The aim of this study was to compare the clinical characteristics, treatments and outcomes of immunocompromised patients with viral severe acute respiratory infections (SARI), to those of immunocompetent patients admitted to an intensive care unit (ICU) across Australia. Retrospective analysis of a prospective, nation-wide, observational registry of 46 ICUs from June 2022 to August 2025. Critically ill adults (age ≥ 18) with laboratory-confirmed viral SARI were included. Immunocompromised status was defined by the presence of any one of the following: chronic immunosuppression, malignant neoplasm, AIDS/HIV, or organ transplantation. Associations between immunocompromised status and in-hospital mortality were evaluated using mixed-effects logistic regression models. Competing risks regression (Fine and Gray models) was used to assess the association between immunocompromised status and risk of hospital discharge within 30 days. Among 4,703 patients with viral SARI who were admitted to ICUs, immunocompromised patients accounted for 908 (19.3

Toll-like receptor 4 (TLR4) is a pattern recognition receptor that binds to pathogen associated molecular patterns (PAMPs) and damage associated molecular patterns (DAMPs). Binding of exogenous or endogenous ligands activates the TLR4 pathway and induces the production of pro-inflammatory cytokines TNF-α, IL-6 and IL-1β and type 1 interferons including IFN-α and IFN-β. TLR4 plays a vital role in host defense against Gram-negative bacterial infections by recognizing lipopolysaccharides (LPS) and inducing inflammatory mediators to clear infection. However, there is emerging evidence that excessive TLR4 activation may be pathogenic in human diseases affecting the central nervous system, cardiovascular, respiratory and metabolic systems, thereby promoting inflammation and autoimmunity. In some diseases, the is conflicting evidence regarding pathogenic versus protective roles. Several TLR4 targeted therapeutics have been developed and studied in animal models, however many of these therapeutics including Eritoran and TAK-242 did not prove to be effective in clinical trials. Overall, TLR4 exhibits context-dependent protective and pathogenic roles across infectious and non-infectious diseases, reflecting the complexity of its signaling in human health and disease.

OBJECTIVES:The COVID-19 pandemic highlighted an urgent need to more efficiently identify patients at highest risk for developing respiratory failure. We investigated whether plasma levels of lung injury biomarkers are associated with progression to respiratory failure among adults hospitalized with COVID-19 pneumonia without respiratory failure at admission. DESIGN:This was a nested case-control study of COVID-19 patients enrolled in the Accelerating COVID-19 Therapeutic Interventions and Vaccines-3 (ACTIV-3)/Therapeutics for Inpatients with COVID-19 (TICO) platform trial who were on less than 20 L/min supplemental oxygen at enrollment. We compared baseline measurements of lung injury biomarkers between participants who progressed to respiratory failure or died by study day 10 (cases) and matched controls who did not progress to respiratory failure or death. Cases and controls were matched 1:1 on age, baseline oxygen requirement, immunomodulator use, and study arm. SETTING:Hospitals enrolling in the ACTIV-3/TICO trials. PATIENTS:Four hundred five cases and 405 matched controls. INTERVENTIONS:None. MEASUREMENTS AND MAIN RESULTS:Baseline levels of plasma interleukin (IL)-6, IL-8, IL-18, tumor necrosis factor receptor, angiopoietin-2, soluble receptor for advanced glycation end-products (sRAGE), C-reactive protein (CRP), and surfactant protein D (SPD) were compared between cases and controls using matched logistic regression. Forward variable selection was used to identify biomarkers that were independently associated with progression to respiratory failure or death in a multivariate model. All lung injury biomarkers with the exception of SPD were significantly associated with progression to respiratory failure or death, with sRAGE demonstrating the highest odds ratio (OR) for each doubling of biomarker level (OR, 1.85; 95% CI, 1.61-2.12). In multivariate regression analysis, sRAGE, IL-6, and CRP were independently associated with progression, with sRAGE as the biomarker with the strongest association. CONCLUSIONS:Baseline levels of plasma lung injury biomarkers are significantly associated with progression to respiratory failure or death among hospitalized COVID-19 patients without respiratory failure at admission. These findings support the potential utility of measuring lung injury biomarkers in patients hospitalized without respiratory failure and should be tested in more heterogeneous patient groups including non-COVID-19 cohorts.

Introduction Immunosuppression is associated with an increased risk of delayed SARS-CoV-2 viral clearance, severe COVID-19 and related death. This heterogeneous group of affected patients includes but is not limited to those with a haematological malignancy, people on immunosuppressive therapy for the treatment of autoimmune/inflammatory diseases and those following bone marrow transplantation (BMT). Immunosuppression is associated with decreased rates of anti-spike IgG seroconversion following COVID-19 vaccination. While clinical guidelines have been established to guide vaccination pre-splenectomy and post-BMT, there are limited data to guide timing of COVID-19 or other booster vaccines in adults commencing new or intensified moderate to severe immunosuppression. The comparison of immunity-boosting regimens for COVID-19 upon initiation of immunosuppressive therapy (CIRCUIT) study was designed to address this knowledge gap. CIRCUIT investigates whether administration of a third (or subsequent) COVID-19 booster vaccine ≤2 weeks prior to immunosuppression provides greater anti-spike IgG-mediated immunity than a booster given 24 weeks after new or intensified immunosuppression, that is, week 24 timepoint (Group 1; n=280). Additionally, the research will investigate whether giving a fourth post-BMT COVID-19 booster vaccine at 9 months post-transplant provides greater anti-spike IgG-mediated immunity than a booster given 15 months post-transplant (Group 2; n=40).Methods and analysis The CIRCUIT study is an open-label, multicentre randomised clinical trial. Participants will be randomised 1:1 to receive either an additional COVID-19 booster ≤2 weeks pre-immunosuppression and a diphtheria/tetanus toxoids (DT) booster at 24 weeks following new or intensified immunosuppression (week 24 timepoint) or receive a DT booster ≤2 weeks pre-immunosuppression and an additional COVID-19 booster at week 24 (Group 1). Group 2 participants who underwent autologous or allogenic BMT in the last 9 months will be randomised 1:1 to either receive a fourth post-BMT COVID-19 booster at 9 or 15 months post-transplant. The primary outcome will be the integrated time-weighted area under the curve anti-SARS-CoV-2 neutralising antibody (NAb) response over 12 months from a SARS-CoV-2 booster as assessed by a high-throughput SARS-CoV-2 NAb platform assay. Key secondary outcomes of the CIRCUIT randomised control trial will include safety and generation of SARS-CoV-2 antigen specific T and B cell responses.Ethics and dissemination The research protocol was approved by the Western Sydney Local Health District Human Research Ethics Committee on 25 August 2022 (Ref no. 2022/PID00782 – 20022/ETH0069). Study results will be published in peer-reviewed medical journals and presented at local and international conferences. All findings regardless of the outcome will be reported.Trial registration number NCT05415267.

Multiparametric flow cytometry (MFC) enables rapid and sensitive quantification of measurable residual disease (MRD) in patients with acute myeloid leukaemia (AML), providing valuable prognostic information and guiding post-remission therapeutic strategies. Given the clinical utility of MFC AML MRD assessment and its inherent technical and analytical complexity, inter-laboratory standardisation is essential to ensure consistency of practice, diagnostic accuracy and reproducibility of results. However, limited options for external quality assessment exist. Representatives from all diagnostic laboratories in Australia and New Zealand currently performing AML MRD testing were invited to attend an in-person workshop to review site-specific practices and develop harmonisation processes. All six participating laboratories demonstrated a high level of concordance with respect to pre-analytical testing; however, greater variation was observed in post-analytical reporting, and a number of consensus recommendations were formulated for harmonisation. Ongoing meetings have also been established to promote continued sharing of expertise between AML MRD laboratories, align analytical strategies and enhance assay validation in accordance with regulatory requirements. These collaborative efforts provide guidance to existing MRD laboratories and those seeking to establish a new MRD service, facilitating sustainable provision of a high-quality regional MFC AML MRD testing network to meet current and anticipated increases in clinical demand.

Oesophageal adenocarcinoma (OAC) outcomes remain poor, with a 5-year survival rate of 20

BACKGROUNDCheckpoint inhibitor-associated autoimmune diabetes mellitus (CIADM) is a rare but life-altering complication of immune checkpoint inhibitor (ICI) therapy. Biomarkers that predict type 1 diabetes (T1D) are unreliable for CIADM.AIMIn the present study, we sought to identify biomarkers for the prediction of CIADM.METHODSFrom our prospective biobank, we identified 14 patients with CIADM who had metastatic melanoma treated with anti-programed antibody death 1 (anti-PD-1) with or without anti-cytotoxic T lymphocyte-associated antibody protein 4 (anti-CTLA4). Controls were selected from the same biobank, matched 2:1. Pretreatment, on-ICI, and post-CIADM serum and PBMCs were analyzed. Serum was analyzed for T1D autoantibodies, C-peptide, glucose, and cytokines. PBMCs were profiled using flow cytometry. Pancreatic volume was measured using CT volumetry.RESULTSBefore treatment, patients with CIADM had smaller pancreatic volume (27% reduction, P = 0.044) and higher anti-glutamic acid decarboxylase autoantibody (anti-GAD) titers (median 2.9 vs. 0, P = 0.01). They had significantly higher baseline proportions of Th17 cells (P = 0.03), higher CD4+ central memory cells (P = 0.04), and lower naive CD4+ T cells (P = 0.01). With ICI treatment, greater declines in pancreatic volume were seen in patients with CIADM (P < 0.0001). Activated CD4+ T cell subsets increased significantly in CIADM and controls with immune-related adverse effects (IRAEs) but not in controls without IRAEs. Using only pretreatment results, we found that pancreatic volume, anti-GAD antibody titers, and the baseline immune flow profile were highly predictive of CIADM development, with an AUC of greater than 0.96.CONCLUSIONSPeople who develop CIADM are immunologically predisposed and have antecedent pancreatic and immunological changes that accurately predict disease with excellent sensitivity. These biomarkers could be used to guide ICI use, particularly when planning treatment for low-risk tumors.FUNDINGNational Health and Medical Research Council (NHMRC) Investigator grants 2033228, 2009476, and 2007839.

Critically unwell patients with acute pancreatitis (AP) are at increased risk of mortality and prolonged ICU length of stay (LOS). We quantified the frequency, risk factors and complications of prolonged ICU LOS in a large cohort of critically unwell adult patients with AP and developed a model to predict a low-risk trajectory ‘survived ICU with ICU LOS ≤7 days’ versus a high-risk trajectory ‘ICU mortality or ICU LOS > 7 days’. A retrospective cohort analysis of adult patients admitted to Australian and New Zealand ICUs with AP between 2003 and 2020 was conducted using the Australian and New Zealand Intensive Care Society Centre for Outcome Reporting and Evaluation database. Data was censored to December 2020 in order to pre-date the COVID-19 pandemic. The incidence, risk factors and outcomes related to prolonged ICU LOS in AP patients was reported. Multivariate logistic regression was used to build a prediction model for a low-risk versus high-risk outcome. Discrimination was performed with 10-fold cross validation and calibration plot analysis was reported. 13,275 patients met inclusion criteria; 60

The immune–epithelial–stromal interactions underpinning intestinal damage in celiac disease (CD) are incompletely understood. To address this, we performed single-cell transcriptomics (RNA sequencing; 86,442 immune, parenchymal and epithelial cells; 35 participants) and spatial transcriptomics (20 participants) on CD intestinal biopsy samples. Here we show that in CD, epithelial populations shifted toward a progenitor state, with interferon-driven transcriptional responses, and perturbation of secretory and enteroendocrine populations. Mucosal T cells showed numeric and functional changes in regulatory and follicular helper-like CD4 + T cells, intraepithelial lymphocytes, CD8 + and γδ T cell subsets, with skewed T cell antigen receptor repertoires. Mucosal changes remained detectable despite treatment, representing a persistent immune–epithelial ‘scar’. Spatial transcriptomics defined transcriptional niches beyond those captured in conventional histological scores, including CD-specific lymphoid aggregates containing T cell–B cell interactions. Receptor–ligand spatial analyses integrated with disease susceptibility gene expression defined networks of altered chemokine and morphogen signaling, and provide potential therapeutic targets for CD prevention and treatment.

Bruton's tyrosine kinase inhibitors (BTKi), widely used in Waldenström macroglobulinemia (WM), are known to impair B cell function, but their broader immunological effects remain unclear. We investigated the T cell compartment in patients with WM receiving BTKi, including those who underwent a supervised treatment pause before a third COVID-19 mRNA vaccine dose, as well as treatment naïve controls. Using flow cytometry, antigen-specific T cell assays, and single-cell RNA sequencing, we found that BTKi-treated patients exhibited a reduction in naïve T cells, enrichment of terminal effector CD8⁺ Temra cells, and lower PD-1 expression. Despite poor vaccine-induced RBD-specific memory B cells, CD4⁺ and CD8⁺ T cell responses to SARS-CoV-2 remained detectable, with enhanced CD8⁺ responses to the omicron variant in BTKi-treated individuals. Single-cell transcriptomics revealed an expansion of CD16⁺ CD56⁺ Granzyme B⁺ NK-like CD8⁺ T cells in BTKi-treated patients, which further increased following BTKi interruption. These cells expressed a potent cytotoxic and NK-like transcriptional phenotype. Our findings identify a novel off-target effect of BTKi therapy: expansion of cytotoxic NK-like CD8⁺ T cells, with implications for immune monitoring and vaccine responsiveness in BTKi-treated patients.

The success of checkpoint inhibitors (CPIs) for cancer has been tempered by immune-related adverse effects including colitis. CPI-induced colitis is hallmarked by expansion of resident mucosal IFNγ cytotoxic CD8+ T cells, but how these arise is unclear. Here, we track CPI-bound T cells in intestinal tissue using multimodal single-cell and subcellular spatial transcriptomics (ST). Target occupancy was increased in inflamed tissue, with drug-bound T cells located in distinct microdomains distinguished by specific intercellular signaling and transcriptional gradients. CPI-bound cells were largely CD4+ T cells, including enrichment in CPI-bound peripheral helper, follicular helper, and regulatory T cells. IFNγ CD8+ T cells emerged from both tissue-resident memory (TRM) and peripheral populations, displayed more restricted target occupancy profiles, and co-localized with damaged epithelial microdomains lacking effective regulatory cues. Our multimodal analysis identifies causal pathways and constitutes a resource to inform novel preventive strategies.

AbstractLymphopenia is a common feature of acute COVID-19 and is associated with increased disease severity and 30-day mortality. Here we aim to define the demographic and clinical characteristics that correlate with lymphopenia in COVID-19 and determine if lymphopenia is an independent predictor of poor clinical outcome. We analysed the ENTER-COVID (Epidemiology of hospitalized in-patient admissions following planned introduction of Epidemic SARS-CoV-2 to highly vaccinated COVID-19 naïve population) dataset of adults (N = 811) admitted for COVID-19 treatment in South Australia in a retrospective registry study, categorizing them as (a) lymphopenic (lymphocyte count < 1 × 109/L) or (b) non-lymphopenic at hospital admission. Comorbidities and laboratory parameters were compared between groups. Multiple regression analysis was performed using a linear or logistic model. Intensive care unit (ICU) patients and non-survivors exhibited lower median lymphocyte counts than non-ICU patients and survivors respectively. Univariate analysis revealed that low lymphocyte counts associated with hypertension and correlated with haemoglobin, platelet count and negatively correlated with urea, creatinine, bilirubin, and aspartate aminotransferase (AST). Multivariate analysis identified age, male, haemoglobin, platelet count, diabetes, creatinine, bilirubin, alanine transaminase, c-reactive protein (CRP) and lactate dehydrogenase (LDH) as independent predictors of poor clinical outcome in COVID-19, while lymphopenia did not emerge as a significant predictor.

Measurable residual disease (MRD) detected by flow cytometry (FC) is well established in paediatric B- lymphoblastic leukaemia (B-ALL) and adult chronic lymphocytic leukaemia (CLL), but its utility in adult B-ALL and adult acute myeloid leukaemia (AML) is less clear. In this prospective MRD study, one of the largest in Australia to date, we examined consecutive bone marrow aspirates from adult participants with B-ALL (n = 47) and AML (n = 87) sent for FC-MRD testing at a quaternary referral hospital in Sydney. FC-MRD results were correlated to corresponding Mol-MRD testing where available and clinical outcomes at three-month intervals over 1 year. B-ALL showed a moderate positive correlation (rs = 0.401, p < 0.001), while there was no correlation between FC-MRD and Mol-MRD for AML (rs = 0.13, p = 0.237). Five FC-MRD patterns were identified which had significant associations with relapse (X2(4) = 31.17(4), p > 0.001) and survival (X2(4) = 13.67, p = 0.008) in AML, but not in B-ALL. The three-month MRD results were also strongly associated with survival in AML, while the association in B-ALL was less evident. There was a moderate correlation between FC-MRD and Mol-MRD in B-ALL but not AML. The association of FC-MRD with relapse and survival was stronger in AML than in B-ALL. Overall, these findings suggest divergent utilities of FC-MRD in AML and B-ALL.

OBJECTIVE:To conduct a multicenter case series characterizing the clinical characteristics at presentation and pancreatic volume changes of patients with checkpoint inhibitor-associated autoimmune diabetes (CIADM). RESEARCH DESIGN AND METHODS:Electronic medical records were reviewed with 36 consecutive patients identified with CIADM, as defined by (1) previous immune checkpoint inhibitor (ICI) therapy, (2) new-onset hyperglycemia (blood glucose level ≥ 11.1 mmol/L and/or glycosylated hemoglobin ≥ 6.5%), and (3) insulin deficiency [C-peptide <0.4 nmol/L or diabetic ketoacidosis (DKA)] within 1 month of presentation. Pancreatic volume was available and measured using computed tomography volumetry for 17 patients with CIADM and 3 sets of control patients: 7 with ICI-related pancreatitis, 13 with asymptomatic ICI-related lipase elevation, and 11 ICI-treated controls for comparison. RESULTS:All patients had either anti-programmed cell death protein 1 or anti-programmed cell death ligand 1 therapy. Median time from ICI commencement to CIADM diagnosis was 15 weeks. At presentation, 25 (69%) had DKA, 27 (84%) had low C-peptide, and, by 1 month, 100% had low C-peptide. Traditional type 1 diabetes autoantibodies were positive in 15/35 (43%). Lipase was elevated in 13/27 (48%) at presentation. In 4 patients with longitudinal lipase testing, elevated levels peaked 1 month prior to CIADM diagnosis. Pancreatic volume was lower pre-ICI in CIADM patients compared with controls and demonstrated a mean decline of 41% from pretreatment to 6 months post-CIADM diagnosis. CONCLUSION:Pronounced biochemical and radiologic changes occur during CIADM pathogenesis. Rapid loss of C-peptide is a distinct characteristic that can be used to aid diagnosis as autoantibodies are often negative.

Measurable residual disease (MRD) is useful for prognostication and for monitoring response to treatment in patients with acute leukaemia. MRD by multiparametric flow cytometry (MFC-MRD) utilises the leukaemia-associated immunophenotype (LAIP) and difference from normal (DfN) strategies to identify the leukaemic clone. Difficulties arise when the LAIP overlaps with normal regeneration, there is clonal evolution, or when the abnormal clone population is exceptionally small e.g., <0.01% of CD45+ cells. Such cases are reported as 'indeterminate'; however, there is little international consensus on this reporting. The relationship between clinical outcomes and indeterminate MFC-MRD is unknown. Here we determine the rate of indeterminate MFC-MRD reporting, its relationship to concurrent molecular MRD results when available, and to clinical outcomes to 12 months. We performed an internal audit of all adult testing for MFC-MRD between January and December 2021. A total of 153 consecutive patients with a diagnosis of acute leukaemia were included. Successive MFC-MRD results and clinical outcomes were recorded over a 12-month period from time of inclusion into the study. In total, 460 MFC-MRD tests from 153 patients were reviewed and 73 (16%) MFC-MRD tests from 54 (35%) patients were reported as indeterminate. The majority (70%) were at low levels between 0.01-0.1% of CD45+ cells. Compared to patients with a negative result, acute myeloid leukaemia (AML) was more frequent in patients who had an indeterminate MFC-MRD (70% vs 36%), and B-cell acute lymphoblastic leukaemia was less common (20% vs 55%). In patients with indeterminate MFC-MRD results, one-third had received either chemotherapy or allogeneic haemopoietic stem cell transplant (aHSCT) within the preceding 3 months. Agreement between MFC and molecular MRD testing was low. Patients with indeterminate MFC-MRD had leukaemia relapse rates below patients with a positive MFC-MRD, but greater than those with negative MFC-MRD (positive 33% vs indeterminate 21% vs negative 8%, p = 0.038). Overall, these findings indicate that indeterminate MFC-MRD results are more common in adults with AML and also in those who have received chemotherapy or aHSCT within the previous 3 months. We report for the first time that indeterminate MFC-MRD is a finding of potential clinical significance, which associates with a numerically higher median relapse rate within 12 months when compared to a negative MFC-MRD result.

Patients with Waldenström macroglobulinaemia (WM) are at increased risk of severe COVID-19 infection and have poor immune responses to COVID-19 vaccination. This study assessed whether a closely monitored pause in Bruton's Tyrosine Kinase inhibitor (BTKi) therapy might result in an improved humoral response to a 3rd COVID-19 vaccine dose. Improved response was observed in WM patients who paused their BTKi, compared to a group who did not pause their BTKi. However, the response was attenuated after BTKi recommencement. This data contributes to our understanding of vaccination strategies in this patient group and may help inform consensus approaches in the future.