Protein Tyrosine Phosphatase Non-Receptor 11 (PTPN11/Shp2) as a Driver Oncogene and a Novel Therapeutic Target in Non-Small Cell Lung Cancer (NSCLC).

PTPN11 encodes the SHP2 protein tyrosine phosphatase that activates the mitogen-activated protein kinase (MAPK) pathway upstream of KRAS and MEK. PTPN11/Shp2 somatic mutations occur frequently in Juvenile myelomonocytic leukaemia (JMML); however, the role of mutated PTPN11 in lung cancer tumourigenesis and its utility as a therapeutic target has not been fully addressed. We applied mass-spectrometry-based genotyping to DNA extracted from the tumour and matched the normal tissue of 356 NSCLC patients (98 adenocarcinomas (LUAD) and 258 squamous cell carcinomas (LUSC)). Further, PTPN11 mutation cases were identified in additional cohorts, including TCGA, Broad, and MD Anderson datasets and the COSMIC database. PTPN11 constructs harbouring PTPN11 E76A, A72D and C459S mutations were stably expressed in IL-3 dependent BaF3 cells and NSCLC cell lines (NCI-H1703, NCI-H157, NCI-H1299). The MAPK and PI3K pathway activation was evaluated using Western blotting. PTPN11/Shp2 phosphatase activity was measured in whole-cell protein lysates using an Shp2 assay kit. The Shp2 inhibitor (SHPi) was assessed both in vitro and in vivo in a PTPN11-mutated cell line for improved responses to MAPK and PI3K targeting therapies. Somatic PTPN11 hotspot mutations occurred in 4/98 (4.1%) adenocarcinomas and 7/258 (2.7%) squamous cells of 356 NSCLC patients. Additional 26 PTPN11 hotspot mutations occurred in 23 and 3 adenocarcinomas and squamous cell carcinoma, respectively, across the additional cohorts. Mutant PTPN11 significantly increased the IL-3 independent survival of Ba/F3 cells compared to wildtype PTPN11 (p < 0.0001). Ba/F3, NCI-H1703, and NCI-H157 cells expressing mutant PTPN11 exhibited increased PTPN11/Shp2 phosphatase activity and phospho-ERK1/2 levels compared to cells expressing wildtype PTPN11. The transduction of the PTPN11 inactivating mutation C459S into NSCLC cell lines led to decreased phospho-ERK, as well as decreased phospho-AKT in the PTPN11-mutated NCI-H661 cell line. NCI-H661 cells (PTPN11-mutated, KRAS-wild type) were significantly more sensitive to growth inhibition by the PI3K inhibitor copanlisib (IC50: 13.9 ± 4.7 nM) compared to NCI-H1703 (PTPN11/KRAS-wild type) cells (IC50: >10,000 nM). The SHP2 inhibitor, in combination with the PI3K targeting therapy copanlisib, showed no significant difference in tumour development in vivo; however, this significantly prevented MAPK pathway induction in vitro (p < 0.0001). PTPN11/Shp2 demonstrated the in vitro features of a driver oncogene and could potentially sensitize NSCLC cells to PI3K inhibition and inhibit MAPK pathway activation following PI3K pathway targeting.

Use of exhaled breath condensate (EBC) in the diagnosis of SARS-COV-2 (COVID-19).

False negatives from nasopharyngeal swabs (NPS) using reverse transcriptase PCR (RT-PCR) in SARS-CoV-2 are high. Exhaled breath condensate (EBC) contains lower respiratory droplets that may improve detection. We performed EBC RT-PCR for SARS-CoV-2 genes (E, S, N, ORF1ab) on NPS-positive (n=16) and NPS-negative/clinically positive COVID-19 patients (n=15) using two commercial assays. EBC detected SARS-CoV-2 in 93.5% (29/31) using the four genes. Pre-SARS-CoV-2 era controls (n=14) were negative. EBC was positive in NPS negative/clinically positive patients in 66.6% (10/15) using the identical E and S (E/S) gene assay used for NPS, 73.3% (11/15) using the N/ORF1ab assay and 14/15 (93.3%) combined.

Characterization of the Inflammatory Response to Severe COVID-19 Illness.

Rationale: Coronavirus disease (COVID-19) is a global threat to health. Its inflammatory characteristics are incompletely understood.Objectives: To define the cytokine profile of COVID-19 and to identify evidence of immunometabolic alterations in those with severe illness.Methods: Levels of IL-1ß, IL-6, IL-8, IL-10, and sTNFR1 (soluble tumor necrosis factor receptor 1) were assessed in plasma from healthy volunteers, hospitalized but stable patients with COVID-19 (COVIDstable patients), patients with COVID-19 requiring ICU admission (COVIDICU patients), and patients with severe community-acquired pneumonia requiring ICU support (CAPICU patients). Immunometabolic markers were measured in circulating neutrophils from patients with severe COVID-19. The acute phase response of AAT (alpha-1 antitrypsin) to COVID-19 was also evaluated.Measurements and Main Results: IL-1ß, IL-6, IL-8, and sTNFR1 were all increased in patients with COVID-19. COVIDICU patients could be clearly differentiated from COVIDstable patients, and demonstrated higher levels of IL-1ß, IL-6, and sTNFR1 but lower IL-10 than CAPICU patients. COVID-19 neutrophils displayed altered immunometabolism, with increased cytosolic PKM2 (pyruvate kinase M2), phosphorylated PKM2, HIF-1α (hypoxia-inducible factor-1α), and lactate. The production and sialylation of AAT increased in COVID-19, but this antiinflammatory response was overwhelmed in severe illness, with the IL-6:AAT ratio markedly higher in patients requiring ICU admission (P < 0.0001). In critically unwell patients with COVID-19, increases in IL-6:AAT predicted prolonged ICU stay and mortality, whereas improvement in IL-6:AAT was associated with clinical resolution (P < 0.0001).Conclusions: The COVID-19 cytokinemia is distinct from that of other types of pneumonia, leading to organ failure and ICU need. Neutrophils undergo immunometabolic reprogramming in severe COVID-19 illness. Cytokine ratios may predict outcomes in this population.

The Royal College of surgeons multidisciplinary guidelines on elective tracheostomy insertion in COVID-19 ventilated patients.

BACKGROUND: The current COVID-19 pandemic has placed enormous strain on healthcare systems worldwide. Understanding of COVID-19 is rapidly evolving. Pneumonia associated with COVID-19 may lead to respiratory failure requiring mechanical ventilation. The rise in patients requiring mechanical ventilation may lead to an increase in tracheostomies being performed in patients with COVID-19. Performing tracheostomy in patients with active SARS-CoV-2 infection poses a number of challenges. METHODS: These guidelines were written following multidisciplinary agreement between Otolaryngology, Head and Neck Surgery, Respiratory Medicine and the Department of Anaesthetics and Critical Care Medicine in the Royal College of Surgeons in Ireland. A literature review was performed and a guideline for elective tracheostomy insertion in patients with COVID-19 proposed. CONCLUSION: The decision to perform tracheostomy in patients with COVID-19 should be undertaken by senior members of the multidisciplinary team. Steps should be taken to minimise risks to healthcare workers.

Achieving Thoracic Oncology data collection in Europe: a precursor study in 35 Countries.

BACKGROUND: A minority of European countries have participated in international comparisons with high level data on lung cancer. However, the nature and extent of data collection across the continent is simply unknown, and without accurate data collection it is not possible to compare practice and set benchmarks to which lung cancer services can aspire. METHODS: Using an established network of lung cancer specialists in 37 European countries, a survey was distributed in December 2014. The results relate to current practice in each country at the time, early 2015. The results were compiled and then verified with co-authors over the following months. RESULTS: Thirty-five completed surveys were received which describe a range of current practice for lung cancer data collection. Thirty countries have data collection at the national level, but this is not so in Albania, Bosnia-Herzegovina, Italy, Spain and Switzerland. Data collection varied from paper records with no survival analysis, to well-established electronic databases with links to census data and survival analyses. CONCLUSION: Using a network of committed clinicians, we have gathered validated comparative data reporting an observed difference in data collection mechanisms across Europe. We have identified the need to develop a well-designed dataset, whilst acknowledging what is feasible within each country, and aspiring to collect high quality data for clinical research.

Eosinophil recruitment to nasal nerves after allergen challenge in allergic rhinitis.

In allergen challenged animal models, eosinophils localize to airway nerves leading to vagally-mediated hyperreactivity. We hypothesized that in allergic rhinitis eosinophils recruited to nasal nerves resulted in neural hyperreactivity. Patients with persistent allergic rhinitis (n=12), seasonal allergic rhinitis (n=7) and controls (n=10) were studied. Inferior nasal turbinate biopsies were obtained before, 8 and 48h after allergen challenge. Eight hours after allergen challenge eosinophils localized to nerves in both rhinitis groups; this was sustained through 48h. Bradykinin challenge, with secretion collection on the contralateral side, was performed to demonstrate nasal nerve reflexes. Twenty fourhours after allergen challenge, bradykinin induced a significant increase in secretions, indicating nasal hyperreactivity. Histological studies showed that nasal nerves expressed both vascular cell adhesion molecule-1 (VCAM-1) and chemokine (C-C motif) ligand 26 (CCL-26). Hence, after allergen challenge eosinophils are recruited and retained at nerves and so may be a mechanism for neural hyperreactivity.

Recovery of a critically ill patient with COVID-19 myocarditis.

Myocarditis is a concerning potential consequence of COVID-19 infection, attributed to ventricular dysfunction, cardiac fibrosis, ventricular arrhythmias, cardiogenic shock, and sudden cardiac death. Recently, the Israeli Health Ministry announced that a small number of cases of myocarditis may be linked to second dose of Pfizer's BioNTech-partnered COVID-19 vaccine. The long-term impact of COVID-19 myocarditis and coronary microthrombosis which has also been described and the best therapies for these complications remain unknown. Indeed, monomorphic ventricular tachycardia and regular ventricular arrhythmias have previously been found to be more common in those recovered from myocarditis than in acute myocarditis itself. Follow-up assessment of cardiac function has been suggested for this cohort to detect and possibly prevent further cardiac events in the rehabilitation phase. Functional capacity has been shown to be a better determinant of long-term morbidity than diagnostic testing alone, but integrated approach is likely the way forward in clinical follow-up. Assessment of residual complications in the post-COVID-19 recovery phase may identify the population burden of long-term cardiac disease as a direct consequence of COVID-19.

Modified Brixia chest X-ray severity scoring system and correlation with intubation, non-invasive ventilation and death in a hospitalised COVID-19 cohort.

INTRODUCTION: There are few existing severity scoring systems in the literature, and no formally widely accepted chest X-ray template for reporting COVID-19 infection. We aimed to modify the chest X-ray COVID-19 severity scoring system from the Brixia scoring system with placement of more emphasis on consolidation and to assess if the scoring tool could help predict intubation. METHODS: A severity chest X-ray scoring system was modified from the Brixia scoring system. PCR positive COVID-19 positive patient's chest X-rays admitted to our hospital over 3 months were reviewed and correlated with; non-invasive ventilation, intubation and death. An analysis was performed using a receiver operating curve to predict intubation from all admission chest X-rays. RESULTS: The median score of all 325 admission chest X-rays was 3 (Interquartile range (IQR) 0-6.5). The median score of admission chest X-rays of those who did not require ICU admission and survived was 1.5 (IQR 0-5); and 9 (IQR 4.75-12) was median admission score of those requiring intubation. The median scores of the pre-intubation ICU chest X-rays was 11.5 (IQR 9-14.125), this increased from a median admission chest X-ray score for this group of 9 (P-value < 0.01). A cut-off score of 6 had a sensitivity of 77% and specificity of 73% in predicting the need for intubation. CONCLUSION: Higher chest X-ray severity scores are associated with intubation, need for non-invasive ventilation and death. This tool may also be helpful in predicting intubation.

Exhaled Breath Condensate (EBC) analysis of circulating tumour DNA (ctDNA) using a lung cancer specific UltraSEEK oncogene panel.

INTRODUCTION: Small diagnostic tissue samples can be inadequate in testing an expanding list of validated oncogenic driver alterations and fail to reflect intratumour heterogeneity (ITGH) in lung cancer. Liquid biopsies are non-invasive and may better reflect ITGH. Most liquid biopsies are performed in the context of circulating tumour DNA (ctDNA) in plasma but Exhaled Breath Condensate (EBC) shows promise as a lung-specific liquid biopsy. METHODS: In this prospective, proof-of-concept study we carried out targeted Next Generation Sequencing (NGS) on diagnostic tissue samples from 125 patients with lung cancer and compared results to plasma and EBC for 5 oncogenic driver mutations (EGFR, KRAS, PIK3CA, ERBB2, BRAF) using an ultrasensitive PCR technique (UltraSEEK™ Lung Panel on the MassARRAY® System, Agena Bioscience, San Diego, CA, USA). RESULTS: There was a significantly higher failure rate due to unamplifiable DNA in tissue NGS (57/125, 45.6%) compared to plasma (27/125, 21.6%, p < 0.001 and EBC (26/125,20.8%, p ≤ 0.001. Consequently, both plasma and EBC identified higher number of mutations compared to tissue NGS. Specifically, there were significantly higher numbers of mutations detected in EGFR, KRAS and PIK3CA in plasma (p = 9.82 × 10-3, p = 3.14 × 10-5, p = 1.95 × 10-3) and EBC (p = 2.18 × 10-3, p = 2.28 × 10-4,p = 0.016) compared to tissue NGS. There was considerable divergence in mutation profiles between plasma and EBC with 34/76 (44%) mutations detected in plasma and 37/74 (41.89%) in EBC unique to their respective liquid biopsy. CONCLUSIONS: The results suggest that EBC is effective in identifying clinically relevant alterations in patients with lung cancer using UltraSEEK™ and has a potential role as an adjunct to plasma testing.

Tumour Genome Characterization of a Rare Case of Pulmonary Enteric Adenocarcinoma and Prior Colon Adenocarcinoma.

Pulmonary enteric adenocarcinoma (PEAC) is a rare variant of lung adenocarcinoma first described in the early 1990s in a lung tumour with overlapping lung and small intestine features. It is a rare tumour with fewer than 300 cases described in the published literature and was only formally classified in 2011. Given these characteristics the diagnosis is challenging, but even more so in a patient with prior gastrointestinal malignancy. A 68-year-old Caucasian female presented with a cough and was found to have a right upper lobe mass. Her history was significant for a pT3N1 colon adenocarcinoma. The resected lung tumour showed invasive lung adenocarcinoma but also features of colorectal origin. Immuno-stains were strongly and diffusely positive for lung and enteric markers. Multi-region, whole-exome sequencing of the mass and archival tissue from the prior colorectal cancer showed distinct genomic signatures with higher mutational burden in the PEAC and very minimal overlap in mutations between the two tumours. This case highlights the challenge of diagnosing rare lung tumours, but more specifically PEAC in a patient with prior gastro-intestinal cancer. Our use of multi-region, next-generation sequencing revealed distinct genomic signatures between the two tumours further supporting our diagnosis, and evidence of PEAC intra-tumour heterogeneity.

Preclinical assessment of a modified Occlutech left atrial appendage closure device in a porcine model.

Left atrial appendage (LAA) closure is being developed as an alternative for stroke prevention in patients with atrial fibrillation that cannot tolerate long-term oral anticoagulation. To assess the feasibility, safety, and performance of a novel modified Occlutech LAA closure device in a preclinical porcine model, the modified Occlutech modified Occlutech Plus LAA closure device was implanted in 12 female pigs (25-39 kg body weight) under fluoroscopic and transesophageal echocardiography (TEE) guidance. Procedural and technical success, as well as safety of LAA closure, were evaluated peri-procedurally and after 4, 8, and 12 weeks. Moreover, after 4, 8 and, 12 weeks animals were sacrificed for pathological analysis (e.g., thrombus formation, device ingrowth, endothelialization, and inflammation). All LAA closure devices were successfully implanted. On follow-up, no serious adverse events such as device-associated thrombus or translocalization/embolization were observed. A clinically non-significant pericarditis was observed in 4 animals at the time of autopsy. Endothelialization of the device was visible after 4 weeks, advanced after 8 weeks and completed after 12 weeks. Immunohistochemistry showed low amounts of inflammatory infiltration on the edges of the device. The results of this study indicate that implantation of a modified Occlutech LAA closure device is feasible with rapid endothelialization and low inflammatory infiltration in a porcine model. Human data are needed to further characterize safety and efficacy.

An integrated multidisciplinary model of COVID-19 recovery care.

BACKGROUND: In January 2020, the WHO declared the SARS-CoV-2 outbreak a public health emergency; by March 11, a pandemic was declared. To date in Ireland, over 3300 patients have been admitted to acute hospitals as a result of infection with COVID-19. AIMS: This article aims to describe the establishment of a COVID Recovery Service, a multidisciplinary service for comprehensive follow-up of patients with a hospital diagnosis of COVID-19 pneumonia. METHODS: A hybrid model of virtual and in-person clinics was established, supported by a multidisciplinary team consisting of respiratory, critical care, infectious diseases, psychiatry, and psychology services. This model identifies patients who need enhanced follow-up following COVID-19 pneumonia and aims to support patients with complications of COVID-19 and those who require integrated community care. RESULTS: We describe a post-COVID-19 service structure together with detailed protocols for multidisciplinary follow-up. One hundred seventy-four patients were discharged from Beaumont Hospital after COVID-19 pneumonia. Sixty-seven percent were male with a median age (IQR) of 66.5 (51-97). Twenty-two percent were admitted to the ICU for mechanical ventilation, 11% had non-invasive ventilation or high flow oxygen, and 67% did not have specialist respiratory support. Early data suggests that 48% of these patients will require medium to long-term specialist follow-up. CONCLUSIONS: We demonstrate the implementation of an integrated multidisciplinary approach to patients with COVID-19, identifying those with increased physical and mental healthcare needs. Our initial experience suggests that significant physical, psychological, and cognitive impairments may persist despite clinical resolution of the infection.

Comparison of suction catheter versus forceps biopsy for sampling of solitary pulmonary nodules guided by electromagnetic navigational bronchoscopy.

BACKGROUND: Electromagnetic navigation has been approved for use as an adjunct to standard bronchoscopy. The diagnostic yield varies depending on the size of the lesion and successful navigation to the lesion. OBJECTIVES: The performance of two different biopsy tools, i.e. catheter aspiration and forceps biopsy, in the diagnosis of small pulmonary nodules (SPN) guided by electromagnetic navigational bronchoscopy (ENB) was examined. METHODS: 54 patients referred for suspected lung cancer underwent ENB and 55 SPN (<3 cm) were sampled using both techniques. Endobronchial ultrasound (EBUS) was used to verify the accuracy of target lesion localization by ENB. Primary end points of the study were successful navigation to the lesion and a positive diagnosis. Patients were followed until a definitive diagnosis was obtained. RESULTS: All 55 lesions were accessed. Two lesions were excluded from data analysis as the patients were lost to follow-up and their diagnoses could not be confirmed. Of the remaining 53 lesions, 40 samples (75.5%) were diagnostic. Compared to forceps biopsy, catheter aspiration was positively correlated with the success rate (36/40 vs. 22/40; p = 0.035). The diagnostic yield was 93% when EBUS verified the lesion location after navigation and only 48% when lesion location was not confirmed. There were no significant complications. CONCLUSIONS: ENB is a useful tool in the evaluation of SPN <3 cm in diameter. For malignant lesions, sampling by catheter aspiration is associated with a higher diagnostic yield than sampling by forceps biopsy alone, in particular when EBUS could not confirm lesion location prior to sampling.

Brief Report on the Detection of the EGFR T790M Mutation in Exhaled Breath Condensate from Lung Cancer Patients.

The EGFR T790M somatic mutation is the most common mechanism of resistance to tyrosine kinase inhibitors in NSCLC. Patients with advanced disease are not always amenable to repeat biopsy for further molecular analysis. Developing noninvasive methods to detect T790M in cell-free DNA in the absence of tissue is being actively investigated. Unfortunately, the low sensitivity of plasma for detection of T790M has limited its clinical use. Exhaled breath condensate (EBC) is an easily collected sample that is known to harbor cell-free DNA, including lung cancer mutations. This report details the potential utility of exhaled breath condensate in the detection of the EGFR T790M mutation.

Proteomic analysis of bronchoalveolar lavage fluid (BALF) from lung cancer patients using label-free mass spectrometry.

BACKGROUND: Lung cancer is the leading cause of cancer-related mortality in both men and women throughout the world. The need to detect lung cancer at an early, potentially curable stage, is essential and may reduce mortality by 20%. The aim of this study was to identify distinct proteomic profiles in bronchoalveolar fluid (BALF) and plasma that are able to discriminate individuals with benign disease from those with non-small cell lung cancer (NSCLC). METHODS: Using label-free mass spectrometry analysis of BALF during discovery-phase analysis, a significant number of proteins were found to have different abundance levels when comparing control to adenocarcinoma (AD) or squamous cell lung carcinoma (SqCC). Validation of candidate biomarkers identified in BALF was performed in a larger cohort of plasma samples by detection with enzyme-linked immunoassay. RESULTS: Four proteins (Cystatin-C, TIMP-1, Lipocalin-2 and HSP70/HSPA1A) were selected as a representative group from discovery phase mass spectrometry BALF analysis. Plasma levels of TIMP-1, Lipocalin-2 and Cystatin-C were found to be significantly elevated in AD and SqCC compared to control. CONCLUSION: The results presented in this study indicate that BALF is an important proximal biofluid for the discovery and identification of candidate lung cancer biomarkers. GENERAL SIGNIFICANCE: There is good correlation between the trend of protein abundance levels in BALF and that of plasma which validates this approach to develop a blood biomarker to aid lung cancer diagnosis, particularly in the era of lung cancer screening. The protein signatures identified also provide insight into the molecular mechanisms associated with lung malignancy.

Novel MRI Technique Enables Non-Invasive Measurement of Atrial Wall Thickness.

Knowledge of atrial wall thickness (AWT) has the potential to provide important information for patient stratification and the planning of interventions in atrial arrhythmias. To date, information about AWT has only been acquired in post-mortem or poor-contrast computed tomography (CT) studies, providing limited coverage and highly variable estimates of AWT. We present a novel contrast agent-free MRI sequence for imaging AWT and use it to create personalized AWT maps and a biatrial atlas. A novel black-blood phase-sensitive inversion recovery protocol was used to image ten volunteers and, as proof of concept, two atrial fibrillation patients. Both atria were manually segmented to create subject-specific AWT maps using an average of nearest neighbors approach. These were then registered non-linearly to generate an AWT atlas. AWT was 2.4 ± 0.7 and 2.7 ± 0.7 mm in the left and right atria, respectively, in good agreement with post-mortem and CT data, where available. AWT was 2.6 ± 0.7 mm in the left atrium of a patient without structural heart disease, similar to that of volunteers. In a patient with structural heart disease, the AWT was increased to 3.1 ± 1.3 mm. We successfully designed an MRI protocol to non-invasively measure AWT and create the first whole-atria AWT atlas. The atlas can be used as a reference to study alterations in thickness caused by atrial pathology. The protocol can be used to acquire personalized AWT maps in a clinical setting and assist in the treatment of atrial arrhythmias.

False-positive restaging PET scans involving the spleen in two patients with aggressive non-Hodgkin lymphoma.

We report 2 patients with aggressive non-Hodgkin lymphoma who had positive restaging PET scans limited to the spleen and no significant uptake in nodal areas of previously known disease. Examination of the resected spleens from both patients revealed extensive inflammation surrounding necrotic tumor with no evidence of viable lymphoma or active infection. It is suggested that close observation of such patients for evidence of progressive disease may be considered as opposed to immediate intervention.

Towards patient-specific modelling of lesion formation during radiofrequency catheter ablation for atrial fibrillation.

Radiofrequency catheter ablation procedures are a first-line method of clinical treatment for atrial fibrillation. However, they suffer from suboptimal success rates and are also prone to potentially serious adverse effects. These limitations can be at least partially attributed to the inter- and intra- patient variations in atrial wall thickness, and could be mitigated by patient-specific approaches to the procedure. In this study, a modelling approach to optimising ablation procedures in subject-specific 3D atrial geometries was applied. The approach enabled the evaluation of optimal ablation times to create lesions for a given wall thickness measured from MRI. A nonliner relationship was revealed between the thickness and catheter contact time required for fully transmural lesions. Hence, our approach based on MRI reconstruction of the atrial wall combined with subject-specific modelling of ablation can provide useful information for improving clinical procedures.

Slow Conduction in the Border Zones of Patchy Fibrosis Stabilizes the Drivers for Atrial Fibrillation: Insights from Multi-Scale Human Atrial Modeling.

Introduction: The genesis of atrial fibrillation (AF) and success of AF ablation therapy have been strongly linked with atrial fibrosis. Increasing evidence suggests that patient-specific distributions of fibrosis may determine the locations of electrical drivers (rotors) sustaining AF, but the underlying mechanisms are incompletely understood. This study aims to elucidate a missing mechanistic link between patient-specific fibrosis distributions and AF drivers. Methods: 3D atrial models integrated human atrial geometry, rule-based fiber orientation, region-specific electrophysiology, and AF-induced ionic remodeling. A novel detailed model for an atrial fibroblast was developed, and effects of myocyte-fibroblast (M-F) coupling were explored at single-cell, 1D tissue and 3D atria levels. Left atrial LGE MRI datasets from 3 chronic AF patients were segmented to provide the patient-specific distributions of fibrosis. The data was non-linearly registered and mapped to the 3D atria model. Six distinctive fibrosis levels (0-healthy tissue, 5-dense fibrosis) were identified based on LGE MRI intensity and modeled as progressively increasing M-F coupling and decreasing atrial tissue coupling. Uniform 3D atrial model with diffuse (level 2) fibrosis was considered for comparison. Results: In single cells and tissue, the largest effect of atrial M-F coupling was on the myocyte resting membrane potential, leading to partial inactivation of sodium current and reduction of conduction velocity (CV). In the 3D atria, further to the M-F coupling, effects of fibrosis on tissue coupling greatly reduce atrial CV. AF was initiated by fast pacing in each 3D model with either uniform or patient-specific fibrosis. High variation in fibrosis distributions between the models resulted in varying complexity of AF, with several drivers emerging. In the diffuse fibrosis models, waves randomly meandered through the atria, whereas in each the patient-specific models, rotors stabilized in fibrotic regions. The rotors propagated slowly around the border zones of patchy fibrosis (levels 3-4), failing to spread into inner areas of dense fibrosis. Conclusion: Rotors stabilize in the border zones of patchy fibrosis in 3D atria, where slow conduction enable the development of circuits within relatively small regions. Our results can provide a mechanistic explanation for the clinical efficacy of ablation around fibrotic regions.