Modulation of Oxidative Stress and Neuroinflammation by Cannabidiol (CBD): Promising Targets for the Treatment of Alzheimer's Disease.

Alzheimer's disease (AD) is a progressive neurodegenerative disease and the most common form of dementia globally. Although the direct cause of AD remains under debate, neuroinflammation and oxidative stress are critical components in its pathogenesis and progression. As a result, compounds like cannabidiol (CBD) are being increasingly investigated for their ability to provide antioxidant and anti-inflammatory neuroprotection. CBD is the primary non-psychotropic phytocannabinoid derived from Cannabis sativa. It has been found to provide beneficial outcomes in a variety of medical conditions and is gaining increasing attention for its potential therapeutic application in AD. CBD is not psychoactive and its lipophilic nature allows its rapid distribution throughout the body, including across the blood-brain barrier (BBB). CBD also possesses anti-inflammatory, antioxidant, and neuroprotective properties, making it a viable candidate for AD treatment. This review outlines CBD's mechanism of action, the role of oxidative stress and neuroinflammation in AD, and the effectiveness and limitations of CBD in preclinical models of AD.

Integrated longitudinal multiomics study identifies immune programs associated with acute COVID-19 severity and mortality.

BACKGROUNDPatients hospitalized for COVID-19 exhibit diverse clinical outcomes, with outcomes for some individuals diverging over time even though their initial disease severity appears similar to that of other patients. A systematic evaluation of molecular and cellular profiles over the full disease course can link immune programs and their coordination with progression heterogeneity.METHODSWe performed deep immunophenotyping and conducted longitudinal multiomics modeling, integrating 10 assays for 1,152 Immunophenotyping Assessment in a COVID-19 Cohort (IMPACC) study participants and identifying several immune cascades that were significant drivers of differential clinical outcomes.RESULTSIncreasing disease severity was driven by a temporal pattern that began with the early upregulation of immunosuppressive metabolites and then elevated levels of inflammatory cytokines, signatures of coagulation, formation of neutrophil extracellular traps, and T cell functional dysregulation. A second immune cascade, predictive of 28-day mortality among critically ill patients, was characterized by reduced total plasma Igs and B cells and dysregulated IFN responsiveness. We demonstrated that the balance disruption between IFN-stimulated genes and IFN inhibitors is a crucial biomarker of COVID-19 mortality, potentially contributing to failure of viral clearance in patients with fatal illness.CONCLUSIONOur longitudinal multiomics profiling study revealed temporal coordination across diverse omics that potentially explain the disease progression, providing insights that can inform the targeted development of therapies for patients hospitalized with COVID-19, especially those who are critically ill.TRIAL REGISTRATIONClinicalTrials.gov NCT04378777.FUNDINGNIH (5R01AI135803-03, 5U19AI118608-04, 5U19AI128910-04, 4U19AI090023-11, 4U19AI118610-06, R01AI145835-01A1S1, 5U19AI062629-17, 5U19AI057229-17, 5U19AI125357-05, 5U19AI128913-03, 3U19AI077439-13, 5U54AI142766-03, 5R01AI104870-07, 3U19AI089992-09, 3U19AI128913-03, and 5T32DA018926-18); NIAID, NIH (3U19AI1289130, U19AI128913-04S1, and R01AI122220); and National Science Foundation (DMS2310836).

Education and diversity in cytopathology: Past, present, and future.

Diversity, equity, and inclusion is a powerful goal which many of us strive toward in medicine, both in patient care and administrative leadership. As the world evolves, the practice of medicine must evolve with it. We are cognizant of the importance of the history of our medical specialties. If we do not acknowledge all parts of our history, we are doomed to repeat it. This special issue is unique and unlike anything that has previously been published in Diagnostic Cytopathology. This issue looks at some of the history of cytopathology. This historical review is followed by some of the present state of cytopathology. There are insights into global cytopathology. The final portion of this issue examines the critical need for cytotechnology schools in the United States. All of these areas are critical to the past, present, and future of cytopathology.

The use of human iPSC-derived alveolar organoids to explore SARS-CoV-2 variant infections and host responses.

Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) primarily targets the respiratory system. Physiologically relevant human lung models are indispensable to investigate virus-induced host response and disease pathogenesis. In this study, we generated human induced pluripotent stem cell (iPSC)-derived alveolar organoids (AOs) using an established protocol that recapitulates the sequential steps of in vivo lung development. AOs express alveolar epithelial type II cell protein markers including pro-surfactant protein C and ATP binding cassette subfamily A member 3. Compared to primary human alveolar type II cells, AOs expressed higher mRNA levels of SARS-CoV-2 entry factors, angiotensin-converting enzyme 2 (ACE2), asialoglycoprotein receptor 1 (ASGR1) and basigin (CD147). Considering the localization of ACE2 on the apical side in AOs, we used three AO models, apical-in, sheared and apical-out for SARS-CoV-2 infection. All three models of AOs were robustly infected with the SARS-CoV-2 irrespective of ACE2 accessibility. Antibody blocking experiment revealed that ASGR1 was the main receptor for SARS-CoV2 entry from the basolateral in apical-in AOs. AOs supported the replication of SARS-CoV-2 variants WA1, Alpha, Beta, Delta, and Zeta and Omicron to a variable degree with WA1 being the highest and Omicron being the least. Transcriptomic profiling of infected AOs revealed the induction of inflammatory and interferon-related pathways with NF-κB signaling being the predominant host response. In summary, iPSC-derived AOs can serve as excellent human lung models to investigate infection of SARS-CoV-2 variants and host responses from both apical and basolateral sides.

Single nucleotide polymorphism (SNP) chromosomal microarray as a diagnostic tool for mucinous tubular and spindle cell carcinoma: A validation study.

Mucinous tubular and spindle cell carcinoma (MTSCC) shows significant overlap with papillary renal cell carcinoma (PRCC), and harbor recurrent copy-number alterations (CNA). We evaluated 16 RCC with features suggestive of MTSCC using chromosomal microarrays. The cohort was comprised of 8 females and males, each, with an age range of 33-79 years (median, 59), and a tumor size range of 3.4-15.5 cm (median, 5.0). Half the tumors were high-grade (8/16, 50%) with features such as necrosis, marked cytologic atypia, and sarcomatoid differentiation, and 5/16 (31%) were high stage (≥pT3a). Three (of 16, 19%) cases had a predominant (>95%) spindle cell component, whereas 5/16 (31%) were composed of a predominant (>95%) epithelial component. Most cases (12/16, 75%) exhibited a myxoid background and/or extravasated mucin, at least focally. Twelve (of 16, 75%) cases demonstrated CNA diagnostic of MTSCC (losses of chromosomes 1, 4, 6, 8, 9, 13, 14, 15, and 22). In addition, 2 high-grade tumors showed loss of CDKN2A/B, and gain of 1q, respectively, both of which are associated with aggressive behavior. Three (of 16, 19%) cases, demonstrated nonspecific CNA, and did not meet diagnostic criteria for established RCC subtypes. One (of 16, 6%) low-grade epithelial predominant tumor (biopsy) demonstrated characteristic gains of 7, 17, and loss of Y, diagnostic of PRCC. MTSCC can be a morphologically heterogenous tumor. Our study validates the detection of characteristic chromosomal CNA for diagnostic use that may be useful in challenging cases with unusual spindle cell or epithelial predominant features, as well as in high-grade tumors.

Qualitative Analysis of Decision to Pursue Electrical Brain Stimulation by Patients With Drug-Resistant Epilepsy and Their Caregivers.

Background and Objectives: To understand why patients with drug-resistant epilepsy (DRE) pursue invasive electrical brain stimulation (EBS). Methods: We interviewed patients with DRE (n = 20) and their caregivers about their experiences in pursuing EBS approximately 1 year post device implant. Inductive analysis was applied to identify key motivating factors. Results: The cohort included participants aged from teens to 50s with deep brain stimulation, vagus nerve stimulation, responsive neurostimulation, and chronic subthreshold cortical stimulation. Patients' motivations included (1) improved quality of life (2) intolerability of antiseizure medications, (3) desperation, and (4) patient-family dynamics. Both patients and caregivers described a desire to alleviate burdens of the other. Patient apprehensions about EBS focused on invasiveness and the presence of electrodes in the brain. Previous experiences with invasive monitoring and the ability to see hardware in person during clinical visits influenced patients' comfort in proceeding with EBS. Despite realistic expectations for modest and delayed benefits, patients held out hope for an exceptionally positive outcome. Discussion: Our findings describe the motivations and decision-making process for patients with DRE who pursue invasive EBS. Patients balance feelings of desperation, personal goals, frustration with medication side effects, fears about surgery, and potential pressure from concerned caregivers. These factors together with the sense that patients have exhausted therapeutic alternatives may explain the limited decisional ambivalence observed in this cohort. These themes highlight opportunities for epilepsy care teams to support patient decision-making processes.

Patient and Caregiver Perceptions of an Interface Design to Communicate Artificial Intelligence-Based Prognosis for Patients With Advanced Solid Tumors.

PURPOSE: Use of artificial intelligence (AI) in cancer care is increasing. What remains unclear is how best to design patient-facing systems that communicate AI output. With oncologist input, we designed an interface that presents patient-specific, machine learning-based 6-month survival prognosis information designed to aid oncology providers in preparing for and discussing prognosis with patients with advanced solid tumors and their caregivers. The primary purpose of this study was to assess patient and caregiver perceptions and identify enhancements of the interface for communicating 6-month survival and other prognosis information when making treatment decisions concerning anticancer and supportive therapy. METHODS: This qualitative study included interviews and focus groups conducted between November and December 2022. Purposive sampling was used to recruit former patients with cancer and/or former caregivers of patients with cancer who had participated in cancer treatment decisions from Utah or elsewhere in the United States. Categories and themes related to perceptions of the interface were identified. RESULTS: We received feedback from 20 participants during eight individual interviews and two focus groups, including four cancer survivors, 13 caregivers, and three representing both. Overall, most participants expressed positive perceptions about the tool and identified its value for supporting decision making, feeling less alone, and supporting communication among oncologists, patients, and their caregivers. Participants identified areas for improvement and implementation considerations, particularly that oncologists should share the tool and guide discussions about prognosis with patients who want to receive the information. CONCLUSION: This study revealed important patient and caregiver perceptions of and enhancements for the proposed interface. Originally designed with input from oncology providers, patient and caregiver participants identified additional interface design recommendations and implementation considerations to support communication about prognosis.

Haloperidol-Induced Neuroleptic Malignant Syndrome: A Case Report.

Neuroleptic malignant syndrome (NMS) is a severe reaction to antipsychotic medications characterized by fever, muscle rigidity, altered mental status, and autonomic dysfunction. Here, we describe the case of a 58-year-old female who presented with altered mental status two days after open reduction and internal fixation of the hip. A rapid response team was called when the patient appeared agitated with increased respiratory demand. After being intubated and moved to the ICU, she became febrile and rigid. A preliminary diagnosis of metabolic encephalopathy of unknown origin was made. Before being transported to the ICU, the patient was given multiple haloperidol doses in addition to her continued at-home medication, paroxetine, for major depressive disorder. The differential diagnosis included a workup for NMS, serotonin syndrome, and infectious processes. Once NMS was determined as the most likely etiology, all antipsychotic and serotonergic medications were discontinued. Then dantrolene and amantadine were administered, which resulted in clinically significant improvement. This case report demonstrates the importance of early identification of and intervention for NMS.

Locations and structures of influenza A virus packaging-associated signals and other functional elements via an in silico pipeline for predicting constrained features in RNA viruses.

Influenza A virus contains regions of its segmented genome associated with ability to package the segments into virions, but many such regions are poorly characterised. We provide detailed predictions of the key locations within these packaging-associated regions, and their structures, by applying a recently-improved pipeline for delineating constrained regions in RNA viruses and applying structural prediction algorithms. We find and characterise other known constrained regions within influenza A genomes, including the region associated with the PA-X frameshift, regions associated with alternative splicing, and constraint around the initiation motif for a truncated PB1 protein, PB1-N92, associated with avian viruses. We further predict the presence of constrained regions that have not previously been described. The extra characterisation our work provides allows investigation of these key regions for drug target potential, and points towards determinants of packaging compatibility between segments.

Edge computing based real-time Nephrops (Nephrops norvegicus) catch estimation in demersal trawls using object detection models.

In demersal trawl fisheries, the unavailability of the catch information until the end of the catching process is a drawback, leading to seabed impacts, bycatches and reducing the economic performance of the fisheries. The emergence of in-trawl cameras to observe catches in real-time can provide such information. This data needs to be processed in real-time to determine the catch compositions and rates, eventually improving sustainability and economic performance of the fisheries. In this study, a real-time underwater video processing system counting the Nephrops individuals entering the trawl has been developed using object detection and tracking methods on an edge device (NVIDIA Jetson AGX Orin). Seven state-of-the-art YOLO models were tested to discover the appropriate training settings and YOLO model. To achieve real-time processing and accurate counting simultaneously, four frame skipping ideas were evaluated. It has been shown that adaptive frame skipping approach, together with YOLOv8s model, can increase the processing speed up to 97.47 FPS while achieving correct count rate and F-score of 82.57% and 0.86, respectively. In conclusion, this system can improve the sustainability of the Nephrops directed trawl fishery by providing catch information in real-time.

Porous Cage Macro-Topography Improves Early Fusion Rates in Anterior Cervical Discectomy and Fusion.

Objectives: Anterior cervical discectomy and fusion (ACDF) aims to improve pain, relieve neural compression, achieve rapid solid bony arthrodesis, and restore cervical alignment. Bony fusion occurs as early as 3 months and up to 24 months after ACDF. The correlations between bony fusion and clinical outcomes after ACDF remain unclear. Macro-topographic and porous features have been introduced to interbody cage technology, aiming to improve the strength of the bone-implant interface to promote early fusion. In this study, we aimed to compare clinical outcomes and CT-evaluated fusion rates in patients undergoing ACDF using one of two different interbody cages: traditional NanoMetalene™ (NM) cages and NM cages with machined porous features (NMRT). Methods: This was a prospective, observational, nonrandomised, cohort study of consecutive patients undergoing ACDF. The NM cage cohort was enrolled first, then the NMRT cohort second. The visual analogue scale, neck disability index, and 12-item Short Form Survey scores were evaluated preoperatively and at 6 weeks, 3 months, and 6 months. The minimum clinical follow-up period was 12 months. Plain radiographs were obtained on postoperative day 2 to assess instrumentation positioning, and computed tomography (CT) was performed at 3 and 6 months postoperatively to assess interbody fusion (Bridwell grade). Results: Eighty-nine (52% male) patients with a mean age of 62 ± 10.5 years were included in this study. Forty-one patients received NM cages, and 48 received NMRT cages. All clinical outcomes improved significantly from baseline to 6 months. By 3 months, the NMRT group had significantly higher CT fusion rates than the NM group (79% vs 56%, p=0.02). By 6 months, there were no significant differences in fusion rates between the NMRT and NM groups (83% vs 78%, p=0.69). The mean Bridwell grade at 6 months was 1.4 ± 0.7 in the NMRT group and 1.8 ± 1.0 in the NM group (p=0.08). Conclusions: With both NM and NMRT cages, serial improvements in postoperative clinical outcomes were associated with fusion progression on CT. NMRT cages demonstrated significantly better fusion at 3 months and a trend toward higher quality of fusion at 6 months compared with NM cages, suggesting earlier cage integration with NMRT. An early 3-month postoperative CT is adequate for fusion assessment in almost 80% of patients undergoing ACDF with an NMRT cage, permitting an earlier return to activity.

Order of Cannabis and Alcohol Use on Pregaming and Non-Pregaming Days among College Students.

OBJECTIVE: Pregaming is common among college students and is associated with heavy drinking and negative alcohol-related consequences. The use of cannabis on pregaming days may exacerbate negative alcohol-related consequences, and the ordering of when cannabis is used on these days may buffer against or intensify these consequences. Considering the growing rates of simultaneous use of cannabis and alcohol among college students, it is necessary to examine the role of pregaming behaviors in the context of cannabis use and resulting effects on alcohol-related consequences. METHOD: In the present study, college students (N=485) completed a baseline survey and 14 days of daily surveys, reporting on daily alcohol and cannabis use and alcohol-related negative consequences. Multilevel Structural Equation Models were fit to evaluate cannabis outcomes on pregaming versus non-pregaming drinking days and ordering effects on alcohol-related consequences controlling for number of drinks, age, and sex. RESULTS: Across all drinking days, pregaming on that day as well as cannabis use during drinking on that day were associated with greater risk for alcohol-related consequences. On days that did not involve pregaming, use of cannabis before drinking was associated with greater risk for negative alcohol-related consequences, while cannabis use after drinking was associated with less risk for consequences. These effects were observed on non-pregaming days only and not on days with pregaming. CONCLUSIONS: Findings have implications for brief interventions with students, as analyses suggested that both cannabis use and pregaming, independent of number of drinks consumed, are risky behaviors associated with alcohol-related consequences.

Generativity as a Traditional Way of Life: Successful aging among Unangan Elders in the Aleutian Pribilof Islands.

Predominantly Western-based biomedical models of successful aging have been used to research, understand, and explain successful aging among diverse populations. With an increasingly heterogeneous older adult population nationwide, scholars have been exploring Indigenous understandings of successful aging. To add to the accumulation of knowledge of diverse Alaska Native populations, this study involved semi-structured qualitative interviews with 20 Unangan Elders from the Aleutian and Pribilof Islands. This community-based participatory research study explores the aging experiences and conceptualization of successful aging of these Elders from this remote and culturally distinct region of Alaska. Thematic analysis was employed to identify themes related to successful aging within this specific region, which supported our previous four themes, or characteristics, of Alaska Native successful aging: physical health, social support and emotional well-being, generativity as a traditional way of life, and community engagement and Inidgenous cultural generativity. Each of these themes or characteristics of Eldership is intertwined and together support successful aging within two remote communities in the Bering Sea. The findings of this study illuminate how Alaska Native Elders can live in geographically diverse regions of the State, yet the values and teachings they possess on successful aging possess the same cultural values and teachings. This study highlighted two new emerging constructs that influence Alaska Native Elders' successful aging based on geographical location. Findings contribute to the thematic saturation of the four main successful aging domains while outlining the importance of future research to conduct deeper investigations into the role of environment and history on Elders' perceptions and understanding of aging.

Ethnoracialized group differences in attitudes and knowledge about schizophrenia and willingness to engage in biomarker research: The UBIGR Study.

Although there is renewed optimism in biomarker research in schizophrenia, there is also need for greater inclusion of historically underrepresented groups in the research. In the present study, we surveyed 599 African American, 352 American Indian/Alaska Native, and 725 NonHispanic White participants about their attitudes toward research, knowledge and attitudes about schizophrenia, and willingness to engage in biomarker testing. Attitudes toward research were examined using the standardized 7-item Research Attitudes Questionnaire (RAQ) measure. Using structural equation modeling (SEM), we tested our predictive model of the likelihood of willingness to engage in biomarker testing for schizophrenia risk. Members of historically underrepresented groups were less willing to engage in biomarker testing. Overall, attitudes toward research, particularly trust, influenced biomarker testing willingness. These findings suggest that factors influencing willingness to engage in schizophrenia biomarker testing may be modifiable by outreach engagement and education.

An Examination of Pregaming Behavior and Motives among Sexual and Gender Minority College Students.

Introduction: Pregaming is a popular but high-risk drinking behavior common among college students. Although sexual and gender minority (SGM) college students are a vulnerable population with regards to hazardous alcohol use and alcohol consequences, there is currently limited research investigating the pregaming behavior of this group. The present study aimed to (1) examine mean level differences in pregaming behaviors and motives between SGM and non-SGM college students and (2) explore how SGM status was associated with pregaming behaviors and if SGM status moderated the association between motives and pregaming behaviors. Methods: The sample consisted of 485 college student drinkers in the US, with 19% (n = 93) identifying as SGM. All participants completed measures of past 30-day pregaming frequency and quantity (yielding a total pregaming drinks outcome) and drinking consequences experienced on pregaming days. Results: SGM participants consumed significantly fewer pregaming drinks than non-SGM participants, but did not significantly differ on alcohol-related consequences or drinking motives. The pregaming motive of intimate pursuit moderated the association between SGM status and total pregaming drinks, such that non-SGM participants with high intimate pursuit motives drank the heaviest. Conclusions: Our findings suggest that SGM students consume significantly fewer pregaming drinks than their non-SGM counterparts. However, they may be at a similar risk of experiencing pregaming consequences as non-SGM students. SGM students were less susceptible to the effect of intimate pursuit motives on pregaming drink consumption. This study offers support for past research regarding the effects of certain pregaming motives on pregaming drink consumption and consequences.

A Deeper Dive into Young Adults' Experiences with E-Cigarettes, E-Cigarette Cessation, and Transitioning to Cigarette Smoking.

Introduction: E-cigarette use among young adults is prevalent, with some voicing their desire to quit using e-cigarettes but needing support to do so. Young adults who use e-cigarettes are at risk for progressing to smoking combustible cigarettes, placing them at risk for severe health consequences. Limited research exists describing young adults' lived experiences with using e-cigarettes, e-cigarette cessation, and progression to combustible cigarettes. Methods: Between July and August 2022, nine focus groups were conducted with 33 young adults who either (1) currently used e-cigarettes, (2) formerly used e-cigarettes, or (3) transitioned to cigarettes. Transcripts were coded and themes were identified independently by two research team members while a third researcher reviewed the coding and themes. Results: Participants described social influences, stress, and curiosity as primary reasons why they initiated e-cigarette use. The most reported negative experiences or consequences associated with e-cigarettes include the health effects, addiction, and financial costs. Participants who transitioned to cigarettes reported social influences, a desire to reduce or quit using e-cigarettes by replacing them with cigarettes, curiosity, and stress as the primary reasons for this progression to combustible cigarettes. Participants described barriers to quitting e-cigarettes, including social influences, withdrawal, and easy access to e-cigarettes, as well as facilitators of quitting, such as social support, change in environment, and finding healthier ways to manage stress. Conclusions: This qualitative work provides an in-depth look into factors that may be helpful in the development of prevention and intervention programs for both e-cigarette and combustible cigarette use in young individuals.

PlasmaBlade-assisted surgical septal myectomy: technique and our experience.

Background: The pulsed-electron avalanche knife (PEAK) PlasmaBlade provides an atraumatic, scalpel-like cutting precision and electrocautery-like hemostasis. PlasmaBlade operates near body temperature, and its long, thin, and malleable tip can overcome the limitations of a surgical knife. In this study, we aimed to evaluate our clinical experience and histopathological outcomes of septal myectomy using PlasmaBlade. Methods: Electronic medical records were reviewed for preoperative, operative, and follow-up data of the patients who underwent septal myectomy using PEAK PlasmaBlade at our institute between January 2019 and December 2022. Histopathology of the myectomy specimens was reviewed for the depth of muscle necrosis and compared with the left atrial appendage (LAA) specimen. Results: Twenty-nine patients underwent septal myectomy using the PEAK PlasmaBlade. No mortality was reported. The mean age was 60.6 ± 12.5 years, and 58.6% of patients were male. Peak left ventricular outflow tract (LVOT) gradients were 40.5 ± 34.9 mmHg at rest and 56.5 ± 34.9 mmHg after provocation. Concomitant procedures performed were LAA ligation in 20 (69.0%), aortic valve replacement in 5 (17.2%), and coronary artery bypass grafting in 3 (10.3%) patients. Postoperative complications were complete heart block in one (3.4%) and ventricular septal defect in two (6.9%) patients. Both the ventricular septal defects were identified intraoperatively and repaired. Histopathology of myectomy specimens demonstrated cautery artifact limited to <50 µm depth compared to >1,000 µm with conventional electrocautery. At a mean follow-up of 8.4 ± 10.3 months, the mean LVOT gradient was 4.4 ± 5.8 mmHg at rest and 9.5 ± 3.3 mmHg after provocation. All patients were alive and in New York Heart Association class I/II. No patient developed complications or required reintervention or reoperation. Conclusion: Adequate septal myectomy can be precisely and safely performed using the PEAK PlasmaBlade with minimal collateral damage.

Lower frequencies of circulating suppressive regulatory T cells and higher frequencies of CD4+ naïve T cells at baseline are associated with severe immune-related adverse events in immune checkpoint inhibitor-treated melanoma.

BACKGROUND: Immune-related adverse events (irAEs) are major barriers of clinical management and further development of immune checkpoint inhibitors (ICIs) for cancer therapy. Therefore, biomarkers associated with the onset of severe irAEs are needed. In this study, we aimed to identify immune features detectable in peripheral blood and associated with the development of severe irAEs that required clinical intervention. METHODS: We used a 43-marker mass cytometry panel to characterize peripheral blood mononuclear cells from 28 unique patients with melanoma across 29 lines of ICI therapy before treatment (baseline), before the onset of irAEs (pre-irAE) and at the peak of irAEs (irAE-max). In the 29 lines of ICI therapy, 18 resulted in severe irAEs and 11 did not. RESULTS: Unsupervised and gated population analysis showed that patients with severe irAEs had a higher frequency of CD4+ naïve T cells and lower frequency of CD16+ natural killer (NK) cells at all time points. Gated population analysis additionally showed that patients with severe irAEs had fewer T cell immunoreceptor with Ig and ITIM domain (TIGIT+) regulatory T cells at baseline and more activated CD38+ CD4+ central memory T cells (TCM) and CD39+ and Human Leukocyte Antigen-DR Isotype (HLA-DR)+ CD8+ TCM at peak of irAEs. The differentiating immune features at baseline were predominantly seen in patients with gastrointestinal and cutaneous irAEs and type 1 diabetes. Higher frequencies of CD4+ naïve T cells and lower frequencies of CD16+ NK cells were also associated with clinical benefit to ICI therapy. CONCLUSIONS: This study demonstrates that high-dimensional immune profiling can reveal novel blood-based immune signatures associated with risk and mechanism of severe irAEs. Development of severe irAEs in melanoma could be the result of reduced immune inhibitory capacity pre-ICI treatment, resulting in more activated TCM cells after treatment.