Axel Cederholm

BackgroundParaneoplastic autoimmunity develops as consequences of immune reactions to cancer and exhibits a wide range of clinical manifestations. The autoimmune signs are often visible before the underlying malignancy is diagnosed, and a prompt diagnosis of paraneoplasia is crucial to enable early tumor detection. We characterized the immune responses underlying the severe mucocutaneous blistering disease paraneoplastic pemphigus.MethodsWe used a two-step approach to proteome-wide autoantibody repertoire analysis and independent validation in patients with paraneoplastic pemphigus (n = 84) and non-paraneoplastic autoimmune blistering diseases (n = 103).ResultsOur findings reveal that paraneoplastic pemphigus features a broad repertoire of disease-specific autoantibodies that mainly target tissue-specific proteins in the skin and mucous membranes. Importantly, we identify SERPINB3 as a major autoantibody target with an expression pattern and clinical association suggesting a role in bronchiolitis obliterans. Autoantibody profiles are similar across neoplasias, except in thymoma patients, who additionally express multiple cytokine autoantibodies.ConclusionsOur findings reveal a disease-defining autoantibody repertoire in paraneoplastic pemphigus that corresponds with clinical manifestations and holds high potential for early cancer detection in patients with blistering disease.

Background: Increased stromal Platelet-derived growth factor receptor beta (PDGFRβ) expression is a hallmark of the desmoplastic tissue reaction in cancer and marks subsets of cancer-associated fibroblasts, pericytes, and smooth muscle cells. However, its functional status in situ has been anticipated from static expression measures, which cannot determine whether high receptor abundance reflects active signaling.Methods: We established two second-generation proximity ligation assays (PLAs) to quantify PDGFRβ activation in the in situ environment of human lung cancer by detecting either phosphorylated PDGFRβ or its interaction with the adaptor protein Grb2. The immunofluorescence-based assays were applied to tissue-microarrays including diagnostic samples from over 600 non-small cell lung cancer (NSCLC) patients.Results: In lung cancer tissue, activation scores correlated with PDGFRβ expression but revealed a more nuanced receptor status, indicating variable activation despite similar expression levels. Higher PDGFRβ activation was associated with increased recurrence risk exclusively in squamous cell carcinoma, a finding not captured by conventional immunohistochemistry. This activation was accompanied by a specific stromal profile enriched for LRRC15- and FAP-positive cells, a pattern absent in adenocarcinomas.Conclusion: PDGFRβ activation status provides functional information beyond receptor expression, uncovering clinically relevant, otherwise overlooked, stromal phenotypes. The approach illustrates the diagnostic potential of functional protein assays in the era of precision medicine.

The E3 ubiquitin ligase Casitas B-lineage lymphoma (CBL) promotes positive selection and antigen responses in mouse T lymphocytes by ubiquitinating ZAP70. Conversely, mouse CBL and CBL-B mutually redundantly regulate SYK ubiquitination and B cell receptor signaling. Here we studied individuals with somatically homozygous CBL loss-of-function variants in leukocytes. Human CBL is largely redundant for the development and function of human T cells. Conversely, B cell development is altered at the immature stage, with a tenfold increase in transitional cells, enhanced survival of autoreactive clones and impaired tolerance manifested by autoantibody production. B cell maturation is intrinsically impaired by reduced apoptosis and dysregulated B cell receptor signaling. CBL deficiency impairs humoral immunity by limiting memory B cell formation and reducing class switching and somatic hypermutation. Consequently, antigen-specific B cell generation and adaptive immune memory are disrupted, predisposing individuals to infection. Human CBL is critical for B cell development and function but redundant for T cell biology.

Background: Interferons play a central role in antiviral defense, but their dysregulation contributes to inflammation and immune dysfunction in respiratory viral infections, including COVID-19. While interferon-stimulated genes (ISGs) are essential effectors of this response, their expression patterns in patients are heterogeneous and not always predictive of disease severity. The immunometabolic consequences of this heterogeneity remain poorly understood.Methods: We analyzed hospitalized COVID-19 patients (n = 37) and uninfected controls (n = 31) using whole-blood transcriptomics, immune cell deconvolution, plasma proteomics, and standardized plasma metabolomics from a previously generated dataset within this cohort. Patients were stratified into low (LIS), moderate (MIS), and high (HIS) ISG score clusters. Plasma innate immune activation markers were measured by ELISA. Interferon-directed antibody reactivity was analyzed by multiplex bead-based assays measuring antigen reactivity. Functional immune responses were assessed via ex vivo stimulation of healthy donor immune cells with patient plasma, and correlations were performed between metabolites and immune activation markers.Results: HIS patients exhibited increased inflammatory mediators and innate immune cell expansion compared with LIS and MIS groups. However, within the HIS group, severe cases displayed distinct metabolic and immune dysregulation. Specifically, severe HIS cases showed reductions in phospholipids, sphingolipids, and tricarboxylic acid cycle intermediates, suggestive of disrupted mitochondrial and lipid metabolism. Plasma from severe HIS patients tended to impair neutrophil and monocyte activation, indicating functional attenuation of innate immune activation within a shared high-ISG background. Correlation analysis revealed that branched-chain lipids, tryptophan-derived metabolites, and a branched-chain dicarboxylic acid were positively associated with immune activation markers. Although type-I interferon neutralization was detected in a subset of patients with IFN antigen reactivity, these samples did not fully account for the observed ISG heterogeneity or disease severity.Conclusions: High ISG expression in COVID-19 defines a transcriptional endotype associated with systemic inflammation and innate immune activation. However, severe cases within this group exhibit metabolic constraints and reduced innate immune responsiveness, supporting an immune-metabolic axis in which inflammatory mediators and altered lipid/energy metabolism intersect with innate immune function. These findings motivate future studies to determine whether interferon-associated immune-metabolic states during acute infection relate to persistent inflammation or post-acute sequelae in selected patient subsets.

Severe COVID-19 is characterized by immune-coagulation dysregulation, yet the contribution of related autoantibodies remains poorly understood. We investigated relationships between plasma autoantibody reactivities, whole-blood transcriptomics, plasma proteomics, and clinical laboratory parameters in a cohort of hospitalized COVID-19 patients. Transcriptomic analysis revealed that 42 curated coagulation and complement cascade genes were upregulated in severe cases compared to healthy controls, with 15 genes, including CR1L, ELANE, ITGA2B, ITGB3, VWF, TFPI, PROS1, MMRN1, and SELP (> 1.2 log2 fold-change), also significantly different from mild cases. Autoantibody profiling against eight coagulation-related proteins (ADAMTS13, Factor V, Protein S, SERPINC1, Apo-H, PROC1, Prothrombin, and PF4) showed reactivities below positivity thresholds across all groups. Using an exploratory approach, in severe cases, subthreshold autoantibody candidates (FDR < 0.25) showed negative correlation trends with select gene expressions and inflammatory markers (Factor V with IL-6 and CXCL10), suggesting potential disease-specific immunomodulatory associations. In contrast, while mild cases exhibited stronger gene-protein correlations, they showed limited associations with antigen reactivities or clinical laboratory parameters. Additionally, no correlations were observed between autoantibodies and platelet-counts or Fibrin-D-dimer levels. Age-associated increases in antigen reactivities were noted in severe disease, implying a role for immunosenescence. These findings support further investigation into the role of subthreshold autoantibody candidates in thromboinflammatory COVID-19 pathogenesis.

While Coronavirus disease 2019 (COVID-19) vaccines have proven to be both effective and generally safe, rare but severe adverse events following immunization (AEFIs) are described. Autoantibodies to platelet factor-4 are associated with catastrophic thrombotic AEFIs, but comprehensive investigations of other autoantibodies are lacking. We aimed to detect and describe autoantibodies targeting coagulation-related proteins in a population-wide cohort (SWEDEGENE) including AEFIs attributed to COVID-19 vaccines in Sweden. Subjects were recruited from December 2020 to October 2022 and were stratified based on diagnosis and COVID-19 exposure. Screening was carried out in two phases, with a multiplex bead-based assay in the first subset (until September 2021) and with targeted assays for the second (until October 2022). Positivity was defined based on absolute, relative, and biological/technical thresholds. Patients with coagulation-related AEFIs were older and the Vaxzevria vaccine was overrepresented in this group. Two cases had antiphospholipid antibodies but none had PF4 antibodies. We identified six positives for protein S autoantibodies. Protein S concentrations were negatively correlated with autoantibody response in patients with immunoreactivity and functional analysis revealed low protein S activity in three subjects. Our population-wide analysis reveals cases with autoantibodies against protein S which possibly underlie coagulopathic AEFIs.

Patients heterozygous for germline CBL loss-of-function (LOF) variants can develop myeloid malignancy, autoinflammation, or both, if some or all of their leukocytes become homozygous for these variants through somatic loss of heterozygosity (LOH) via uniparental isodisomy. We observed an upregulation of the inflammatory gene expression signature in whole blood from these patients, mimicking monogenic inborn errors underlying autoinflammation. Remarkably, these patients had constitutively activated monocytes that secreted 10 to 100 times more inflammatory cytokines than those of healthy individuals and CBL LOF heterozygotes without LOH. CBL-LOH hematopoietic stem and progenitor cells (HSPCs) outgrew the other cells, accounting for the persistence of peripheral monocytes homozygous for the CBL LOF variant. ERK pathway activation was required for the excessive production of cytokines by both resting and stimulated CBL-LOF monocytes, as shown in monocytic cell lines. Finally, we found that about 1 in 10,000 individuals in the UK Biobank were heterozygous for CBL LOF variants and that these carriers were at high risk of hematological and inflammatory conditions.

FMS-related tyrosine kinase 3 ligand (FLT3L), encoded by FLT3LG, is a hematopoietic factor essential for the development of natural killer (NK) cells, B cells, and dendritic cells (DCs) in mice. We describe three humans homozygous for a loss-of-function FLT3LG variant with a history of various recurrent infections, including severe cutaneous warts. The patients’ bone marrow (BM) was hypoplastic, with low levels of hematopoietic progenitors, particularly myeloid and B cell precursors. Counts of B cells, monocytes, and DCs were low in the patients’ blood, whereas the other blood subsets, including NK cells, were affected only moderately, if at all. The patients had normal counts of Langerhans cells (LCs) and dermal macrophages in the skin but lacked dermal DCs. Thus, FLT3L is required for B cell and DC development in mice and humans. However, unlike its murine counterpart, human FLT3L is required for the development of monocytes but not NK cells.

Infants with biallelic IL7R loss-of-function variants have severe combined immune deficiency (SCID) characterized by the absence of autologous T lymphocytes, but normal counts of circulating B and NK cells (T–B+NK+ SCID). We report 6 adults (aged 22 to 59 years) from 4 kindreds and 3 ancestries (Colombian, Israeli Arab, Japanese) carrying homozygous IL7 loss-of-function variants resulting in combined immunodeficiency (CID). Deep immunophenotyping revealed relatively normal counts and/or proportions of myeloid, B, NK, and innate lymphoid cells. By contrast, the patients had profound T cell lymphopenia, with low proportions of innate-like adaptive mucosal-associated invariant T and invariant NK T cells. They also had low blood counts of T cell receptor (TCR) excision circles, recent thymic emigrant T cells and naive CD4+ T cells, and low overall TCR repertoire diversity, collectively indicating impaired thymic output. The proportions of effector memory CD4+ and CD8+ T cells were high, indicating IL-7–independent homeostatic T cell proliferation in the periphery. Intriguingly, the proportions of other T cell subsets, including TCRγδ+ T cells and some TCRαβ+ T cell subsets (including Th1, Tfh, and Treg) were little affected. Peripheral CD4+ T cells displayed poor proliferation, but normal cytokine production upon stimulation with mitogens in vitro. Thus, inherited IL-7 deficiency impairs T cell development less severely and in a more subset-specific manner than IL-7R deficiency. These findings suggest that another IL-7R–binding cytokine, possibly thymic stromal lymphopoietin, governs an IL-7–independent pathway of human T cell development.

Human inborn errors of thymic T cell tolerance underlie the production of autoantibodies (auto-Abs) neutralizing type I IFNs, which predispose to severe viral diseases. We analyze 131 female patients with X-linked dominant incontinentia pigmenti (IP), heterozygous for loss-of-function (LOF) NEMO variants, from 99 kindreds in 10 countries. Forty-seven of these patients (36%) have auto-Abs neutralizing IFN-alpha and/or IFN-omega, a proportion 23 times higher than that for age-matched female controls. This proportion remains stable from the age of 6 years onward. On imaging, female patients with IP have a small, abnormally structured thymus. Auto-Abs against type I IFNs confer a predisposition to life-threatening viral diseases. By contrast, patients with IP lacking auto-Abs against type I IFNs are at no particular risk of viral disease. These results suggest that IP accelerates thymic involution, thereby underlying the production of auto-Abs neutralizing type I IFNs in at least a third of female patients with IP, predisposing them to life-threatening viral diseases.

We report two unrelated adults with homozygous (P1) or compound heterozygous (P2) private loss-of-function variants of V-Rel Reticuloendotheliosis Viral Oncogene Homolog B (RELB). The resulting deficiency of functional RelB impairs the induction of NFKB2 mRNA and NF-κB2 (p100/p52) protein by lymphotoxin in the fibroblasts of the patients. These defects are rescued by transduction with wild-type RELB complementary DNA (cDNA). By contrast, the response of RelB-deficient fibroblasts to Tumor Necrosis Factor (TNF) or IL-1β via the canonical NF-κB pathway remains intact. P1 and P2 have low proportions of naïve CD4+ and CD8+ T cells and of memory B cells. Moreover, their naïve B cells cannot differentiate into immunoglobulin G (IgG)- or immunoglobulin A (IgA)-secreting cells in response to CD40L/IL-21, and the development of IL-17A/F-producing T cells is strongly impaired in vitro. Finally, the patients produce neutralizing autoantibodies against type I interferons (IFNs), even after hematopoietic stem cell transplantation, attesting to a persistent dysfunction of thymic epithelial cells in T cell selection and central tolerance to some autoantigens. Thus, inherited human RelB deficiency disrupts the alternative NF-κB pathway, underlying a T- and B cell immunodeficiency, which, together with neutralizing autoantibodies against type I IFNs, confers a predisposition to viral, bacterial, and fungal infections.

BACKGROUND. Weakly virulent environmental mycobacteria (EM) can cause severe disease in HLA-DRB1*15:02 or 16:02 adults harboring neutralizing anti-IFN-γ autoantibodies (nAIGAs). The overall prevalence of nAIGAs in the general population is unknown, as are the penetrance of nAIGAs in HLA-DRB1*15:02 or 16:02 individuals and the proportion of patients with unexplained, adult-onset EM infections carrying nAIGAs.METHODS. This study analyzed the detection and neutralization of anti-IFN-γ autoantibodies (auto-Abs) from 8,430 healthy individuals of the general population, 257 HLA-DRB1*15:02 or 16:02 carriers, 1,063 patients with autoimmune disease, and 497 patients with unexplained severe disease due to EM.RESULTS. We found that anti-IFN-γ auto-Abs detected in 4,148 of 8,430 healthy individuals (49.2%) from the general population of an unknown HLA-DRB1 genotype were not neutralizing. Moreover, we did not find nAIGAs in 257 individuals carrying HLA-DRB1* 15:02 or 16:02. Additionally, nAIGAs were absent in 1,063 patients with an autoimmune disease. Finally, 7 of 497 patients (1.4%) with unexplained severe disease due to EM harbored nAIGAs.CONCLUSION. These findings suggest that nAIGAs are isolated and that their penetrance in HLA-DRB1*15:02 or 16:02 individuals is low, implying that they may be triggered by rare germline or somatic variants. In contrast, the risk of mycobacterial disease in patients with nAIGAs is high, confirming that these nAIGAs are the cause of EM disease.

Type I interferons act as gatekeepers against viral infection, and autoantibodies that neutralize these signaling molecules have been associated with COVID-19 severity and adverse reactions to the live-attenuated yellow fever vaccine. On this background, we sought to examine whether autoantibodies against type I interferons were associated with adverse events following COVID-19 vaccination. Our nationwide analysis suggests that type I interferon autoantibodies were not associated with adverse events after mRNA or viral-vector COVID-19 vaccines.

We describe humans with rare biallelic loss-of-function PTCRA variants impairing pre-alpha T cell receptor (pre-TCR alpha) expression. Low circulating naive alpha beta T cell counts at birth persisted over time, with normal memory alpha beta and high gamma delta T cell counts. Their TCR alpha repertoire was biased, which suggests that noncanonical thymic differentiation pathways can rescue alpha beta T cell development. Only a minority of these individuals were sick, with infection, lymphoproliferation, and/or autoimmunity. We also report that 1 in 4000 individuals from the Middle East and South Asia are homozygous for a common hypomorphic PTCRA variant. They had normal circulating naive alpha beta T cell counts but high gamma delta T cell counts. Although residual pre-TCR alpha expression drove the differentiation of more alpha beta T cells, autoimmune conditions were more frequent in these patients compared with the general population.

Patients with autoimmune polyendocrinopathy syndrome type 1 (APS-1) caused by autosomal recessive AIRE deficiency produce autoantibodies that neutralize type I interferons (IFNs)1,2, conferring a predisposition to life-threatening COVID-19 pneumonia3. Here we report that patients with autosomal recessive NIK or RELB deficiency, or a specific type of autosomal-dominant NF-κB2 deficiency, also have neutralizing autoantibodies against type I IFNs and are at higher risk of getting life-threatening COVID-19 pneumonia. In patients with autosomal-dominant NF-κB2 deficiency, these autoantibodies are found only in individuals who are heterozygous for variants associated with both transcription (p52 activity) loss of function (LOF) due to impaired p100 processing to generate p52, and regulatory (IκBδ activity) gain of function (GOF) due to the accumulation of unprocessed p100, therefore increasing the inhibitory activity of IκBδ (hereafter, p52LOF/IκBδGOF). By contrast, neutralizing autoantibodies against type I IFNs are not found in individuals who are heterozygous for NFKB2 variants causing haploinsufficiency of p100 and p52 (hereafter, p52LOF/IκBδLOF) or gain-of-function of p52 (hereafter, p52GOF/IκBδLOF). In contrast to patients with APS-1, patients with disorders of NIK, RELB or NF-κB2 have very few tissue-specific autoantibodies. However, their thymuses have an abnormal structure, with few AIRE-expressing medullary thymic epithelial cells. Human inborn errors of the alternative NF-κB pathway impair the development of AIRE-expressing medullary thymic epithelial cells, thereby underlying the production of autoantibodies against type I IFNs and predisposition to viral diseases.