Imaging in pediatric spondyloarthritis.

PURPOSE OF REVIEW: Imaging is used in the diagnosis of peripheral and axial disease in juvenile spondyloarthritis (JSpA). Imaging of the joints and entheses in children and adolescents can be challenging for those unfamiliar with the appearance of the maturing skeleton. These differences are key for rheumatologists and radiologists to be aware of. RECENT FINDINGS: In youth, skeletal variation during maturation makes the identification of arthritis, enthesitis, and sacroiliitis difficult. A great effort has been put forward to define imaging characteristics seen in healthy children in order to more accurately identify disease. Additionally, there are novel imaging modalities on the horizon that are promising to further differentiate normal physiologic changes versus disease. SUMMARY: This review describes the current state of imaging, limitations, and future imaging modalities in youth, with key attention to differences in imaging interpretation of the peripheral joints, entheses, and sacroiliac joint in youth and adults.

Biological and clinical roles of IL-18 in inflammatory diseases.

Several new discoveries have revived interest in the pathogenic potential and possible clinical roles of IL-18. IL-18 is an IL-1 family cytokine with potent ability to induce IFNγ production. However, basic investigations and now clinical observations suggest a more complex picture. Unique aspects of IL-18 biology at the levels of transcription, activation, secretion, neutralization, receptor distribution and signalling help to explain its pleiotropic roles in mucosal and systemic inflammation. Blood biomarker studies reveal a cytokine for which profound elevation, associated with detectable 'free IL-18', defines a group of autoinflammatory diseases in which IL-18 dysregulation can be a primary driving feature, the so-called 'IL-18opathies'. This impressive specificity might accelerate diagnoses and identify patients amenable to therapeutic IL-18 blockade. Pathogenically, human and animal studies identify a preferential activation of CD8+ T cells over other IL-18-responsive lymphocytes. IL-18 agonist treatments that leverage the site of production or subversion of endogenous IL-18 inhibition show promise in augmenting immune responses to cancer. Thus, the unique aspects of IL-18 biology are finally beginning to have clinical impact in precision diagnostics, disease monitoring and targeted treatment of inflammatory and malignant diseases.

Hyperferritinemia screening to aid identification and differentiation of patients with hyperinflammatory disorders.

High ferritin is an important and sensitive biomarker for hemophagocytic lymphohistiocytosis (HLH), a diverse and deadly group of cytokine storm syndromes. Early action to prevent immunopathology in HLH often includes empiric immunomodulation, which can complicate etiologic work-up and prevent collection of early/pre-treatment research samples. To address this, we instituted an alert system where serum ferritin > 1000ng/mL triggered real-time chart review, assessment of whether the value reflected "inflammatory hyperferritnemia (IHF)", and biobanking of remnant samples from consenting IHF patients. We extracted relevant clinical data; periodically measured serum total IL-18, IL-18 binding protein (IL-18BP), and CXCL9; retrospectively classified patients by etiology into infectious, rheumatic, or immune dysregulation; and subjected a subgroup of samples to a 96-analyte biomarker screen. 180 patients were identified, 30.5% of which had IHF. Maximum ferritin levels were significantly higher in patients with IHF than with either hemoglobinopathy or transplant, and highly elevated total IL-18 levels were distinctive to patients with Stills Disease and/or Macrophage Activation Syndrome (MAS). Multi-analyte analysis showed elevation in proteins associated with cytotoxic lymphocytes in all IHF samples when compared to healthy controls and depression of proteins such as ANGPT1 and VEGFR2 in samples from hyperferritinemic sepsis patients relative to non-sepsis controls. This single-center, real-time IFH screen proved feasible and efficient, validated prior observations about the specificity of IL-18, enabled early sample collection from a complex population, suggested a unique vascular biomarker signature in hyperferritinemic sepsis, and expanded our understanding of IHF heterogeneity.

In-utero exposure to immunosuppressive medications resulting in abnormal newborn screening for severe combined immunodeficiency: a case series on natural history and management.

Exposure to immunosuppressive medication in utero is an important cause of secondary T cell lymphopenia in infancy, which can be detected via T cell receptor excision circle (TREC) quantification on severe combined immunodeficiency (SCID) newborn screening (NBS). At present, there is a paucity of literature surrounding management of these infants. A protocol including recommendations for vaccinations and follow-up is needed to augment care. Patients referred to immunology for abnormal TREC results on NBS were identified as having in utero exposure to immunosuppressive medications and were followed until lymphopenia improved. The natural history of these patients' lymphopenia was used to develop general management guidelines. Four infants with low TRECs secondary to in utero immunosuppressive exposure were evaluated. Medication exposures included azathioprine, infliximab, hydroxychloroquine, and fingolimod. All infants were born full term. TRECs ranged from 101-206 (normal value in IL ≥ 250 at time of testing, B-actin control). T cell lymphopenia (CD3 < 1500) was present in 50% of cases. Undetectably low effector CD4 naïve T cell population was present in 100% of cases. Mitogen proliferation was uniformly normal. Severity of TREC abnormality did not correlate with presence of T cell lymphopenia. Immune abnormalities normalized in 75% patients by age 4 months. All age-appropriate vaccinations, including live vaccines, were administered to all patients by age 4 months. It is critical to assess for in utero immunosuppressive exposure in infants with abnormal TREC results on NBS. In the infants evaluated, secondary T cell lymphopenia associated with maternal immunosuppressive use resolved or significantly improved by age 4 months. Once abnormal TREC count is deemed to be secondary to in utero immunosuppression and there are no other contraindications, infants may safely receive live vaccination, are able to drink breast milk, and do not require prophylactic anti-microbials.

Improvement of SLC29A3 spectrum disorder-related sensorineural hearing loss after initiation of IL-6 inhibitor.

Tocilizumab is reported to reduce systemic inflammation in individuals with SLC29A3 spectrum disorder, but its effect on hearing loss has not been described. The authors present a boy toddler with a history of prematurity, dysphagia, hypersplenism, hyperpigmentation, short height and hearing loss who was referred to the immunology clinic. He initially presented shortly after birth with abnormal hearing screens followed by positive urine test for cytomegalovirus. However, the infection was determined to be postnatally acquired and hearing loss most likely from genetic causes given a family history of hearing loss and consanguinity. A pathogenic variant in SLC29A3 was found on whole-exome sequencing and given concern for SLC29A3 spectrum disorder, steroids were started. Following concerns for development of side effects with chronic steroid use, he was switched to interleukin 6 inhibitor therapy. The patient's inflammatory markers decreased on tocilizumab, and his sensorineural hearing loss was notable for improvement and stabilisation on therapy.

Metabolic Glycan Labeling-Based Screen to Identify Bacterial Glycosylation Genes.

Bacterial cell surface glycans are quintessential drug targets due to their critical role in colonization of the host, pathogen survival, and immune evasion. The dense cell envelope glycocalyx contains distinctive monosaccharides that are stitched together into higher order glycans to yield exclusively bacterial structures that are critical for strain fitness and pathogenesis. However, the systematic study and inhibition of bacterial glycosylation enzymes remains challenging. Bacteria produce glycans containing rare sugars refractory to traditional glycan analysis, complicating the study of bacterial glycans and the identification of their biosynthesis machinery. To ease the study of bacterial glycans in the absence of detailed structural information, we used metabolic glycan labeling to detect changes in glycan biosynthesis. Here, we screened wild-type versus mutant strains of the gastric pathogen Helicobacter pylori, ultimately permitting the identification of genes involved in glycoprotein and lipopolysaccharide biosynthesis. Our findings provide the first evidence that H. pylori protein glycosylation proceeds via a lipid carrier-mediated pathway that overlaps with lipopolysaccharide biosynthesis. Protein glycosylation mutants displayed fitness defects consistent with those induced by small molecule glycosylation inhibitors. Broadly, our results suggest a facile approach to screen for bacterial glycosylation genes and gain insight into their biosynthesis and functional importance, even in the absence of glycan structural information.

Genetic Variants Related to Longer Telomere Length are Associated with Increased Risk of Renal Cell Carcinoma.

BACKGROUND: Relative telomere length in peripheral blood leukocytes has been evaluated as a potential biomarker for renal cell carcinoma (RCC) risk in several studies, with conflicting findings. OBJECTIVE: We performed an analysis of genetic variants associated with leukocyte telomere length to assess the relationship between telomere length and RCC risk using Mendelian randomization, an approach unaffected by biases from temporal variability and reverse causation that might have affected earlier investigations. DESIGN, SETTING, AND PARTICIPANTS: Genotypes from nine telomere length-associated variants for 10 784 cases and 20 406 cancer-free controls from six genome-wide association studies (GWAS) of RCC were aggregated into a weighted genetic risk score (GRS) predictive of leukocyte telomere length. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Odds ratios (ORs) relating the GRS and RCC risk were computed in individual GWAS datasets and combined by meta-analysis. RESULTS AND LIMITATIONS: Longer genetically inferred telomere length was associated with an increased risk of RCC (OR=2.07 per predicted kilobase increase, 95% confidence interval [CI]:=1.70-2.53, p<0.0001). As a sensitivity analysis, we excluded two telomere length variants in linkage disequilibrium (R2>0.5) with GWAS-identified RCC risk variants (rs10936599 and rs9420907) from the telomere length GRS; despite this exclusion, a statistically significant association between the GRS and RCC risk persisted (OR=1.73, 95% CI=1.36-2.21, p<0.0001). Exploratory analyses for individual histologic subtypes suggested comparable associations with the telomere length GRS for clear cell (N=5573, OR=1.93, 95% CI=1.50-2.49, p<0.0001), papillary (N=573, OR=1.96, 95% CI=1.01-3.81, p=0.046), and chromophobe RCC (N=203, OR=2.37, 95% CI=0.78-7.17, p=0.13). CONCLUSIONS: Our investigation adds to the growing body of evidence indicating some aspect of longer telomere length is important for RCC risk. PATIENT SUMMARY: Telomeres are segments of DNA at chromosome ends that maintain chromosomal stability. Our study investigated the relationship between genetic variants associated with telomere length and renal cell carcinoma risk. We found evidence suggesting individuals with inherited predisposition to longer telomere length are at increased risk of developing renal cell carcinoma.

Pharmacogenomic Markers of Targeted Therapy Toxicity in Patients with Metastatic Renal Cell Carcinoma.

BACKGROUND: Targeted therapy (TT) in metastatic renal cell carcinoma (mRCC) may be associated with a high rate of toxicity that undermines treatment efficacy and patient quality of life. Polymorphisms in genes involved in the pharmacokinetic pathways of TTs may predict toxicity. OBJECTIVE: To investigate whether selected single-nucleotide polymorphisms (SNPs) in three core genes involved in the metabolism and transport of sunitinib and the mTOR inhibitors everolimus and temsirolimus are associated with adverse events (AEs). DESIGN, SETTING, AND PARTICIPANTS: Germline DNA was extracted from blood or normal kidney tissue from mRCC patients of Caucasian ethnicity in two cohorts treated with either sunitinib (n=159) or mTOR inhibitors (n=62). Six SNPs in three candidate genes (CYP3A4: rs2242480, rs4646437, and rs2246709; CYP3A5: rs15524; and ABCB1: rs2032582 and rs1045642) were analyzed. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Primary endpoints were grade ≥3 AEs for all patients; grade ≥3 hypertension in the sunitinib cohort, and any grade pneumonitis in the mTOR inhibitors cohort. A logistic regression model was used to assess the association between SNPs and AEs, with adjustment for relevant clinical factors. RESULTS AND LIMITATIONS: In total, 221 samples were successfully genotyped for the selected SNPs. In the sunitinib cohort, the CYP3A4 rs464637 AG variant was associated with a lower risk of high-grade AEs (odds ratio 0.27, 95% confidence interval 0.08-0.88; p=0.03), but no SNPs were associated with hypertension. In the mTOR inhibitor cohort, none of the selected SNPs was associated with analyzed toxicities. CONCLUSIONS: We observed an association between CYP3A4 polymorphisms and toxicity outcomes in mRCC patients treated with sunitinib, but not with everolimus or temsirolimus. Our findings are exploratory in nature, and further validation in independent and larger cohorts is needed. PATIENT SUMMARY: We found that variants of CYP3A4, a gene involved in drug metabolism, are associated with sunitinib toxicity. This information may help in better selection of patients for targeted therapies in metastatic renal cell carcinoma.