Pro-resolving lipid mediator reduces amyloid-ß42-induced gene expression in human monocyte-derived microglia.

JOURNAL/nrgr/04.03/01300535-202503000-00031/figure1/v/2024-06-17T092413Z/r/image-tiff Specialized pro-resolving lipid mediators including maresin 1 mediate resolution but the levels of these are reduced in Alzheimer's disease brain, suggesting that they constitute a novel target for the treatment of Alzheimer's disease to prevent/stop inflammation and combat disease pathology. Therefore, it is important to clarify whether they counteract the expression of genes and proteins induced by amyloid-ß. With this objective, we analyzed the relevance of human monocyte-derived microglia for in vitro modeling of neuroinflammation and its resolution in the context of Alzheimer's disease and investigated the pro-resolving bioactivity of maresin 1 on amyloid-ß42-induced Alzheimer's disease-like inflammation. Analysis of RNA-sequencing data and secreted proteins in supernatants from the monocyte-derived microglia showed that the monocyte-derived microglia resembled Alzheimer's disease-like neuroinflammation in human brain microglia after incubation with amyloid-ß42. Maresin 1 restored homeostasis by down-regulating inflammatory pathway related gene expression induced by amyloid-ß42 in monocyte-derived microglia, protection of maresin 1 against the effects of amyloid-ß42 is mediated by a re-balancing of inflammatory transcriptional networks in which modulation of gene transcription in the nuclear factor-kappa B pathway plays a major part. We pinpointed molecular targets that are associated with both neuroinflammation in Alzheimer's disease and therapeutic targets by maresin 1. In conclusion, monocyte-derived microglia represent a relevant in vitro microglial model for studies on Alzheimer's disease-like inflammation and drug response for individual patients. Maresin 1 ameliorates amyloid-ß42-induced changes in several genes of importance in Alzheimer's disease, highlighting its potential as a therapeutic target for Alzheimer's disease.

Microglia lactylation in relation to central nervous system diseases.

The development of neurodegenerative diseases is closely related to the disruption of central nervous system homeostasis. Microglia, as innate immune cells, play important roles in the maintenance of central nervous system homeostasis, injury response, and neurodegenerative diseases. Lactate has been considered a metabolic waste product, but recent studies are revealing ever more of the physiological functions of lactate. Lactylation is an important pathway in lactate function and is involved in glycolysis-related functions, macrophage polarization, neuromodulation, and angiogenesis and has also been implicated in the development of various diseases. This review provides an overview of the lactate metabolic and homeostatic regulatory processes involved in microglia lactylation, histone versus non-histone lactylation, and therapeutic approaches targeting lactate. Finally, we summarize the current research on microglia lactylation in central nervous system diseases. A deeper understanding of the metabolic regulatory mechanisms of microglia lactylation will provide more options for the treatment of central nervous system diseases.

Atypical local and global biological motion perception in children with attention deficit hyperactivity disorder.

Perceiving biological motion (BM) is crucial for human survival and social interaction. Many studies have reported impaired BM perception in autism spectrum disorder, which is characterised by deficits in social interaction. Children with attention deficit hyperactivity disorder (ADHD) often exhibit similar difficulties in social interaction. However, few studies have investigated BM perception in children with ADHD. Here, we compared differences in the ability to process local kinematic and global configurational cues, two fundamental abilities of BM perception, between typically developing and ADHD children. We further investigated the relationship between BM perception and social interaction skills measured using the Social Responsiveness Scale and examined the contributions of latent factors (e.g. sex, age, attention, and intelligence) to BM perception. The results revealed that children with ADHD exhibited atypical BM perception. Local and global BM processing showed distinct features. Local BM processing ability was related to social interaction skills, whereas global BM processing ability significantly improved with age. Critically, general BM perception (i.e. both local and global BM processing) may be affected by sustained attentional ability in children with ADHD. This relationship was primarily mediated by reasoning intelligence. These findings elucidate atypical BM perception in ADHD and the latent factors related to BM perception. Moreover, this study provides new evidence that BM perception is a hallmark of social cognition and advances our understanding of the potential roles of local and global processing in BM perception and social cognitive disorders.

A leak K+ channel TWK-40 sustains the rhythmic motor program.

Leak potassium (K+) currents, conducted by two-pore domain K+ (K2P) channels, are critical for the stabilization of the membrane potential. The effect of K2P channels on motor rhythm remains enigmatic. We show here that the K2P TWK-40 contributes to the rhythmic defecation motor program (DMP) in Caenorhabditis elegans. Disrupting TWK-40 suppresses the expulsion defects of nlp-40 and aex-2 mutants. By contrast, a gain-of-function (gf) mutant of twk-40 significantly reduces the expulsion frequency per DMP cycle. In situ whole-cell patch clamping demonstrates that TWK-40 forms an outward current that hyperpolarize the resting membrane potential of dorsorectal ganglion ventral process B (DVB), an excitatory GABAergic motor neuron that activates expulsion muscle contraction. In addition, TWK-40 substantially contributes to the rhythmic activity of DVB. Specifically, DVB Ca2+ oscillations exhibit obvious defects in loss-of-function (lf) mutant of twk-40. Expression of TWK-40(gf) in DVB recapitulates the expulsion deficiency of the twk-40(gf) mutant, and inhibits DVB Ca2+ oscillations in both wild-type and twk-40(lf) animals. Moreover, DVB innervated enteric muscles also exhibit rhythmic Ca2+ defects in twk-40 mutants. In summary, these findings establish TWK-40 as a crucial neuronal stabilizer of DMP, linking leak K2P channels with rhythmic motor activity.

A nomogram for predicting neurogenic lower urinary tract dysfunction in patients with acute ischemic stroke: A retrospective study.

AIMS: To investigate the risk factors for neurogenic lower urinary tract dysfunction (NLUTD) in patients with acute ischemic stroke (AIS), and develop an internally validated predictive nomogram. The study aims to offer insights for preventing AIS-NLUTD. METHODS: We conducted a retrospective study on AIS patients in a Shenzhen Hospital from June 2021 to February 2023, categorizing them into non-NLUTD and NLUTD groups. The bivariate analysis identified factors for AIS-NLUTD (p < 0.05), integrated into a least absolute shrinkage and selection operator (LASSO) regression model. Significant variables from LASSO were used in a multivariate logistic regression for the predictive model, resulting in a nomogram. Nomogram performance and clinical utility were evaluated through receiver operating characteristic curves, calibration curves, decision curve analysis (DCA), and clinical impact curve (CIC). Internal validation used 1000 bootstrap resamplings. RESULTS: A total of 373 participants were included in this study, with an NLUTD incidence rate of 17.7% (66/373). NIHSS score (OR = 1.254), pneumonia (OR = 6.631), GLU (OR = 1.240), HGB (OR = 0.970), and hCRP (OR = 1.021) were used to construct a predictive model for NLUTD in AIS patients. The model exhibited good performance (AUC = 0.899, calibration curve p = 0.953). Internal validation of the model demonstrated strong discrimination and calibration abilities (AUC = 0.898). Results from DCA and CIC curves indicated that the prediction model had high clinical utility. CONCLUSIONS: We developed a predictive model for AIS-NLUTD and created a nomogram with strong predictive capabilities, assisting healthcare professionals in evaluating NLUTD risk among AIS patients and facilitating early intervention.

[Analysis of genetic variants and molecular pathogenesis in a Chinese pedigree affected with Multiple epiphyseal dysplasia].

OBJECTIVE: To analyze the genetic variant and molecular pathogenesis in a Chinese pedigree affected with Multiple epiphyseal dysplasia (MED). METHODS: A MED pedigree which had presented at the Beijing Jishuitan Hospital Affiliated to Capital Medical University on September 13, 2020 was selected as the study subject. Clinical data of the pedigree were collected. Peripheral blood samples were drawn from pedigree members for the extraction of genomic DNA. Whole exome sequencing (WES) was carried out for the pedigree. Candidate variant was verified by Sanger sequencing. Wild type and mutant SLC26A2 expression plasmids were constructed and transfected into human primary chondrocytes. The effect of the variants on the protein localization and cell proliferation was determined by immunofluorescence and CCK8 assays. RESULTS: WES and Sanger sequencing revealed that the proband has harbored compound heterozygous variants of the SLC26A2 gene, including a paternally derived c.484G>T (p.Val162Leu) missense variant and a maternally derived c.485_486delTG (p.Val162Glyfs*12) frameshifting variant. The SLC26A2WT and its mutant SLC26A2Val162Leu and SLC26A2Val162Glyfs*12 expression plasmids were distributed in the nuclei and cytoplasm of human primary chondrocytes. Compared with SLC26A2WT, the expressions of SLC26A2Val162Leu and SLC26A2Val162Glyfs*12 were decreased, along with reduced proliferation of human primary chondrocytes. CONCLUSION: The c.484G>T and c.485_486delTG compound heterozygous variants of the SLC26A2 gene may affect the proliferation of human primary chondrocytes and underlay the pathogenesis of MED in this pedigree.

Evaluating health literacy from an organizational perspective: A cross-sectional study of community health centers.

OBJECTIVES: To investigate community health centers' (CHCs) health literacy. DESIGN: A cross-sectional study. SAMPLE: A total of 374 CHCs were surveyed and 258 CHCs responded, with an effective questionnaire response rate of 69.0%. MEASUREMENTS: Data were collected by using a self-developed health literacy assessment tool to survey CHCs' health literacy throughout Taiwan from January to December 2019. RESULTS: The item of organizational health literacy (OHL) with the highest proportion of CHCs not implementing them was "Design of easy-to-use computer applications and new media" (47.3% not yet achieved), followed by "Involving target audiences in document and service development" (34.9% not yet achieved). CHCs located in northern Taiwan had higher health literacy achievement scores than those in other regions, and those in urban areas had higher health literacy achievement scores than those in general and remote areas. CONCLUSIONS: This study identified items with poor implementation of OHL and found regional differences in health literacy among CHCs. The findings can inform the development of targeted interventions to improve health literacy in underperforming CHCs and guide policymakers in allocating resources to regions and areas in need of.

Corrigendum: Artemisinin reduces PTSD-like symptoms, improves synaptic plasticity, and inhibits apoptosis in rats subjected to single prolonged stress.

[This corrects the article DOI: 10.3389/fphar.2024.1303123.].

Complement C3a/C3aR and C5a/C5aR deposits accelerate the progression of advanced IgA nephropathy to end-stage renal disease.

IgA nephropathy (IgAN) is still one of the leading causes of end-stage kidney disease (ESRD), and complement system activation is a key to the pathogenesis of IgAN. The role of complement C3a/C3aR and C5a/C5aR in late stage of IgAN remains unknown. Renal specimens of 75 IgAN patients at the stage 4 CKD were stained using immunofluorescence and immunohistochemistry. The primary outcome was a composite of end-stage renal disease (ESRD) and death. Associations of complement components with baseline clinicopathological characteristics and outcomes were assessed using multivariable Cox regression and Spearman analyses. During a median follow-up of 15.0 months, 27 patients progressed to ESRD and none died. Lower eGFR [hazards ratio (HR), 0.827, 95% confidence interval (CI), 0.732-0.935; P = 0.002] and glomerular C3 deposition (HR, 3.179, 95% CI, 1.079-9.363; P = 0.036) were predictive of time to ESRD in stage 4 CKD IgAN. Higher expression of C3a (P = 0.010), C3aR (P = 0.005), C5a (P = 0.015), and C5aR (P < 0.001) was identified in ESRD group than in non-ESRD group. Glomerular C3a/C3aR and C5a/C5aR deposits were both correlated with a lower baseline eGFR, higher baseline 24 h-urinary protein (24 h-UP) and faster decline of eGFR. Besides, C3a and C5a deposits were found in patients with high S (S1) and T (T1/2) scores, respectively. Complement C3a/C3aR and C5a/C5aR in IgAN patients with stage 4 CKD may portend a faster deterioration of kidney function.

Integrated analysis of genes shared between type 2 diabetes mellitus and osteoporosis.

Background: The relationship between type 2 diabetes mellitus (T2DM) and osteoporosis (OP) has been widely recognized in recent years, but the mechanism of interaction remains unknown. The aim of this study was to investigate the genetic features and signaling pathways that are shared between T2DM and OP. Methods: We analyzed the GSE76894 and GSE76895 datasets for T2DM and GSE56815 and GSE7429 for OP from the Gene Expression Omnibus (GEO) database to identify shared genes in T2DM and OP, and we constructed coexpression networks based on weighted gene coexpression network analysis (WGCNA). Shared genes were then further analyzed for functional pathway enrichment. We selected the best common biomarkers using the least absolute shrinkage and selection operator (LASSO) algorithm and validated the common biomarkers, followed by RT-PCR, immunofluorescence, Western blotting, and enzyme-linked immunosorbent assay (ELISA) to validate the expression of these hub genes in T2DM and OP mouse models and patients. Results: We found 8,506 and 2,030 DEGs in T2DM and OP, respectively. Four modules were identified as significant for T2DM and OP using WGCNA. A total of 19 genes overlapped with the strongest positive and negative modules of T2DM and OP. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed these genes may be involved in pantothenate and CoA biosynthesis and the glycosaminoglycan biosynthesis-chondroitin sulfate/dermatan sulfate and renin-angiotensin system signaling pathway. The LASSO algorithm calculates the six optimal common biomarkers. RT-PCR results show that LTB, TPBG, and VNN1 were upregulated in T2DM and OP. Immunofluorescence and Western blot show that VNN1 is upregulated in the pancreas and bones of T2DM model mice and osteoporosis model mice. Similarly, the level of VNN1 in the sera of patients with T2DM, OP, and T2DM and OP was higher than that in the healthy group. Conclusion: Based on the WGCNA and LASSO algorithms, we identified genes and pathways that were shared between T2DM and OP. Both pantothenate and CoA biosynthesis and the glycosaminoglycan biosynthesis-chondroitin sulfate/dermatan sulfate and renin-angiotensin systems may be associated with the pathogenesis of T2DM and OP. Moreover, VNN1 may be a potential diagnostic marker for patients with T2DM complicated by OP. This study provides a new perspective for the systematic study of possible mechanisms of combined OP and T2DM.

Machine learning to predict the early recurrence of intrahepatic cholangiocarcinoma: A systematic review and meta­analysis.

The prediction of early recurrent of intrahepatic cholangiocarcinoma (ICC) has been widely investigated; however, the predictive value is currently insufficient. To determine the effectiveness of machine learning (ML) for the diagnosis of early recurrent intrahepatic cholangiocarcinoma (ICC), particularly in comparison with clinical models, the present study aimed to determine which ML model had the best diagnostic performance for inpatients with recurrent ICC. In order to search for studies which could be included, three electronic databases were screened from inception to November 2023. A pairwise meta-analysis was performed to evaluate the diagnostic accuracy of the random effects model. A network meta-analysis was performed to identify the most effective ML-based diagnostic model based on the surface under the cumulative ranking curve score. A total of 5 studies of acceptable quality containing 1,247 patients with ICC were included in the present study. Following pairwise meta-analysis, it was found that the ML-based diagnostic accuracy was greater than that of clinical models (surface under the cumulative ranking curve score closer to 1, with significant differences), which initially proved that the ML-based diagnostic power was more optimal than that of clinical models. According to the network meta-analysis, the nomogram performed the best, indicating that this ML model achieved the best diagnostic accuracy for patients with recurrent ICC. In conclusion, the application of ML-based diagnostic models for patients with recurrent ICC was more optimal than the application of the clinical model. The nomogram model ranked first among the models and is therefore recommended for patients with recurrent ICC.

O-GlcNAc signaling: implications for stress-induced adaptive response pathway in the tumor microenvironment.

The tumor microenvironment (TME) consists of tumor cells, non-tumor cells, extracellular matrix, and signaling molecules, which can contribute to tumor initiation, progression, and therapy resistance. In response to starvation, hypoxia, and drug treatments, tumor cells undergo a variety of deleterious endogenous stresses, such as hypoxia, DNA damage, and oxidative stress. In this context, to survive the difficult situation, tumor cells evolve multiple conserved adaptive responses, including metabolic reprogramming, DNA damage checkpoints, homologous recombination, up-regulated antioxidant pathways, and activated unfolded protein responses. In the last decades, the protein O-GlcNAcylation has emerged as a crucial causative link between glucose metabolism and tumor progression. Here, we discuss the relevant pathways that regulate the above responses. These pathways are adaptive adjustments induced by endogenous stresses in cells. In addition, we systematically discuss the role of O-GlcNAcylation-regulated stress-induced adaptive response pathways (SARPs) in TME remodeling, tumor progression, and treatment resistance. We also emphasize targeting O-GlcNAcylation through compounds that modulate OGT or OGA activity to inhibit tumor progression. It seems that targeting O-GlcNAcylated proteins to intervene in TME may be a novel approach to improve tumor prognosis.

COVID-19 is associated with changes in brain function and structure: a multimodal meta-analysis of neuroimaging studies.

The actual role of coronavirus disease 2019 (COVID-19) in brain damage has been increasingly reported, necessitating a meta-analysis to collate and summarize the inconsistent findings from functional imaging and voxel-based morphometry (VBM) studies. A comprehensive voxel-wise meta-analysis of the whole brain was conducted to identify alterations in functional activity and gray matter volume (GMV) between COVID-19 patients and healthy controls (HCs) by using Seed-based d Mapping software. We included 15 functional imaging studies (484 patients with COVID-19, 534 HCs) and 9 VBM studies (449 patients with COVID-19, 388 HCs) in the analysis. Overall, patients with COVID-19 exhibited decreased functional activity in the right superior temporal gyrus (STG) (extending to the right middle and inferior temporal gyrus, insula, and temporal pole [TP]), left insula, right orbitofrontal cortex (OFC) (extending to the right olfactory cortex), and left cerebellum compared to HCs. For VBM, patients with COVID-19, relative to HCs, showed decreased GMV in the bilateral anterior cingulate cortex/medial prefrontal cortex (extending to the bilateral OFC), and left cerebellum, and increased GMV in the bilateral amygdala (extending to the bilateral hippocampus, STG, TP, MTG, and right striatum). Moreover, overlapping analysis revealed that patients with COVID-19 exhibited both decreased functional activity and increased GMV in the right TP (extending to the right STG). The multimodal meta-analysis suggests that brain changes of function and structure in the temporal lobe, OFC and cerebellum, and functional or structural alterations in the insula and the limbic system in COVID-19. These findings contribute to a better understanding of the pathophysiology of brain alterations in COVID-19. SIGNIFICANCE STATEMENT: This first large-scale multimodal meta-analysis collates existing neuroimaging studies and provides voxel-wise functional and structural whole-brain abnormalities in COVID-19. Findings of this meta-analysis provide valuable insights into the dynamic brain changes (from infection to recovery) and offer further explanations for the pathophysiological basis of brain alterations in COVID-19.

A double boronic acid affinity "sandwich" SERS biosensor based on magnetic boronic acid controllable-oriented imprinting for high-affinity biomimetic specific recognition and rapid detection of target glycoproteins.

Transferrin (TRF), recognized as a glycoprotein clinical biomarker and therapeutic target, has its concentration applicable for disease diagnosis and treatment monitoring. Consequently, this study developed boronic acid affinity magnetic surface molecularly imprinted polymers (B-MMIPs) with pH-responsitivity as the "capture probe" for TRF, which have high affinity similar to antibodies, with a dissociation constant of (3.82 ± 0.24) × 10-8 M, showing 7 times of reusability. The self-copolymerized imprinted layer synthesized with dopamine (DA) and 3-Aminophenylboronic acid (APBA) as double monomers avoided nonspecific binding sites and produced excellent adsorption properties. Taking the gold nanostar (AuNS) with a branch tip "hot spot" structure as the core, the silver-coated AuNS functionalized with the biorecognition element 4-mercaptophenylboronic acid (MPBA) was employed as a surface-enhanced Raman scattering (SERS) nanotag (AuNS@Ag-MPBA) to label TRF, thereby constructing a double boronic acid affinity "sandwich" SERS biosensor (B-MMIPs-TRF-SERS nanotag) for the highly sensitive detection of TRF. The SERS biosensor exhibited a detection limit for TRF of 0.004 ng/mL, and its application to spiked serum samples confirmed its reliability and feasibility, demonstrating significant potential for clinical TRF detection. Moreover, the SERS biosensor designed in this study offers advantages in stability, detection speed (40 min), and cost efficiency. The portable Raman instrument for SERS detection fulfills the requirements for point-of-care testing.

Electronic Structure Modification of MnO2 Nanosheet Arrays with Enhanced Water Oxidation Activity and Stability by Nitrogen Plasma.

The strategic design of catalysts for the oxygen evolution reaction (OER) is crucial in tackling the substantial energy demands associated with hydrogen production in electrolytic water splitting. Despite extensive research on birnessite (δ-MnO2) manganese oxides to enhance catalytic activity by modulating Mn3+ species, the ongoing challenge is to simultaneously stabilize Mn3+ while improving overall activity. Herein, oxygen (O) vacancies and nitrogen (N) doping have been simultaneously introduced into the MnO2 through a simple nitrogen plasma approach, resulting in efficient OER performance. The optimized N-MnO2v electrocatalyst exhibits outstanding OER activity in alkaline electrolyte, reducing the overpotential by nearly 160 mV compared to pure pristine MnO2 (from 476 to 312 mV) at 10 mA cm-2, and a small Tafel slope of 89 mV dec-1. Moreover, it demonstrates excellent durability over a 122 h stability test. The introduction of O vacancies and incorporation of N not only fine-tune the electronic structure of MnO2, increasing the Mn3+ content to enhance overall activity, but also play a crucial role in stabilizing Mn3+, thereby leading to exceptional stability over time. Subsequently, density functional theory calculations validate the optimized electronic structure of MnO2 achieved through the two engineering methods, effectively lowering the intermediate adsorption free energy barrier. Our synergistic approach, utilizing nitrogen plasma treatment, opens a pathway to concurrently enhance the activity and stability of OER electrocatalysts, applicable not only to Mn-based but also to other transition metal oxides.

Zirconium ion mediated collagen nanofibrous hydrogels with high mechanical strength.

Low mechanical strength is still the key question for collagen hydrogel consisting of nanofibrils as hard tissue repair scaffolds with no loss of biological function. In this work, novel collagen nanofibrous hydrogels with high mechanical strength were fabricated based on the pre-protection of trisodium citrate masked Zr(SO4)2 solution for collagen self-assembling nanofibrils and then further coordination with Zr(SO4)2 solution. The mature collagen nanofibrils with d-period were observed in Zr(IV) mediated collagen hydrogels by AFM when the Zr(IV) concentration was ≥ 10 mmol/L, and the distribution of zirconium element was uniform. Due to the coordination of Zr(IV) with ─COOH, ─NH2 and ─OH within collagen and the tighter entanglement of collagen nanofibrils, the elastic modulus and compressive strength of Zr(IV) mediated collagen nanofibrous hydrogel were 208.3 and 1103.0 kPa, which were approximate 77 and 12 times larger than those of pure collagen hydrogel, respectively. Moreover, the environmental stability such as thermostability, swelling ability and biodegradability got outstanding improvements and could be regulated by Zr(IV) concentration. Most importantly, the resultant hydrogel showed excellent biocompatibility and even accelerated cell proliferation.

Insights into the epitranscriptomic role of N6-methyladenosine on aging skeletal muscle.

The modification of RNA through the N6-methyladenosine (m6A) has emerged as a growing area of research due to its regulatory role in gene expression and various biological processes regulating the expression of genes. m6A RNA methylation is a post-transcriptional modification that is dynamic and reversible and found in mRNA, tRNA, rRNA, and other non-coding RNA of most eukaryotic cells. It is executed by special proteins known as "writers," which initiate methylation; "erasers," which remove methylation; and "readers," which recognize it and regulate the expression of the gene. Modification by m6A regulates gene expression by affecting the splicing, translation, stability, and localization of mRNA. Aging causes molecular and cellular damage, which forms the basis of most age-related diseases. The decline in skeletal muscle mass and functionality because of aging leads to metabolic disorders and morbidities. The inability of aged muscles to regenerate and repair after injury poses a great challenge to the geriatric populace. This review seeks to explore the m6A epigenetic regulation in the myogenesis and regeneration processes in skeletal muscle as well as the progress made on the m6A epigenetic regulation of aging skeletal muscles.

Improving health system responses when patients are harmed: a protocol for a multistage mixed-methods study.

INTRODUCTION: At least 10% of hospital admissions in high-income countries, including Australia, are associated with patient safety incidents, which contribute to patient harm ('adverse events'). When a patient is seriously harmed, an investigation or review is undertaken to reduce the risk of further incidents occurring. Despite 20 years of investigations into adverse events in healthcare, few evaluations provide evidence of their quality and effectiveness in reducing preventable harm.This study aims to develop consistent, informed and robust best practice guidance, at state and national levels, that will improve the response, learning and health system improvements arising from adverse events. METHODS AND ANALYSIS: The setting will be healthcare organisations in Australian public health systems in the states of New South Wales, Queensland, Victoria and the Australian Capital Territory. We will apply a multistage mixed-methods research design with evaluation and in-situ feasibility testing. This will include literature reviews (stage 1), an assessment of the quality of 300 adverse event investigation reports from participating hospitals (stage 2), and a policy/procedure document review from participating hospitals (stage 3) as well as focus groups and interviews on perspectives and experiences of investigations with healthcare staff and consumers (stage 4). After triangulating results from stages 1-4, we will then codesign tools and guidance for the conduct of investigations with staff and consumers (stage 5) and conduct feasibility testing on the guidance (stage 6). Participants will include healthcare safety systems policymakers and staff (n=120-255) who commission, undertake or review investigations and consumers (n=20-32) who have been impacted by adverse events. ETHICS AND DISSEMINATION: Ethics approval has been granted by the Northern Sydney Local Health District Human Research Ethics Committee (2023/ETH02007 and 2023/ETH02341).The research findings will be incorporated into best practice guidance, published in international and national journals and disseminated through conferences.