title: Clofazimine Biocrystal Accumulation in Macrophages Upregulates Interleukin 1 Receptor Antagonist Production To Induce a Systemic Anti-Inflammatory State.
abstract: Clofazimine (CFZ) is a poorly soluble antibiotic and anti-inflammatory drug indicated for the treatment of leprosy. In spite of its therapeutic value, CFZ therapy is accompanied by the formation of drug biocrystals that accumulate within resident tissue macrophages, without obvious toxicological manifestations. Therefore, to specifically elucidate the off-target consequences of drug bioaccumulation in macrophages, we compared the level of inflammasome activation in CFZ-accumulating organs (spleen, liver and lung) in mice after 2 and 8 weeks of CFZ treatment when the drug exists in soluble and insoluble (biocrystalline) forms, respectively. Surprisingly, the results showed a drastic reduction in caspase 1 and interleukin-1β (IL-1β) cleavage in the livers of mice treated with CFZ for 8 weeks (8-week-CFZ-treated mice) compared to 2-week-CFZ-treated and control mice, which was accompanied by a 3-fold increase in hepatic IL-1 receptor antagonist (IL-1RA) production and a 21-fold increase in serum IL-1RA levels. In the lung and spleen, IL-1β cleavage and tumor necrosis factor alpha expression were unaffected by soluble or biocrystal CFZ forms. Functionally, there was a drastic reduction of carrageenan- and lipopolysaccharide-induced inflammation in the footpads and lungs, respectively, of 8-week-CFZ-treated mice. This immunomodulatory activity of CFZ biocrystal accumulation was attributable to the upregulation of IL-1RA, since CFZ accumulation had minimal effect in IL-1RA knockout mice or 2-week-CFZ-treated mice. In conclusion, CFZ accumulation and biocrystal formation in resident tissue macrophages profoundly altered the host's immune system and prompted an IL-1RA-dependent, systemic anti-inflammatory response.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Gi S
authors.initials: GS
authors.lastname: Yoon
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Rahul K
authors.initials: RK
authors.lastname: Keswani
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Sudha
authors.initials: S
authors.lastname: Sud
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Rzeczycki
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Mikhail D
authors.initials: MD
authors.lastname: Murashov
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Tony A
authors.initials: TA
authors.lastname: Koehn
authors.affiliation: Department of Internal Medicine, University of Michigan Medical Center, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Theodore J
authors.initials: TJ
authors.lastname: Standiford
authors.affiliation: Department of Clinical Pharmacy, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Kathleen A
authors.identifier: 0000-0003-0238-7774
authors.initials: KA
authors.lastname: Stringer
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA grosania@umich.edu.
authors.forename: Gus R
authors.initials: GR
authors.lastname: Rosania
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D002351:Carrageenan; D020170:Caspase 1 / Q000378:metabolism; D002991:Clofazimine / Q000494:pharmacology*; D058847:Inflammasomes / Q000276:immunology*; D007249:Inflammation / Q000188:drug therapy; D053577:Interleukin-1 Receptor Accessory Protein / Q000096:biosynthesis* / Q000235:genetics; D053583:Interleukin-1beta / Q000378:metabolism; D008070:Lipopolysaccharides; D008099:Liver / Q000378:metabolism; D008168:Lung / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D015398:Signal Transduction / Q000276:immunology; D013154:Spleen / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000893:Anti-Inflammatory Agents; C587672:IL1B protein, mouse; C507767:Il1rap protein, mouse; D058847:Inflammasomes; D053577:Interleukin-1 Receptor Accessory Protein; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D002351:Carrageenan; D002991:Clofazimine; D020170:Caspase 1