Poster - Bacterial capnine blocks transcription of human antimicrobial peptides

Type: Poster presentation
Presented by: Trevor Marshall, PhD
Conference: Third International Conference on Metagenomics
Location: University of California, San Diego
Date: July 11-13, 2007
Additional content: poster (includes a number of Wirostko photographs); post at Nature Precedings


The US CDC believes that 65% of all infections in developed countries may be caused by pathogens in biofilms A structured community of microorganisms encapsulated within a self-developed protective matrix and living together.. Electron Microscopy has shown that these bacterial communities can evade phagocytosis, and persist in the cytoplasm of monocytes, macrophages, lymphocytes and neutrophils. Three decades ago, Wirostko, et al, found such intraphagocytic communities in Crohn’s disease, Juvenile Rheumatoid Arthritis and Sarcoidosis1). However, the mechanism(s) by which such persistent bacteria could evade the immune system have remained elusive. Recently, 16S RNA from species of gliding bacteria never thought to be able to survive in-vivo, have been found in surgically removed biofilms.2) This study set out to identify whether the genomes of these gliding bacteria might yield insight into mechanisms by which such persistent pathogens could evade phagocytosis.


A single Type 1 Nuclear ReceptorIntracellular receptor proteins that bind to hydrophobic signal molecules (such as steroid and thyroid hormones) or intracellular metabolites and are thus activated to bind to specific DNA sequences which affects transcription., the VDRThe Vitamin D Receptor. A nuclear receptor located throughout the body that plays a key role in the innate immune response. (commonly known as the ‘Vitamin D ReceptorA nuclear receptor located throughout the body that plays a key role in the innate immune response.’), is responsible for transcription of LL-37, the human Cathelicidin Family of antimicrobial peptides found primarily in immune cells and transcribed by the Vitamin D Receptor. antimicrobial peptide, as well as the beta Defensin anti-microbial peptides defB2/defB43). Disabling transcription by the VDR would allow a pathogen to persist inside phagocytes without threat from these anti-microbial peptides. Static molecular modeling (primarily using AutoDock) was used to screen a number of proteins and peptides known to be produced by the genomes of the gliding bacteria.


A candidate bacterial sulfonolipid, Capnine, was identified to have a nanomolar Ki for the ligand binding pocket (LBP) of the VDR. Molecular Dynamics simulation of the human VDR in complex with Capnine confirmed that this substance is indeed stable in the VDR LBP, and that its action is that of a strong transcriptional antagonist.


Medical Metagenomics has demonstrated the ability to deliver important results in silicoExperiment technique performed on computer or via computer emulation., potentially underpinning an infectious pathogenesis for idiopathicnic illness.4)5)


Wirostko E, Johnson LA, Wirostko BM, Farris RL. Mycoplasma-like organisms and ophthalmic disease. Trans Am Ophthalmol Soc. 1993;91:85-94; discussion 95-8.
[PMID: 8140710] [PMCID: 1298461]
Dempsey KE, Riggio MP, Lennon A, Hannah VE, Ramage G, Allan D, Bagg J. Identification of bacteria on the surface of clinically infected and non-infected prosthetic hip joints removed during revision arthroplasties by 16S rRNA gene sequencing and by microbiological culture. Arthritis Res Ther. 2007;9(3):R46. doi: 10.1186/ar2201.
[PMID: 17501992] [PMCID: 2206354] [DOI: 10.1186/ar2201]
Wang T, Tavera-Mendoza LE, Laperriere D, Libby E, MacLeod NB, Nagai Y, Bourdeau V, Konstorum A, Lallemant B, Zhang R, Mader S, White JH. Large-scale in silico and microarray-based identification of direct 1,25-dihydroxyvitamin D3 target genes. Mol Endocrinol. 2005 Nov;19(11):2685-95. doi: 10.1210/me.2005-0106. Epub 2005 Jul 7.
[PMID: 16002434] [DOI: 10.1210/me.2005-0106]
Waterhouse JC, Marshall TG, Fenter B, Mangin M, Blaney G: High levels of active 1,25-dihydroxyvitamin DPrimary biologically active vitamin D hormone. Activates the vitamin D nuclear receptor. Produced by hydroxylation of 25-D. Also known as 1,25-dihydroxycholecalciferol, 1,25-hydroxyvitamin D and calcitirol. despite low levels of the 25-hydroxyvitamin D precursor - Implications of dysregulated vitamin D for diagnosis and treatment of Chronic Disease. In Vitamin D: New Research. Volume 1. Edited by: Stoltz VD. New York: Nova Science Publishers; 2006. ISBN: 1-60021-000-7
Marshall TG: VDR Nuclear Receptor Competence is the Key to Recovery from Chronic Inflammatory and AutoimmuneA condition or disease thought to arise from an overactive immune response of the body against substances and tissues normally present in the body Disease. Abstract presentation, DMM2006, Karolinska Institute, May 2006. Copy available from URL https://autoimmunityresearch.org/karolinska-handout.pdf
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