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Mark Simons


dr.marksimons@gmail.com
Mentor: Michael Apicella, M.D.
Lab Phone: 353-5654

Interactions of Neisseria gonorrhoeae with Human Neutrophils

Infection with Neisseria gonorrhoeae in males results in an acute urethritis with a massive infiltration of polymorphonuclear leukocytes (PMN). Despite the impressive inflammatory response, gonococcal urethritis often persisted for weeks to months prior to antibiotic therapy suggesting that this organism could resist PMN killing mechanisms. To determine whether N. gonorrhoeae survives within PMN, we developed a phagocytosis assay that mimics the interactions between gonococci and PMN during in vivo infection. Our findings demonstrate that gonococci are internalized by PMN and survive killing. Increasing numbers of intraceullar gonococci can be seen over time, suggesting surviving bacteria may replicate within PMN. Viability counts and pulse-labeling experiments demonstrated that intracellular gonococci are viable and metabolically active. These results suggest that gonococci that survive initial killing persist over time and are capable of replicating within PMN. We are currently investigating the extent of gonococcal survial within PMN and are beginning to address the mechanisms this organism uses to evade intraceullular killing. These studies will contribute to a better understanding of how the infection persists over time, propagates, and is transmitted between hosts.

Abstracts:

Simons MP, Nauseef WM and Apicella MA. Neisseria gonorrhoeae Survive and Proliferate within Polymorphonuclear Leukocytes, International Pathogenic Neisseria Conference, 9/2002.

Simons MP, Nauseef WM and Apicella MA. Neisseria gonorrhoeae Survive and Proliferate within Polymorphonuclear Leukocytes, Midwest Microbial Pathogenesis Conference, 9/2002.

Simons MP, Nauseef WM and Apicella MA. Survival of Neisseria gonorrhoeae within Human Polymorphonuclear Leukocytes, Midwest Microbial Pathogenesis Conference 10/2003.

Simons MP, Nauseef WM and Apicella MA. Neisseria gonorrhoeae Delays Apoptosis and Replicates within Polymorphonuclear Leukocytes. International Pathogenic Neisseria Conference, 9/20004.

Publications:

Simons MP, Nauseef WM, Griffith TS, Apicella MA. Neisseria gonorrhoeae delays the onset of apoptosis in polymorphonuclear leukocytes. Cell Microbiol. 2006 Nov;8(11):1780-90. Epub 2006 Jun 27. PubMed PMID: 16803582.

Seib KL, Simons MP, Wu HJ, McEwan AG, Nauseef WM, Apicella MA, Jennings MP. Investigation of oxidative stress defenses of Neisseria gonorrhoeae by using a human polymorphonuclear leukocyte survival assay. Infect Immun. 2005 Aug;73(8):5269-72. PubMed PMID: 16041054; PubMed Central PMCID: PMC1201195.

Simons MP, Nauseef WM, Apicella MA. Interactions of Neisseria gonorrhoeae with adherent polymorphonuclear leukocytes. Infect Immun. 2005 Apr;73(4):1971-7. PubMed PMID: 15784537; PubMed Central PMCID: PMC1087443.



Honors and Awards

  • Poster Presentation Award, Molecular Biology Retreat, Fall 2001. Poster Presentation Award, College
  • Teaching: General Microbiology, Spring 2001; Principles of Infectious Disease, Fall 2001; Dental Mi
  • Poster, Midwest Microbial Pathogenesis Conference, 10/01. Poster, International Pathogenic Neisser