Effect of colchicine on the murine immune response induced by Aggregatibacter actinomycetemcomitans

Host-directed antimycobacterial activity of colchicine, an anti-gout drug, via strengthened host innate resistance reinforced by the IL-1β/PGE2 axis

BACKGROUND AND PURPOSE

To diversify and expand possible tuberculosis (TB) drug candidates and maximize limited global resources, we investigated the effect of colchicine, an FDA-approved anti-gout drug, against Mycobacterium tuberculosis (Mtb) infection because of its immune-modulating effect.

EXPERIMENTAL APPROACH

We evaluated the intracellular anti-Mtb activity of different concentrations of colchicine in murine bone marrow-derived macrophages (BMDMs). To elucidate the underlying mechanism, RNA sequencing, biological and chemical inhibition assays, and Western blot, quantitative real-time PCR, enzyme-linked immunosorbent assay (ELISA) and immunohistochemical analyses were employed. Finally, type I interferon-dependent highly TB-susceptible A/J mice were challenged with virulent Mtb H37Rv, and the host-directed therapeutic effect of oral colchicine administration on bacterial burdens and lung inflammation was assessed 30 days post-infection (2.5 mg·kg^-1 every two days).

KEY RESULTS

Colchicine reinforced the anti-Mtb activity of BMDMs without affecting cell viability, indicating that colchicine facilitated macrophage immune activation upon Mtb infection. The results from RNA sequencing, NLRP3 knockout BMDM, IL-1 receptor blockade, and immunohistochemistry analyses revealed that this unexpected intracellular anti-Mtb activity of colchicine was mediated through NLRP3-dependent IL-1β signalling and Cox-2-regulated PGE₂ production in macrophages. Consequently, the TB-susceptible A/J mouse model showed remarkable protection, with decreased bacterial loads in both the lungs and spleens of oral colchicine-treated mice, with significantly elevated Cox-2 expression at infection sites.

CONCLUSIONS AND IMPLICATIONS

The repurposing of colchicine against Mtb infection in this study highlights its unique function in macrophages upon Mtb infection and its novel potential use in treating TB as host-directed or adjunctive therapy.

COlchicine to Prevent PeriprocEdural myocardial Injury in Percutaneous Coronary Intervention (COPE-PCI): A descriptive cytokine pilot sub-study

BACKGROUND

High levels of inflammation pre- and post-percutaneous coronary intervention (PCI) are associated with worse outcomes. Recent trials have suggested a benefit from treating inflammation with colchicine in coronary artery disease. In this randomised pilot COPE-PCI sub-study, we aimed to determine if administration of colchicine pre-PCI, would attenuate the inflammatory effect of PCI.

METHODS

PCI patients were randomised to colchicine or placebo, 6 to 24-hours pre-procedure. Study blood samples were taken immediately pre-PCI, and 24-hours post-procedure. Samples were tested for a broad array of inflammatory biomarkers including high-sensitive(hs)-CRP, leucocyte counts, and hs-troponin-. Periprocedural Myocardial Injury (PM-Injury) was defined as per the ESC Third Universal Definitions of Myocardial Infarction.

RESULTS

Thirty-six were randomised to colchicine and 39 to placebo. Treatment groups were similar for baseline variables. The median time from drug administration to pre-PCI blood sampling was 18-hours. Overall inflammation was low across the patient population, pre- & post-PCI hsCRP was <1.4 mg/L. Colchicine patients had numerically lower levels of pre-PCI cytokines: IL-1β (p = 0.01), IL-6 (p = 0.02), IL-10 (p = 0.01), IFNγ (p = 0.01), TNFα (p = 0.02) and WBC-count (p = 0.04). Post-PCI (38-hours post-drug) measures of inflammation were similar between treatment arms. Absolute troponin change (post-PCI - pre-PCI levels) was less in colchicine patients (p = 0.02).

CONCLUSION

The reduction in PCI-related myocardial injury that resulted from colchicine given on median 18 h pre-PCI, was associated with numerically lower levels of inflammation pre-PCI but no difference one day post-PCI in the colchicine vs placebo groups.

CLINICAL TRIAL REGISTRATION

The trial was publicly registered at www.anzctr.org.au, Trial ID: ACTRN12615000485538.

Effects of colchicine on gingival inflammation, apoptosis, and alveolar bone loss in experimental periodontitis

BACKGROUND

The aim of the study was to investigate the effects of colchicine on cytokine production, apoptosis, alveolar bone loss, and oxidative stress in an experimental model of periodontitis in rats.

METHODS

Forty-eight rats were divided equally into four groups: healthy (H); periodontitis (P); periodontitis+colchicine low dose (CL, 30 μg/kg/day), and periodontitis+colchicine high dose (CH, 100 μg/kg/day). After 11 days, interleukin (IL) -1β, IL-8, and IL-10 were analyzed in gingival samples using Enzyme-Linked ImmunoSorbent Assay. Receptor activator of nuclear factor kappa-B ligand (RANKL), osteoprotegerin (OPG), total oxidative stress (TOS), total antioxidant status (TAS), and oxidative stress index (OSI) were measured in gingiva and serum. Alveolar bone volume was evaluated via micro-CT. Apoptotic cells were detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay in histological sections.

RESULTS

Colchicine treatment significantly reduced IL-1β, IL-8, RANKL, RANKL/OPG, TOS, OSI, and bone volume ratio levels, and increased TAS levels compared to group P (p < 0.05). High dose colchicine treatment (CH) significantly decreased TUNEL+ cell counts compared to group P (p < 0.05).

CONCLUSIONS

These finding suggest that colchicine has a prophylactic potential for the prevention of periodontal tissue destruction through anti-inflammatory, anti-oxidative, anti-apoptotic, and bone-protective effects.