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Juvenile idiopathic arthritis is a heterogeneous group of diseases characterised by arthritis of unknown origin with onset before age of 16 years. Pivotal studies in the past 5 years have led to substantial progress in various areas, ranging from disease classification to new treatments. Gene expression profiling studies have identified different immune mechanisms in distinct subtypes of the disease, and can help to redefine disease classification criteria. Moreover, immunological studies have shown that systemic juvenile idiopathic arthritis is an acquired autoinflammatory disease, and have led to successful studies of both interleukin-1 and interleukin-6 blockade. In other forms of the disease, synovial inflammation is the consequence of a disturbed balance between proinflammatory effector cells (such as T-helper-17 cells), and anti-inflammatory regulatory cells (such as FOXP3-positive regulatory T cells). Moreover, specific soluble biomarkers (S100 proteins) can guide individual treatment. Altogether these new developments in genetics, immunology, and imaging are instrumental to better define, classify, and treat patients with juvenile idiopathic arthritis.

ObjectivesYttrium-90 (Y90)-radioembolisation (RE) significantly regresses locally advanced hepatocellular carcinoma and delays disease progression. The current study is designed to deeply interrogate the immunological impact of Y90-RE, which elicits a sustained therapeutic response.DesignTime-of-flight mass cytometry and next-generation sequencing (NGS) were used to analyse the immune landscapes of tumour-infiltrating leucocytes (TILs), tumour tissues and peripheral blood mononuclear cells (PBMCs) at different time points before and after Y90-RE.ResultsTILs isolated after Y90-RE exhibited signs of local immune activation: higher expression of granzyme B (GB) and infiltration of CD8+ T cells, CD56+ NK cells and CD8+ CD56+ NKT cells. NGS confirmed the upregulation of genes involved in innate and adaptive immune activation in Y90-RE-treated tumours. Chemotactic pathways involving CCL5 and CXCL16 correlated with the recruitment of activated GB+CD8+ T cells to the Y90-RE-treated tumours. When comparing PBMCs before and after Y90-RE, we observed an increase in tumour necrosis factor-α on both the CD8+ and CD4+ T cells as well as an increase in percentage of antigen-presenting cells after Y90-RE, implying a systemic immune activation. Interestingly, a high percentage of PD-1+/Tim-3+CD8+ T cells coexpressing the homing receptors CCR5 and CXCR6 denoted Y90-RE responders. A prediction model was also built to identify sustained responders to Y90-RE based on the immune profiles from pretreatment PBMCs.ConclusionHigh-dimensional analysis of tumour and systemic immune landscapes identified local and systemic immune activation that corresponded to the sustained response to Y90-RE. Potential biomarkers associated with a positive clinical response were identified and a prediction model was built to identify sustained responders prior to treatment.

BackgroundSteatotic liver disease-related hepatocellular carcinoma (SLD-HCC), a rising global challenge, is characterised by unique tumour microenvironment (TME) adaptations.ObjectiveThis study investigates the immune microenvironment and interactions driving immunosuppression and potential resistance to immunotherapy in SLD-HCC.DesignWe employed single-cell transcriptomics, cytometry by time-of-flight (CyTOF) and two independent spatial transcriptomics platforms to study the TME of 22 SLD-HCC and 31 non-SLD-HCC cases. Findings were further validated using multiplex immunohistochemistry in an independent cohort of 103 patients, an HCC model and an immunotherapy-treated patient cohort to evaluate clinical relevance.ResultsOur findings revealed significant alterations in immune and lipid metabolism pathways, particularly in regulatory T cells (Tregs) and cancer-associated fibroblasts (CAFs), suggesting distinct cellular adaptations to a high-fat TME and general immunosuppression. CyTOF revealed a cold, immunosuppressive TME with reduced CD8+ T cells and increased Tregs. Spatial transcriptomics further highlighted distinct Treg–CAF clusters localised at tumour margins, suggesting a spatially organised immunosuppressive niche. Mechanistically, tumour necrosis factor superfamily member 14 (TNFSF14)-tumour necrosis factor receptor superfamily member 14 (TNFRSF14)-mediated Treg–CAF interaction was identified as a critical driver of immunotherapy resistance in SLD-HCC. Blocking TNFRSF14 in an HCC model fed with a high-fat diet resulted in reduced Tregs, increased active CD8+ and memory CD4+ T cells, and a synergistic effect with anti-programmed cell death protein 1 therapy to enhance antitumour immunity and overcome immunotherapy resistance in SLD-HCC.ConclusionThis study uncovers critical immune and metabolic adaptations in SLD-HCC, identifying TNFSF14-TNFRSF14 signalling as a key driver of immunotherapy resistance. Targeting this signalling axis enhances antitumour immunity and improves immunotherapy efficacy, offering a promising therapeutic strategy for SLD-HCC.

The human gut microbiota plays a key role in neurochemical communication, especially through the gut–brain axis. There is growing evidence that the gut microbiota influences dopamine metabolism through both production and consumption mechanisms. Two key bacterial enzymes are central to this process: tyrosine decarboxylase (TDC), which primarily catalyzes the decarboxylation of tyrosine to tyramine but can also act on L-DOPA to produce dopamine in certain bacterial strains, and aromatic L-amino acid decarboxylase (AADC), which can convert precursors such as L-DOPA, tryptophan, or 5-hydroxytryptophan into bioactive amines including dopamine, tryptamine, and serotonin. Identifying the bacterial families corresponding to TDC and AADC enzymes opens new avenues for clinical intervention, particularly in neuropsychiatric and neurodegenerative disorders, such as Parkinson’s disease. Moreover, elucidating strain-specific microbial contribution and host-microbe interactions may enable personalized therapeutic strategies, such as selective microbial enzyme inhibitors or tailored probiotics, to optimize dopamine metabolism. Emerging technologies, including biosensors and organ-on-chip platforms, offer new tools to monitor and manipulate microbial dopamine activity. This article explores the bacterial taxa capable of producing or consuming dopamine, focusing on the enzymatic mechanisms involved and the methodologies available for studying these processes in vivo.

Mechanisms underlying paediatric acute respiratory distress syndrome (PARDS) remain poorly understood, limiting advances in diagnosis and treatment. To address this, we conduct a high-dimensional, multi-omics analysis of paired pulmonary and blood samples from children with PARDS and age-matched controls. Our approach includes transcriptomics, proteomics, flow and mass cytometry, and single-cell RNA sequencing, with further validation using cytokine assays and in vitro models. Severe PARDS is characterised by three convergent immune abnormalities; Pulmonary CD8 + T cells display an interferon-driven cytotoxic profile, with exhaustion and apoptosis genes; Pulmonary T cells and myeloid cells exhibit strong interferon-stimulated gene expression; Distinct macrophage subsets show high interferon but suppressed IL-1 pathway genes, associated with impaired leukocyte chemotaxis, phagocytosis, and M1-polarization. This is mirrored by reduced pulmonary IL-1α/β and elevated IFN-γ. The systemic IL-1 signature is similarly dampened, while interferon responses are compartmentalised to the lung. Using an in vitro model, IFN-γ priming is shown to suppress TLR7-induced IL-1 β production through transcriptional inhibition of downstream inflammatory pathways, recapitulating the immune signature observed in patients. Our results reveal interferon-driven immune dysregulation and IL-1 suppression as central features of severe PARDS, highlighting parallels and differences from adult ARDS and underscoring the need for paediatric-specific therapeutic strategies. Paediatric acute respiratory distress syndrome (ARDS) is a potentially life-threatening condition in children, understanding the immuno-pathology is of importance. Here the authors employ a high-dimensionality approach to identify dysregulated immune pathways underpinning the condition, and find important differences compared to ARDS in adults.

Intravesical Bacillus Calmette-Guerin (BCG) is an effective immunotherapy for non-muscle invasive bladder cancer (NMIBC). However, recurrence and progression remain frequent warranting deeper insights into its mechanism. We herein comprehensively profiled blood and tissues obtained from NMIBC patients before, during and after BCG treatment using cytometry by time-of-flight (CyTOF) and RNA sequencing to identify the key immune subsets crucial for anti-tumor activity. We observed the temporal changes of peripheral immune subsets including NKT cells, central memory CD4 + T cells, CD8 + T cells and regulatory T cells (Treg) during the course of BCG. Gene expression analysis revealed enriched immune pathways involving in T cell activation and chemotaxis, as well as a more diversified T cell receptor repertoire in post-BCG tissues. Moreover, tissue multiplexed-immunofluorescence (mIF) showed baseline densities of non-Treg and CD8 + PD-1 + T cells were predictive of response and better recurrence-free survival after BCG. Remarkably, post-BCG tissues from responders were found to be infiltrated with more active CD8 + PD-1 - T cells and non-Treg CD4 + FOXP3 - T cells; but increased exhausted CD8 + PD-1 + T cells were found in non-responders. Taken together, we identified predictive biomarkers for response and uncovered the post-treatment expansion of exhausted PD-1 + CD8 + T cells as key to BCG resistance, which could potentially be restored by combining with anti-PD-1 immunotherapy.

ObjectivesPaediatric acute respiratory distress syndrome (PARDS) is a heterogeneous condition and identifying a specific biomarker remains a challenge. We aimed to validate the association of plasma soluble receptor for advanced glycation end-products (sRAGE) and angiopoietin-2 (Ang-2) with PARDS diagnosis, and its prognostic performance.MethodsThis prospective observational study included children with PARDS and non-PARDS critical illness. Plasma sRAGE and Ang-2 levels were measured using enzyme-linked immunosorbent assays. Comparisons were made between PARDS versus non-PARDS critical illness and survivors versus non-survivors. Multivariable logistic regression was used to determine the association between biomarkers and intensive care unit (ICU) mortality after adjusting for age and the Pediatric Index of Mortality 3 score.Results93 and 117 patients with PARDS and non-PARDS critical illness, respectively, were included in this study. Plasma sRAGE was higher in PARDS versus non-PARDS critical illness (2981 (1027 to 6198) vs 1575 (864 to 2994) pg/mL; p=0.002) and in non-survivors vs survivors (5323 (1647 to 8261) vs 1601 (864 to 3572); p<0.001). Plasma Ang-2 was elevated in non-survivors versus survivors (3054 (1760 to 6808) vs 1748 (845 to 3868); p=0.002), though there was no difference between PARDS and non-PARDS groups. In the multivariable model, sRAGE demonstrated an independent association with PARDS diagnosis (adjusted OR (aOR) 1.01 95% CI 1.01 to 1.02; p=0.003) and ICU mortality (aOR 1.02 (95% CI 1.01 to 1.03); p<0.001), whereas there was no association observed with Ang-2.ConclusionWithin an ICU cohort, only sRAGE demonstrated an association with the diagnosis of PARDS and ICU mortality, which remained after controlling for confounders.

Background Alzheimer’s disease (AD), dementia with Lewy bodies (DLB), and Parkinson’s disease dementia (PDD) collectively represent the majority of dementia cases worldwide. While these subtypes share clinical, genetic, and pathological features, their transcriptomic similarities and differences remain poorly understood. Methods We applied single-nucleus RNA-sequencing (snRNA-seq) to prefrontal cortex samples from individuals with non-cognitive impairment control (NCI), and dementia subtypes (AD, DLB, and PDD) to investigate cell type-specific gene expression patterns and pathways underlying pathological similarities and differences across dementia subtypes. SnRNA-seq findings were validated through RNAscope, immunohistochemistry, and additional biochemical analyses in human tissues and cellular models. Results SnRNA-seq analysis revealed elevated microglial proportions across all dementia subtypes compared to NCI. Further analysis of cell type-specific transcriptomes identified overlapping differentially expressed genes (DEGs) between microglia and oligodendrocytes across all dementia subtypes. While AD showed molecular similarities to NCI, PDD and DLB were clustered more closely together, sharing a greater number of DEGs and related pathways, predominantly associated with microglia. Investigation of interactions between microglia and oligodendrocytes revealed a distinct microglial state in all dementia subtypes. MSR1 , a gene encoding a scavenger receptor, was upregulated in microglia across all dementia subtypes, along with its associated gene HSPA1A in oligodendrocytes. RNAscope supported the potential interaction between microglia and oligodendrocytes, where these cells were in closer proximity to each other in human cortical tissues of PDD compared to NCI. MSR1 expression was significantly increased in cortical primary microglia from PD mice compared with non-transgenic (NTg) mice. Additionally, the expression of myelin-associated genes ( MBP , MOBP , and PLP1 ) was significantly upregulated in PD microglia compared to NTg, supporting the presence of the distinct microglia. Furthermore, MSR1-positive microglia colocalised with MBP in cortical tissue of PDD patients, suggesting a functional role of MSR1 in myelin debris clearance. Overexpression of MSR1 in microglial cells enhanced their phagocytic activity toward myelin, and reciprocally, myelin treatment upregulated MSR1 protein levels, indicating enhanced MSR1-mediated myelin phagocytosis. Conclusions Our findings provide novel insights into the cell type-specific role of microglial MSR1 in AD, DLB, and PDD, linking its increased phagocytic capacity to myelin defects as a common feature of neurodegenerative dementias.

There is limited information on the functional neutralizing capabilities of breastmilk SARS-CoV-2-specific antibodies and the potential adulteration of breastmilk with vaccine mRNA after SARS-CoV-2 mRNA vaccination. We conducted a prospective cohort study of lactating healthcare workers who received the BNT162b2 vaccine and their infants. The presence of SARS-CoV-2 neutralizing antibodies, antibody isotypes (IgG, IgA, IgM) and intact mRNA in serum and breastmilk was evaluated at multiple time points using a surrogate neutralizing assay, ELISA, and PCR, over a 6 week period of the two-dose vaccination given 21 days apart. Thirty-five lactating mothers, median age 34 years (IQR 32-36), were included. All had detectable neutralizing antibodies in the serum immediately before dose 2, with significant increase in neutralizing antibody levels 7 days after this dose [median 168.4 IU/ml (IQR 100.7-288.5) compared to 2753.0 IU/ml (IQR 1627.0-4712.0), p <0.001]. Through the two vaccine doses, all mothers had detectable IgG1, IgA and IgM isotypes in their serum, with a notable increase in all three antibody isotypes after dose 2, especially IgG1 levels. Neutralizing antibodies were detected in majority of breastmilk samples a week after dose 2 [median 13.4 IU/ml (IQR 7.0-28.7)], with persistence of these antibodies up to 3 weeks after. Post the second vaccine dose, all (35/35, 100%) mothers had detectable breastmilk SARS-CoV-2 spike RBD-specific IgG1 and IgA antibody and 32/35 (88.6%) mothers with IgM. Transient, low intact vaccine mRNA levels was detected in 20/74 (27%) serum samples from 21 mothers, and 5/309 (2%) breastmilk samples from 4 mothers within 1 weeks of vaccine dose. Five infants, median age 8 months (IQR 7-16), were also recruited - none had detectable neutralizing antibodies or vaccine mRNA in their serum. Majority of lactating mothers had detectable SARS-CoV-2 antibody isotypes and neutralizing antibodies in serum and breastmilk, especially after dose 2 of BNT162b2 vaccination. Transient, low levels of vaccine mRNA were detected in the serum of vaccinated mothers with occasional transfer to their breastmilk, but we did not detect evidence of infant sensitization. Importantly, the presence of breastmilk neutralising antibodies likely provides a foundation for passive immunisation of the breastmilk-fed infant.