A Novel Homozygous Mutation Causing Complete TYK2 Deficiency, with Severe Respiratory Viral Infections, EBV-Driven Lymphoma, and Jamestown Canyon Viral Encephalitis.

Autosomal recessive tyrosine kinase 2 (TYK2) deficiency is characterized by susceptibility to mycobacterial and viral infections. Here, we report a 4-year-old female with severe respiratory viral infections, EBV-driven Burkitt-like lymphoma, and infection with the neurotropic Jamestown Canyon virus. A novel, homozygous c.745C > T (p.R249*) variant was found in TYK2. The deleterious effects of the TYK2 lesion were confirmed by immunoblotting; by evaluating functional responses to IFN-α/ß, IL-10, and IL-23; and by assessing its scaffolding effect on the cell surface expression of cytokine receptor subunits. The effects of the mutation could not be pharmacologically circumvented in vitro, suggesting that alternative modalities, such as hematopoietic stem cell transplantation or gene therapy, may be needed. We characterize the first patient from Canada with a novel homozygous mutation in TYK2.

Immunological effects and safety of live rotavirus vaccination after antenatal exposure to immunomodulatory biologic agents: a prospective cohort study from the Canadian Immunization Research Network.

BACKGROUND: People with inflammatory or autoimmune diseases are recommended to continue immunomodulatory biologic agents throughout pregnancy. However, concerns regarding potential immunosuppression in infants exposed to biologic agents have led to recommendations to avoid live vaccines in the first 6-12 months of life. We aimed to examine whether live rotavirus vaccine could be administered safely to infants exposed to biologic agents, assessed in the Canadian Special Immunization Clinic (SIC) Network. METHODS: In this prospective cohort study, infants exposed to biologic agents in utero were referred to one of six SIC sites in Canada for rotavirus vaccination recommendations. Children with other contraindications to rotavirus vaccination or older than 15 weeks were excluded. Clinical and laboratory evaluations were conducted according to a standard clinical pathway. Data were collected for relevant medical history, pregnancy outcomes, biologic agent exposure history, physical examination, laboratory results of the child, SIC recommendations for rotavirus vaccination, rotavirus vaccine series completion, and adverse events after immunisation. After parental consent, deidentified data were transferred to a central database for analysis. Children recommended for rotavirus vaccination were followed up for 8 months after series initiation to ascertain severe and serious adverse events, including severe diarrhoea, vomiting, and intussusception. FINDINGS: Between May 1, 2017, and Dec 31, 2021, 202 infants were assessed and 191 eligible infants were enrolled (97 [51%] were female and 94 [49%] were male). When including those exposed to multiple agents, the most common biologic agents to which infants were exposed were infliximab (67 [35%] of 191), adalimumab (49 [26%]), ustekinumab (18 [9%]), and vedolizumab (17 [9%]). Biologic agent exposure continued into the third trimester for 178 (93%) infants. No clinically significant abnormalities in lymphocyte subsets, quantitative immunoglobulins, or mitogen responses were detected. After SIC assessment, rotavirus vaccination was recommended for 187 (98%) of 191 infants, all of whom were followed up. By end of follow-up on Aug 19, 2022, 168 (90%) infants had initiated rotavirus vaccination; 150 (80%) completed the series. No serious adverse events after immunisation were reported, but three (2%) infants required medical attention, one for vomiting and change in stools who was subsequently diagnosed with gastroesophageal reflux disease, one for rash on labia unrelated to vaccination, and one for vomiting and diarrhoea associated with a milk allergy. INTERPRETATION: Findings from this study suggest that lymphocyte subsets and the safety of live rotavirus vaccination are generally not affected by in-utero exposure to biologic agents. Rotavirus vaccination can be offered to infants exposed to anti-TNF agents in utero. FUNDING: Public Health Agency of Canada and Canadian Institutes of Health Research through the Canadian Immunization Research Network.

Long-Term Immune Reconstitution in ADA-Deficient Patients Treated With Elapegademase: A Real-World Experience.

BACKGROUND: ADAGEN, a bovine-based enzyme replacement therapy (ERT), has been used to treat adenosine deaminase severe combined immunodeficiency (ADA-SCID). In 2018, ADAGEN was replaced by REVCOVI (elapegademase), a modified bovine recombinant protein. OBJECTIVE: To determine the real-life long-term benefits of REVCOVI in ADA-SCID. METHODS: Data on ERT, infectious and noninfectious complications, and metabolic and immune evaluations were collected from 17 patients with ADA-SCID treated for 6 months or more with REVCOVI. RESULTS: Eleven patients had previously received ADAGEN for 16 to 324 months, whereas 6 patients were ERT-naive. REVCOVI was administered twice weekly at 0.4 mg/kg/wk in ERT-naive patients, whereas patients transitioning to REVCOVI from ADAGEN typically continued at the same frequency and equivalent dosing as ADAGEN, resulting in a significantly lower (P = .007) total REVCOVI dose in the transitioning group. REVCOVI treatment in the ERT-naive group led to the resolution of many clinical and laboratory complications of ADA deficiency, whereas there were no new adverse effects among the transitioning patients. REVCOVI treatment increased plasma ADA activity and decreased dAXP (which included deoxyadenosine mono-, di-, and tri phosphate) among most patients, effects that persisted throughout the 7- to 37-month treatment periods, except in 2 patients with incomplete adherence. Among some patients, after 0.5 to 6 months, injection frequency was reduced to once a week, while maintaining adequate metabolic profiles. All ERT-naive infants treated with REVCOVI demonstrated an increase in the number of CD4+ T and CD19+ B cells, although these counts remained stable but lower than normal in most transitioning patients. CONCLUSIONS: REVCOVI is effective for the management of ADA-SCID.

Canadian Association of Gastroenterology Clinical Practice Guideline for Immunizations in Patients With Inflammatory Bowel Disease (IBD)-Part 2: Inactivated Vaccines.

BACKGROUND AND AIMS: The effectiveness and safety of vaccinations can be altered by immunosuppressive therapies, and perhaps by inflammatory bowel disease (IBD) itself. These recommendations developed by the Canadian Association of Gastroenterology and endorsed by the American Gastroenterological Association, aim to provide guidance on immunizations in adult and pediatric patients with IBD. This publication focused on inactivated vaccines. METHODS: Systematic reviews evaluating the efficacy, effectiveness, and safety of vaccines in patients with IBD, other immune-mediated inflammatory diseases, and the general population were performed. Critical outcomes included mortality, vaccine-preventable diseases, and serious adverse events. Immunogenicity was considered a surrogate outcome for vaccine efficacy. Certainty of evidence and strength of recommendations were rated according to the GRADE (Grading of Recommendation Assessment, Development, and Evaluation) approach. Key questions were developed through an iterative online platform, and voted on by a multidisciplinary group. Recommendations were formulated using the Evidence-to-Decision framework. Strong recommendation means that most patients should receive the recommended course of action, whereas a conditional recommendation means that different choices will be appropriate for different patients. RESULTS: Consensus was reached on 15 of 20 questions. Recommendations address the following vaccines: Haemophilus influenzae type b, recombinant zoster, hepatitis B, influenza, pneumococcus, meningococcus, tetanus-diphtheria-pertussis, and human papillomavirus. Most of the recommendations for patients with IBD are congruent with the current Centers for Disease Control and Prevention and Canada's National Advisory Committee on Immunization recommendations for the general population, with the following exceptions. In patients with IBD, the panel suggested Haemophilus influenzae type b vaccine for patients older than 5 years of age, recombinant zoster vaccine for adults younger than 50 year of age, and hepatitis B vaccine for adults without a risk factor. Consensus was not reached, and recommendations were not made for 5 statements, due largely to lack of evidence, including double-dose hepatitis B vaccine, timing of influenza immunization in patients on biologics, pneumococcal and meningococcal vaccines in adult patients without risk factors, and human papillomavirus vaccine in patients aged 27-45 years. CONCLUSIONS: Patients with IBD may be at increased risk of some vaccine-preventable diseases. Therefore, maintaining appropriate vaccination status in these patients is critical to optimize patient outcomes. In general, IBD is not a contraindication to the use of inactivated vaccines, but immunosuppressive therapy may reduce vaccine responses.

Canadian Association of Gastroenterology Clinical Practice Guideline for Immunizations in Patients With Inflammatory Bowel Disease (IBD)-Part 2: Inactivated Vaccines.

BACKGROUND AND AIMS: The effectiveness and safety of vaccinations can be altered by immunosuppressive therapies, and perhaps by inflammatory bowel disease (IBD) itself. These recommendations developed by the Canadian Association of Gastroenterology and endorsed by the American Gastroenterological Association, aim to provide guidance on immunizations in adult and pediatric patients with IBD. This publication focused on inactivated vaccines. METHODS: Systematic reviews evaluating the efficacy, effectiveness, and safety of vaccines in patients with IBD, other immune-mediated inflammatory diseases, and the general population were performed. Critical outcomes included mortality, vaccine-preventable diseases, and serious adverse events. Immunogenicity was considered a surrogate outcome for vaccine efficacy. Certainty of evidence and strength of recommendations were rated according to the GRADE (Grading of Recommendation Assessment, Development, and Evaluation) approach. Key questions were developed through an iterative online platform, and voted on by a multidisciplinary group. Recommendations were formulated using the Evidence-to-Decision framework. Strong recommendation means that most patients should receive the recommended course of action, whereas a conditional recommendation means that different choices will be appropriate for different patients. RESULTS: Consensus was reached on 15 of 20 questions. Recommendations address the following vaccines: Haemophilus influenzae type b, recombinant zoster, hepatitis B, influenza, pneumococcus, meningococcus, tetanus-diphtheria-pertussis, and human papillomavirus. Most of the recommendations for patients with IBD are congruent with the current Centers for Disease Control and Prevention and Canada's National Advisory Committee on Immunization recommendations for the general population, with the following exceptions. In patients with IBD, the panel suggested Haemophilus influenzae type b vaccine for patients older than 5 years of age, recombinant zoster vaccine for adults younger than 50 year of age, and hepatitis B vaccine for adults without a risk factor. Consensus was not reached, and recommendations were not made for 5 statements, due largely to lack of evidence, including double-dose hepatitis B vaccine, timing of influenza immunization in patients on biologics, pneumococcal and meningococcal vaccines in adult patients without risk factors, and human papillomavirus vaccine in patients aged 27-45 years. CONCLUSIONS: Patients with IBD may be at increased risk of some vaccine-preventable diseases. Therefore, maintaining appropriate vaccination status in these patients is critical to optimize patient outcomes. In general, IBD is not a contraindication to the use of inactivated vaccines, but immunosuppressive therapy may reduce vaccine responses.

High-dose steroid and heparin: a novel therapy for cerebral vasculitis associated with presumed group A Streptococcus meningitis.

Cerebral vasculitis is a serious complication of bacterial meningitis that can cause significant morbidity and mortality due to stroke. Currently, there are no treatment guidelines or safety and efficacy studies on the management of cerebral vasculitis in this context. Herein, we report a case of a previously well 11-year-old girl who presented with acute otitis media that progressed to mastoiditis and fulminant meningitis. Group A Streptococcus was found in blood and ear-fluid cultures (lumbar puncture was unsuccessful). Her decreased level of consciousness persisted despite appropriate antimicrobial treatment, and repeat MRI revealed extensive large vessel cerebral vasculitis. Based on expert opinion and a presumed inflammatory mechanism, her cerebral vasculitis was treated with 7 days of pulse intravenous methylprednisolone followed by oral prednisone taper. She was also treated with intravenous heparin. Following these therapies, she improved clinically and radiographically with no adverse events. She continues to undergo rehabilitation with improvement.

Rubella Virus Infected Macrophages and Neutrophils Define Patterns of Granulomatous Inflammation in Inborn and Acquired Errors of Immunity.

Rubella virus (RuV) has recently been found in association with granulomatous inflammation of the skin and several internal organs in patients with inborn errors of immunity (IEI). The cellular tropism and molecular mechanisms of RuV persistence and pathogenesis in select immunocompromised hosts are not clear. We provide clinical, immunological, virological, and histological data on a cohort of 28 patients with a broad spectrum of IEI and RuV-associated granulomas in skin and nine extracutaneous tissues to further delineate this relationship. Combined immunodeficiency was the most frequent diagnosis (67.8%) among patients. Patients with previously undocumented conditions, i.e., humoral immunodeficiencies, a secondary immunodeficiency, and a defect of innate immunity were identified as being susceptible to RuV-associated granulomas. Hematopoietic cell transplantation was the most successful treatment in this case series resulting in granuloma resolution; steroids, and TNF-α and IL-1R inhibitors were moderately effective. In addition to M2 macrophages, neutrophils were identified by immunohistochemical analysis as a novel cell type infected with RuV. Four patterns of RuV-associated granulomatous inflammation were classified based on the structural organization of granulomas and identity and location of cell types harboring RuV antigen. Identification of conditions that increase susceptibility to RuV-associated granulomas combined with structural characterization of the granulomas may lead to a better understanding of the pathogenesis of RuV-associated granulomas and discover new targets for therapeutic interventions.

Clostridium septicum myonecrosis in a pediatric patient with a self-reported penicillin allergy.

Infections with Clostridium septicum are especially rare in pediatric patients. C. septicum is the most common cause of spontaneous myonecrosis and is usually associated with comorbid malignancy. Treatment of choice for cases of C. septicum myonecrosis is prompt and thorough surgical debridement and antimicrobial therapy with high dose penicillin. The experience and management of C. septicum infections in patients who are unable to take penicillin are not well described, and the optimal duration of therapy is largely unknown. We describe a case of spontaneous myonecrosis in a 14-year-old receiving cytotoxic chemotherapy for Burkitt's lymphoma who had an anecdotal history of a penicillin allergy. Her infection was initially treated with ceftazidime and metronidazole in concert with debridement but was ultimately cured with 3 weeks of intravenous penicillin therapy following a graded penicillin challenge in hospital. We observed a delayed inflammatory tissue response to a C. septicum skin, soft tissue infection that temporally corresponded to neutrophil reconstitution in our patient with severe neutropenia. Our experience demonstrates that C. septicum myonecrosis can present indolently and progress rapidly and highlights the need for clinical vigilance and repeat "second-look" surgeries. Our case also emphasizes the importance of de-labelling penicillin allergies.

Les infections à Clostridium septicum sont particulièrement rares chez les patients d'âge pédiatrique. Le C. septicum, qui est la principale cause de myonécrose spontanée, est généralement associé à des malignités. Le traitement de première intention de la myonécrose à C. septicum consiste à effectuer un débridement chirurgical rapide et minutieux et un traitement antimicrobien au moyen d'une forte dose de pénicilline. L'expérience et la prise en charge des infections à C. septicum ne sont pas bien décrites chez les patients qui ne sont pas en mesure de prendre de la pénicilline, et on ne connaît pas vraiment la durée optimale du traitement. Les auteurs décrivent le cas d'une myonécrose spontanée chez une adolescente de 14 ans qui a reçu une chimiothérapie cytotoxique pour traiter un lymphome de Burkitt et qui a une allergie non démontrée à la pénicilline. Son infection a d'abord été traitée par de la ceftazidime et du métronidazole, conjointement avec le débridement, mais a fini par être guérie au bout de trois semaines de traitement intraveineux à la pénicilline après un test de provocation graduel à la pénicilline à l'hôpital. Les auteurs ont observé une réponse inflammatoire tardive des tissus à une infection de la peau et des tissus mous au C. septicum qui correspondait temporellement à la reconstitution des neutrophiles chez la patiente atteinte d'une grave neutropénie. Selon leur expérience, la myonécrose à C. septicum peut se manifester sous forme indolente et progresser rapidement, ce qui fait ressortir l'importance de la vigilance clinique et des secondes interventions chirurgicales. Ce cas démontre également l'importance de désétiqueter les allergies à la pénicilline.

Cutaneous granulomas as the presenting manifestation of Griscelli syndrome type 2.

Griscelli syndrome type 2 is a rare autosomal recessive disorder characterized by hypopigmentation, silvery hair, and immunological dysfunction with no primary neurological impairment. We report an 18-month-old girl with Griscelli syndrome type 2 who presented to the dermatology department for cutaneous granulomas that developed following live-attenuated vaccination. Two compound heterozygous variants in the RAB27A gene were subsequently identified. She developed hemophagocytic lymphohistiocytosis, the key immunological concern, at age 5 years.

Waning Vaccine Immunity and Vaccination Responses in Children Treated for Acute Lymphoblastic Leukemia: A Canadian Immunization Research Network Study.

BACKGROUND: There is no uniform guideline for postchemotherapy vaccination of children with acute lymphoblastic leukemia (ALL). We evaluated waning immunity to 14 pneumococcal serotypes, pertussis toxin (PT), tetanus toxoid (TT) and varicella, and immunogenicity of postchemotherapy diphtheria, tetanus, pertussis, hepatitis B, polio, and Haemophilus influenzae type b (DTaP-IPV-Hib) and pneumococcal vaccination among previously vaccinated children treated for ALL. METHODS: This was a multicenter trial of children with ALL enrolled 4-12 months postchemotherapy completion. Exclusion criteria included: infant ALL, relapsed ALL, and stem cell transplant recipients. Immunocompetent children were recruited as controls. Postchemotherapy participants received DTaP-IPV-Hib and 13-valent pneumococcal conjugate vaccine (PCV13) concurrently, followed by 23-valent pneumococcal polysaccharide vaccine (PPV23) 2 months later. Serology was measured at baseline, 2 and 12 months postvaccination. Adverse events were captured via surveys. RESULTS: At enrollment, postchemotherapy participants (n = 74) were less likely than controls (n = 78) to be age-appropriately immunized with DTaP (41% vs 89%, P < .001) and PCV (59% vs 79%, P = .008). Geometric mean concentrations (GMCs) to TT, PT, PCV serotypes, and varicella were lower in postchemotherapy participants than controls after adjusting for previous vaccine doses (P < .001). Two months postvaccination, GMCs to TT, PT, and PCV serotypes increased from baseline (P < .001 for all antigens) and remained elevated at 12 months postvaccination. Antibody levels to PPV23 serotypes also increased postvaccination (P < .001). No serious adverse events were reported. CONCLUSIONS: Children treated for ALL had lower antibody levels than controls against pneumococcal serotypes, tetanus, pertussis, and varicella despite previous vaccination. Postchemotherapy vaccination with DTaP-IPV-Hib, PCV13, and PPV23 was immunogenic and well tolerated. Children with ALL would benefit from systematic revaccination postchemotherapy. CLINICAL TRIALS REGISTRATION: NCT02447718.

From mother to baby: antenatal exposure to monoclonal antibody biologics.

INTRODUCTION: More women with autoimmune and inflammatory conditions are being treated with monoclonal antibody biologics (mAbs) during their pregnancy, to maintain clinical remission. The use of anti-tumor necrosis factor alpha agents in pregnancy appears to be safe but less is known regarding other mAbs, such as anti-integrins and anti-cytokine agents. There are currently no comprehensive guidelines on how to manage the exposed infants. Areas covered: We review recent literature to assess the impact of mAbs on birth and early infant outcomes, including what is currently known about maternal and infant drug levels at birth and drug clearance in the infant. We describe the potential risks of infections and reported hematological and immunological effects of antenatal mAbs exposure on the infant and provide guidance on the management of the exposed infant. Expert opinion: Exposed infants should be monitored closely. Certain mAb exposures require specific testing and management. Safety monitoring should be done in a multidisciplinary approach and should include pediatric care providers. The current clinical experience with anti-tumor necrosis factor agents in pregnancy cannot be extrapolated to other mAbs. Long-term observational studies and a multicenter international registry are needed to better appreciate the impact of exposure, especially to newer mAbs.

Long-Term Outcome of Adenosine Deaminase-Deficient Patients-a Single-Center Experience.

PURPOSE: Inherited defects in the adenosine deaminase (ADA) enzyme can cause severe combined immune deficiency (SCID) and systemic abnormalities. Management options for ADA-deficient patients include enzyme replacement therapy (ERT), hematopoietic stem cell transplantation (HSCT), and gene therapy (GT). Here, we describe the long-term benefits of these treatments. METHODS: Survival, infections, systemic sequelae, and laboratory assessments were recorded for all ADA-deficient SCID patients, managed at a single center since 1985, who survived 5 or more years following treatment. RESULTS: Of 20 ADA-deficient patients, the 8 (40%) who survived 5 or more years (range 6-29.5 years, median 14 years) were included in the study. Among the long-term survivors, two patients were treated exclusively with ERT, five underwent HSCT (three from HLA-matched sibling donors, two from HLA-mismatched related donors), and one received GT. The long-term survivors often suffered from recurrent respiratory infections; however, opportunistic infections occurred in only one patient. Systemic sequelae included lung disease such as bronchiectasis and asthma (four patients), neurologic abnormalities (six patients), metabolic disturbances (two patients), allergy and autoimmunity (six patients), and neoplasms (three patients). Normal CD4+ T cell numbers and function, as well as antibody production, were usually observed after HSCT and GT, but not after ERT. Late deaths occurred in two patients at 15 and 25 years after HSCT, respectively, and were attributed to respiratory failure. CONCLUSIONS: ADA-deficient patients commonly suffer from long-term complications, emphasizing the need for improved management and for multi-disciplinary follow-up.

Immunization practices in acute lymphocytic leukemia and post-hematopoietic stem cell transplant in Canadian Pediatric Hematology/Oncology centers.

There are no Canadian immunization guidelines for children treated for malignancy. Guidelines do exist for patients who underwent hematopoietic stem cell transplant (HSCT), but they provide broad timeframes for initiating vaccination; there is no standard schedule. The optimal approach to immunization in these populations is unclear. We sought to describe immunization practices at Canadian Pediatric Hematology/Oncology centers. A 43-item online questionnaire was distributed to the 16 programs in the C(17) research network of pediatric hematology/oncology centers to capture information on timing and criteria for immunization of patients with acute lymphocytic leukemia (ALL) and those who have undergone HSCT. At each center, 1-2 physicians or pharmacists completed the survey to reflect center-wide immunization practices. Responses were received from 11/16 (69%) programs; 11 respondents reported on practices for patients with ALL and 9 reported on practices for patients who are post-HSCT. In 5/11 ALL programs (45%) re-immunization is recommended routinely after chemotherapy, starting 3-6 months post-chemotherapy. In HSCT programs, timing of pneumococcal conjugate vaccination (PCV) varied from 3 months post-HSCT (4 programs) to 12 months post-HSCT (4 programs). Live vaccines were administered 24 months post-HSCT in 8/9 programs. All HSCT programs considered graft-versus-host-disease and 7 considered discontinuation of immunosuppression in immunization decisions. Pediatric hematology/oncology programs were divided in regards to re-immunization of patients with ALL post-chemotherapy. After HSCT, timing of PCV administration varied, with 4 programs initiating immunization later than Canadian guidelines recommend (3-9 months post-HSCT). These findings suggest a need to standardize immunization practices in these populations.

Measuring glomerular filtration rate with cystatin C and beta-trace protein in children with spina bifida.

PURPOSE: We compared the diagnostic performance of cystatin C and beta-trace protein with serum creatinine and the Schwartz formula for the estimation of glomerular filtration rate in children with spina bifida. MATERIALS AND METHODS: Cystatin C, beta-trace protein and serum creatinine in children who underwent routine measurement of glomerular filtration rate were obtained in a prospective study. A spina bifida group (27 measurements in 27 patients 1.4 to 20.0 years old, 15 female, 12 male) was compared with a group of controls (211 measurements in 201 patients with various other renal pathologies 1.0 to 20.2 years old, 89 female, 122 male). All patients underwent nuclear medicine clearance investigations with 99mtechnetium diethylenetetraminepentaacetic acid. Z scores were calculated for body mass index, height and weight. Receiver operating characteristic (ROC) analysis and ROC plots were done to assess their diagnostic accuracy. RESULTS: Serum creatinine and the Schwartz formula did not correlate with glomerular filtration rate in the patients with spina bifida. Correlation coefficients for cystatin C were 0.45 and 0.84 in the spina bifida and control groups, respectively, while correlation coefficients for beta-trace protein were 0.31 and 0.75, respectively. For both groups ROC area was highest for cystatin C (up to 0.97 ROC area in control group). CONCLUSIONS: Only cystatin C served as a suitable marker to estimate glomerular filtration rate in patients with spina bifida. Cystatin C proved to be a superior marker in patients with spina bifida. In the control group the Schwartz formula was comparable to cystatin C and beta-trace protein, although cystatin C remained superior.