Screening for potential adjuvants administered by the pulmonary route for tuberculosis vaccines.
Tuberculosis (TB) infects one third of the world's population, and new infections occur at a rate of 1/s. Better vaccines are needed than the live mycobacterium Bacille Calmette-Guérin (BCG). Alveolar macrophages (AMPhis) play a central role in pulmonary manifestations of TB. Targeting immunomodulators to AMPhis, the first line of defense against Mycobacterium tuberculosis (Mtb), may initiate a potent cell-mediated immune response. Muramyl dipeptide (MDP) and trehalose dibehenate (TDB) have elicited strong immune response when delivered to the lungs as aerosols. AMPhis show toxicity in response to some immunomodulators. The objective of this work was to screen the immunomodulators MDP and/or TDB encapsulated in microparticles (MPs) and to evaluate certain indicators of toxicity in human AMPhi-like cells. Poly(lactide-co-glycolide) (PLGA) MPs containing MDP and/or TDB were prepared by spray-drying. The morphology, particle size distribution, and immunomodulator encapsulation efficiency of MPs were examined. THP-1 cells were exposed to these MPs for 24 h and characteristics of cell morphology, tumor necrosis factor-alpha (TNF-alpha) release, lactate dehydrogenase (LDH), N-acetyl-beta-D: -glucosaminidase (NAG) and alkaline phosphatase (ALP) activity in AMPhi culture supernatants were measured. MTT assay was used to assess the viability of cells. Spray-drying produced low-density MPs having volume median diameters between 4 and 6 microm as measured by laser diffraction and projected area diameter between 3 and 5 microm calculated by microscopy. More TNF-alpha was produced by THP-1 cells exposed to MPs composed of PLGA-MDP or PLGA alone than PLGA-TDB. LDH release following exposure to MPs of PLGA-MDP and PLGA alone was greater than controls. NAG release was higher following exposure to MPs of PLGA alone or PLGA-MDP 0.1% than PLGA-TDB (0.1% and 1.0%). Cells remained viable after exposure to MPs as per MTT assay. PLGA-MDP MPs demonstrated statistically elevated indicators of biochemical responses in cell culture compared to PLGA-TDB MPs, but the extent of their potential to elicit adverse effects in vivo must be studied independently.
Wang
Chenchen
C
Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Kerr Hall, Campus Box #7360, Room #1310, Chapel Hill, North Carolina 27599, USA.
Muttil
Pavan
P
Lu
Dongmei
D
Beltran-Torres
Adela Ayulia
AA
Garcia-Contreras
Lucila
L
Hickey
Anthony J
AJ
D000119:Acetylmuramyl-Alanyl-Isoglutamine / Q000008:administration & dosage* / Q000276:immunology; D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D000818:Animals; D002460:Cell Line; D002470:Cell Survival; D004339:Drug Compounding; D055808:Drug Discovery; D006801:Humans; D019344:Lactic Acid; D008262:Macrophage Activation / Q000187:drug effects; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000201:enzymology / Q000502:physiology / Q000648:ultrastructure; D051379:Mice; D008855:Microscopy, Electron, Scanning; D009000:Monocytes / Q000187:drug effects / Q000201:enzymology / Q000648:ultrastructure; D010316:Particle Size; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D014199:Trehalose; D032581:Tuberculosis Vaccines / Q000008:administration & dosage*
D000276:Adjuvants, Immunologic; D032581:Tuberculosis Vaccines; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D000119:Acetylmuramyl-Alanyl-Isoglutamine; D014199:Trehalose