Knock-in mouse models for CMTX1 show a loss of function phenotype in the peripheral nervous system

The X-linked form of Charcot-Marie-Tooth disease (CMTX1) is the second most common form of CMT. In this study we used CRISPR/Cas9 to develop new "knock-in" models of CMTX1 that are more representative of the spectrum of mutations seen with CMTX1 than the Cx32 knockout (KO) mouse model used previously. We compared mice of four genotypes - wild-type, Cx32KO, p.T55I, and p.R75W. Sciatic motor conduction velocity slowing was the most robust electrophysiologic indicator of neuropathy, showing reductions in the Cx32KO by 3 months and in the p.T55I and p.R75W mice by 6 months. At both 6 and 12 months, all three mutant genotypes showed reduced four limb and hind limb grip strength compared to WT mice. Performance on 6 and 12 mm width balance beams revealed deficits that were most pronounced at on the 6 mm balance beam at 6 months of age. There were pathological changes of myelinated axons in the femoral motor nerve in all three mutant lines by 3 months of age, and these became more pronounced at 6 and 12 months of age; sensory nerves (femoral sensory and the caudal nerve of the tail) appeared normal at all ages examined. Our results demonstrate that mice can be used to show the pathogenicity of human GJB1 mutations, and these new models for CMTX1 should facilitate the preclinical work for developing treatments for CMTX1.

Molecular and cellular pathogenesis of endothelial lining in atrial fibrillation

INTRODUCTION

Atrial Fibrillation (AF) is a cardiac arrhythmia that is caused by a miscoordination between the heart's upper and lower chambers. von Willebrand Factor (vWF) is a glycoprotein that aids the formation of blood clots by helping platelets adhere to the blood vessels and to one another. Once a blood clot begins to break down, it releases a protein fragment known as D-Dimer. Due to the nature of its production, D-Dimer levels can often be used as an indicator for the presence of a blood clot in the circulatory system. Interleukin-6 (IL-6) is a cytokine that helps regulate immune response. It is produced by monocytes and macrophages in response to an infection or a tissue injury.

PURPOSE

The aim of this research was to analyze how levels of biomarkers of inflammation and thrombosis vary between AF patients and a normal human plasma group (NHP).

HYPOTHESIS

Biomarkers of inflammation and thrombosis are present at higher levels in AF patients when compared to an NHP group.

MATERIALS AND METHODS

The AF samples (n=53) were collected following the IRB protocols at Loyola University Medical Center and Loyola Heart & Vascular clinics, while the NHP group blood samples (n=48) were obtained from a centralized blood bank known as George King Biomedical (Overland Park, Kansas). vWF, D-Dimer, and IL-6 levels were measured in both the AF group and the NHP using commercially available sandwich ELISA kits.

STATISTICAL ANALYSIS

The biomarker levels were analyzed using PRISM GraphPad, IBM Statistical Package for Social Sciences (SPSS), and Microsoft Excel for important statistical characteristics, including mean, median, mode, standard error of the mean (SEM), standard deviation, minimum, maximum, and interquartile range. In addition, tests for normal distribution, quartile analysis, unpaired t-tests, skewness, correlation analysis, and Mann-Whitney tests were conducted. Lastly, the data was broken down into every tenth percentile to assess the distribution of the data.

RESULTS

The data was organized using the following format: Mean ± SEM. When all the biomarkers were compared, there was no significant correlation between the three (all correlations were positive with r-values below 0.2); however, they all showed an upregulation in the AF group when compared to the NHP group. For vWF, there was a 6663.785% increase in the AF group (AF 4796.200 ± 286.155 vs. NHP 70.910 ± 7.268). For D-Dimer there was a 386.549% increase in the AF group (AF 913.379 ± 125.634 vs. NHP 187.726 ± 31.320). Lastly, for IL-6 there was a 253.002% increase in the AF group (AF 4.409 ± 1.125 vs. NHP 1.249 ± 0.178). Furthermore, when the statistical significances between the biomarkers and the NHP group were analyzed, it was found that all three data groups held a p-value less than 0.05 (<0.001 for vWF, <0.001 for D-Dimer, and 0.0087 for IL-6), deeming the data statistically significant and thus the null hypothesis is rejected for all three data sets.

CONCLUSION

The above research supports the hypothesis that there will be an upregulation in biomarkers of inflammation and thrombosis (vWF, D-Dimer, IL-6) in AF patients.