Biophysical characterization of RelA-p52 NF-κB dimer-A link between the canonical and the non-canonical NF-κB pathway.

The NF-κB family consists of the key transcription factors of the NF-κB signaling pathway, well known for its role in innate immune response, organogenesis, and a variety of cellular processes. The five NF-κB subunits-RelA, RelB, c-Rel, p50, and p52-are functional dimers, each of which share a conserved DNA binding domain which contains the dimerization domain (DD) as well. The NF-κB subunits can form 15 potential dimers among themselves of which, RelA-p50 is extensively studied and has largely become synonymous with NF-κB for transcription activation. While various reports have highlighted the importance of NF-κB subunit specificity in the transcription regulation of certain target genes, the dynamic nature of the NF-κB dimer composition is not well understood. In this study, we biophysically characterized six combinatorial dimers from three NF-κB subunits: RelA, p50, and p52, using NMR spectroscopy and differential scanning calorimetry. We show that the dimer composition is dynamic and can readily undergo exchange although at varied rates. Among the six dimers formed, RelA-p52 is found to be the most stable dimer with RelA-RelA being the least. Our results provide a plausible explanation as to why the RelA-p52 heterodimer is active during the later stages of the NF-κB activation and serve as a link between the canonical and non-canonical NF-κB pathway.

Unconventional p65/p52 NF-κB module regulates key tumor microenvironment-related genes in breast tumor-associated macrophages (TAMs).

The complex heterogeneity of tumor microenvironment (TME) of triple-negative breast cancer (TNBC) presents a significant obstacle to cytotoxic immune response and successful treatment, building up one of the most hostile oncological phenotypes. Among the most abundant TME components, tumor-associated macrophages (TAMs) have pivotal pro-tumoral functions, involving discordant roles for the nuclear factor kappa-B (NF-κB) transcription factors and directing to higher levels of pathway complexity. In both resting macrophages and TAMs, we recently revealed the existence of the uncharacterized NF-κB p65/p52 dimer. In the present study, we demonstrated its enhanced active nuclear localization in TAMs and validated selected immune target genes as directly regulated by dimer binding on DNA sequences. We demonstrated by ChIP-qPCR that p65/p52 enrichment on HSPG2 and CSF-1 regulatory regions is strictly dependent on macrophage polarization and tumor environment. Our data provide novel mechanisms of transcriptional regulation in TAMs, orchestrated by the varied and dynamic nature of NF-κB combinations, which needs to be considered when targeting this pathway in cancer therapies. Our results offer p65/p52, together with identified regulatory regions on genes impacting macrophage behavior and tumor biology, as novel molecular targets for TNBC, aimed at modulating TAMs functions towards anti-tumoral phenotypes and thus improving cancer treatment outcomes.

Inherited human RelB deficiency impairs innate and adaptive immunity to infection.

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-1ß 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.

Non-canonical NF-κB signaling limits the tolerogenic ß-catenin-Raldh2 axis in gut dendritic cells to exacerbate intestinal pathologies.

Dendritic cell (DC) dysfunction is known to exacerbate intestinal pathologies, but the mechanisms compromising DC-mediated immune regulation in this context remain unclear. Here, we show that intestinal dendritic cells from a mouse model of experimental colitis exhibit significant levels of noncanonical NF-κB signaling, which activates the RelB:p52 heterodimer. Genetic inactivation of this pathway in DCs alleviates intestinal pathologies in mice suffering from colitis. Deficiency of RelB:p52 diminishes transcription of Axin1, a critical component of the ß-catenin destruction complex, reinforcing ß-catenin-dependent expression of Raldh2, which imparts tolerogenic DC attributes by promoting retinoic acid synthesis. DC-specific impairment of noncanonical NF-κB signaling leads to increased colonic numbers of Tregs and IgA+ B cells, which promote luminal IgA production and foster eubiosis. Experimentally introduced ß-catenin haploinsufficiency in DCs with deficient noncanonical NF-κB signaling moderates Raldh2 activity, reinstating colitogenic sensitivity in mice. Finally, inflammatory bowel-disease patients also display a deleterious noncanonical NF-κB signaling signature in intestinal DCs. In sum, we establish how noncanonical NF-κB signaling in dendritic cells can subvert retinoic acid synthesis to fuel intestinal inflammation.

Disseminated tuberculosis is associated with impaired T cell immunity mediated by non-canonical NF-κB pathway.

OBJECTIVES: The mechanism that leads to disseminated tuberculosis in HIV-negative patients is still largely unknown. T cell subsets and signaling pathways that were associated with disseminated tuberculosis were investigated. METHODS: Single-cell profiling of whole T cells was performed to identify T cell subsets and enriched signaling pathways that were associated with disseminated tuberculosis. Flow cytometric analysis and blocking experiment were used to investigate the findings obtained by transcriptome sequencing. RESULTS: Patients with disseminated tuberculosis had depleted Th1, Tc1 and Tc17 cell subsets, and IFNG was the most down-regulated gene in both CD4 and CD8 T cells. Gene Ontology analysis showed that non-canonical NF-κB signaling pathway, including NFKB2 and RELB genes, was significantly down-regulated and was probably associated with disseminated tuberculosis. Expression of several TNF superfamily ligands and receptors, such as LTA and TNF genes, were suppressed in patients with disseminated tuberculosis. Blocking of TNF-α and soluble LTα showed that TNF-α was involved in IFN-γ production and LTα influenced TNF-α expression in T cells. CONCLUSIONS: Impaired T cell IFN-γ response mediated by suppression of TNF and non-canonical NF-κB signaling pathways might be responsible for disseminated tuberculosis.

Clinical, Immunological, and Genetic Features in Patients with NFKB1 and NFKB2 Mutations: a Systematic Review.

BACKGROUND: Inborn errors of immunity (IEIs) encompass various diseases with diverse clinical and immunological symptoms. Determining the genotype-phenotype of different variants in IEI entity precisely is challenging, as manifestations can be heterogeneous even in patients with the same mutated gene. OBJECTIVE: In the present study, we conducted a systematic review of patients recorded with NFKB1 and NFKB2 mutations, two of the most frequent monogenic IEIs. METHODS: The search for relevant literature was conducted in databases including Web of Science, PubMed, and Scopus. Information encompassing demographic, clinical, immunological, and genetic data was extracted from cases reported with mutations in NFKB1 and NFKB2. The comprehensive features of manifestations in patients were described, and a comparative analysis of primary characteristics was conducted between individuals with NFKB1 loss of function (LOF) and NFKB2 (p52-LOF/IκBδ-gain of function (GOF)) variants. RESULTS: A total of 397 patients were included in this study, 257 had NFKB1 mutations and 140 had NFKB2 mutations. There were 175 LOF cases in NFKB1 and 122 p52LOF/IκBδGOF cases in NFKB2 pivotal groups with confirmed functional implications. NFKB1LOF and p52LOF/IκBδGOF predominant cases (81.8% and 62.5% respectively) initially presented with a CVID-like phenotype. Patients with NFKB1LOF variants often experienced hematologic autoimmune disorders, whereas p52LOF/IκBδGOF patients were more susceptible to other autoimmune diseases. Viral infections were markedly higher in p52LOF/IκBδGOF cases compared to NFKB1LOF (P-value < 0.001). NFKB2 (p52LOF/IκBδGOF) patients exhibited a greater prevalence of ectodermal dysplasia and pituitary gland involvement than NFKB1LOF patients. Most NFKB1LOF and p52LOF/IκBδGOF cases showed low CD19 + B cells, with p52LOF/IκBδGOF having more cases of this type. Low memory B cells were more common in p52LOF/IκBδGOF patients. CONCLUSIONS: Patients with NFKB2 mutations, particularly p52LOF/IκBδGOF, are at higher risk of viral infections, pituitary gland involvement, and ectodermal dysplasia compared to patients with NFKB1LOF mutations. Genetic testing is essential to resolve the initial complexity and confusion surrounding clinical and immunological features. Emphasizing the significance of functional assays in determining the probability of correlations between mutations and immunological and clinical characteristics of patients is crucial.

A case of novel NFKB2 variant with hypertensive emergency and nephrotic syndrome leading to CKD 5D.

Nuclear factor kappa B (NF-κB) family plays a central role in the human immune system. Heterozygous variants in NFKB2 typically cause immunodeficiency with various degrees of central adrenal insufficiency, autoimmunity, and ectodermal dysplasia. No reported case has presented kidney failure as an initial symptom. Moreover, documentation of kidney involvement of this disease is limited. CASE DIAGNOSIS: A 2-year-old female who presented with dyspnea and hypertensive emergency in the setting of new-onset nephrotic syndrome with acute-on chronic kidney injury with resultant chronic kidney disease (CKD) was found to have a novel heterozygous N-terminal variant in NFKB2 (c.880del: p. Tyr294Ilefs*4) with mild hypogammaglobulinemia, but no adrenal insufficiency or ectodermal dysplasia. She became dialysis-dependent during her initial hospitalization and developed CKD stage 5D, requiring continued peritoneal dialysis. She is currently awaiting kidney transplantation. CONCLUSIONS: Whether nephrotic syndrome or kidney injury or failure is the primary symptom of this variant or secondary to some event remains unknown. Further case accumulation is warranted.

Autoantibodies against type I IFNs in humans with alternative NF-κB pathway deficiency.

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.

TRIM55 promotes noncanonical NF-κB signaling and B cell-mediated immune responses by coordinating p100 ubiquitination and processing.

The ubiquitination-dependent processing of NF-κB2 (also known as p100) is a critical step in the activation of the noncanonical NF-κB pathway. We investigated the molecular mechanisms regulating this process and showed that TRIM55 was the E3 ubiquitin ligase that mediated the ubiquitination of p100 and coordinated its processing. TRIM55 deficiency impaired noncanonical NF-κB activation and B cell function. Mice with a B cell-specific Trim55 deficiency exhibited reduced germinal center formation and antibody production. These mice showed less severe symptoms than those of control mice upon the induction of a systemic lupus-like disease, suggesting B cell-intrinsic functions of TRIM55 in humoral immune responses and autoimmunity. Mechanistically, the ubiquitination of p100 mediated by TRIM55 was crucial for p100 processing by VCP, an ATPase that mediates ubiquitin-dependent protein degradation by the proteasome. Furthermore, we found that TRIM55 facilitated the interaction between TRIM21 and VCP as well as TRIM21-mediated K63-ubiquitination of VCP, both of which were indispensable for the formation of the VCP-UFD1-NPL4 complex and p100 processing. Together, our results reveal a mechanism by which TRIM55 fine-tunes p100 processing and regulates B cell-dependent immune responses in vivo, highlighting TRIM55 as a potential therapeutic target for lupus-like disease.

Analysis of NFKB1 and NFKB2 gene expression in the blood of patients with sudden sensorineural hearing loss.

OBJECTIVES: Sudden Sensorineural Hearing Loss (SSNHL) is an increasingly common health problem today. Although the direct mortality rate of this disorder is relatively low, its impact on quality of life is enormous; this is why accurate identification of pathogenesis and influencing factors in the disease process can play an essential role in preventing and treating the disease. Acute inflammation, which leads to chronic inflammation due to aberrant expression of inflammation-mediating genes, may play a significant role in the pathogenesis of the disease. The essential Nuclear factor kappa B (NF-kB) pathway genes, NFKB1 and NFKB2, serve as prothrombotic agents when expressed abnormally, compromising the cochlea by disrupting the endolymphatic potential and causing SSNHL. METHODS: This study investigates the expression levels of NFKB1 and NFKB2 in peripheral blood (PB) through a quantitative polymerase chain reaction in 50 Iranian patients with SSNHL, and 50 healthy volunteers were of the same age and sex as controls. RESULTS: As a result, NFKB2 expression levels in patients were higher than in controls, regardless of sex or age (posterior beta = 0.619, adjusted P-value = 0.016), and NFKB1 expression levels did not show significant differences between patients and controls. The expression levels of NFKB1 and NFKB2 had significantly strong positive correlations in both SSNHL patients and healthy individuals (r = 0.620, P = 0.001 and r = 0.657, P 0.001, respectively), suggesting the presence of an interconnected network. CONCLUSION: NFKB2 has been identified as a significant inflammatory factor in the pathophysiology of SSNHL disease. Inflammation can play an essential role in developing SSNHL, and our findings could be used as a guide for future research.

How do nuclear factor kappa B (NF-κB)1 and NF-κB2 defects lead to the incidence of clinical and immunological manifestations of inborn errors of immunity?

INTRODUCTION: Genetic defects affect the manner of the immune system's development, activation, and function. Nuclear factor-kappa B subunit 1 (NF-κB1) and NF-κB2 are involved in different biological processes, and deficiency in these transcription factors may reveal clinical and immunological difficulties. AREAS COVERED: This review article gathers the most frequent clinical and immunological remarkable characteristics of NF-κB1 and NF-κB2 deficiencies. Afterward, an effort is made to describe the biological mechanism, which is likely to be the cause of these clinical and immunological abnormalities. EXPERT OPINION: The present review article has explained the mechanism of contributions of the NF-κB1 and NF-κB2 deficiency in revealing immunodeficiency symptoms, specifically immunological and clinical manifestations. These mechanisms demonstrate the importance of NF-κB1 and NF-κB2 signaling pathways for B and T cell development, activation, antibody production, and immunotolerance. The manifestation of a mutation can range from no symptoms to severe complications in a family.

NF-κB1 and NF-κB2 are the transcription factors that have an essential role in the development and function of the immune system. Several mutations in the NF-κBs could lead to inborn errors of immune manifestations.There are different reports of NF-κB mutations with various clinical and immunological manifestations, whereas the mechanisms behind the appearance of these have been less discussed. We collected frequent clinical and immunological manifestations from the literature and discussed the likely biological cause of their occurrence. Here we clarify the potential mechanism that defects in NF-κB1 and NF-κB2 signaling lead to inadequate B and T cells function, specifically, insufficient switched memory B cells and class-switched antibodies and autoimmunity. We also focused on the straight correlation between deficiencies in immune system responses caused by defects in NF-κB and susceptibility to recurrent infections and other clinical problems.Since our understanding of the mechanisms of signaling pathways such as NF-κB deficiencies from genetic mutations to clinical manifestations in PIDs is limited, further in vitro and animal model studies are necessary to assess these pathways' comprehensive roles in immunodeficiency more accurately. [Figure: see text].

Nfkb2 deficiency and its impact on plasma cells and immunoglobulin expression in murine small intestinal mucosa.

The alternative (noncanonical) nuclear factor-κB (NF-κB) signaling pathway predominantly regulates the function of the p52/RelB heterodimer. Germline Nfkb2 deficiency in mice leads to loss of p100/p52 protein and offers protection against a variety of gastrointestinal conditions, including azoxymethane/dextran sulfate sodium (DSS)-induced colitis-associated cancer and lipopolysaccharide (LPS)-induced small intestinal epithelial apoptosis. However, the common underlying protective mechanisms have not yet been fully elucidated. We applied high-throughput RNA-Seq and proteomic analyses to characterize the transcriptional and protein signatures of the small intestinal mucosa of naïve adult Nfkb2-/- mice. Those data were validated by immunohistochemistry and quantitative ELISA using both small intestinal tissue lysates and serum. We identified a B-lymphocyte defect as a major transcriptional signature in the small intestinal mucosa and immunoglobulin A as the most downregulated protein by proteomic analysis in Nfkb2-/- mice. Small intestinal immunoglobulins were dramatically dysregulated, with undetectable levels of immunoglobulin A and greatly increased amounts of immunoglobulin M being detected. The numbers of IgA-producing, cluster of differentiation (CD)138-positive plasma cells were also reduced in the lamina propria of the small intestinal villi of Nfkb2-/- mice. This phenotype was even more striking in the small intestinal mucosa of RelB-/- mice, although these mice were equally sensitive to LPS-induced intestinal apoptosis as their RelB+/+ wild-type counterparts. NF-κB2/p52 deficiency confers resistance to LPS-induced small intestinal apoptosis and also appears to regulate the plasma cell population and immunoglobulin levels within the gut.NEW & NOTEWORTHY Novel transcriptomic analysis of murine proximal intestinal mucosa revealed an unexpected B cell signature in Nfkb2-/- mice. In-depth analysis revealed a defect in the CD38+ B cell population and a gut-specific dysregulation of immunoglobulin levels.

A novel approach for relapsed/refractory FLT3mut+ acute myeloid leukaemia: synergistic effect of the combination of bispecific FLT3scFv/NKG2D-CAR T cells and gilteritinib.

BACKGROUND: Patients with relapsed/refractory acute myeloid leukaemia (AML) with FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) have limited treatment options and poor prognosis. Therefore, novel treatment modalities are needed. Since high expression of natural killer group 2 member D ligands (NKG2DLs) can be induced by FLT3 inhibitors, we constructed dual-target FLT3 single-chain fragment variable (scFv)/NKG2D-chimeric antigen receptor (CAR) T cells, and explored whether FLT3 inhibitors combined with FLT3scFv/NKG2D-CAR T cells could have synergistic anti-leukaemia effects. METHODS: FLT3scFv and NKG2D expression in CAR T cells, FLT3 and NKG2DL expression in AML cells, and the in vitro cytotoxicity of combining CAR T cells with gilteritinib were assessed by flow cytometry. The therapeutic effect was evaluated in a xenograft mouse model established by injection of MOLM-13 cells. Mechanisms underlying the gilteritinib-induced NKG2DL upregulation were investigated using siRNA, ChIP-QPCR and luciferase assays. RESULTS: The FLT3scFv/NKG2D-CAR T cells specifically lysed AML cells both in vitro and in the xenograft mouse model. The efficacy of FLT3scFv/NKG2D-CAR T cells was improved by gilteritinib-pretreatment. The noncanonical NF-κB2/Rel B signalling pathway was found to mediate gilteritinib-induced NKG2DL upregulation in AML cells. CONCLUSIONS: Bispecific FLT3scFv/NKG2D-CAR T cells can effectively eradicate AML cells. The FLT3 inhibitor gilteritinib can synergistically improve this effect by upregulating NF-κB2-dependent NKG2DL expression in AML cells.

Disseminated Coccidioidomycosis as the First Presentation of a C-Terminal NFKB2 Pathogenic Variant: A Case Report and Review of the Literature.

INTRODUCTION: Although most cases of coccidioidomycosis are subclinical or self-limited respiratory disease, 1% lead to extrathoracic dissemination and become fatal, especially in patients with an associated immunodeficiency. Up to 30%-50% of patients with defects in cell-mediated immunity, those with AIDS and recipients of solid-organ transplants, may develop disseminated coccidioidomycosis (DC). Within the primary immunodeficiencies, an uncommon group is caused by C-terminal NFKB2 pathogenic variants. MATERIALS AND METHODS: We performed a literature search of core databases. Written informed consent for the study and for publication was obtained. CASE PRESENTATION: A 7-year-old Mexican girl, eldest of 3 sisters, no relevant family history, and a history of recurrent upper respiratory infections and alopecia totalis was admitted with DC involving pulmonary, soft tissue, skin, bone and joint compromise. The immunodeficiency assessment showed low IgM and NK cells. We found an NFKB2 de novo heterozygous nonsense mutation of c.2611C>T (p.Gln871*). She was treated with liposomal amphotericin B and itraconazole with surgical debridement. The clinical phenotype of this primary immunodeficiency is characterized by antibody deficiency and associated broncho-pulmonary predisposition to infection, but moreover also opportunistic infections and autoimmunity, most recognizable alopecia and adrenocorticotropic hormone-deficiency. After 1 year of her discharge, she continues under surveillance with antifungal therapy with itraconazole and replacement intravenous immunoglobulin until today. CONCLUSION: This is the first case report of DC in a patient with an NFKB2 pathogenic variant and it illustrates the importance of screening for primary immunodeficiencies in patients with disseminated fungal infections.

NFKB2 inhibits NRG1 transcription to affect nucleus pulposus cell degeneration and inflammation in intervertebral disc degeneration.

Extracellular matrix degradation, reactive oxygen species (ROS) generation, and inflammation in nucleus pulposus (NP) cells contribute to the progression of intervertebral disc degeneration (IDD). NRGs (Neuregulins) play a vital role in the development of the nervous system. In the present study, we found that NRG1 was downregulated within degenerative intervertebral disc and NP tissues, according to both bioinformatics and experimental analyses. Within IL-1ß-stimulated NP cells, we observed degenerative and inflammatory changes, including inhibited cell viability, promoted cell apoptosis and ROS accumulation, reduced collagen II and aggrecan proteins, elevated MMP-3/13 and ADAMTS-4/5 proteins, and upregulated IL-6 and TNF-α mRNA levels. Within IL-1ß-stimulated NP cells, NRG1 expression was also downregulated. NRG1 overexpression attenuated, whereas NRG1 silencing aggravated IL-1ß-induced degenerative and inflammatory changes. Moreover, NRG1 regulated ErbB2/3 activation, contributing to the NRG1 protective function in NP cells. NFKB2 directly targeted the promoter region of NRG1 and inhibited NRG1 expression. In IL-1ß-stimulated NP cells, silencing NFKB2 attenuated, whereas silencing NRG1 aggravated the degenerative changes and inflammation; the effects of NFKB2 silencing were significantly reversed by NRG1 silencing. In conclusion, NRG1 expression is downregulated within degenerative NP tissue samples and IL-1ß-stimulated NP cells. NRG1 might protect against IL-1ß-induced degenerative changes and inflammation. The upregulated NFKB2 might be the reason of NRG1 downregulation in degenerative NP tissues.

Severe SARS-CoV-2 disease in the context of a NF-κB2 loss-of-function pathogenic variant.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus that emerged recently and has created a global pandemic. Symptomatic SARS-CoV-2 infection, termed coronavirus disease 2019 (COVID-19), has been associated with a host of symptoms affecting numerous organ systems, including the lungs, cardiovascular system, kidney, central nervous system, gastrointestinal tract, and skin, among others. OBJECTIVE: Although several risk factors have been identified as related to complications from and severity of COVID-19, much about the virus remains unknown. The host immune response appears to affect the outcome of disease. It is not surprising that patients with intrinsic or secondary immune compromise might be particularly susceptible to complications from SARS-CoV-2 infection. Pathogenic loss-of-function or gain-of-function heterozygous variants in nuclear factor-κB2 have been reported to be associated with either a combined immunodeficiency or common variable immunodeficiency phenotype. METHODS: We evaluated the functional consequence and immunologic phenotype of a novel NFKB2 loss of function variant in a 17-year-old male patient and describe the clinical management of SARS-CoV-2 infection in this context. RESULTS: This patient required a 2-week hospitalization for SARS-CoV-2 infection, including 7 days of mechanical ventilation. We used biologic therapies to avert potentially fatal acute respiratory distress syndrome and treat hyperinflammatory responses. The patient had an immunologic phenotype of B-cell dysregulation with decreased switched memory B cells. Despite the underlying immune dysfunction, he recovered from the infection with intense management. CONCLUSIONS: This clinical case exemplifies some of the practical challenges in management of patients with SARS-CoV-2 infection, especially in the context of underlying immune dysregulation.

Nfkb2 variants reveal a p100-degradation threshold that defines autoimmune susceptibility.

NF-κB2/p100 (p100) is an inhibitor of κB (IκB) protein that is partially degraded to produce the NF-κB2/p52 (p52) transcription factor. Heterozygous NFKB2 mutations cause a human syndrome of immunodeficiency and autoimmunity, but whether autoimmunity arises from insufficiency of p52 or IκB function of mutated p100 is unclear. Here, we studied mice bearing mutations in the p100 degron, a domain that harbors most of the clinically recognized mutations and is required for signal-dependent p100 degradation. Distinct mutations caused graded increases in p100-degradation resistance. Severe p100-degradation resistance, due to inheritance of one highly degradation-resistant allele or two subclinical alleles, caused thymic medullary hypoplasia and autoimmune disease, whereas the absence of p100 and p52 did not. We inferred a similar mechanism occurs in humans, as the T cell receptor repertoires of affected humans and mice contained a hydrophobic signature of increased self-reactivity. Autoimmunity in autosomal dominant NFKB2 syndrome arises largely from defects in nonhematopoietic cells caused by the IκB function of degradation-resistant p100.

BET inhibitor suppresses melanoma progression via the noncanonical NF-κB/SPP1 pathway.

Background: Bromodomain and extra-terminal domain (BET) inhibitors have shown profound efficacy against hematologic malignancies and solid tumors in preclinical studies. However, the underlying molecular mechanism in melanoma is not well understood. Here we identified secreted phosphoprotein 1 (SPP1) as a melanoma driver and a crucial target of BET inhibitors in melanoma. Methods: Bioinformatics analysis and meta-analysis were used to evaluate the SPP1 expression in normal tissues, primary melanoma, and metastatic melanoma. Real-time PCR (RT-PCR) and Western blotting were employed to quantify SPP1 expression in melanoma cells and tissues. Cell proliferation, wound healing, and Transwell assays were carried out to evaluate the effects of SPP1 and BET inhibitors in melanoma cells in vitro. A xenograft mouse model was used to investigate the effect of SPP1 and BET inhibitors on melanoma in vivo. Chromatin immunoprecipitation (ChIP) assay was performed to evaluate the regulatory mechanism of BET inhibitors on SPP1. Results: SPP1 was identified as a melanoma driver by bioinformatics analysis, and meta-analysis determined it to be a diagnostic and prognostic biomarker for melanoma. SPP1 overexpression was associated with poor melanoma prognosis, and silencing SPP1 suppressed melanoma cell proliferation, migration, and invasion. Through a pilot drug screen, we identified BET inhibitors as ideal therapeutic agents that suppressed SPP1 expression. Also, SPP1 overexpression could partially reverse the suppressive effect of BET inhibitors on melanoma. We further demonstrated that bromodomain-containing 4 (BRD4) regulated SPP1 expression. Notably, BRD4 did not bind directly to the SPP1 promoter but regulated SPP1 expression through NFKB2. Silencing of NFKB2 resembled the phenotype of BET inhibitors treatment and SPP1 silencing in melanoma. Conclusion: Our findings highlight SPP1 as an essential target of BET inhibitors and provide a novel mechanism by which BET inhibitors suppress melanoma progression via the noncanonical NF-κB/SPP1 pathway.