Jim Keijser
A5031309505- SARS-CoV-2 and COVID-19 Research
- COVID-19 Clinical Research Studies
- Peripheral Neuropathies and Disorders
- Long-Term Effects of COVID-19
- Monoclonal and Polyclonal Antibodies Research
- Immunotherapy and Immune Responses
- Viral gastroenteritis research and epidemiology
- Heparin-Induced Thrombocytopenia and Thrombosis
- Dermatological and COVID-19 studies
- Salmonella and Campylobacter epidemiology
- Multiple Sclerosis Research Studies
- Systemic Lupus Erythematosus Research
- Vaccine Coverage and Hesitancy
- Intramuscular injections and effects
- Immunodeficiency and Autoimmune Disorders
- Biosimilars and Bioanalytical Methods
- Systemic Sclerosis and Related Diseases
- Glycosylation and Glycoproteins Research
- Respiratory viral infections research
- Viral Infections and Immunology Research
- Protein purification and stability
- Hepatitis Viruses Studies and Epidemiology
- Rheumatoid Arthritis Research and Therapies
- Dermatology and Skin Diseases
- Social Media in Health Education
Sanquin
2021-2025
Amsterdam University Medical Centers
2022-2024
Amsterdam UMC Location University of Amsterdam
2024
Bipar
2024
DDL Diagnostic Laboratory
2010
Reinier de Graaf Hospital
2007
Abstract During the COVID‐19 pandemic, daily life of many patients with dermatological immune‐mediated inflammatory diseases (DIMIDs), such as atopic dermatitis (AD), psoriasis, and vitiligo, was impacted by social restrictions caused (fear of) morbidity, mortality associated COVID‐19, vaccine hesitancy. This prospective observational, multicenter, multidisciplinary cohort study explored impact disease vaccination on DIMIDs, specifically AD, vitiligo. Data from DIMIDs were collected part...
IgG antibodies are important mediators of vaccine-induced immunity through complement- and Fc receptor-dependent effector functions. Both influenced by the composition conserved N-linked glycan located in domain. Here, we compared anti-Spike (S) IgG1 glycosylation profiles response to mRNA, adenoviral, protein-based COVID-19 vaccines mass spectrometry (MS). All induced a transient increase antigen-specific galactosylation sialylation. An initial, afucosylated was membrane-encoding S protein...
Abstract Background The noninflammatory immunoglobulin G4 (IgG4) is linked to tolerance and unique humans. Although poorly understood, prolonged antigenic stimulation IL‐4‐signaling along the T helper 2‐axis may be instrumental in IgG4 class switching. Recently, repeated SARS‐CoV‐2 mRNA vaccination has been skewing. widely used immunosuppressive drugs have shown only moderately affect humoral responses vaccination, effect on switching not investigated. Methods Here we study impact of such...
Objectives To compare the cumulative incidence and disease severity of reported SARS-CoV-2 omicron breakthrough infections between patients with immune-mediated inflammatory diseases (IMID) on immunosuppressants controls, to investigate determinants for infections. Methods Data were used from an ongoing national prospective multicentre cohort study vaccination responses in IMID Netherlands (Target-to-B! (T2B!) study). Patients wih controls (patients not healthy controls) who completed...
Background Research on the disease severity of COVID-19 in patients with rheumatic immune-mediated inflammatory diseases (IMIDs) has been inconclusive, and long-term prospective data development SARS-CoV-2 antibodies these are lacking. Methods Adult IMIDs from Amsterdam Rheumatology Immunology Center, were invited to participate. All asked recruit their own sex-matched age-matched control subject. Clinical collected via online questionnaires (at baseline, after 1–4 5–9 months follow-up)....
SARS-CoV-2-specific CD8
The annual number of episodes clinical gastroenteritis caused by Campylobacter spp. in Netherlands is estimated to be 75 000, i.e. once per 200 person life-years. This based on extrapolation culture results from population-based studies. culture-confirmed cases infection peaks the first 3 years life and again between ages 20 25 years. seroepidemiology describes relationship age exposure reflects both symptomatic asymptomatic infections. Using a validated ELISA system, antibodies were...
Abstract Background Patients with immune-mediated inflammatory diseases (IMIDs) on immunosuppressants (ISPs) may have impaired long-term humoral immune responses and increased disease activity after SARS-CoV-2 infection. We aimed to investigate against a primary infection in unvaccinated IMID patients ISPs. Methods active treatment ISPs controls (i.e. not ISP healthy controls) confirmed before first vaccination were included from an ongoing prospective cohort study (T2B! study). Clinical...
Abstract Background Repeated mRNA vaccination against SARS-CoV-2 has been shown to induce class switching IgG4, a non-inflammatory human antibody subclass linked tolerance. Although poorly understood, prolonged antigenic stimulation and IL-4 signalling may be instrumental in IgG4 switching. We others have previously that widely used immunosuppressive drugs such as methotrexate (MTX) TNF inhibitors (TNFi) minor inhibitory impact on humoral responses. However, the of is unknown. Aim To study...
During the COVID-19 pandemic, certain disease modifying therapies (DMTs) used in multiple sclerosis (MS), such as anti-CD20 therapies, have been associated with decreased humoral responses after SARS-CoV-2 vaccination. Hybrid immunity, referring to immunity both vaccination and infection might increase responses.This was a substudy of two prospective cohort studies on antibodies RBD-specific IgG titers patients MS healthy controls who had experienced prior first were compared those without...
Abstract Background: Patients with immune-mediated inflammatory diseases (IMIDs) on immunosuppressants (ISPs) may have impaired long-term humoral immune responses and increased disease activity after SARS-CoV-2 infection. We aimed to investigate against a primary infection in unvaccinated IMID patients ISPs. Methods: active treatment ISPs controls (i.e. not ISP healthy controls) confirmed before first vaccination were included from an ongoing prospective cohort study (T2B! study). Clinical...
Background: Humoral responses after SARS-CoV-2 vaccination are greatly impaired in multiple sclerosis (MS) patients on fingolimod. Effects of repeated and infections long-term unclear. Methods: Prospective study 60 MS fingolimod measuring humoral up to four vaccinations 8 months fourth vaccination. Results: Anti-WH1 antibody titers increased with each additional At follow-up further most developed new against the BA.1 omicron variant. Conclusion: Repeated boost immunity and, probably...
Background Rheumatoid factors (RFs) are autoantibodies that target the Fc region of IgG, and found in patients with rheumatic diseases as well healthy population. Many studies suggest an immune trigger may (transiently) elicit RF responses. However, discrepancies between different make it difficult to determine if which degree reactivity can be triggered by vaccination or infection. Objective We quantitatively explored longitudinal responses after SARS-CoV-2 infection a well-defined, large...
During the COVID-19 pandemic, we developed a digital research platform to longitudinally investigate COVID-19-related outcomes in patients with rheumatic diseases and healthy controls. We used home finger-prick testing order collect serum samples remotely increase overall efficiency of platform. The aim present study was evaluate success rate finger prick patients' perspective towards prick. Serum were collected up five times during follow-up, either via venepuncture at institute or from...
Background Despite impaired humoral responses in patients treated with immunosuppressants (ISPs), recent studies found similar severity of SARS-CoV-2 breakthrough infections compared to controls. One potential explanation is the rapid generation upon infection, but evidence lacking. Objectives To investigate longitudinal dynamics antibody repertoire after delta and omicron immune-mediated inflammatory diseases (IMID) on ISPs Methods As prospective sub-study national Target-to-B! (T2B!)...
<h3>Background</h3> Previous studies have shown that using a finger prick as the primary method for blood withdrawal is an efficient way to collect samples remotely, and data on levels from are directly comparable obtained by venepuncture. During COVID-19 pandemic, we therefore complemented our large digital research platform with serum collection via home testing in order without need of visits hospital. This repeatedly enabled us rapidly answer new relevant clinical questions about...
Background: Despite impaired humoral responses after SARS-CoV-2 vaccination, the incidence and severity of breakthrough infections is not increased in patients with immune-mediated inflammatory diseases (IMID) on immunosuppressants (ISPs). This could be explained by preserved recall but data are lacking. study aimed to investigate longitudinal dynamics response delta omicron IMID ISPs compared controls.Methods: a sub-study ongoing national Target-to-B! (T2B!) study, focusing vaccination...
Background: The primary objective of this study was to compare the incidence and severity SARS-CoV-2 breakthrough infections between vaccinated patients with immune-mediated inflammatory diseases (IMIDs) using immunosuppressants, controls (IMID without immunosuppressants healthy controls). secondary explore determinants infections, including humoral immune responses after vaccination.Methods: In we pooled data collected in two large ongoing prospective multi-center cohort studies (Target...