Use of Teduglutide in the Management of Gastrointestinal Graft-versus-Host Disease in Children and Young Adults.

Loss of intestinal L cells and reduced levels of glucagon-like peptide-2 (GLP-2) have been implicated in acute graft-versus-host disease (GVHD) in murine models. Teduglutide, a human recombinant GLP-2 analog, may be beneficial in acute gastrointestinal (GI) GVHD owing to its known tissue protective and regenerative functions. We retrospectively reviewed patients who received teduglutide for treatment of GI GVHD. Endoscopy was performed at diagnosis and at completion of the teduglutide course. GLP-1 immunohistochemistry (IHC) was performed at diagnosis and the end of teduglutide therapy in 2 patients to evaluate L cells. We initiated daily teduglutide 0.05 mg/kg subcutaneously as adjunctive therapy in 3 pediatric patients with refractory GI GVHD. All 3 patients had resolution of GI GVHD following completion of the teduglutide course, as evidenced by reduced apoptosis and regenerative changes on post-treatment endoscopy. Reportable GLP-1 IHC in 2 patients demonstrated increased L cells at the end of teduglutide treatment compared to at diagnosis. No adverse effects to teduglutide were observed. Teduglutide is a promising adjunctive and non-immune suppressive agent for managing acute GI GVHD.

Factor XII promotes the thromboinflammatory response in a rat model of venoarterial extracorporeal membrane oxygenation.

BACKGROUND: Factor XII (FXII) is a multifunctional protease capable of activating thrombotic and inflammatory pathways. FXII has been linked to thrombosis in extracorporeal membrane oxygenation (ECMO), but the role of FXII in ECMO-induced inflammatory complications has not been studied. We used novel gene-targeted FXII- deficient rats to evaluate the role of FXII in ECMO-induced thromboinflammation. METHODS: FXII-deficient (FXII-/-) Sprague-Dawley rats were generated using CRISPR/Cas9. A minimally invasive venoarterial (VA) ECMO model was used to compare wild-type (WT) and FXII-/- rats in 2 separate experimental cohorts: rats placed on ECMO without pharmacologic anticoagulation and rats anticoagulated with argatroban. Rats were maintained on ECMO for 1 hour or until circuit failure occurred. Comparisons were made with unchallenged rats and rats that underwent a sham surgical procedure without ECMO. RESULTS: FXII-/- rats were maintained on ECMO without pharmacologic anticoagulation with low resistance throughout the 1-hour experiment. In contrast, WT rats placed on ECMO without anticoagulation developed thrombotic circuit failure within 10 minutes. Argatroban provided a means to maintain WT and FXII-/- rats on ECMO for the 1-hour time frame without thrombotic complications. Analyses of these rats demonstrated that ECMO resulted in increased neutrophil migration into the liver that was significantly blunted by FXII deficiency. ECMO also resulted in increases in high molecular weight kininogen cleavage and complement activation that were abrogated by genetic deletion of FXII. CONCLUSIONS: FXII initiates hemostatic system activation and key inflammatory sequelae in ECMO, suggesting that therapies targeting FXII could limit both thromboembolism and inopportune inflammatory complications in this setting.

Transcriptome analysis in acute gastrointestinal graft-versus host disease reveals a unique signature in children and shared biology with pediatric inflammatory bowel disease.

We performed transcriptomic analyses on freshly frozen (n=21) and paraffin-embedded (n=35) gastrointestinal (GI) biopsies from children with and without acute acute GI graft-versus-host disease (GvHD) to study differential gene expressions. We identified 164 significant genes, 141 upregulated and 23 downregulated, in acute GvHD from freshy frozen biopsies. CHI3L1 was the top differentially expressed gene in acute GvHD, involved in macrophage recruitment and bacterial adhesion. Mitochondrial genes were among the top downregulated genes. Immune deconvolution identified a macrophage cellular signature. Weighted gene co-expression network analysis showed enrichment of genes in the ERK1/2 cascade. Transcriptome data from 206 ulcerative colitis (UC) patients were included to uncover genes and pathways shared between GvHD and UC. Comparison with the UC transcriptome showed both shared and distinct pathways. Both UC and GvHD transcriptomes shared an innate antimicrobial signature and FCγ1RA/CD64 was upregulated in both acute GvHD (log-fold increase 1.7, P=0.001) and UC. Upregulation of the ERK1/2 cascade pathway was specific to GvHD. We performed additional experiments to confirm transcriptomics. Firstly, we examined phosphorylation of ERK (pERK) by immunohistochemistry on GI biopsies (acute GvHD n=10, no GvHD n=10). pERK staining was increased in acute GvHD biopsies compared to biopsies without acute GvHD (P=0.001). Secondly, plasma CD64, measured by enzyme-linked immunsorbant assay (n=85) was elevated in acute GI GvHD (P<0.001) compared with those without and was elevated in GVHD compared with inflammatory bowel disease (n=47) (P<0.001), confirming the upregulated expression seen in the transcriptome.

T-cell infiltrate intensity is associated with delayed response to treatment in late acute cellular rejection in pediatric liver transplant recipients.

BACKGROUND: Late acute cellular rejection (ACR) is associated with donor-specific antibodies (DSA) development, chronic rejection, and allograft loss. However, accurate predictors of late ACR treatment response are lacking. ACR is primarily T-cell mediated, yet B cells and plasma cells (PC) also infiltrate the portal areas during late ACR. To test the hypothesis that the inflammatory milieu is associated with delayed response (DR) to rejection therapy, we performed a single-center retrospective case-control study of pediatric late liver ACR using multiparameter immunofluorescence for CD4, CD8, CD68, CD20, and CD138 to identify immune cell subpopulations. METHODS: Pediatric liver transplant recipients transplanted at <17 years of age and treated for biopsy-proven late ACR between January 2014 and 2019 were stratified into rapid response (RR) and DR based on alanine aminotransferase (ALT) normalization within 30 days of diagnosis. All patients received IV methylprednisolone as an initial rejection treatment. Immunofluorescence was performed on archived formalin-fixed paraffin embedded (FFPE) liver biopsy tissue. RESULTS: Liver biopsies from 60 episodes of late ACR in 54 patients were included in the analysis, of which 33 were DR (55%). Anti-thymocyte globulin was only required in the DR group. The frequency of liver-infiltrating CD20+ and CD8+ lymphocytes and the prevalence of autoantibodies were higher in the DR group. In univariate logistic regression analysis, serum gamma-glutamyl transpeptidase (GGT) level at diagnosis, but not ALT, Banff score or presence of DSA, predicted DR. CONCLUSIONS: Higher serum GGT level, presence of autoantibodies, and increased CD8+ T-cell infiltration portends DR in late ACR treatment in children.

Targeting the contact system in a rabbit model of extracorporeal membrane oxygenation.

Previous studies suggested that contact pathway factors drive thrombosis in mechanical circulation. We used a rabbit model of veno-arterial extracorporeal circulation (VA-ECMO) to evaluate the role of factors XI and XII in ECMO-associated thrombosis and organ damage. Factors XI and XII (FXI, FXII) were depleted using established antisense oligonucleotides before placement on a blood-primed VA-ECMO circuit. Decreasing FXII or FXI to < 5% of baseline activity significantly prolonged ECMO circuit lifespan, limited the development of coagulopathy, and prevented fibrinogen consumption. Histological analysis suggested that FXII depletion mitigated interstitial pulmonary edema and hemorrhage whereas heparin and FXI depletion did not. Neither FXI nor FXII depletion was associated with significant hemorrhage in other organs. In vitro analysis showed that membrane oxygenator fibers (MOFs) alone are capable of driving significant thrombin generation in a FXII- and FXI-dependent manner. MOFs also augment thrombin generation triggered by low (1 pM) or high (5 pM) tissue factor concentrations. However, only FXI elimination completely prevented the increase in thrombin generation driven by MOFs, suggesting MOFs augment thrombin-mediated FXI activation. Together, these results suggest that therapies targeting FXII or FXI limit thromboembolic complications associated with ECMO. Further studies are needed to determine the contexts wherein targeting FXI and FXII, either alone or in combination, would be most beneficial in ECMO. Moreover, studies are also needed to determine the potential mechanisms coupling FXII to end-organ damage in ECMO.

A Murine Model of Veno-Arterial Extracorporeal Membrane Oxygenation.

The mechanisms driving the pathologic state created by extracorporeal membrane oxygenation (ECMO) remain poorly defined. We developed the first complete blood-primed murine model of veno-arterial ECMO capable of maintaining oxygenation and perfusion, allowing molecular studies that are unavailable in larger animal models. Fifteen C57BL/6 mice underwent ECMO by cannulating the left common carotid artery and the right external jugular vein. The mean arterial pressure was measured through cannulation of the femoral artery. The blood-primed circuit functioned well. Hemodynamic parameters remained stable and blood gas analyses showed adequate oxygenation of the animals during ECMO over a 1-hour timeframe. A significant increase in plasma-free hemoglobin was observed following ECMO, likely secondary to hemolysis within the miniaturized circuit components. Paralleling clinical data, ECMO resulted in a significant increase in plasma levels of multiple proinflammatory cytokines as well as evidence of early signs of kidney and liver dysfunction. These results demonstrate that this novel, miniature blood-primed ECMO circuit represents a functional murine model of ECMO that will provide unique opportunities for further studies to expand our knowledge of ECMO-related pathologies using the wealth of available genetic, pharmacological, and biochemical murine reagents not available for other species.

Ingested Foreign Bodies Can Cause Appendicitis and Perforation: A Multi-Institutional Case Series.

INTRODUCTION: Appendicular foreign bodies are a rare, under-described cause of appendicitis. We performed this study to determine the varied causes and consequences of foreign-body appendicitis. METHODS: On retrospective review of the pathology archives of seven institutions, we identified 56 appendix specimens containing a foreign body (defined as ingested, non-digestible material). We recorded the type of foreign body, patient age and sex, and other findings, as available. RESULTS: Mean patient age was 7.7 years (range: 1 day-18 years). The foreign bodies included hair, plant material, magnets, other metallic material, BB pellets, foreign material not otherwise specified, and other miscellaneous objects. Of 48 cases with available clinical information, 31 patients presented with abdominal pain, and 22 were preoperatively diagnosed as having appendicitis/appendicular inflammation. Seven patients had appendiceal perforation (13%). The foreign body was grossly identified in 34/47 cases with available gross descriptions. Twenty-seven cases had an identifiable foreign body microscopically; 10 were associated with giant cell reaction. DISCUSSION: Hair and plant materials were the most common foreign objects found in the appendix; they often cause mucosal damage and giant cell reaction. Metallic objects were less common. Although appendicular foreign bodies in children are rare and sometimes asymptomatic, they may lead to perforation.

Lethal Pediatric Cerebral Vasculitis Triggered by Severe Acute Respiratory Syndrome Coronavirus 2.

BACKGROUND: We report the clinical, radiological, laboratory, and neuropathological findings in support of the first diagnosis of lethal, small-vessel cerebral vasculitis triggered by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a pediatric patient. PATIENT DESCRIPTION: A previously healthy, eight-year-old Hispanic girl presented with subacute left-sided weakness two weeks after a mild febrile illness. SARS-CoV-2 nasopharyngeal swab was positive. Magnetic resonance imaging revealed an enhancing right frontal lobe lesion with significant vasogenic edema. Two brain biopsies of the lesion showed perivascular and intraluminal lymphohistiocytic inflammatory infiltrate consistent with vasculitis. Despite extensive treatment with immunomodulatory therapies targeting primary angiitis of the central nervous system, she experienced neurological decline and died 93 days after presentation. SARS-CoV-2 testing revealed positive serum IgG and positive cerebrospinal fluid IgM. Comprehensive infectious, rheumatologic, hematologic/oncologic, and genetic evaluation did not identify an alternative etiology. Postmortem brain autopsy remained consistent with vasculitis. CONCLUSION: This is the first pediatric presentation to suggest that SARS-CoV-2 can lead to a fatal, postinfectious, inflammatory small-vessel cerebral vasculitis. Our patient uniquely included supportive cerebrospinal fluid and postmortem tissue analysis. While most children recover from the neurological complications of SARS-CoV-2, we emphasize the potential mortality in a child with no risk factors for severe disease.

Immuno-transcriptomic profiling of extracranial pediatric solid malignancies.

We perform an immunogenomics analysis utilizing whole-transcriptome sequencing of 657 pediatric extracranial solid cancer samples representing 14 diagnoses, and additionally utilize transcriptomes of 131 pediatric cancer cell lines and 147 normal tissue samples for comparison. We describe patterns of infiltrating immune cells, T cell receptor (TCR) clonal expansion, and translationally relevant immune checkpoints. We find that tumor-infiltrating lymphocytes and TCR counts vary widely across cancer types and within each diagnosis, and notably are significantly predictive of survival in osteosarcoma patients. We identify potential cancer-specific immunotherapeutic targets for adoptive cell therapies including cell-surface proteins, tumor germline antigens, and lineage-specific transcription factors. Using an orthogonal immunopeptidomics approach, we find several potential immunotherapeutic targets in osteosarcoma and Ewing sarcoma and validated PRAME as a bona fide multi-pediatric cancer target. Importantly, this work provides a critical framework for immune targeting of extracranial solid tumors using parallel immuno-transcriptomic and -peptidomic approaches.

Neonatal Lung Disease Associated with TBX4 Mutations.

Variable lung disease was documented in 2 infants with heterozygous TBX4 mutations; their clinical presentations, pathology, and outcomes were distinct. These findings demonstrate that TBX4 gene mutations are associated with neonatal respiratory failure and highlight the wide spectrum of clinicopathological outcomes that have implications for patient diagnosis and management.