Laboratory of Sasha Shafikhani, PhD

Pseudomonas aeruginosa is an opportunistic pathogen that is an important cause of hospital-acquired infections. Despite constant exposure to this pathogen, healthy individuals do not get infected. In the setting of injured epithelium or immunocompromised host, however, P. aeruginosa is able to colonize and can cause devastating diseases in burn patients, patients on respiratory ventilators, contact lens wearers, cancer and AIDS patients, diabetic foot ulcer, and is one of the major causes of death in patients afflicted with cystic fibrosis. This highlights the importance of continued research on this pathogen in order to further our understanding of its mechanisms of infection and to develop effective means to combat and manage the diseases caused by it. P. aeruginosa is the epitome of an opportunistic pathogen of humans. P. aeruginosa does not infect uncompromised tissues, yet there is hardly any tissue that this pathogen cannot infect if the tissue defences are compromised in some manner. A number of in vitro and ex vivo studies support the notion that injured epithelium (wound) is a preferred niche for P. aeruginosa infections. We have demonstrated that P. aeruginosa employs a variety of novel virulence strategies, including inhibition of cytokinesis and induction of cell death to inhibit wound healing and cause more damage both in vitro and in vivo.

Our work

Our lab is highly multidisciplinary in nature. We conduct projects that involve bacterial pathogenesis, cancer biology, and chronic wound healing. The primary focus of our lab is (i) to determine the virulence mechanisms in the bacterial pathogen, particularly Pseudomonas aeruginosa; (ii) to determine the eukaryotic host responses that are intended to control bacterial pathogen infections; and (iii) to employ bacterial toxins as molecular tools to dissect important mammalian cellular processes such as cytokinesis, apoptotic program cell death, and apoptotic compensatory proliferation signalling. We are actively conducting research in the following general areas:

  1. Using appropriate animal models to assess the impact of P. aeruginosa on tissue repair in normal and in diabetic skin wounds: We are interested in understanding why diabetic wounds are prone to bacterial infection and why the microbiome in diabetic wounds shifts toward pathogenic bacteria, which in turn drive diabetic wound toward chronic and non-healing state.
     
  2. Identification and characterization of a natural pathogen-specific antimicrobial factor: We have discovered that normal tissues express natural antimicrobial factor(s) that can distinguish and destroy pathogenic bacteria among beneficial commensal microflora. We are attempting to identify this factor. These studies could lead to the development of a new class of antibiotics that can selectively target and destroy pathogenic bacteria amongst normal flora. Current antibiotics do not discriminate against pathogenic bacteria and normal flora.
     
  3. Using P. aeruginosa to study the exotoxin-mediated apoptosis and to dissect the apoptotic compensatory proliferation signalling: A major research focus in our laboratory has been to study the mechanisms by which ExoT- an exotoxin produced by Pseudomonas aeruginosa pathogenic bacterium- induces apoptosis in target epithelial cells. We have discovered that target epithelial cells, when induced to die apoptotically, produce and release compensatory vesicles that stimulate proliferation in surrounding cells. We have also found that ExoT can induce potent apoptosis but also blocks compensatory proliferation. Given that majority of cancer cytotoxic therapeutics induce apoptosis in target tumor cells, compensatory proliferation signaling could significantly limit their effectiveness, contributing to the disappointing outcomes associated with existing therapeutic agents against cancer. Understanding the mechanism of compensatory proliferation signaling could lead to the development of novel targeted therapies that could improve the effectiveness of current cancer therapies by inhibiting this process.
     
  4. Using Pseudomonas aeruginosa toxins in therapy against cancer: We have found that certain Pseudomonas aeruginosa toxins are far more potent inducers of cytotoxicity than known therapies. We are developing these toxins as potential chemotherapy drugs.
 
Wound Healing Process
This movie shows wound healing of epithelial cells in the absence of infection.
 
ExoT and Wound Damage
This movie shows how ExoT-expressing Pseudomonas aeruginosa exacerbates wound damage of epithelial cells.
 
Expression of ExoT-GFP in Melanoma Cells
This movie shows that expression of ExoT-GFP (green) in melanoma cells is sufficient to kill melanoma. (Yellow and red cells are dead cells.)
 
ExoT-induced Cell Death
This movie shows that ExoT induces cell death in anoikis apoptosis sensitive HeLa cells but not in anoikis- resistant HeLa S3 cells. (Red cells are dead.)
 
Apoptotic Compensatory Proliferation Signaling

This movie shows apoptotic compensatory proliferation signaling whereby a dying cell (green) releases a vesicle that stimulates proliferation in a bystander cells upon contact.

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Technology

Our approach is multipronged and multidisciplinary in nature. We use leading-edge technology, including time-lapse videomicroscopy, stable cell lines and animal modeling, to carry out research in our laboratory.

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Current funding

  • 1R01DK107713-01A1 (source: NIH/NIDDK, role: PI)
  • R21AI110685-01 (source: NIH/NIAID, role: PI)
  • Breast Cancer Research Fund (source: Bears Care, role: PI)

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Our team

Shafikhani lab team

(Left to right) Sasha Shafikhani, PhD; Amber Kaminski; Janet Zayas; Kajal Gupta, PhD; Douglas Gilbert; Joe Goldufsky, PhD

Current lab members

   
Kajal Gupta, PhD, postdoctoral fellow
Email: kajal_gupta@rush.edu
Kajal Gupta

Ruchi Roy, PhD, postdoctoral fellow
Email: ruchi_roy@rush.edu

Ruchi Roy, PhD
Douglas Gilbert, research assistant
Email: douglas_z_gilbert@rush.edu
Doug Gilbert
Janet Zayas, PhD graduate student
Email: janet_p_zayas@rush.edu
Janet Zayas

Former lab members

   
Stephen Wood, PhD

Stephen Wood

Joe Goldufsky, PhD Joe Goldufsky
Amber Kaminski, MS Amber Kaminski

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Contact us

Sasha Shafikhani, PhD
Rush University Department of Internal Medicine and the Rush Cancer Center

Phone: (312) 942-1368
Fax: (312) 942-2808
Email: sasha_shafikhani@rush.edu

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