Khatib, Sami

Background: Viral myocarditis presents a significant burden of disease, particularly among children and young adults. However, clinical guidelines and treatment strategies for pediatric patients are derived from those for adult patients due to a lack of pediatric data. Current animal models of viral myocarditis use adult mice, so conclusions from these models cannot necessarily be extrapolated to the pediatric population. We sought to develop a juvenile mouse model of myocarditis to examine differences between these two distinct clinical populations. Methods: Male and female BALB/c 3-4-week-old 'juvenile' and 8-week-old 'adult' mice were infected intraperitoneally with 103 PFU of heart-passaged coxsackievirus B3. Sera was used to evaluate testosterone and estradiol levels. Cardiac histological evaluations included overall inflammation, fibrosis, and specific cell-type infiltration. RNA was extracted from cardiac tissue and evaluated for changes in gene expression of cell-type markers, complement components, and NLRP3 inflammasome components. Results: Juvenile mice exhibited more severe inflammation than adult mice but no sex differences in overall inflammation. Juvenile mice demonstrated increased infiltration of CD11b+ cells, F4/80+ cells, and CD3+ T-cells vs. adults. Inflammasome genes NLRP3 and caspase-1 were significantly increased in juvenile compared with adult myocarditis. Conclusions: This paper is the first to describe a juvenile mouse model of coxsackievirus B3 myocarditis and provides a direct comparison to a translational adult mouse model. Juvenile mice had greater cardiac inflammation than adults. This model replicates clinical populations and provides a valuable tool to study age as a factor in the pathogenesis of myocarditis.

Abstract Background Radiation-induced heart disease (RIHD) may develop months to years following radiation therapy for cancers near the heart such as lung or breast cancer. Several mouse models of RIHD exist to study the pathogenesis of disease, but to our knowledge no studies have examined whether sex differences exist in RIHD in mice. Methods Female and male BALB/cJ mice received one whole heart dose of 22 Gray (Gy) radiation via a C5 collimator vs. sham controls that received 0 Gy, anesthesia and were placed in the X-ray machine for the same length of time. Mechanisms of cardiotoxicity were examined at 24 h (innate cardiotoxicity), day 10 (acute cardiotoxicity) and day 35 (chronic cardiotoxicity) post irradiation. Results Females and males developed dsDNA breaks from radiation at day 10 but females had more damage than males ( p < 0.001). Vessel area and cardiac hypertrophy were increased by radiation at day 10 and 35 but were higher in males than females at day 35 ( p < 0.001, p = 0.001, respectively). Bulk RNA sequencing of the heart at day 10 revealed that females and males developed similar gene pathway responses to radiation by upregulating cellular repair pathways and downregulated mitochondrial function. However, females upregulated the master regulator of mitochondrial function, Pgc1α ( p = 0.0001), suggesting improved mitochondrial repair in females. By day 35, males developed heart failure with reduced ejection fraction (HFrEF), inflammatory dilated cardiomyopathy (iDCM) and fibrosis while females developed heart failure with preserved ejection fraction (HFpEF) without inflammation or fibrosis. Conclusions We observed sex differences in nearly every cardiac parameter that we examined following radiation exposure. BALB/c males exposed to 22 Gy radiation developed HFrEF and iDCM by day 35 while females developed HFpEF. Further research is needed to better understand mechanisms driving sex differences in RIHD using translational animal models.

Abstract Objectives Patients with hypermobile Ehlers–Danlos syndrome (hEDS) and hypermobility spectrum disorders (HSD) experience a wide array of symptoms and system disorders. This study aimed to identify whether differences occurred in 115 self-reported symptoms and comorbidities in patients diagnosed with hEDS or HSD. Methods In this study we analysed self-reported data from an EDS Clinic intake questionnaire in patients diagnosed with hEDS, HSD or no hypermobile conditions. Results From 1 November 2019 to 7 March 2024, the EDS Clinic saw 2088 patients. Using the 2017 diagnostic criteria, 66.5% were diagnosed with HSD (n = 1389), 20.3% with hEDS (n = 423), 10.6% with historic HSD (H-HSD) or localized HSD (L-HSD) (n = 256) (hypermobile controls) and 2.6% were not diagnosed with hEDS, HSD, H-HSD or L-HSD (n = 55) (controls). Symptoms/comorbidities that occurred with high prevalence in both hEDS and HSD included joint pain (hEDS 82.0%, HSD 88.9%), allergy (hEDS 77.0%, HSD 77.0%), subluxations (hEDS 71.2%, HSD 72.6%), brain fog (hEDS 70.0%, HSD 74.7%), headache (hEDS 68.1%, HSD 69.1%), anxiety (hEDS 60.3%, HSD 69.3%), depression (hEDS 52.2%, HSD 58.0%), migraine (hEDS 53.7%, HSD 52.5%), nausea (hEDS 54.6%, HSD 59.5%) and constipation (hEDS 53.0%, HSD 57.2%). In contrast, 9/115 (8%) symptoms/comorbidities were self-reported significantly more often in hEDS but 42/115 (37%) in HSD. hEDS patients reported more symptoms that suggest a defect in collagen, such as dislocation, hernias and rectal prolapse, while HSD patients reported more joint, muscle, allergy, neurological, gastrointestinal, sleep and psychological symptoms/comorbidities. Conclusion Although we found an overlap in some symptoms and comorbidities self-reported by hEDS/HSD patients, such as allergy/atopy, headache/migraine and gastrointestinal symptoms, our findings suggest key differences exist between the two diagnoses, suggesting that hEDS and HSD may be distinct conditions.

Abstract Background Myocarditis is an inflammation of the heart muscle most often caused by an immune response to viral infections. Sex differences in the immune response during myocarditis have been well described but upstream mechanisms in the heart that might influence sex differences in disease are not completely understood. Methods Male and female BALB/c wild type mice received an intraperitoneal injection of heart-passaged coxsackievirus B3 (CVB3) or vehicle control. Bulk-tissue RNA-sequencing was conducted to better understand sex differences in CVB3 myocarditis. We performed enrichment analysis to understand sex differences in the transcriptional landscape of myocarditis and identify candidate transcription factors that might drive sex differences in myocarditis. Results The hearts of male and female mice with myocarditis were significantly enriched for pathways related to an innate and adaptive immune response compared to uninfected controls. When comparing females to males with myocarditis, males were enriched for inflammatory pathways and gene changes that suggested worse mitochondrial transcriptional support (e.g., mitochondrial electron transport genes). In contrast, females were enriched for pathways related to mitochondrial respiration and bioenergetics, which were confirmed by higher transcript levels of master regulators of mitochondrial function including peroxisome proliferator-activated receptor gamma coactivator 1 (PGC1α), nuclear respiratory factor 1 (NRF1) and estrogen-related receptor alpha (ERRα). TRANSFAC analysis identified ERRa as a transcription factor that may mediate sex differences in mitochondrial function during myocarditis. Conclusions Master regulators of mitochondrial function were elevated in females with myocarditis compared to males and may promote sex differences in mitochondrial respiratory transcript expression during viral myocarditis resulting in less severe myocarditis in females following viral infection.