Journal of the Pediatric Infectious Diseases Society

BackgroundThe epidemiology of suspected pediatric meningoencephalitis has shifted in the era of conjugate vaccines and multiplex PCR diagnostics, with viral pathogens now predominating over bacterial causes. Updated epidemiologic data are essential to adapt diagnostic and therapeutic algorithms to current clinical practice. MethodsThis retrospective single-center study included children and adolescents <18 years who underwent lumbar puncture with cerebrospinal fluid multiplex PCR for suspected central nervous system infection at a tertiary-care pediatric hospital in Germany between 2016 and 2024. Clinical, laboratory, and outcome data were extracted from electronic medical records. Cerebrospinal fluid was analyzed using the BioFire(R) FilmArray(R) Meningitis/Encephalitis Panel. Statistical analyses included descriptive statistics, nonparametric group comparisons, receiver operating characteristic analyses. ResultsAmong 1,198 included children, definite bacterial meningitis was diagnosed in 13 (1.1%), definite viral meningitis in 80 (6.7%), aseptic meningitis of unknown etiology in 131 (11.0%), confirmed/probable encephalitis in 53 (4.4%), and possible encephalitis in 34 (2.8%). Bacterial meningitis accounted for 5.8% of all meningitis cases. A causative pathogen was identified in all bacterial meningitis cases, most commonly Streptococcus pneumoniae (n = 7). Enterovirus (n = 52) and parechovirus (n = 9) predominated in viral meningitis, whereas an infectious etiology was identified in only 13 of 53 confirmed/probable encephalitis cases. The Bacterial Meningitis Score showed a sensitivity of 80.0% and a specificity of 57.6%. The recently published UK-ChiMES-pre- and post-lumbar puncture scores demonstrated sensitivities of 84.6% and 76.9% and specificities of 86.3% and 92.7%, respectively. DiscussionBacterial meningitis was rare in this contemporary cohort, while viral and etiologically unresolved infections predominated despite routine multiplex PCR diagnostics. Clinical prediction scores supported risk stratification, with the UK-ChiMES-pre-lumbar puncture score showing the most favorable balance between sensitivity and specificity and potential to guide diagnostic decisions and antiinfective therapy.

BackgroundPrimary amoebic meningoencephalitis (PAM) is a rapidly progressive and often fatal central nervous system infection caused by Naegleria fowleri. Despite widespread environmental exposure to this free-living amoeba, clinical disease is rare, suggesting that it requires not only exposure to the amoeba but also a host vulnerability. Yet, the immune mechanisms controlling protection vs. susceptibility to N. fowleri remain poorly understood. MethodsWe conducted comprehensive clinical, immunological, and genetic investigations in one of the few survivors of PAM. We performed high-dimensional immune profiling using Cytometry by Time-Of-Flight (CyTOF) to assess immune cell composition and activation state. We employed whole-exome sequencing (WES) to identify rare genetic variants that affect host responses. Functional immune assays were used to assess serum-mediated amoebicidal activity in vitro and to characterize key host defense pathways. ResultsA previously healthy pediatric patient was diagnosed with PAM. Contrary to other cases, her clinical course lasted for more than 2 months before she recovered with miltefosine treatment. Immunologic evaluation showed this patient had normal numbers and frequencies of major lymphoid and myeloid immune cells. WES revealed a homozygous deletion in the complement component 2 (C2) gene, resulting in a complete absence of circulating C2 protein and abolishing classical complement pathway activity. Normal human serum induced complement-mediated lysis of N. fowleri trophozoites in vitro, whereas complement-depleted normal human serum and serum from our patient both failed to deposit membrane attack complex (MAC) or kill N. fowleri. MAC deposition and amoebicidal activity were restored by supplementing the patients serum with purified human C2 protein. ConclusionOur study demonstrates that PAM can be caused by a monogenic inborn error of immunity (IEI) and that the complement system is critical for human immunity against Naegleria fowleri.

Patients with myasthenia gravis (MG) may produce autoantibodies neutralizing type I interferons (AAN-I-IFN), which have been shown to underlie severe viral diseases, including critical COVID-19 pneumonia, in patients without MG. We studied an international cohort of 85 unvaccinated SARS-CoV-2-infected MG patients with no antiviral treatment. Hypoxemic pneumonia occurred in 48 of these patients, including 22 (45.8%) with AAN-I-IFN, which neutralized both IFN-2 and IFN-{omega} in 14 (29.2%) patients. Six (16.2%) of the remaining 37 patients had AAN-I-IFN, which neutralized both IFN-2 and IFN-{omega} in three patients. The risk of hypoxemic pneumonia was greater in MG patients with AAN-I-IFN neutralizing 10 ng/mL of both IFN-2 and IFN-{omega} (odds ratio and 95% confidence interval (OR [95% CI]): 12.7 [2.1-78.9], p=0. 0010) or IFN-2 at any dose (4.7 [1.5-15.0], p=0.0054) than in those without such autoantibodies. The risk of AAN-I-IFN production was much higher in MG patients than in the general population (28.9 [10.8-77.7], p=4.9x10-27). Fourteen patients had thymoma, which increased the risk of AAN-I-IFN (64% versus 27%, (OR [95% CI]: 5.6 [1.6-19.4], p=0.0050) and hypoxemic pneumonia (9.2 [1.9-44.2]; p=0.0019). Thymoma is, thus, associated with a higher risk of producing AAN-I-IFN, and these autoantibodies are associated with a higher risk of developing life-threatening COVID-19 pneumonia in patients with MG.

Background: Infections of the central nervous system (CNS) in children remain a major cause of mortality and long-term disability globally, particularly in low- and middle-income countries (LMICs), where a high proportion of cases lack an identified pathogen. Sporadically, human parvovirus 4 (PARV4) has been detected in a small number of cerebrospinal fluid (CSF) from children with CNS infections, but its pathogenic role is unclear. We investigated the prevalence, clinical impact, and genomic characteristics of PARV4 in children with suspected meningitis. Methods: We retrospectively analyzed CSF samples collected from children with WHO-defined suspected meningitis at the largest pediatric hospital in Bangladesh between 2015-2022. All samples underwent routine diagnostics, including bacterial culture and serological testing. Additional testing for PARV4 and parvovirus B19 was performed using qPCR of samples with >9 white blood cell (WBC)/ul followed by metagenomic sequencing of a subset. Clinical and laboratory data were extracted from patient records. Associations between PARV4 detection and mortality were assessed using logistic regression, adjusting for age, WBC count, and co-infections. Genomic and phylogenetic analyses were conducted on PARV4-positive samples. Findings: Among 2,793 CSF samples with >9 WBC/ul, 526 (18.8%) were PARV4-positive. The median age of PARV4-positive cases was lower than that of PARV4-negative cases (4 vs 7 months, p<0.001). Co-infections were more common among PARV4-positive cases (49.6%) than PARV4-negative cases (16.4%). PARV4 positivity was independently associated with increased in-hospital mortality (adjusted odds ratio 2.09, 95%CI:1.46-2.96; p<0.001). Phylogenetic analysis indicated most strains belonged to genotype 2, with two sequences forming a distinct clade. Interpretation: PARV4 is frequently detected in the CSF of children with suspected meningitis and is associated with increased in-hospital mortality. Its high prevalence, detection early in life, and frequent co-infection with other pathogens highlight the need to investigate PARV4 as an emerging CNS pathogen in LMICs. Funding: Gates Foundation

Background: Several large multisite studies have been conducted to describe etiology-specific burden of diarrhea among children in low-resource settings. Here, we combined data across studies to describe geographic and temporal trends in incidence and attributable fractions (AFs) of etiology-specific moderate-to-severe diarrhea (MSD), and to evaluate etiology-specific case fatality ratios (CFRs). Methods: We harmonized case definitions and analytic methods across the Global Enteric Multicenter Study (GEMS), Malnutrition and Enteric Disease (MAL-ED), Vaccine Impact on Diarrhea in Africa (VIDA), AntiBiotics for Children with severe Diarrhea (ABCD), and Enterics for Global Health (EFGH) studies. Cases were 6-35-month-olds with acute MSD. Incidence estimates for GEMS, VIDA, and EFGH were adjusted for enrollment, healthcare seeking, and diagnostic testing. AFs were calculated as the proportion of MSD cases attributed to each etiology, and CFRs were estimated within 14 and 90 days of an MSD episode. Findings: Pre-rotavirus vaccine introduction, rotavirus had the highest incidence and was the leading etiology among 6-11-month-olds, accounting for approximately 22-28% of MSD; the proportion of diarrhea due to rotavirus declined following vaccine introduction, with average AF 10-11% in Africa and Asia. Shigella incidence was highest among 12-23-month-olds and was the dominant etiology among 12-23 and 24-35-month-olds, causing approximately one-third to one-half of MSD. Overall, 90-day mortality declined substantially over time, from 2.21% in GEMS to 0.30% in EFGH. Bacterial (2.52%) and protozoal pathogens (3.55%) had higher average CFRs than viral pathogens (1.42%). Conclusion: Harmonized analysis of five multisite studies reveals consistent evidence that rotavirus and Shigella are the dominant causes of MSD in children under three years in low-resource settings, with burden shifting toward Shigella following rotavirus vaccine introduction.

BackgroundMultiple countries reported unprecedented increases in invasive group A streptococcal (iGAS) disease following widespread SARS-CoV-2 circulation. Whether this surge reflects reduced pathogen exposure during non-pharmaceutical interventions ("immunity debt") or effects of SARS-CoV-2 infection on host immunity remains unresolved. MethodsWe conducted a population-based time-series analysis of weekly iGAS incidence in central Ontario, Canada (population {approx}11 million) from March 2011 through March 2024 (676 weeks). Using negative binomial panel regression, we modeled acute (2-week lagged) and cumulative SARS-CoV-2 exposure while adjusting for seasonality, secular trends, age, and sex. Population attributable fractions (PAFs) were estimated by counterfactual prediction. Specificity was assessed through negative control analyses (influenza, RSV). The immunity debt hypothesis was evaluated using cumulative streptococcal exposure as a predictor of iGAS. ResultsAmong 2,906 iGAS episodes, 34.3% during the pandemic period were associated with acute SARS-CoV-2 effects (range by age group: 16.5-39.1%). Models incorporating cumulative SARS-CoV-2 burden showed markedly better fit ({Delta}AIC=-157.5); cumulative exposure was strongly associated with iGAS (IRR 1.193, 95% CI 1.151-1.235), increasing the estimated PAF to 66.7%. Cumulative effects were strongest in children (IRR 1.309). SARS-CoV-2 was comparably associated with non-invasive streptococcal disease, with no increase in invasion propensity. Cumulative streptococcal exposure was not protective (overall IRR 1.000, p=0.730); where significant, the association was positive, opposite to immunity debt predictions. ConclusionsCumulative SARS-CoV-2 burden was strongly associated with pandemic-era iGAS incidence. Cumulative streptococcal exposure did not support the immunity debt hypothesis. These ecological findings are consistent with SARS-CoV-2-associated immune dysregulation and warrant individual-level confirmation.

ObjectivesTo identify and validate plasma host-response protein biomarkers that improve discrimination of bacterial infection in febrile infants [&le;]90 days of age, and to assess whether novel biomarkers add value beyond established markers. MethodsSub-study of the prospective multicentre Febrile Infant Diagnostic Assessment and Outcome (FIDO) cohort. Novel biomarkers were identified through plasma proteomic profiling (Olink(R)) and combined with biomarkers and signatures from the literature for verification using Luminex and ELISA platforms. Diagnostic performance of novel biomarkers, established markers (CRP, PCT), and multi-protein signatures was evaluated. ResultsProteomic profiling of 110 samples identified 174 proteins differentially expressed between bacterial and viral infections, revealing distinct pathogen-specific immune signatures. Verification in the full cohort (n=445) demonstrated PCT had the highest individual accuracy for invasive bacterial infection (IBI) (AUC 0.89). Combining PCT with novel biomarkers, particularly lipocalin-2 (LCN2), improved discrimination (AUC 0.96). Diagnostic performance for the combined IBI/urinary tract infection (UTI) outcome was consistently lower (AUC <0.8). ConclusionsFebrile infants demonstrate biologically coherent host-response signatures that can be leveraged diagnostically. A PCT-LCN2 combination showed excellent accuracy for identifying IBI and may support future biomarker-guided diagnostic strategies, while reliable discrimination of UTI remains challenging.

Background: Human metapneumovirus (hMPV) is commonly associated with respiratory tract infections (RTIs) in young children. Methods: We estimated the annual hospital incidence of hMPV RTIs in children under 5 years in Scotland from 2017 to 2023 using national hospital and laboratory data. Incidence outside Lothian, where testing practices were uncertain, was extrapolated from Lothian laboratory data, where hMPV testing was advised for all RTI admissions. We also examined the severity and mortality of laboratory-confirmed hMPV cases. We developed similar estimates for RSV and Influenza A for comparison. Results: This analysis included 1,462 laboratory-confirmed hMPV hospitalisations in children aged under 5 years. The extrapolated hMPV hospital incidence ranged from 19 per 100,000 to 537 per 100,000 in children aged under 5 years. The extrapolated incidence was two to three times higher than that based on laboratory-confirmed data. Hospital incidence was higher in infants than in toddlers. hMPV incidence dropped substantially during the 2020/21 season, followed by a rebound during the 2021/22 season. About 10% of hMPV RTI hospital admissions required hospital stay [&ge;]5 days, but <1% required intensive care unit admissions or resulted in in-hospital death. RSV hospital incidence appeared substantially higher than the hMPV hospital incidence in this population. Conclusions: hMPV RTIs contribute to a substantial hospital burden in young children in Scotland. However, the RSV RTI burden is likely to be higher in the population unvaccinated against both viruses. Improved surveillance and diagnosis strategies are required to develop robust hospital burden estimates.

Crimean Congo hemorrhagic fever (CCHF) disease, caused by CCHF virus (CCHFV), poses a significant fatality risk whose underlying pathological mechanisms, including the contribution of coagulation factors imbalances and platelets abnormalities, remain poorly understood. Here we present a meta-analysis and meta-regression analysis using clinical data from coagulation assays and platelet parameters as predictive disease indices with the goal of uncovering pathognomonic factors and to pave a path for the development of effective therapeutic approaches. MethodsWe systematically analyzed published studies reporting coagulation assays and platelet indices in patients with confirmed CCHF. Data from 1,779 patients across published studies were analyzed to assess associations between laboratory parameters and fatality risk, while evaluating heterogeneity and prognostic significance. ResultsFatal outcomes were strongly associated with elevated liver enzymes (AST: 1116.71 {+/-} 1454.08 IU/mL; ALT: 446.56 {+/-} 457.41 IU/mL) and prolonged clotting times (PT: 19.53 {+/-} 6.57 s; aPTT: 64.02 {+/-} 23.13 s; INR: 1.53 {+/-} 0.56). D-dimer levels did not significantly predict fatality. Thrombocytopenia and coagulopathy emerged as independent risk factors for adverse outcomes. Notably, protein C and protein S levels did not differ between survivors and non-survivors, suggesting that the coagulopathy is not purely consumptive or a result of impaired hepatic synthesis. In contrast, mildly reduced antithrombin levels (83.65 {+/-} 19.90) were weighted toward increased mortality. Simple SummaryCrimean-Congo Hemorrhagic Fever (CCHF) causes high mortality through hemorrhage, but whether this reflects thrombocytopenia alone or combined coagulopathy remains unclear. We conducted meta-analyses of studies each of coagulation parameters (PT, aPTT, INR, fibrinogen, D-dimer, protein C and protein S, antithrombin) from survivors vs non-survivors. Fatal cases showed combined thrombocytopenia and coagulopathy (elevated PT/aPTT/INR, reduced fibrinogen/antithrombin) and liver damage (elevated AST/ALT). Protein C and protein S were unaffected, suggesting complex mechanisms beyond simple consumption or hepatic failure. These findings indicate coagulopathy contributes independently of thrombocytopenia to CCHF hemorrhage, supporting combined platelet and coagulation factor replacement therapy.

BackgroundRespiratory tract infections range from asymptomatic colonisation to an invasive disease. Recent studies suggest that nasopharyngeal microbiota may influence this variability. Emerging evidence points to Dolosigranulum pigrum, a nasopharyngeal commensal, as a potentially protective bacterium. This study aimed to identify variables associated with the presence of D. pigrum in the nasopharynx of children with varying respiratory health statuses. MethodsNasopharyngeal aspirates were collected from children <18 years who were asymptomatic (n=65), had banal viral infection (n=48), or Invasive Pneumococcal Disease (IPD) (n=27). The presence of D. pigrum was defined as >0.1% of total sequences obtained by 16S rRNA gene sequencing. Variables included sex, breastfeeding, delivery mode, S. pneumoniae carriage, respiratory viruses and clinical features. ResultsAmong 140 children (73 males, 67 females), D. pigrum was detected in 79 (56.4%): 44/65 in the healthy group; 26/48 of viral and 9/27 IPD cases. Multivariate analysis revealed significant associations with health status and sex. Healthy children were more likely to carry D. pigrum than IPD cases (44/79 vs. 26/79; p= 0.028). Males were more frequently D. pigrum carriers than females (48/79 vs. 31/79; p= 0.033). ConclusionD. Pigrum was associated with respiratory health, being more prevalent in healthy children, and showed potential sex-related differences.

BackgroundNeonatal disorders such as post-infectious hydrocephalus exhibit a higher incidence in Africa, where the intricate relationships between genetic ancestry, environmental exposures, and other risk factors likely contribute to the increased incidence. MethodsTo start to characterize the common genetic architecture of Ugandan infants, we analyzed genome sequencing data from 1,030 Ugandan infants recruited from studies targeting neonatal sepsis and hydrocephalus. We employed genetic admixture analysis and integrated geospatial data to examine the relationships between genetic backgrounds and disease prevalence within this cohort. ResultsOur results identified four distinct genetic admixture groups, each correlating strongly with specific geographic distributions across Uganda. Notably, a predominance of one admixture group, most common in northern Uganda, was overrepresented in the participants with post-infectious hydrocephalus. ConclusionThis study underscores the importance of genetic factors in disease manifestation at the population level, and a role for such precision public health approaches in complex neonatal disorders in African populations.

Klebsiella pneumoniae (KP) isolates belonging to multi-locus sequence type 258 (ST258) are a frequent cause of hospital-associated outbreaks and display extensive multidrug resistance. The KP ST258 lineage consists of two genetically distinct clades, called Clade 1 and Clade 2. These two clades are genetically related to one another, but are historically distinguished by having different capsular polysaccharide types. While bacteria belonging to both clades are isolated from clinical infections, Clade 2 is isolated more frequently compared to Clade 1. To investigate drivers of this difference in clade prevalence, we collected 172 clinical KP ST258 isolates from patients at a single medical center. Clinical review showed that patients infected with Clade 2 isolates were more acutely ill than Clade 1-infected patients, despite having fewer comorbidities. We also found that Clade 2 isolates were more resistant to killing by human serum, despite binding more complement protein C3 than Clade 1 isolates. Additionally, mice infected with a Clade 2 isolate had increased bacterial dissemination from the lungs to the liver and spleen than mice infected with a Clade 1 isolate, and this dissemination required an intact capsule locus. Increased dissemination in mice was not due to differential serum killing, as mouse serum was unable to kill isolates of either clade, but dissemination was associated with decreased macrophage uptake of the Clade 2 isolate. Taken together, these data suggest that KP ST258 Clade 2 is more virulent than Clade 1, though the specific mechanisms at play appear to differ between mice and humans.

Abstract Introduction: Streptococcus is the second genus involved in bone and joint infections (BJIs) after Staphylococcus. Streptococcus agalactiae is the predominant Streptococcus species implicated in BJIs. However, unlike Staphylococcus-related BJIs, data on S. agalactiae infections remain scarce. Methods: We conducted a retrospective cohort study from the West Region cohort of the CRIOAc registry among six university hospitals including all microbiologically confirmed streptococcal BJI in adults between 2014 and 2023. Results: 1454 patients were included, with a median age of 67 years and 65% male. S. agalactiae was the predominant streptococcal species involved 423/1454(29%). The most prevalent comorbidities identified were obesity (378/1454;26%) and diabetes mellitus (343/1454;24%). Prosthetic joint infections (PJIs) were the most common (653/1454;45%), although diabetic foot osteitis was less prevalent overall, it was significantly more associated with S. agalactiae infections (48/423;11% versus 70/1031;7%, p=0.05). S. agalactiae BJIs were more frequently lower-limb infections and chronic infections (240/423;57% versus 502/1031;49%, p=0.04). Half of the cohort had a polymicrobial infection and were slightly more frequent with S. agalactiae BJIs (235/423;56% versus 498/1031;48%, p=0.1). These results were consistent with a sensitivity analysis excluding diabetic foot related osteitis. Logistic regression analysis identified arteriopathy (OR: 4.16; IC95:1.64-11.24, p=0.003), and obesity (OR: 2.57; IC95: 1.41-4.78, p=0.002) as specific risk factors for S. agalactiae BJIs. Conclusion: S. agalactiae emerges as a prominent and distinct pathogen in complex streptococcal BJIs, with specific risk factors such as arteriopathy, obesity and diabetes mellitus, and more chronic infections.

PurposeWhile genomic testing is integral to pediatric inborn errors of immunity (IEI) care, few studies have examined strategies to support its optimal delivery. This study aimed to characterize a pediatric IEI cohort and assess the impact of implementing a mainstream model-of-care (MoC). Materials/MethodsComprehensive chart audit was conducted for patients ([&le;]18y) who received IEI genomic testing in Queensland, Australia, from 2017-2025. Descriptive analyses captured demographic and clinical characteristics, genomic testing and results, and management outcomes. Inferential analyses assessed changes in genomic practices pre-MoC (<2021) and post-MoC ([&ge;]2021). Results322 patients met eligibility criteria (n=481 genomic test). Diagnostic yield (27.6%) varied by testing indication, with the highest rate among phagocytic defects (n=4/4;100%) and severe combined immunodeficiency (n=8/10;80%). Very-early-onset inflammatory bowel disease had the lowest diagnostic yield (n=3/68;4.4%), prompting changes to testing criteria. Molecular diagnosis resulted in management changes for 90.5% patients. Genomic testing was widely used pre-MoC (n=251 genomic tests). All outcomes significantly improved pre-and post-MoC (p<0.05): duplicate testing decreased (13.9% to 0%); variants of uncertain significance reduced (37.7% to 7.1%); informed consent documentation increased (70.5% to 88.4%); and diagnostic yield increased (16.2% to 27.4%). ConclusionTargeted interventions are needed to support delivery of genomic testing and strengthen service effectiveness.

BackgroundMpox-related ophthalmic disease (MPOXROD) ranges from mild conjunctivitis to sight-threatening keratitis, however, data based on systematic ophthalmological assessment are scarce. We aimed to characterise the prevalence, features, and temporal evolution of MPOXROD during a clade Ib mpox outbreak. MethodsWe conducted MBOTE-EYE, a prospective ophthalmological sub-study, nested within a clinical characterisation cohort in Kamituga, South-Kivu, Democratic Republic of the Congo. All hospitalised patients with mpox confirmed by PCR in the prior 48 hours were eligible. Participants underwent comprehensive ophthalmological examination at enrolment, discharge, and days 29 and 59 post-diagnosis. Conjunctival swabs were collected for monkeypox virus PCR testing. MPOXROD was defined as conjunctivitis, scleritis, keratitis, uveitis, or optic nerve involvement. Risk factors were assessed using mixed-effects Poisson regression. FindingsBetween 28 October 2024 and 30 June 2025, 310 participants were enrolled (median age 14 years, IQR 2.5-25.0; 53.5% female, n=166/310). At enrolment, conjunctivitis was present in 36.1% (95% CI 31.0-41.6%, n=112/310), keratitis in 7.7% (95% CI 5.3-11.3%), and anterior uveitis in 0.6% (95% CI 0.2-2.3%). Overall, 43.2% (95% CI 37.8-48.8%) developed MPOXROD during follow-up, most often bilaterally. Visual acuity <8/10 occurred in 22.9% (95% CI 17.6-29.2%, n=24/310), and persistent blindness in 0.9% (95% CI 0.24-5.5%, n=2/225), due to ulcerative keratitis. Periorbital lesions (adjusted risk ratio [aRR] 2.82, 95% CI 1.40-5.69) and severe malnutrition (aRR 5.06, 2.25-11.38) were independently associated with MPOXROD. Conjunctival swabs with PCR Ct values < 25 occurred exclusively in participants with active MPOXROD. InterpretationOphthalmic involvement in clade Ib mpox is common and frequently bilateral, with a substantial burden of keratitis and risk of vision loss, particularly in young children and severely malnourished individuals. These findings highlight the need for systematic eye examinations in mpox care and provide critical evidence to inform future trials of targeted ophthalmic therapies. FundingNone of the funders had a role in study design, analysis, interpretation, or writing.

Anti-phospholipid (APL) autoantibodies confer a high risk for adverse pregnancy outcomes, especially in Systemic Lupus Erythematosus (SLE). While human TLR8 (huTLR8) has been implicated in APL antibody-mediated placental injury in vitro, its in vivo role in pregnancy is unexplored. We report a novel mouse model of pregnancy loss in SLE-prone mice expressing huTLR8. Placental analysis revealed early developmental defects starting post-implantation, including a thin junctional zone, impaired vascularization, infarcts, and inflammation. Profound immune dysregulation was evident at E8.5 including increased myeloid cells and CD8 T cells and decreased uterine natural killer (uNK) cells. RNA sequencing revealed downregulated pregnancy-specific glycoproteins, reduced uNK cell-associated genes, and an upregulated myeloid cell signature. Bone marrow chimera studies demonstrated preferential activation of huTLR8-expressing placental Ly6C+ monocytes. Spatial transcriptomics at E9.5 confirmed uNK cell loss, decreased IL15 expression by both stromal and myeloid cells, and discrete inflammatory aggregates in the maternal layers containing myeloid cells and IFN{gamma}-expressing CD8 T cells. We propose that huTLR8, likely through myeloid cell activation and cytolytic T cell recruitment, drives placental injury in the context of SLE and APL autoantibodies. This model provides a valuable platform to dissect early pathogenic events in APL-associated pregnancy loss and identify new therapeutic targets.

Lupus nephritis (LN) is a leading cause of morbidity in pediatric systemic lupus erythematosus (pSLE) due to suboptimal kidney remission rates and the sequelae of prolonged intensive immunosuppressive therapy. LN is patchy, with some glomeruli severely damaged while others remain histologically unaffected in the same kidney. Using spatial transcriptomic technology, we interrogated microanatomic transcriptional differences between histologically damaged and unaffected glomeruli in pSLE LN to understand local drivers of renal injury. Despite SLE being a disease of Type I interferon (IFN), IFN gene response does not associate with local glomerular damage. Rather, damage associates with a transcriptional module of higher expression of myeloid cell markers, C5AR1 (encoding the receptor for complement component 5a [C5a]), early complement components, and fibrosis genes. Bulk RNA-sequencing of C5a stimulated human monocyte-derived-macrophages revealed upregulation of tissue-remodeling and fibrosis-related pathways reversible by the C5aR1 inhibiting drug avacopan. These same C5a-inducible fibrosis genes were significantly upregulated in histologically damaged versus unaffected LN glomeruli providing a mechanistic link between C5a-C5aR1 signaling and early fibrosis in proliferative lupus nephritis. Our data provide insight into an understudied connection between complement activation and fibrosis relevant in SLE and likely other inflammatory diseases of complement activation.

Co-designed research in paediatric HSCT is limited. We sought to determine research priorities which represent the shared priorities of patients, parents, carers, and healthcare professionals (HCP) within Australia, New Zealand, the Netherlands and United Kingdom. An international, multiphase priority-setting methodology was implemented in partnership with the James Lind Alliance and delivered over an 18-month period. Part 1: an international scoping survey asked respondents to submit their research uncertainties related to paediatric HSCT. Part 2: summarising and evidence-checking the submitted uncertainties. Part 3: interim prioritisation survey. Part 4: consensus workshop. In the first international scoping survey, 667 topic ideas were suggested (45% by consumers, 55% by HCP), which were categorized into 80 summary questions. After systematic literature review, 35 summary questions were judged to be true uncertainties (i.e. not answered by existing evidence). These 35 uncertainties were included in a second interim prioritisation survey, completed by 224 participants. From those, a shortlist of 19 questions was drawn. After a multistakeholder workshop, consensus was reached on the top 10 priorities. The PSP identified important research gaps in the management of paediatric HSCT. Priority areas included: implementing personalised medicine approaches, improving immune recovery and adjunct interventions such as exercise, nutrition and microbiome-directed strategies.

Coccidioidomycosis presents clinically as a spectrum ranging from self-limiting Uncomplicated Valley Fever (UVF) in most cases to life-threatening Disseminated Coccidioidomycosis (DCM) in rare individuals. A few patterns of immunologic deficits allowing for dissemination have been identified, though the specific defects in most individuals with DCM remain undefined. We hypothesized that chronic antigen exposure in DCM engenders a state of T cell exhaustion. From a cohort of over 300 subjects with confirmed diagnoses of coccidioidomycosis, circulating T cell phenotypes were characterized via flow cytometry and Coccidioides-specific T cell responses were measured using the Activation-Induced Marker (AIM) assay. Male sex was significantly associated with disseminated disease (odds ratio 2.5; 95% CI: 1.5 - 4.0). 52% of subjects showed Coccidioides-specific T cell responses in our AIM assay. We noted a significant difference in subjects sampled in the first year of diagnosis, where only 8% of DCM subjects had T cell responses during this time, as compared to 44% of UVF subjects (p = 0.04). Among DCM patients with detectable AIM responses, CD4+ T cells demonstrated an exhausted phenotype with elevated PD-1 expression compared to UVF subjects. In vitro PD-1 blockade augmented IFN{gamma} production in most tested DCM subjects. These findings suggest that dissemination may occur in some individuals during a period of impaired antigen-specific T-cell activity. Importantly, these responses can be augmented in vitro by PD-1 blocking antibodies, supporting further study of immune checkpoint therapy as an adjunct to antifungal treatment in disseminated coccidioidomycosis.

Objectives: Group B Streptococcus (GBS) is a leading cause of neonatal mortality worldwide. However, the global burden of early-onset GBS disease (EOD-GBS) has not been fully elucidated. We aimed to describe the geographical distribution and epidemiological characteristics of the EOD-GBS burden, and analyze its association with socio-economic development and universal health coverage. Methods: We used data from the Global Burden of Disease Study 2021 and the Universal Health Coverage Service Coverage Index (UHC-SCI) to calculate estimated annual percentage changes (EAPCs) of EOD-GBS mortality. Sex differences were analyzed using the conservative overlap assessment. The geographical distribution of EOD-GBS clinical presentations and mortality was mapped. Health inequality analysis was conducted to evaluate the relationship between the sociodemographic index (SDI), UHC-SCI, and EOD-GBS burden. Results: Global EOD-GBS mortality decreased by nearly 50% from 1990 (693.41 per 100,000) to 2021 (348.80 per 100,000). However, the decline was not uniform: the most significant decrease occurred in high-middle SDI regions (EAPC: -7.17%), and the slowest in low SDI regions (EAPC: -2.23%). Male neonates accounted for the most EOD-GBS deaths, particularly in high SDI regions. Lower respiratory infections were common in Asia and Oceania; meningitis was more prominent in Europe. Inequality analysis revealed a phenomenon of "absolute convergence but relative differentiation": as social development and universal health coverage improves, the absolute mortality gap between countries narrowed, but relative burden concentrated increasingly among the poorest populations. Conclusions: The global burden of EOD-GBS has decreased substantially, but there are marked differences among countries. Continued socioeconomic development and expanded universal health coverage are critical to further reduce neonatal mortality.