Currently, antimicrobial resistance causes 23,000 deaths each year in the United States and 700,000 deaths worldwide . A 2016 study by the Wellcome Trust predicts that by 2050 , the emergence rate of new strains will exceed the US Food and Drug Administration's approval rate for new antimicrobials - meaning that the mortality rate of antibiotic resistant strains will More than the number of cancer deaths.

Dr. Hong Bo, a researcher at the University of Minnesota, helped discover the first example of an effective gene therapy drug that uses nanotherapeutics to provide short interfering RNA ( siRNA ) against immune system cells to fight deadly bacterial infections. The study, published in the journal Nature Communications , was completed by a team at the University of Minnesota ; the University of California, San Diego ( UCSD ) ; the Sanford Burnham Institute for Medical Discovery ( SBMDI ) ; and the Korea Advanced Institute of Science and Technology ( KAIST ).

Pang, an assistant professor at the University of Minnesota School of Pharmacy, said: " This study fully demonstrates the enormous potential of targeted nanotechnology for the treatment of various human diseases.

“ This is a very good example of a fusion study, ” said Michael Sailor of the University of California, San Diego . “ In order for this concept to work, we need to combine our nanomaterial expertise at UCSD with KAIST 's membrane and cell biology expertise with peptide and disease models developed by our biomedical partners at SBMDI and UMN . ”

The team further explored gene therapy, an underutilized method to combat bacterial infections and enhance the body's immune system. siRNA gene therapy enhances the ability of some innate immune cells to attack bacteria while shutting down the inflammatory response that interferes with the recovery of the immune system.

Through this treatment, it is hoped that a wide range of bacterial infections, including emerging strains, can be attacked. Although it is very difficult to deliver siRNA in vivo , the study found that siRNA treatment completely recovered from lethal bacterial infection by saving 100 % of mice infected with lethal doses of staphylococci . Staphylococcus aureus pneumonia.

" A short peptide recognizes macrophages, an important type of immune cell, selectively at the site of infection, " Pang added. “In combination with nanomaterials with unique advantages in drug carriers, we can effectively deliver gene therapy where it is needed and achieve complete recovery from deadly bacterial infections. ”

The research team incorporated three features into the nanoparticle design:

·         Producing a porous nanoparticle host that protects its siRNA payload from premature degradation in the bloodstream ;

·         A peptide that selectively targets macrophages , a white blood cell capable of attacking foreign microorganisms and signaling an invader

·         A chemical coating called a fusion lipid is designed to allow nanoparticles to penetrate macrophages and deliver their gene therapy drugs to the appropriate compartments within the cell.

Pang believes that this study is the first example of effective gene therapy for deadly bacterial infections using nanotherapeutics to deliver siRNA to target macrophages. The research team demonstrated for the first time that siRNA treatment can completely recover from a deadly bacterial infection.

More information: Byungji Kim et al. Immunogene therapy using fusion nanoparticles modulates macrophage response to S. aureus, Nature Communications (2018). DOI: 10.1038 / s41467-018-04390-7