IL-13 protects from C. difficile Colitis

OBJECTIVES

Clostridioides difficile infection (CDI) is the leading hospital-acquired infection in North America. We have previously discovered that antibiotic disruption of the gut microbiota decreases intestinal IL-33 and IL-25 and increases susceptibility to CDI. We further found that IL-33 promotes protection through type 2 Innate Lymphoid Cells (ILC2s), which produce IL-13. However, the contribution of IL-13 to disease has never been explored.

METHODS

We used a validated model of CDI in mice, in which we neutralized via blocking antibodies, or administered recombinant protein, IL-13 to assess the role of this cytokine during infection using weight and clinical scores. Fluorescent activated cell sorting (FACS) was used to characterize myeloid cell population changes in response to IL-13 manipulation.

RESULTS

We found that administration of IL-13 protected, and anti-IL-13 exacerbated CDI. Additionally, we observe alterations to the monocyte/macrophage cells following neutralization of IL-13 as early as day three post infection. We also observed elevated accumulation of myeloid cells by day four post-infection following IL-13 neutralization. Neutralization of the decoy receptor, IL-13Rα2, resulted in protection from disease, likely through increased available endogenous IL-13.

CONCLUSIONS

Our data highlight the protective role of IL-13 in protecting from more severe CDI and the association of poor responses with a dysregulated monocyte-macrophage compartment. These results increase our understanding of type 2 immunity in CDI and may have implications for treating disease in patients.

Enantiomeric separation of metoprolol and alpha-hydroxymetoprolol by liquid chromatography and fluorescence detection using a chiral stationary phase

A sensitive and stereoselective high-performance liquid chromatographic assay for the determination of the enantiomers of metoprolol (R- and S-) and the diastereoisomers of alpha-hydroxymetoprolol (IIA, IIB) in plasma is reported. Chromatography involved direct separation of enantiomers using a Chirobiotic T bonded phase column (250 x 4.6 mm) and a mobile phase consisting of acetonitrile-methanol-methylene chloride-glacial acetic acid-triethylamine (56:30:14:2:2, v/v). Solid-phase extraction using silica bonded with ethyl group (C2) was used to extract the compounds of interest from plasma and atenolol was used as the internal standard. The column effluent was monitored using fluorescence detection with excitation and emission wavelengths of 225 and 310 nm, respectively. S-Metoprolol, R-metoprolol, IIB and IIA eluted at about 5.9, 6.7, 7.3 and 8.2 min without any interfering peaks. The calibration curve was linear over the range of 0.5 to 100 ng/ml for each isomer of metoprolol and 1 to 100 ng/ml for each isomer of alpha-hydroxymetoprolol (IIA & IIB). The mean intra-run accuracies were in the range of 96.2 to 114% for R-metoprolol, 94.0 to 111% for S-metoprolol, 90.2 to 110% for IIA, and 94.6 to 106% for IIB. The mean intra-run precisions were all in the range of 2.2 to 12.0% for R-metoprolol, 2.1 to 11.1% for S-metoprolol, 1.9 to 14.5% for IIA, and 3.2 to 11.0% for IIB. The lowest level of quantitation for the enantiomers of metoprolol was 0.5 ng/ml and 1.0 ng/ml for alpha-hydroxymetoprolol (IIA and IIB). The absolute recoveries for each analyte was > or = 95%. The validated method accurately quantitated the enantiomers of parent drug and metabolite after a single dose of an extended release metoprolol formulation.

Identification of formulation and manufacturing variables that influence in vitro dissolution and in vivo bioavailability of propranolol hydrochloride tablets

The purpose of this study was to evaluate the effect of formulation and processing changes on the dissolution and bioavailability of propranolol hydrochloride tablets. Directly compressed blends of 6 kg (20,000 units) were prepared by mixing in a 16-qt V blender and tablets were compressed on an instrumented Manesty D3B tablet press. A half-factorial (2(5-1), Resolution V) design was used to study the following variables: filler ratio (lactose/dicalcium phosphate), sodium starch glycolate level, magnesium stearate level, lubricant blend time, and compression force. The levels and ranges of the excipients and processing changes studied represented level 2 or greater changes as indicated by the Scale-up and Post Approval Changes (SUPAC-IR) Guidance. Changes in filler ratio, disintegrant level, and compression force were significant in affecting percent drug released (Q) in 5 min (Q5) and Q10. However, changes in magnesium stearate level and lubricant blend time did not influence Q5 and Q10. Hardness was found to be affected by changes in all of the variables studied. Some interaction effects between the variables studied were also found to be significant. To examine the impact of formulation and processing variables on in vivo absorption, three batches were selected for a bioavailability study based on their dissolution profiles. Thirteen subjects received four propranolol treatments (slow-, medium-, and fast-dissolving formulations and Inderal 80 mg) separated by 1 week washout according to a randomized crossover design. The formulations were found to be bioequivalent with respect to the log Cmax and log AUC0-infinity. The results of this study suggest that (i) bioavailability/bioequivalency studies may not be necessary for propranolol and perhaps other class 1 drugs after level 2 type changes, and (ii) in vitro dissolution tests may be used to show bioequivalence of propranolol formulations with processing or formulation changes within the specified level 2 ranges examined.