Biomedical subjects

Daniel L Kastner

Publications and source records attributed to Daniel L Kastner.

4 recordsLinked to original sources

PubMed2026

Biologic-biologic and biologic-JAK inhibitor combination therapy in refractory systemic autoinflammatory diseases.

OBJECTIVES: Systemic autoinflammatory diseases (SAIDs) arise from genetic defects in innate immunity, leading to dysregulated activation of inflammatory pathways, including interleukin (IL)-1, IL-6, TNF, and JAK/STAT. Clinical manifestations range from recurrent fever to severe complications such as encephalitis and AA amyloidosis. Management aims to control inflammation using immunosuppressive agents and targeted monotherapies (biologics or JAK inhibitors). Advanced combination therapy (ACT), defined as the use of biologics and/or JAK inhibitors in combination, has emerged as a strategy for refractory disease. METHODS: In this observational retrospective longitudinal cohort study, patients with SAIDs treated with ACT were included. Demographic, clinical, treatment, and safety data were collected. Treatment response was assessed using a composite outcome incorporating corticosteroid dose, C-reactive protein (CRP), and clinical improvement and categorized as non-response, partial response, or complete response. RESULTS: Thirty-eight patients (median age 30 years [range 4-76]) were included. The most common indications for ACT were pyogenic arthritis, pyoderma gangrenosum and acne (PAPA), mevalonate kinase deficiency (MKD), and undifferentiated SAIDs. Most patients had disease-related complications and were dependent on glucocorticoids and/or opioids to control inflammation and pain, respectively. Following multiple ACT trials, complete response was observed in 21 patients (55.3%), partial response in 12 (31.6%), and no response in 5 (13.1%). Overall, 65 ACT regimens were administered, most commonly combining IL-1 and TNF inhibitors. Thirty-nine regimens were discontinued because of lack of efficacy, secondary loss of response, or adverse events. At the final follow-up, 26 patients (68%) remained on ACT, with a median treatment duration of 60 months (range, 11-186). CONCLUSIONS: ACT offers significant clinical benefits for patients with difficult-to-treat SAIDs, though challenges such as secondary loss of efficacy and infection risks remain.

Humans↗

PubMed2026

Deficiency of AP1M2 Causes a New Autoinflammatory Disease With Colitis.

OBJECTIVE: This study was the first to identify the biallelic loss-of-function variant in AP1M2 as the cause of autoinflammatory disease with colitis and aimed to elucidate the pathogenesis of AP1M2 deficiency in mice and humans. METHODS: We collected a blood sample and serum sample from a patient for genetic diagnosis and determination of inflammatory cytokines, respectively. Ap1m2-deficient mice on the C57BL/6 background and DLD-1 cells were used to dissect the functional role of Ap1m2 in serum and intestines. Stereo-seq was performed on Ap1m2-/- and Ap1m2-/-::Tnfr1-/- mouse samples to investigate the regulatory role of Tnfr1 signaling in the pathogenesis of Ap1m2 deficiency-caused intestinal inflammation. Superrevolution imaging and clathrin-coated vesicle enrichment were used to explore the molecular mechanism by which AP1M2 suppresses NF-κB activation and chemokine production. RESULTS: Ap1m2-/- mice exhibited elevated chemokine production in serum and spontaneously developed intestinal inflammation, which phenocopies the patient with the AP1M2 variant. Mechanistically, the deficiency of intestinal epithelial specific AP1M2 expression resulted in accumulation of TNFR1-signaling downstream proteins, including RIPK1, TBK1, IKKα/β, and NEMO, leading to enhanced NF-κB activation and subsequent chemokine overproduction. Tnfr1 knockout rescued gastrointestinal inflammation induced by Ap1m2 deficiency through suppressing NF-κB activation and chemokine production. CONCLUSION: This study identifies the deficiency of AP1M2 as the cause of a new autoinflammatory disease with colitis and highlights the critical function of AP-1 in suppressing NF-κB activation and chemokine production.

Animals↗

PubMed2025

Diagnostic Implications and Correlates of Plasma Adenosine Deaminase 2 Activity and ADA2 Variants.

OBJECTIVE: Deficiency of adenosine deaminase 2 (DADA2) is a monogenic autoinflammatory disease manifested as polyarteritis nodosa, stroke, and bone marrow failure. Leveraging an international cohort of 200 DADA2 cases, we aimed to characterize the diagnostic utility of a plasma ADA2 enzyme activity assay and understand the implications of residual ADA2 activity. METHODS: Data were collected from individuals who underwent ADA2 testing from 2018 to 2025. Plasma ADA2 activity was determined using an established spectrophotometric assay. ADA2 variants were analyzed in transfected cells by enzyme assay and western blotting. RESULTS: We determined that plasma ADA2 activity is 99.0% and 96.0% sensitive and 99.7% and 98.8% specific in distinguishing genetically confirmed DADA2 cases from controls and carriers, respectively. Eighteen individuals with DADA2 (9%) possessed detectable ADA2 activity, including several cases with levels seen in carriers. Residual ADA2 activity was associated with the vasculitis/inflammatory phenotype but not with disease severity. Genotype analysis revealed that 14 of 18 cases with residual plasma activity possessed at least one hypomorphic missense variant with greater than 20% residual ADA2 function when overexpressed in 293T cells, often occurring in trans with a more deleterious variant. In vitro analysis revealed that missense ADA2 variants exert variable dominant-negative effects by forming large intracellular protein aggregates via disulfide bond formation at a cysteine residue (Cys408). CONCLUSION: We confirmed the utility of plasma ADA2 activity as a diagnostic assay and showed that the inflammatory phenotype of DADA2 occurred in cases with residual activity. In vitro findings illustrate potential interactions of ADA2 variants to synergistically disrupt protein function.

Humans↗

PubMed2021

Somatic Mutations in UBA1 Define a Distinct Subset of Relapsing Polychondritis Patients With VEXAS.

OBJECTIVE: Somatic mutations in UBA1 cause a newly defined syndrome known as VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic syndrome). More than 50% of patients currently identified as having VEXAS met diagnostic criteria for relapsing polychondritis (RP), but clinical features that characterize VEXAS within a cohort of patients with RP have not been defined. We undertook this study to define the prevalence of somatic mutations in UBA1 in patients with RP and to create an algorithm to identify patients with genetically confirmed VEXAS among those with RP. METHODS: Exome and targeted sequencing of UBA1 was performed in a prospective observational cohort of patients with RP. Clinical and immunologic characteristics of patients with RP were compared based on the presence or absence of UBA1 mutations. The random forest method was used to derive a clinical algorithm to identify patients with UBA1 mutations. RESULTS: Seven of 92 patients with RP (7.6%) had UBA1 mutations (referred to here as VEXAS-RP). Patients with VEXAS-RP were all male, were on average ≥45 years of age at disease onset, and commonly had fever, ear chondritis, skin involvement, deep vein thrombosis, and pulmonary infiltrates. No patient with VEXAS-RP had chondritis of the airways or costochondritis. Mortality was greater in VEXAS-RP than in RP (23% versus 4%; P = 0.029). Elevated acute-phase reactants and hematologic abnormalities (e.g., macrocytic anemia, thrombocytopenia, lymphopenia, multiple myeloma, myelodysplastic syndrome) were prevalent in VEXAS-RP. A decision tree algorithm based on male sex, a mean corpuscular volume >100 fl, and a platelet count <200 ×103 /μl differentiated VEXAS-RP from RP with 100% sensitivity and 96% specificity. CONCLUSION: Mutations in UBA1 were causal for disease in a subset of patients with RP. This subset of patients was defined by disease onset in the fifth decade of life or later, male sex, ear/nose chondritis, and hematologic abnormalities. Early identification is important in VEXAS given the associated high mortality rate.

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