Prevalence of previously undiagnosed psychiatric symptom groupings in pediatric patients with bladder and bowel dysfunction.

INTRODUCTION AND OBJECTIVE: The incidence of concomitant psychiatric disorders in conjunction with bladder and bowel dysfunction (BBD) is thought to be higher than the general population. The identification of these disorders with validated tools followed by management may improve urological outcomes. The objective of this study was to determine the prevalence of undiagnosed psychiatric symptom groupings in children presenting with BBD. METHODS: Consecutive patients 6-18 yrs with a clinical diagnosis of BBD, a score ≥11 on the Vancouver Symptom Score (VSS) and no prior psychiatric diagnoses were recruited. Two validated questionnaires (Child Behavior Checklist for Ages 6-18 (CBCL) and Autism Spectrum Quotient 10 (AQ-10)) were used to screen for psychiatric comorbidities. Descriptive statistics for demographic variables were presented. Distribution of VSS for normal & abnormal categories (borderline/clinical) of CBCL scores were compared by Mann-Whitney U test. Spearman correlation coefficient was used to examine the relationship between VSS domain scores and CBCL. RESULTS: From Sept 2017-May 2022, 50 (17 male) of 110 eligible patients completed the study. Median VSS was 18 (11-33), indicating significant BBD. In 36 patients (72 %), at least one of the CBCL subscales scored as borderline/clinical. Thirty-two patients (64 %) scored in the abnormal range for Internalizing symptoms, 21 (42 %) for Externalizing symptoms, and 31 (62 %) for Total problem scores. Four patients of 48(8 %) scored ≥6 on the AQ-10. The only significant correlation found between CBCL and VSS sub scores was with the Bowel Habit Domain of VSS and Internalizing CBCL T-scores (P = 0.02). CONCLUSION: This study identified a high prevalence of previously undiagnosed psychiatric symptom groupings in patients presenting with BBD, with a higher prevalence of internalizing and externalizing symptoms and autism traits than reported in the general population. These findings should encourage urologists to use validated tools to screen for psychiatric comorbidities with referral for further assessment as appropriate. This may prevent unnecessary urological testing, save valuable health resources and potentially improve treatment outcomes of BBD in this population.

Age-specific determinants of psychiatric outcomes after the first COVID-19 wave: baseline findings from a Canadian online cohort study.

BACKGROUND: Canadians endured unprecedented mental health (MH) and support access challenges during the first COVID-19 wave. Identifying groups of individuals who remain at risk beyond the acute pandemic phase is key to guiding systemic intervention efforts and policy. We hypothesized that determinants of three complementary, clinically actionable psychiatric outcomes would differ across Canadian age groups. METHODS: The Personal Impacts of COVID-19 Survey (PICS) was iteratively developed with stakeholder feedback, incorporating validated, age-appropriate measures. Baseline, cross-sectional online data collected between November 2020-July 2021 was used in analyses. Age group-specific determinants were sought for three key baseline MH outcomes: (1) current probable depression, generalized anxiety disorder, obsessive-compulsive disorder and/or suicide attempt during COVID-19, (2) increased severity of any lifetime psychiatric diagnosis, and (3) inadequate MH support access during COVID-19. Multivariable logistic regression models were constructed for children, youth (self- and parent-report), young adults (19-29 years) and adults over 29 years, using survey type as a covariate. Statistical significance was defined by 95% confidence interval excluding an odds ratio of one. RESULTS: Data from 3140 baseline surveys were analyzed. Late adolescence and early adulthood were identified as life phases with the worst MH outcomes. Poverty, limited education, home maker/caregiver roles, female and non-binary gender, LGBTQ2S + status and special educational, psychiatric and medical conditions were differentially identified as determinants across age groups. INTERPRETATION: Negative psychiatric impacts of COVID-19 on Canadians that include poor access to MH support clearly persisted beyond the first wave, widening pre-existing inequity gaps. This should guide policy makers and clinicians in current and future prioritization efforts.

Prevalence of pediatric acute-onset neuropsychiatric syndrome (PANS) in children and adolescents with eating disorders.

BACKGROUND: Pediatric obsessive-compulsive disorder (OCD) and eating disorder symptoms frequently overlap, clouding diagnostic certainty and hypothesized etiologic factors. Pediatric acute-onset neuropsychiatric syndrome (PANS) is defined by abrupt emergence of core obsessive-compulsive behaviours and/or food restriction with concurrent, ancillary cognitive and behavioral symptoms. Inflammatory and immune processes have putative roles in both PANS and a related described condition with cardinal obsessive-compulsive or tic symptoms, known as pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS). While prevalence of PANS and PANDAS has been examined in tic, movement disorder and OCD populations, this has not yet been systematically examined in a pediatric eating disorder sample. OBJECTIVES: To identify the lifetime prevalence of those meeting PANS and/or PANDAS criteria within a pediatric eating disorder cohort. METHODS: Convenience sampling method was utilized to select consecutive youth (ages 8-18-years) presenting to an interdisciplinary pediatric eating disorder subspecialty program with a confirmed eating disorder and completed parent-report PANS/PANDAS questionnaire (n = 100). A parent-reported measure was used to establish lifetime prevalence rates for PANS and PANDAS. Descriptive and exploratory comparative analyses were conducted between PANS and non-PANS groups. Continuous measures were analyzed using two-tailed independent sample t-tests and categorical measures were analyzed using two-tailed Fisher's exact tests. RESULTS: Among participants, 52% (n = 52) met PANS criteria and 0% (n = 0) met PANDAS diagnostic criteria. Core, abrupt-onset PANS symptoms included both food restriction and obsessive-compulsive symptoms in 63.5% (n = 33), food restriction only in 25% (n = 13), and obsessive-compulsive symptoms only in 11.5% (n = 6) of participants. In comparison to those who did not meet PANS criteria, those in the PANS subgroup were less likely to be male and more commonly prescribed a selective serotonin reuptake inhibitor medication. Significant group differences did not emerge for onset age, body mass index, eating disorder type or comorbid psychiatric/medical/autoimmune illness. CONCLUSION: Lifetime prevalence of symptoms in keeping with PANS diagnostic criteria within a pediatric eating disorder cohort was notably higher than that previously reported in OCD or tic disorder cohorts. The overlap between starvation effects and ancillary PANS symptoms may challenge the practical utility of this putative syndrome within the eating disorder population.

The connections and overlap between eating disorders and obsessive­compulsive disorder (OCD) are complicated and not fully understood. A syndrome described in the past decade (pediatric acute-onset neuropsychiatric syndrome; PANS) is characterized by a sudden, dramatic onset of food restriction and/or obsessive­compulsive symptoms in combination with several other behavioural and cognitive changes; a related condition is associated with sudden onset obsessive­compulsive symptoms or tics after streptococcal infection (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection; PANDAS). Rates of PANS and PANDAS have been reported in OCD and tic populations but not in eating disorders. We set out to screen a group of youth at a pediatric eating disorders program for lifetime symptoms of PANS and PANDAS. Among 100 eating disorder affected-youth in this study, approximately half (52%) met criteria for PANS, and none met criteria for PANDAS. However, the overlap between several PANS diagnostic criteria items and effects of starvation on both cognition and behaviour clouds the potential utility of this putative subtype within eating disorders populations.

Bowel and Bladder Dysfunction Is Associated with Psychiatric Comorbidities and Functional Impairment in Pediatric Obsessive-Compulsive Disorder.

Objective: Neuropsychiatric disorders are common in children with bowel and bladder dysfunction (BBD), a syndrome associated with urinary frequency, urgency, holding, incontinence, and constipation. We evaluated BBD symptom severity in children and youth attending a tertiary care obsessive-compulsive disorder (OCD) clinic. Methods: Consecutive patients attending initial OCD assessments between 2016 and 2020 were invited to participate in a registry study. Diagnosis of OCD and comorbidities was established by structured clinical interview. OCD severity and impact were assessed with the Children's Yale-Brown Obsessive-Compulsive Scale (CY-BOCS) and the Child Obsessive Compulsive Impact Scale (COIS-R; self-report), respectively. BBD symptoms were quantified with the Vancouver Symptom Score (VSS), a validated self-report measure. Results: One hundred twelve participants completed the VSS (mean age 13.5 ± 3.3, range 7-20). Based on a cutoff score of 11 corresponding to pediatric urologist-diagnosed BBD, 30.4% of participants screened positive, including more females than males (39.3% vs. 21.4%; p = 0.04). Daytime urinary incontinence was present in a greater proportion of participants with OCD forbidden thoughts (34.8% vs. 8.2%, p = 0.002), major depressive disorder (MDD; 38.5% vs. 6.8%, p = 0.001), and somatization disorder (60% vs. 9%, p = 0.001) compared with those without. A regression model including CY-BOCS, COIS-R, psychiatric comorbidities, medications, age, and gender explained 52.2% of the variance in VSS; COIS-R, tic disorder, and MDD were significant predictors. Conclusion: BBD symptoms are common and associated with high OCD-related impairment and psychiatric comorbidities. Standardized assessment may facilitate identification of BBD symptoms in this population and is critical to mitigating long-term physical and mental health impacts. Further studies are required to assess the relationship between BBD and OCD treatment outcomes.

Development of IMPAACT (Impairment Measure for Parental Food Allergy-Associated Anxiety and Coping Tool), a validated tool to screen for food allergy-associated parental anxiety.

BACKGROUND: Parents commonly experience anxiety owing to their children's food allergies (FAs). Although FA-specific anxiety screening tools for adult and pediatric patients exist, a tool for parents with children with food allergy is lacking. OBJECTIVE: To develop and validate a tool that measures parental anxiety related to their child's FA. METHODS: To construct the instrument, items were developed based on consultations with stakeholders and review of existing literature. The instrument was then pilot tested, and items were modified based on relevance, importance, item-total correlations, and fit with the instrument's overall factor structure. The modified instrument was validated through assessing internal validity (reliability), convergent and discriminant validity, concurrent validity, and practical usefulness at 2 time points (precoronavirus disease 2019 and current). RESULTS: The scale showed excellent reliability (Cronbach's α = 0.95). It had a 4-factor structure that was replicated at the 2 time points. The 4 subscales were moderately correlated (between r = 0.438 and 0.744). The scale showed excellent convergent and discriminatory validity, correlating moderately with State Trait Anxiety Inventory and Generalized Anxiety Disorder, and highly with Food Allergy Quality of Life-Parental Burden. It also showed excellent concurrent validity, differentiating among many external variables. Most importantly, it successfully differentiated parents in need of psychological support for problems related to their child's FA. CONCLUSION: The Impairment Measure for Parental Food Allergy-associated Anxiety and Coping Tool fills a gap in the existing literature as a validated screening tool for parental anxiety associated with a child's FA, employing a multi-factor structure addressing multiple dimensions of anxiety and its functional impacts. It has excellent internal and external validity and is well-suited for use in both research and clinical settings to quickly determine which parents of children with FA are in need of further psychological support.

Severe symptoms predict salivary interleukin-6, interleukin-1ß, and tumor necrosis factor-α levels in children and youth with obsessive-compulsive disorder.

OBJECTIVE: Childhood-onset obsessive-compulsive disorder (OCD) has been associated with immune dysregulation, including aberrant plasma inflammatory markers and increased rates of infectious and immune-mediated disorders. Saliva may provide a minimally-invasive tool for assessing oral mucosal immunity and inflammatory biomarkers in this population. The primary aim of this study was to compare salivary defense proteins and inflammatory mediators in saliva from children and youth with OCD and healthy controls, and evaluate their associations with measures of oral health and OCD phenotype. METHODS: In this cross-sectional observational study, saliva was collected from 41 children and youth with childhood-onset OCD and 46 healthy controls. Levels of lysozyme, α-amylase, secretory immunoglobulin A (sIgA), C-reactive protein (CRP), interleukin-6 (IL-6), IL-1ß, and tumor necrosis factor-α (TNF-α) were quantified by enzyme-linked immunosorbent assays or electrochemiluminescent-based immunoassays. RESULTS: All analytes were detectable in saliva. When adjusting for salivary flow rate and total protein, multiple linear regression models including demographic variables, oral health measures, and OCD status explained a significant proportion of the variance in IL-6, IL-1ß, and sIgA but not TNF-α, CRP, α-amylase, or lysozyme levels. Diagnosis of OCD was associated with significantly higher IL-6 (ß = 0.403, p = 0.026), while severity of OCD was a significant predictor of increased cytokines (IL-6, ß = 0.325, p = 0.009; IL-1ß, ß = 0.284, p = 0.020; TNF-α, ß = 0.269, p = 0.036), but not other analytes. CONCLUSION: These data point to the feasibility of analyzing soluble immune mediators in the saliva in childhood-onset OCD, suggesting that pro-inflammatory cytokines are associated with OCD diagnosis and symptom severity. Further work is required to elucidate the factors contributing to this association and implications for clinical practice.

Celecoxib versus placebo as an adjunct to treatment-as-usual in children and youth with obsessive-compulsive disorder: protocol for a single-site randomised quadruple-blind phase II study.

BACKGROUND: Cyclooxygenase (COX) enzymes oxidise arachidonic acid to prostaglandins, which modulate neuronal function and inflammation in the central nervous system. Consensus guidelines suggest non-steroidal anti-inflammatory drugs as a possible adjunctive approach in adults with obsessive-compulsive disorder (OCD) and in children with acute-onset OCD subtypes. However, there is limited evidence to support this approach. The primary objective of this study is to determine the efficacy of the COX-2-selective inhibitor celecoxib as an adjunct to treatment-as-usual in children and youth with moderate-to-severe OCD. The safety of this intervention including adverse events will also be systematically assessed. METHODS: The Adjunctive CElecoxib in childhood-onset OCD (ACE-OCD) study is a single-centre randomised, quadruple-blind, placebo-controlled superiority trial with two parallel groups: celecoxib 100 mg twice daily and placebo. Treatments will be added to participants' routine clinical care, which will not change over the course of the study. Target recruitment is 80 participants ages 7-18 with no recent treatment changes. The primary outcome is OCD severity after 12 weeks of treatment, measured by clinician-administered Children's Yale-Brown Obsessive Compulsive Scale (CY-BOCS). Secondary outcomes include CY-BOCS score after 6 weeks; difference in the proportion of participants achieving a clinically meaningful response or remission; mean clinical global impression of severity and improvement after 6 and 12 weeks; and proportion of participants reporting adverse events possibly or probably related to the study intervention. The primary analyses, carried out according to intention-to-treat principles, will compare the celecoxib to placebo group on each outcome of interest, adjusting for baseline scores using analysis of covariance or logistic regression. Participants will be offered a 12-week open-label celecoxib extension and will be invited to participate in an ancillary study for biomarker analyses. ETHICS AND DISSEMINATION: This protocol has been approved by the University of British Columbia Children's and Women's Research Ethics Board and has received a No Objection Letter from Health Canada. The findings will be disseminated in peer-reviewed journals and presentations to multiple stakeholders including patients, parents and healthcare providers. TRIAL REGISTRATION NUMBER: NCT04673578.

Food-allergy-specific anxiety and distress in parents of children with food allergy: A systematic review.

BACKGROUND: Parenting a child with food allergy (FA) can lead to impaired quality of life and family functioning. Anxiety is a critical component of FA-associated distress and a potential target for therapeutic intervention. This systematic review aimed to clarify the concept of FA-specific anxiety (FAA) and its antecedents, consequences, and correlates and to determine the extent to which existing FA-specific outcome measures capture symptoms of parental distress and FAA. METHODS: MEDLINE, EMBASE, PsycINFO, and CENTRAL were searched for qualitative and quantitative studies examining distress or anxiety in parents of children with FA through August 2020. This review was registered with PROSPERO (CRD42020208316) and conducted in accordance with PRISMA guidelines. RESULTS: Ninety-eight studies were included in the final narrative synthesis. Most participants were mothers, and reporting of demographic data was limited. Parents identified anxiety as the most burdensome form of FA-specific emotional distress. Several allergy-related factors as well as medical and psychosocial interventions were associated with reduced parental anxiety and distress. However, affective, cognitive, and behavioral dimensions of FAA were only partially addressed by existing measures for general anxiety symptoms and FA-specific parental factors. CONCLUSIONS: FAA contributes to distress and functional impairment among parents of children with FA. Current FA-specific parent measures fail to adequately capture dimensions of FAA, suggesting that further work is needed to improve the assessment and monitoring of FAA and its impacts. Characterization of this construct represents an initial step in developing standardized methods for assessing and monitoring FAA in clinical populations.

Modulation of Innate Immunity by Amyloidogenic Peptides.

Amyloid formation contributes to the development of progressive metabolic and neurodegenerative diseases, while also serving functional roles in host defense. Emerging evidence suggests that as amyloidogenic peptides populate distinct aggregation states, they interact with different combinations of pattern recognition receptors (PRRs) to direct the phenotype and function of tissue-resident and infiltrating innate immune cells. We review recent evidence of innate immunomodulation by distinct forms of amyloidogenic peptides produced by mammals (humans, non-human primates), bacteria, and fungi, as well as the corresponding cell-surface and intracellular PRRs in these interactions, in human and mouse models. Our emerging understanding of peptide aggregate-innate immune cell interactions, and the factors regulating the balance between amyloid function and pathogenicity, might aid the development of anti-amyloid and immunomodulating therapies.

Immune-Related Comorbidities in Childhood-Onset Obsessive Compulsive Disorder: Lifetime Prevalence in the Obsessive Compulsive Disorder Collaborative Genetics Association Study.

Objective: To evaluate the lifetime prevalence of infectious, inflammatory, and autoimmune disorders in a multisite study of probands with childhood-onset obsessive compulsive disorder (OCD) and their first-degree relatives. Methods: Medical questionnaires were completed by 1401 probands and 1045 first-degree relatives in the OCD Collaborative Genetics Association Study. Lifetime prevalence of immune-related diseases was compared with the highest available population estimate and reported as a point estimate with 95% adjusted Wald interval. Worst-episode OCD severity and symptom dimensions were assessed with the Yale-Brown Obsessive Compulsive Scale (YBOCS) and Symptom Checklist (YBOCS-CL). Results: Probands reported higher-than-expected prevalence of scarlet fever (4.0 [3.1-5.2]% vs. 1.0%-2.0%, z = 1.491, p < 0.001, n = 1389), encephalitis or meningitis (1.4 [0.9-2.1]% vs. 0.1%-0.4%, z = 5.913, p < 0.001, n = 1393), rheumatoid arthritis (1.1 [0.6-2.0]% vs. 0.2%-0.4%, z = 3.416, p < 0.001, n = 949) and rheumatic fever (0.6 [0.3-1.2]% vs. 0.1%-0.2%, z = 3.338, p < 0.001, n = 1390), but not systemic lupus erythematosus, diabetes, asthma, multiple sclerosis, psoriasis, or inflammatory bowel disease. First-degree relatives reported similarly elevated rates of scarlet fever, rheumatic fever, and encephalitis or meningitis independent of OCD status. There was no association between worst-episode severity and immune-related comorbidities, although probands reporting frequent ear or throat infections had increased severity of cleaning-/contamination-related symptoms (mean factor score 2.5 ± 0.9 vs. 2.3 ± 1.0, t = 3.183, p = 0.002, n = 822). Conclusion: These data suggest high rates of streptococcal-related and other immune-mediated diseases in patients with childhood-onset OCD and are consistent with epidemiological studies in adults noting familial clustering. Limitations include potential reporting bias and absence of a control group, underscoring the need for further prospective studies characterizing medical and psychiatric disease clusters and their interactions in children. Such studies may ultimately improve our understanding of OCD pathogenesis and aid in the development of adjunctive immune-modulating therapeutic strategies.

Periodic fever syndromes: beyond the single gene paradigm.

Familial Mediterranean fever (FMF) is the most common monogenic autoinflammatory disease in Canada and is characterized by a clinical syndrome of episodic inflammatory symptoms. Traditionally, the disease is defined by autosomal recessive inheritance of MEFV gene variants, yet FMF also not uncommonly manifests in individuals with only one identified disease-associated allele. Increasing availability and affordability of gene sequencing has led to the identification of multiple MEFV variants; however, they are often of unknown clinical significance. Variants in other genes affecting overlapping or distinct inflammatory signaling pathways - together with gene-environment interactions including epigenetic modulation - likely underlie the significant genetic and phenotypic heterogeneity seen among patients with this disease. We review recent evidence of the expanding spectrum of FMF genotype and phenotype and suggest that current drug funding schemes restricting biologic agents to patients with homozygous mutations have not kept pace with our biological understanding of the disease.

Challenges in the diagnosis and treatment of pediatric obsessive-compulsive disorder.

Obsessive-compulsive disorder (OCD) affects 1%-3% of children worldwide and has a profound impact on quality of life for patients and families. Although our understanding of the underlying etiology remains limited, data from neuroimaging and genetic studies as well as the efficacy of serotonergic medications suggest the disorder is associated with the fundamental alterations in the function of cortico-striato-thalamocortical circuits. Significant delays to diagnosis are common, ultimately leading to more severe functional impairment with long-term developmental consequences. The clinical assessment requires a detailed history of specific OCD symptoms as well as psychiatric and medical comorbidities. Standardized assessment tools may aid in evaluating and tracking symptom severity and both individual and family functioning. In the majority of children, an interdisciplinary approach that combines cognitive behavioral therapy with a serotonin reuptake inhibitor leads to meaningful symptom improvement, although some patients experience a chronic, episodic course. There are limited data to guide the management of treatment-refractory illness in children, although atypical antipsychotics and glutamate-modulating agents may be used cautiously as augmenting agents. This review outlines a clinical approach to the diagnosis and management of OCD, highlighting associated challenges, and limitations to our current knowledge.

Clinical practice variation and need for pediatric-specific treatment guidelines among rheumatologists caring for children with ANCA-associated vasculitis: an international clinician survey.

BACKGROUND: Because pediatric antineutrophil cytoplasmic antibody-associated vasculitis is rare, management generally relies on adult data. We assessed treatment practices, uptake of existing clinical assessment tools, and interest in pediatric treatment protocols among rheumatologists caring for children with granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). METHODS: A needs-assessment survey developed by an international working group of pediatric rheumatologists and two nephrologists was circulated internationally. Data were summarized with descriptive statistics. Pearson's chi-square tests were used in inferential univariate analyses. RESULTS: The 209 respondents from 36 countries had collectively seen ~1600 children with GPA/MPA; 144 had seen more than two in the preceding 5 years. Standardized and validated clinical assessment tools to score disease severity, activity, and damage were used by 59, 63, and 36%, respectively; barriers to use included lack of knowledge and limited perceived utility. Therapy varied significantly: use of rituximab rather than cyclophosphamide was more common among respondents from the USA (OR = 2.7 [1.3-5.5], p = 0.0190, n = 139), those with >5 years of independent practice experience (OR = 3.8 [1.3-12.5], p = 0.0279, n = 137), and those who had seen >10 children with GPA/MPA in their careers (OR = 4.39 [2.1-9.1], p = 0.0011, n = 133). Respondents who had treated >10 patients were also more likely to continue maintenance therapy for at least 24 months (OR = 3.0 [1.4-6.4], p = 0.0161, n = 127). Ninety six percent of respondents believed in a need for pediatric-specific treatment guidelines; 46% supported adaptation of adult guidelines while 69% favoured guidelines providing a limited range of treatment options to allow comparison of effectiveness through a registry. CONCLUSIONS: These data provide a rationale for developing pediatric-specific consensus treatment guidelines for GPA/MPA. While pediatric rheumatologist uptake of existing clinical tools has been limited, guideline uptake may be enhanced if outcomes of consensus-derived treatment options are evaluated within the framework of an international registry.

ABCA1 deficiency and cellular cholesterol accumulation increases islet amyloidogenesis in mice.

AIMS/HYPOTHESIS: Islet amyloid, a pathological feature of type 2 diabetes, forms from the aggregation of islet amyloid polypeptide (IAPP), a beta cell peptide that is produced and co-secreted with insulin. Cholesterol regulates amyloid-ß processing, deposition and clearance, promoting amyloidogenesis in the brain. ATP-binding cassette transporter 1 (ABCA1) is a cholesterol efflux transporter that when absent increases and when overexpressed reduces brain amyloid-ß deposition in mouse models of Alzheimer's disease. We examined whether alterations in ABCA1 expression and islet cholesterol content could also modulate islet amyloidogenesis. METHODS: Thioflavin S staining for amyloid was performed in islets isolated from mice with beta cell expression of human IAPP (hIAPP (Tg/o)) and cultured for 8 days following cholesterol loading, microRNA-33 overexpression (to reduce ABCA1 expression) or palmitate treatment in the presence or absence of ABCA1 overexpression or mevastatin treatment (to reduce cholesterol synthesis). hIAPP (Tg/o) mice were crossed with beta cell-specific Abca1-knockout mice (hIAPP (Tg/o) Abca1 (ßKO)) and glucose tolerance and amyloid formation were assessed. RESULTS: Cholesterol loading and microRNA-33-induced reduction in islet ABCA1 expression increased Thioflavin S-positive amyloid in hIAPP (Tg/o) islets. Palmitate treatment also increased amyloid formation and this was reduced by both ABCA1 overexpression and mevastatin treatment. hIAPP (Tg/o) Abca1 (ßKO) mice had increased islet cholesterol, accompanied by fasting hyperglycaemia, glucose intolerance, impaired in vivo insulin secretion and an increased islet proinsulin:insulin ratio. Amyloid area was increased in cultured hIAPP (Tg/o) Abca1 (ßKO) islets compared with hIAPP (Tg/o) controls. CONCLUSIONS/INTERPRETATION: These data suggest that elevations in islet cholesterol may lead to increases in IAPP aggregation and islet amyloid formation, further worsening beta cell function and glucose homeostasis.

Differential Activation of Innate Immune Pathways by Distinct Islet Amyloid Polypeptide (IAPP) Aggregates.

Aggregation of islet amyloid polypeptide (IAPP) contributes to beta cell dysfunction in type 2 diabetes and islet transplantation. Like other amyloidogenic peptides, human IAPP induces macrophage IL-1ß secretion by stimulating both the synthesis and processing of proIL-1ß, a pro-inflammatory cytokine that (when chronically elevated) impairs beta cell insulin secretion. We sought to determine the specific mechanism of IAPP-induced proIL-1ß synthesis. Soluble IAPP species produced early during IAPP aggregation provided a Toll-like-receptor-2- (TLR2-) dependent stimulus for NF-κB activation in HEK 293 cells and bone marrow-derived macrophages (BMDMs). Non-amyloidogenic rodent IAPP and thioflavin-T-positive fibrillar amyloid produced by human IAPP aggregation failed to activate TLR2. Blockade of TLR6 but not TLR1 prevented hIAPP-induced TLR2 activation, consistent with stimulation of a TLR2/6 heterodimer. TLR2 and its downstream adaptor protein MyD88 were required for IAPP-induced cytokine production by BMDMs, a process that is partially dependent on autoinduction by IL-1. BMDMs treated with soluble but not fibrillar IAPP provided a TLR2-dependent priming stimulus for ATP-induced IL-1ß secretion, whereas late IAPP aggregates induced NLRP3-dependent IL-1ß secretion by LPS-primed macrophages. Moreover, inhibition of TLR2 and depletion of islet macrophages prevented up-regulation of Il1b and Tnf expression in human IAPP-expressing transgenic mouse islets. These data suggest participation by both soluble and fibrillar aggregates in IAPP-induced islet inflammation. IAPP-induced activation of TLR2 and secretion of IL-1 may be important therapeutic targets to prevent amyloid-associated beta cell dysfunction.

IL-1 mediates amyloid-associated islet dysfunction and inflammation in human islet amyloid polypeptide transgenic mice.

AIMS/HYPOTHESIS: Aggregation of islet amyloid polypeptide (IAPP) to form amyloid contributes to beta cell dysfunction in type 2 diabetes. Human but not non-amyloidogenic rodent IAPP induces islet macrophage proIL-1ß synthesis. We evaluated the effect of IL-1 receptor antagonist (IL-1Ra) on islet inflammation and dysfunction in a mouse model of type 2 diabetes with amyloid formation. METHODS: Lean and obese male mice (A/a or A(vy)/A at the agouti locus, respectively) with or without beta cell human IAPP expression (hIAPP(Tg/0)) were treated with PBS or IL-1Ra (50 mg kg(-1) day(-1)) from 16 weeks of age. Intraperitoneal glucose and insulin tolerance tests were performed after 8 weeks. Pancreases were harvested for histology and gene expression analysis. RESULTS: Aggregation of human IAPP was associated with marked upregulation of proinflammatory gene expression in islets of obese hIAPP(Tg/0) mice, together with amyloid deposition and fasting hyperglycaemia. IL-1Ra improved glucose tolerance and reduced plasma proinsulin:insulin in both lean and obese hIAPP(Tg/0) mice with no effect on insulin sensitivity. The severity and prevalence of islet amyloid was reduced by IL-1Ra in lean hIAPP (Tg/0) mice, suggesting a feed-forward mechanism by which islet inflammation promotes islet amyloid at the early stages of disease. IL-1Ra limited Il1a, Il1b, Tnf and Ccl2 expression in islets from obese hIAPP(Tg/0) mice, suggesting an altered islet inflammatory milieu. CONCLUSIONS/INTERPRETATION: These data provide the first in vivo evidence­using a transgenic mouse model with amyloid deposits resembling those found in human islets­that IAPP-induced beta cell dysfunction in type 2 diabetes may be mediated by IL-1. Anti-IL-1 therapies may limit islet inflammation and dysfunction associated with amyloid formation.