithelial cells (MET).

It is repeated multiple times during embryonic development and ultimately paves the way for the formation of organs in the human body. Tumor cells can reactivate the program. Although this is a completely normal process during embryogenesis, it also plays an important role in the spread of tumor cells within the body and in the formation of metastases.

Tumor cells are able to reactivate the EMT/MET program. By doing so, they obtain characteristics of stem cells and develop strong resistance to classical and state-of-the-art targeted cancer therapies. An EMT also makes it easier for cancer cells to break away from the primary tumor, to penetrate into surrounding tissue and into blood vessels, to spread throughout the body and to form metastases in distant organs, which is ultimately responsible for the death of most cancer patients.

Regulation the cellular EMT program prevents the development of malignant tumors and the formation of metastases such as in the case of breast cancer, researchers focused specifically on microRNAs (miRNAs), a class of very short non-coding RNAs with a considerable effect on gene regulation.
          haleplushearty.blogspot.com