HLA-DRB1*1501 and VDR Polymorphisms and Survival of Mycobacterium Tuberculosis in Human Macrophages Exposed to Inhalable Microparticles

Abstract

Aim: We examined whether HLA-DRB1*1501 and four VDR SNPs influence the macrophage response to infection with Mycobacterium tuberculosis (Mtb) via innate immune versus drug treatment or drug delivery mechanisms. Materials & methods: Monocyte-derived macrophages from 24 healthy donors were infected with Mtb in vitro . Survival of intracellular bacilli and secretion of cytokines and nitric oxide by the infected cells were monitored with and without exposure to isoniazid and rifabutin. Results: Haplotype analysis was conducted, and an arbitrary score of genetic ‘susceptibility‘ (S ) score ranging from -3 to +3 was assigned to donors based on the presence or absence of genetic markers. S scores correlated more strongly with Mtb survival (r = 0.68) than TNF and nitric oxide (NO; r = ∼0.01–0.11). A specific haplotype was significantly associated with decreased Mtb survival (p < 0.05), increased NO and decreased IL-10/IL-4. Macrophages with S scores ≥ 2 secreted significantly (p < 0.05) more IL-10 and IL-4, and less NO upon infection, and supported Mtb survival. Microparticulate drugs showed higher bactericidal activity than free drugs, irrespective of S score. Conclusion:S score predicts colonization of macrophages by Mtb, as does haplotype analysis. Drug-containing microparticles are superior to free drugs across diverse genetic backgrounds.

Original submitted 12 June 2012; Revision submitted 4 January 2013

KEYWORDS::

• cytokines
• haplotype
• HLA
• microspheres
• nitric oxide
• PCR
• RFLP
• SNPs
• VDR

Financial & competing interests disclosure

Funded by the Council of Scientific and Industrial Research, India, through Project Numbers NWP0035 and BSC0112, this is CDRI Publication Number 8403. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Ethical conduct of research

The authors state that they have obtained appropriate institutional review board approval or have followed the principles outlined in the Declaration of Helsinki for all human or animal experimental investigations. In addition, for investigations involving human subjects, informed consent has been obtained from the participants involved.

Additional information

Funding

unded by the Council of Scientific and Industrial Research, India, through Project Numbers NWP0035 and BSC0112, this is CDRI Publication Number 8403. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials dis-cussedin the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript.