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Overlapping clinical and pathomechanistic features can complicate the diagnosis and treatment of inflammatory skin diseases, including psoriasis and atopic dermatitis (AD). Spatial transcriptomics allows the identification of disease- and cell-specific molecular signatures that may advance biomarker development and future treatments. This study identified transcriptional signatures in keratinocytes and sub-basal CD4 + and CD8 + T lymphocytes from patients with psoriasis and AD. In silico prediction of ligand:receptor interactions delivered key signalling pathways (interferon, effector T cells, stroma cell and matrix biology, neuronal development, etc.). Targeted validation of selected transcripts, including CCL22, RELB, and JUND, in peripheral blood T cells suggests the chosen approach as a promising tool also in other inflammatory diseases. Psoriasis and AD are characterized by transcriptional dysregulation in T cells and keratinocytes that may be targeted therapeutically. Spatial transcriptomics is a valuable tool in the search for molecular signatures that can be used as biomarkers and/or therapeutic targets., Competing Interests: Declaration of competing interest C.M.H. received unrestricted research funding from Novartis (psoriasis) and Merck (MISP; lupus nephritis), participated in advisory boards organized by Novartis (CNO/CRMO). The other authors have no financial conflicts of interest., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Chronic nonbacterial osteomyelitis (CNO), an autoinflammatory bone disease primarily affecting children, can cause pain, hyperostosis and fractures, affecting quality-of-life and psychomotor development. This study investigated CNO-associated variants in P2RX7, encoding for the ATP-dependent trans-membrane K + channel P2X7, and their effects on NLRP3 inflammasome assembly. Whole exome sequencing in two related transgenerational CNO patients, and target sequencing of P2RX7 in a large CNO cohort (N = 190) were conducted. Results were compared with publicly available datasets and regional controls (N = 1873). Findings were integrated with demographic and clinical data. Patient-derived monocytes and genetically modified THP-1 cells were used to investigate potassium flux, inflammasome assembly, pyroptosis, and cytokine release. Rare presumably damaging P2RX7 variants were identified in two related CNO patients. Targeted P2RX7 sequencing identified 62 CNO patients with rare variants (32.4%), 11 of which (5.8%) carried presumably damaging variants (MAF <1%, SIFT "deleterious", Polyphen "probably damaging", CADD >20). This compared to 83 of 1873 controls (4.4%), 36 with rare and presumably damaging variants (1.9%). Across the CNO cohort, rare variants unique to one (Median: 42 versus 3.7) or more (≤11 patients) participants were over-represented when compared to 190 randomly selected controls. Patients with rare damaging variants more frequently experienced gastrointestinal symptoms and lymphadenopathy while having less spinal, joint and skin involvement (psoriasis). Monocyte-derived macrophages from patients, and genetically modified THP-1-derived macrophages reconstituted with CNO-associated P2RX7 variants exhibited altered potassium flux, inflammasome assembly, IL-1β and IL-18 release, and pyroptosis. Damaging P2RX7 variants occur in a small subset of CNO patients, and rare P2RX7 variants may represent a CNO risk factor. Observations argue for inflammasome inhibition and/or cytokine blockade and may allow future patient stratification and individualized care., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Psoriasis is an autoimmune/inflammatory disorder primarily affecting the skin. Chronic joint inflammation triggers the diagnosis of psoriatic arthritis (PsA) in approximately one-third of psoriasis patients. Although joint disease typically follows the onset of skin psoriasis, in around 15% of cases it is the initial presentation, which can result in diagnostic delays. The pathophysiological mechanisms underlying psoriasis and PsA are not yet fully understood, but there is evidence pointing towards epigenetic dysregulation involving CD4 + and CD8 + T-cells., Objectives: The aim of this study was to investigate disease-associated DNA methylation patterns in CD4 + T-cells from psoriasis and PsA patients that may represent potential diagnostic and/or prognostic biomarkers., Methods: PBMCs were collected from 12 patients with chronic plaque psoriasis and 8 PsA patients, and 8 healthy controls. CD4 + T-cells were separated through FACS sorting, and DNA methylation profiling was performed (Illumina EPIC850K arrays). Bioinformatic analyses, including gene ontology (GO) and KEGG pathway analysis, were performed using R. To identify genes under the control of interferon (IFN), the Interferome database was consulted, and DNA Methylation Scores were calculated., Results: Numbers and proportions of CD4 + T-cell subsets (naïve, central memory, effector memory, CD45RA re-expressing effector memory cells) did not vary between controls, skin psoriasis and PsA patients. 883 differentially methylated positions (DMPs) affecting 548 genes were identified between controls and "all" psoriasis patients. Principal component and partial least-squares discriminant analysis separated controls from skin psoriasis and PsA patients. GO analysis considering promoter DMPs delivered hypermethylation of genes involved in "regulation of wound healing, spreading of epidermal cells", "negative regulation of cell-substrate junction organization" and "negative regulation of focal adhesion assembly". Comparing controls and "all" psoriasis, a majority of DMPs mapped to IFN-related genes (69.2%). Notably, DNA methylation profiles also distinguished skin psoriasis from PsA patients (2,949 DMPs/1,084 genes) through genes affecting "cAMP-dependent protein kinase inhibitor activity" and "cAMP-dependent protein kinase regulator activity". Treatment with cytokine inhibitors (IL-17/TNF) corrected DNA methylation patterns of IL-17/TNF-associated genes, and methylation scores correlated with skin disease activity scores (PASI)., Conclusion: DNA methylation profiles in CD4 + T-cells discriminate between skin psoriasis and PsA. DNA methylation signatures may be applied for quantification of disease activity and patient stratification towards individualized treatment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Natoli, Charras, Hofmann, Northey, Russ, Schulze, McCann, Abraham and Hedrich.)

Chronic nonbacterial osteomyelitis (CNO) is an autoinflammatory bone disease that primarily affects children and adolescents. CNO is associated with pain, bone swelling, deformity, and fractures. Its pathophysiology is characterized by increased inflammasome assembly and imbalanced expression of cytokines. Treatment is currently based on personal experience, case series and resulting expert recommendations. Randomized controlled trials (RCTs) have not been initiated because of the rarity of CNO, expired patent protection of some medications, and the absence of agreed outcome measures. An international group of fourteen CNO experts and two patient/parent representatives was assembled to generate consensus to inform and conduct future RCTs. The exercise delivered consensus inclusion and exclusion criteria, patent protected (excludes TNF inhibitors) treatments of immediate interest (biological DMARDs targeting IL-1 and IL-17), primary (improvement of pain; physician global assessment) and secondary endpoints (improved MRI; improved PedCNO score which includes physician and patient global scores) for future RCTs in CNO., Competing Interests: Declaration of Competing Interest In the past, CMH received research funding from Novartis for research in psoriasis (secukinumab programme, 2017–2019). In the past 5 years, CMH received speaker's honoraria from Roche, and was involved in advisory boards hosted by Novartis and Cancer Research UK (CRUK). CMH, PJF, HJG, and YZ participated in advisory boards on the use of canakinumab in inflammatory bone disease hosted by Novartis. RML is a consultant to Novartis and SOBI., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Deciphering signaling pathways that regulate the complex interplay between inflammation and cell death is a key challenge in understanding innate immune responses. Over recent years, receptor interacting protein (RIP) kinases have been described to regulate the interplay between inflammation and cell death. Whereas RIP1 and 3, the most well described members of the RIP kinase family, play important roles in necroptosis, RIP2's involvement in regulating inflammation, cell death processes and cancer is less well described and controversially discussed. Here, we demonstrate that RIP2 exerts immune regulatory functions by regulating mitochondrial damage and mitochondrial superoxide production in response to SV40 LT-induced genotoxic stress by the induction of ULK1-phosphorylation, therefore regulating the expression of interferon stimulated genes (ISGs) and NLRP3-inflammasome dependent IL-1β release. Because RIP2 is upregulated and/or activated in autoimmune/inflammatory disease and cancer, observations from this study promise implications of RIP kinases in human disease., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Psoriasis is a T cell-mediated chronic autoimmune/inflammatory disease. While some patients experience disease limited to the skin (skin psoriasis), others develop joint involvement (psoriatic arthritis; PsA). In the absence of disease- and/or outcome-specific biomarkers, and as arthritis can precede skin manifestations, diagnostic and therapeutic delays are common and contribute to disease burden and damage accrual. Objective: Altered epigenetic marks, including DNA methylation, contribute to effector T cell phenotypes and altered cytokine expression in autoimmune/inflammatory diseases. This project aimed at the identification of disease-/outcome-specific DNA methylation signatures in CD8 + T cells from patients with psoriasis and PsA as compared to healthy controls. Method: Peripheral blood CD8 + T cells from nine healthy controls, 10 psoriasis, and seven PsA patients were collected to analyze DNA methylation marks using Illumina Human Methylation EPIC BeadChips (>850,000 CpGs per sample). Bioinformatic analysis was performed using R ( minfi, limma, ChAMP , and DMRcate packages). Results: DNA methylation profiles in CD8 + T cells differentiate healthy controls from psoriasis patients [397 Differentially Methylated Positions (DMPs); 9 Differentially Methylated Regions (DMRs) when ≥CpGs per DMR were considered; 2 DMRs for ≥10 CpGs]. Furthermore, patients with skin psoriasis can be discriminated from PsA patients [1,861 DMPs, 20 DMRs (≥5 CpGs per region), 4 DMRs (≥10 CpGs per region)]. Gene ontology (GO) analyses considering genes with ≥1 DMP in their promoter delivered methylation defects in skin psoriasis and PsA primarily affecting the BMP signaling pathway and endopeptidase regulator activity, respectively. GO analysis of genes associated with DMRs between skin psoriasis and PsA demonstrated an enrichment of GABAergic neuron and cortex neuron development pathways. Treatment with cytokine blockers associated with DNA methylation changes [2,372 DMPs; 1,907 DMPs within promoters, 7 DMRs (≥5 CpG per regions)] affecting transforming growth factor beta receptor and transmembrane receptor protein serine/threonine kinase signaling pathways. Lastly, a methylation score including TNF and IL-17 pathway associated DMPs inverse correlates with skin disease activity scores (PASI). Conclusion: Patients with skin psoriasis exhibit DNA methylation patterns in CD8 + T cells that allow differentiation from PsA patients and healthy individuals, and reflect clinical activity of skin disease. Thus, DNA methylation profiling promises potential as diagnostic and prognostic tool to be used for molecular patient stratification toward individualized treatment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Charras, Garau, Hofmann, Carlsson, Cereda, Russ, Abraham and Hedrich.)

Effector CD4 + T lymphocytes contribute to inflammation and tissue damage in psoriasis, but the underlying molecular mechanisms remain poorly understood. The transcription factor CREMα controls effector T cell function in people with systemic autoimmune diseases. The inhibitory surface coreceptor PD-1 plays a key role in the control of effector T cell function and its therapeutic inhibition in patients with cancer can cause psoriasis. In this study, we show that CD4 + T cells from patients with psoriasis and psoriatic arthritis exhibit increased production of IL-17 but decreased expression of IL-2 and PD-1. In genetically modified mice and Jurkat T cells CREMα expression was linked to low PD-1 levels. We demonstrate that CREMα is recruited to the proximal promoter of PDCD1 in which it trans -represses gene expression and corecruits DNMT3a-mediating DNA methylation. As keratinocytes limit inflammation by PD-1 ligand expression and, in this study, reported reduced expression of PD-1 on CD4 + T cells is linked to low IL-2 and high IL-17A production, our studies reveal a molecular pathway in T cells from people with psoriasis that can deserve clinical exploitation., (Copyright © 2021 by The American Association of Immunologists, Inc.)

Receptor-interacting protein 2 (RIP2) is a kinase that is involved in downstream signaling of nuclear oligomerization domain (NOD)-like receptors NOD1 and 2 sensing bacterial peptidoglycans. RIP2-deficiency or targeting of RIP2 by pharmaceutical inhibitors partially ameliorates inflammatory diseases by reducing pro-inflammatory signaling in response to peptidoglycans. However, RIP2 is widely expressed and interacts with several other proteins suggesting additional functions outside the NOD-signaling pathway. In this review, we discuss the immunological functions of RIP2 and its possible role in autoinflammation and immunity., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Pro-inflammatory caspase-1 is a key player in innate immunity. Caspase-1 processes interleukin (IL)-1β and IL-18 to their mature forms and triggers pyroptosis. These caspase-1 functions are linked to its enzymatic activity. However, loss-of-function missense mutations in CASP1 do not prevent autoinflammation in patients, despite decreased IL-1β production. In vitro data suggest that enzymatically inactive caspase-1 drives inflammation via enhanced nuclear factor κB (NF-κB) activation, independent of IL-1β processing. Here, we report two mouse models of enzymatically inactive caspase-1-C284A, demonstrating the relevance of this pathway in vivo. In contrast to Casp1 -/- mice, caspase-1-C284A mice show pronounced hypothermia and increased levels of the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α) and IL-6 when challenged with lipopolysaccharide (LPS). Caspase-1-C284A signaling is RIP2 dependent and mediated by TNF-α but independent of the NLRP3 inflammasome. LPS-stimulated whole blood from patients carrying loss-of-function missense mutations in CASP1 secretes higher amounts of TNF-α. Taken together, these results reveal non-canonical caspase-1 signaling in vivo., Competing Interests: Declaration of Interests The authors declare no competing interests., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Effector CD4 + T cells with increased IL-17A and reduced IL-2 production contribute to tissue inflammation and organ damage in systemic lupus erythematosus (SLE). Increased expression of the transcription factor cAMP response element modulator (CREM) α promotes altered cytokine expression in SLE. The aim of this study was to investigate CREMα-mediated events favoring effector CD4 + T cells in health and disease. Using CRISPR/Cas9 genome editing and lentiviral transduction, we generated CREMα-deficient and CREMα-overexpressing Jurkat T cells. Gene expression and regulatory events were assessed using luciferase reporter assays and chromatin immunoprecipitation. Interaction between CREMα and p300 was investigated using proximity ligation assays, coimmunoprecipitation, and knockdown of p300. Gene expression profiles of modified cells were compared with CD4 + T cells from patients with juvenile-onset SLE. We show that CREMα induces dual specificity protein phosphatase (DUSP) 4 in effector CD4 + T cells through corecruitment of p300. The transcriptional coactivator p300 mediates histone acetylation at DUSP4, prompting increased gene expression. Using DUSP4 transfection models and genetically modified CREM-deficient and CREMα-overexpressing T cells, we demonstrate the molecular underpinnings by which DUSP4 induces IL-17A while limiting IL-2 expression. We demonstrate that CD4 + T cells from patients with juvenile-onset SLE share phenotypical features with CREMα-overexpressing CD4 + T cells, including increased DUSP4 expression and imbalanced IL-17A and IL-2 production. Taken together, we describe CREMα-mediated mechanisms that involve the transcriptional upregulation of DUSP4, leading to imbalanced cytokine production by effector T cells. Our findings identify the CREMα/DUSP4 axis as a promising candidate in the search for biomarkers and therapeutic targets in SLE., (Copyright © 2019 by The American Association of Immunologists, Inc.)

CASP1 variants result in reduced enzymatic activity of procaspase-1 and impaired IL-1β release. Despite this, affected individuals can develop systemic autoinflammatory disease. These seemingly contradictory observations have only partially been explained by increased NF-κB activation through prolonged interaction of variant procaspase-1 with RIP2. To identify further disease underlying pathomechanisms, we established an in vitro model using shRNA-directed knock-down of procaspase-1 followed by viral transduction of human monocytes (THP-1) with plasmids encoding for wild-type procaspase-1, disease-associated CASP1 variants (p.L265S, p.R240Q) or a missense mutation in the active center of procaspase-1 (p.C285A). THP1-derived macrophages carrying CASP1 variants exhibited mutation-specific molecular alterations. We here provide in vitro evidence for abnormal pyroptosome formation (p.C285A, p.240Q, p.L265S), impaired nuclear (pro)caspase-1 localization (p.L265S), reduced pro-inflammatory cell death (p.C285A) and changes in macrophage deformability that may contribute to disease pathophysiology of patients with CASP1 variants. This offers previously unknown molecular pathomechanisms in patients with systemic autoinflammatory disease., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Monogenic autoinflammatory disorders are characterized by dysregulation of the innate immune system, for example by gain-of-function mutations in inflammasome-forming proteins, such as NOD-like receptor family CARD-containing 4 protein (NLRC4)., Objective: Here we investigate the mechanism by which a novel mutation in the leucine-rich repeat (LRR) domain of NLRC4 (c.G1965C, p.W655C) contributes to autoinflammatory disease., Methods: We studied 2 unrelated patients with early-onset macrophage activation syndrome harboring the same de novo mutation in NLRC4. In vitro inflammasome complex formation was quantified by using flow cytometric analysis of apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) specks. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 techniques and lentiviral transduction were used to generate THP-1 cells with either wild-type or mutant NLRC4 cDNA. Cell death and release of IL-1β/IL-18 were quantified by using flow cytometry and ELISA, respectively., Results: The p.W655C NLRC4 mutation caused increased ASC speck formation, caspase-1-dependent cell death, and IL-1β/IL-18 production. ASC contributed to p.W655C NLRC4-mediated cytokine release but not cell death. Mutation of p.W655 activated the NLRC4 inflammasome complex by engaging with 2 interfaces on the opposing LRR domain of the oligomer. One key set of residues (p.D1010, p.D1011, p.L1012, and p.I1015) participated in LRR-LRR oligomerization when triggered by mutant NLRC4 or type 3 secretion system effector (PrgI) stimulation of the NLRC4 inflammasome complex., Conclusion: This is the first report of a mutation in the LRR domain of NLRC4 causing autoinflammatory disease. c.G1965C/p.W655C NLRC4 increased inflammasome activation in vitro. Data generated from various NLRC4 mutations provides evidence that the LRR-LRR interface has an important and previously unrecognized role in oligomerization of the NLRC4 inflammasome complex., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

The pathophysiology of chronic nonbacterial osteomyelitis (CNO) remains incompletely understood. Increased NLRP3 inflammasome activation and IL-1β release in monocytes from CNO patients was suggested to contribute to bone inflammation. Here, we dissect immune cell infiltrates and demonstrate the involvement of monocytes across disease stages. Differences in cell density and immune cell composition may help to discriminate between BOM and CNO. However, differences are subtle and infiltrates vary in CNO. In contrast to other cells involved, monocytes are a stable element during all stages of CNO, which makes them a promising candidate in the search for "drivers" of inflammation. Furthermore, we link increased expression of inflammasome components NLRP3 and ASC in monocytes with site-specific DNA hypomethylation around the corresponding genes NLRP3 and PYCARD. Our observations deliver further evidence for the involvement of pro-inflammatory monocytes in the pathophysiology of CNO. Cellular and molecular alterations may serve as disease biomarkers and/or therapeutic targets., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Celiac disease (CD) is an autoimmune/inflammatory condition triggered by dietary gluten intake in genetically predisposed individuals. Though associations with MHC class II HLA-DQ2 or -DQ8 are the primary and necessary genetic predisposition for CD, >97% of genetically predisposed individuals never develop CD. Cytokines were measured in the serum of CD patients and controls. Possible associations with IL10 promoter variants were investigated. Cytokine expression from PBMCs was monitored in response to gluten exposure, or CD3/TCR complex stimulation in the absence or presence of recombinant IL-10. Serum cytokines varied between patients with CD at the time of diagnosis, after dietary elimination of gluten, and healthy controls. Serum IL-17A reflected disease activity. Reduced IL-10 serum levels and altered IL-10 expression by PBMCs coincided with IL10 promoter haplotypes that encode for "low" IL-10 expression (ATA). Increased prevalence of ATA IL10 promoter haplotypes and subsequently reduced IL-10 expression may be an immunological cofactor in individuals genetically predisposed for the development of CD. Resulting cytokine imbalances may be utilized as disease biomarkers in CD., (Copyright © 2018 Elsevier Inc. All rights reserved.)

There is no consensus about the hemodynamic significance and, therefore, the need to treat a persistent ductus arteriosus in preterm newborns. Since the diagnosis of a hemodynamically significant persistent ductus arteriosus (hsPDA) is made by a summary of non-uniform echo-criteria in combination with the clinical deterioration of the preterm neonate, standardized clinical and ultrasound scoring systems are needed. The objective of this study was the development of a clinical score for the detection and follow-up of hsPDA. In this observational cohort study of 154 preterm neonates (mean gestational age 28.1 weeks), clinical signs for the development of hsPDA were recorded in a standardized score and compared to echocardiography. Analyzing the significance of single score parameters compared to the diagnosis by echocardiography, we developed a short clinical score (calculated sensitivity 84% and specificity 80%). In conclusion , this clinical diagnostic PDA score is non-invasive and quickly to implement. The continuous assessment of defined clinical parameters allows for a more precise diagnosis of hemodynamic significance of PDA and, therefore, should help to detect preterm neonates needing PDA-treatment. The score, therefore, allows a more targeted use of echocardiography in these very fragile preterm neonates.

Purpose of Review: Chronic non-bacterial osteomyelitis (CNO) with its most severe form chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory bone disorder. We summarize the clinical presentation, diagnostic approaches, most recent advances in understanding the pathophysiology, and available treatment options and outcomes in CNO/CRMO., Recent Findings: Though the exact molecular pathophysiology of CNO/CRMO remains somewhat elusive, it appears likely that variable defects in the TLR4/MAPK/inflammasome signaling cascade result in an imbalance between pro- and anti-inflammatory cytokine expressions in monocytes from CNO/CRMO patients. In this context, we present previously unpublished data on cytokine and chemokine expression in monocytes and tissues. CNO/CRMO is an autoinflammatory bone disorder resulting from imbalanced cytokine expression from innate immune cells. Though the exact molecular pathophysiology remains unclear, variable molecular defects appear to result in inflammasome activation and pro-inflammatory cytokine expression in monocytes from CNO/CRMO patients. Recent advances suggest signaling pathways and single molecules as biomarkers for CNO/CRMO as well as future treatment targets.

Objectives: Chronic recurrent multifocal osteomyelitis (CRMO), the most severe form of chronic nonbacterial osteomyelitis (CNO), is an autoinflammatory bone disorder. In the absence of diagnostic criteria or biomarkers, CNO/CRMO remains a diagnosis of exclusion. The aim of this study was to identify biomarkers for diagnosing multifocal disease (CRMO)., Study Design: Sera from 71 pediatric CRMO patients, 11 patients with osteoarticular infections, 62 patients with juvenile idiopathic arthritis (JIA), 7 patients with para-infectious or reactive arthritis, and 43 patients with acute leukemia or lymphoma, as well as 59 healthy individuals were collected. Multiplex analysis of 18 inflammation- and/or bone remodeling-associated serum proteins was performed. Statistical analysis included univariate ANOVA, discriminant analysis, univariate receiver operating characteristic (ROC) analysis, and logistic regression analyses., Results: For 14 of 18 blood serum proteins, significant differences were determined between CRMO patients, at least one alternative diagnosis, or healthy controls. Multi-component discriminant analysis delivered five biomarkers (IL-6, CCL11/eotaxin, CCL5/RANTES, collagen Iα, sIL-2R) for the diagnosis of CRMO. ROC analysis allowed further reduction to a core set of 2 biomarkers (CCL11/eotaxin, IL-6) that are sufficient to discern between CRMO, healthy controls, and alternative diagnoses., Conclusion: Serum biomarkers CCL11/eotaxin and IL-6 differentiate between patients with CRMO, healthy controls, and alternative diagnoses (leukemia and lymphoma, osteoarticular infections, para-infectious arthritis, and JIA). Easily accessible biomarkers may aid in diagnosing CRMO. Further studies testing biomarkers in larger unrelated cohorts are warranted.

Chronic non-bacterial osteomyelitis (CNO) belongs to the growing spectrum of autoinflammatory diseases and primarily affects the skeletal system. Peak onset ranges between 7 and 12 years of age. The clinical spectrum of CNO covers sometimes asymptomatic inflammation of single bones at the one end and chronically active or recurrent multifocal osteitis at the other.Despite the intense scientific efforts, the exact molecular mechanisms of CNO remain unknown. Recent data suggest CNO as a genetically complex disorder with dysregulated TLR4/MAPK/inflammasome signaling cascades resulting in an imbalance between pro- and anti-inflammatory cytokine expression, leading to osteoclast activation and osteolytic lesions.In this manuscript, the current understanding of molecular patho-mechanisms in CNO will be discussed.

Chronic nonbacterial osteomyelitis (CNO) is an autoinflammatory bone disorder, covering a clinical spectrum with asymptomatic inflammation of single bones at the one end, and chronic recurrent multifocal osteomyelitis (CRMO) at the other end. The exact molecular pathophysiology of CNO remains largely unknown. Provided familial clusters and the association with inflammatory disorders of the skin and intestine suggest a genetic predisposition. Recently, profound dysregulation of cytokine responses was demonstrated in CRMO. Failure to produce antiinflammatory cytokines interleukin (IL)-10 and IL-19 contributes to activation of inflammasomes and subsequent IL-1β release. In IL-10-deficient and in CNO-prone chronic multifocal osteomyelitis mice, IL-1β was linked to bone inflammation. Further, alterations to the gut microbiome were suggested in contributing to IL-1β release from innate immune cells in mice, offering an interesting target in the search for molecular mechanisms in CNO. Here, we summarize clinical presentation and treatment options in CNO/CRMO, current pathophysiological concepts, available mouse models, and promising future scientific directions.

Caspase-1 is a key player during the initiation of pro-inflammatory innate immune responses, activating pro-IL-1β in so-called inflammasomes. A subset of patients with recurrent febrile episodes and systemic inflammation of unknown origin harbor mutations in CASP1 encoding caspase-1. CASP1 variants result in reduced enzymatic activity of caspase-1 and impaired IL-1β secretion. The apparent paradox of reduced IL-1β secretion but systemic inflammation led to the hypothesis that CASP1 mutations may result in variable protein interaction clusters, thus activating alternative signaling pathways. To test this hypothesis, we established and characterized an in vitro system of transduced immortalized murine macrophages expressing either WT or enzymatically inactive (p.C284A) procaspase-1 fusion reporter proteins. Macrophages with variant p.C284A caspase-1 did not secrete IL-1β and exhibited reduced inflammatory cell death, referred to as pyroptosis. Caspase-1 and apoptosis-associated speck-like protein containing a CARD (ASC) formed cytosolic macromolecular complexes (so-called pyroptosomes) that were significantly increased in number and size in cells carrying the p.C284A caspase-1 variant compared with WT caspase-1. Furthermore, enzymatically inactive caspase-1 interacted with ASC longer and with increased intensity compared with WT caspase-1. Applying live cell imaging, we documented for the first time that pyroptosomes containing enzymatically inactive variant p.C284A caspase-1 spread during cell division. In conclusion, variant p.C284A caspase-1 stabilizes pyroptosome formation, potentially enhancing inflammation by two IL-1β-independent mechanisms: pyroptosomes convey an enhanced inflammatory stimulus through the recruitment of additional proteins (such as RIP2, receptor interacting protein kinase 2), which is further amplified through pyroptosome and cell division., (© 2016 by The American Society for Biochemistry and Molecular Biology, Inc.)

Chronic recurrent multifocal osteomyelitis (CRMO), the most severe form of chronic nonbacterial osteomyelitis, is an autoinflammatory bone disorder. A timely diagnosis and treatment initiation is complicated by the absence of widely accepted diagnostic criteria and an incomplete pathophysiological understanding. The aim of this study was to determine biomarkers for the diagnosis and follow-up of CRMO. Serum of 56 CRMO patients was collected at the time of diagnosis. As controls, sera from treatment-naïve age-matched patients with Crohn's disease (N = 62) or JIA (N = 28) as well as healthy individuals (N = 62) were collected. Multiplex analysis of 25 inflammation markers was performed. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U tests, canonical discriminant analysis, and mixed model variance analysis. Mostly monocyte-derived serum proteins were detectable and differed significantly between groups: IL-1RA, IL-2R, IL-6, IL-12, eotaxin, MCP-1, MIP-1b, RANTES. Multicomponent discriminant analysis allowed for the definition of algorithms differentiating between CRMO, Crohn's disease, and healthy controls. Persistently high levels of MCP-1, IL-12, sIL-2R correlated with incomplete remission in follow-up samples from CRMO patients. Discrimination algorithms allow differentiation between patients with CRMO or Crohn's disease, and healthy individuals. IL-12, MCP-1, and sIL-2R can act as markers for treatment response. Though confirmation of our findings in larger multiethnical cohorts is warranted, they may prove valuable to differentiate between otherwise healthy individuals or Crohn's disease patients with "bone pain" and CRMO patients. The elevation of mainly monocyte-derived pro-inflammatory serum proteins supports the hypothesis of pro-inflammatory monocyte/macrophages driving inflammation in CRMO.

Chronic recurrent multifocal osteomyelitis (CRMO) is characterized by reduced activation of protein kinases ERK1 and 2 in monocytes resulting in impaired IL-10 expression. IL10 and its homologs IL19 and IL20 are organized in the IL10 cluster on chromosome 1q32. IL-10 and IL-19 are immune-regulatory cytokines, while IL-20 acts in a pro-inflammatory manner. The NLRP3 inflammasome, a multi-protein complex forming in response to innate stimuli, mediates IL-1β cleavage and release. Here, we investigated IL-10-related cytokine expression in CRMO monocytes, underlying molecular events, and effects on inflammatory responses. We observed reduced anti-inflammatory IL-10 and IL-19 expression, and enhanced IL-20 expression in CRMO monocytes. Reduced IL-10 and IL-19 expression was associated with impaired Sp-1 recruitment to regulatory regions, contributing to NLRP3 inflammasome activation, which may induce inflammatory bone-loss. Our findings underscore the importance of balanced receptor-, cell-, and tissue-specific cytokine expression for immune homeostasis, providing additional arguments for cytokine blocking strategies in CRMO., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Subcellular localization studies and life cell imaging approaches usually benefit from fusion-reporter proteins, such as enhanced green fluorescent protein (EGFP) and mCherry to the proteins of interest. However, such manipulations have several risks, including protein misfolding, altered protein shuttling, or functional impairment when compared to the wild-type proteins. Here, we demonstrate altered subcellular distribution and function of the pro-inflammatory enzyme procaspase-1 as a result of fusion with the reporter protein mCherry. Our observations are of central importance to further investigations of subcellular behavior and possible protein-protein interactions of naturally occurring genetic variants of human procaspase-1 which have recently been linked to autoinflammatory disorders., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Caspase-1 is a proinflammatory enzyme that is essential in many inflammatory conditions including infectious, autoimmune, and autoinflammatory disorders. The inflammation is mainly mediated by the generation of inflammasomes that activate caspase-1 and subsequently interleukin (IL)-1β and IL-18. In addition, homotypic CARD/CARD interaction of procaspase-1 with RIP2 and thereby activation of the NF-κB pathways may play some role in the inflammation. However, normally, this pathway seems to become downregulated rapidly by the cleavage and excretion of RIP2 by active (pro-)caspase-1. In patients with unexplained recurrent systemic inflammation, CASP1 variants were detected, which often destabilized the caspase-1 dimer interface. Obviously, the resulting decreased or abrogated enzymatic activity and IL-1β production did not prevent the febrile episodes. As an unexpected finding, the inactive procaspase-1 variants significantly enhanced proinflammatory signaling by increasing RIP2 mediated NF-κB activation in an in vitro cell transfection model. A likely reason is the failure of inactive procaspase-1 to cleave bound RIP2 and also to mediate its excretion out of the intracelluar space thereby keeping the RIP2-NF-κB pathway upregulated. Hence, proinflammatory effects of enzymatically inactive procaspase-1 variants may partially explain the inflammatory episodes of the patients.

The proinflammatory enzyme caspase-1 plays an important role in the innate immune system and is involved in a variety of inflammatory conditions. Rare naturally occurring human variants of the caspase-1 gene (CASP1) lead to different protein expression and structure and to decreased or absent enzymatic activity. Paradoxically, a significant number of patients with such variants suffer from febrile episodes despite decreased IL-1β production and secretion. In this study, we investigate how variant (pro)caspase-1 can possibly contribute to inflammation. In a transfection model, such variant procaspase-1 binds receptor interacting protein kinase 2 (RIP2) via Caspase activation and recruitment domain (CARD)/CARD interaction and thereby activates NF-κB, whereas wild-type procaspase-1 reduces intracellular RIP2 levels by enzymatic cleavage and release into the supernatant. We approach the protein interactions by coimmunoprecipitation and confocal microscopy and show that NF-κB activation is inhibited by anti-RIP2-short hairpin RNA and by the expression of a RIP2 CARD-only protein. In conclusion, variant procaspase-1 binds RIP2 and thereby activates NF-κB. This pathway could possibly contribute to proinflammatory signaling.

Compared to children of other age groups neonates show an increased thrombotic risk. The acute therapy depends on thrombus age, the localisation of vascular occlusion and the severity of the underlying disease. The treatment of choice is represented by the administration of unfractionated (UFH) or low molecular weight heparin (LMWH). If loss of limbs or organs is imminent, the application of thrombolytic treatment with recombinant tissue-type plasminogen activator (rt-PA) should be considered whilst taking into account the associated bleeding risk. We report on two patients in which thrombolytic therapy has been conducted successfully.

Sterile bone inflammation is the hallmark of autoinflammatory bone disorders, including chronic nonbacterial osteomyelitis (CNO) with its most severe form chronic recurrent multifocal osteomyelitis (CRMO). Autoinflammatory osteopathies are the result of a dysregulated innate immune system, resulting in immune cell infiltration of the bone and subsequent osteoclast differentiation and activation. Interestingly, autoinflammatory bone disorders are associated with inflammation of the skin and/or the intestine. In several monogenic autoinflammatory bone disorders mutations in disease-causing genes have been reported. However, regardless of recent developments, the molecular pathogenesis of CNO/CRMO remains unclear.Here, we discuss the clinical presentation and molecular pathophysiology of human autoinflammatory osteopathies and animal models with special focus on CNO/CRMO. Treatment options in monogenic autoinflammatory bone disorders and CRMO will be illustrated.

Absence of the ductus venosus (ADV) is a rare vascular anomaly. Its prognosis depends on the pathway of the umbilical flow to the systemic venous circulation, and the presence or absence of associated structural or chromosomal anomalies, sometimes resulting in hydrops fetalis. In cases with isolated ADV in the absence of associated anomalies, survival rates are as high as 85%, depending on the shunt situation. Here, we report a patient with ADV and extrahepatic umbilical vein drainage with favorable outcome after intrauterine reversal of early signs of cardiac failure. Diagnosis was made after the appearance of moderate cardiomegaly in the 25th gestational week. Thus, in the case of cardiomegaly with or without further signs of cardiac failure, ultrasound imaging of the venous duct should be considered., (Copyright © 2012 Wiley Periodicals, Inc.)

Caspase-1 (Interleukin-1 Converting Enzyme, ICE) is a proinflammatory enzyme that plays pivotal roles in innate immunity and many inflammatory conditions such as periodic fever syndromes and gout. Inflammation is often mediated by enzymatic activation of interleukin (IL)-1β and IL-18. We detected seven naturally occurring human CASP1 variants with different effects on protein structure, expression, and enzymatic activity. Most mutations destabilized the caspase-1 dimer interface as revealed by crystal structure analysis and homology modeling followed by molecular dynamics simulations. All variants demonstrated decreased or absent enzymatic and IL-1β releasing activity in vitro, in a cell transfection model, and as low as 25% of normal ex vivo in a whole blood assay of samples taken from subjects with variant CASP1, a subset of whom suffered from unclassified autoinflammation. We conclude that decreased enzymatic activity of caspase-1 is compatible with normal life and does not prevent moderate and severe autoinflammation., (© 2012 Wiley Periodicals, Inc.)

Chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory bone disorder of unknown origin. We previously demonstrated that monocytes from CRMO patients fail to express the immune-modulatory cytokine interleukin-10 (IL-10) in a chromatin dependent manner. Here, we demonstrate that attenuated extracellular-signal regulated kinase (ERK)1 and 2 signaling in response to TLR4 activation results in failure to induce IL-10 expression in monocytes from CRMO patients. Attenuated ERK1/2 activation results in 1) reduced levels of Sp-1, a transcription factor that induces IL-10 expression in monocytes, and 2) impaired H3S10 phosphorylation of the IL10 promoter, an activating epigenetic mark. The pro-inflammatory cytokines tumor necrosis factor (TNF)α and IL-6 are not negatively affected, resulting in an imbalance towards pro-inflammatory cytokines. Thus, impaired ERK1/2 signaling with subsequently reduced Sp-1 expression and H3S10 phosphorylation of the IL10 promoter may centrally contribute to the pathophysiology of CRMO., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Objective: Evaluation of lung function parameters and additional use of prostaglandin E1 (PGE1) for the stabilisation of cardiopulmonary function in patients with congenital diaphragmatic hernia (CDH) and pulmonary hypertension (PHT)., Design: Observational study., Patients: Between 2007 and 2009 8 patients with CDH have been treated in our pediatric intensive care unit (gestational age 34 + 0 - 40 + 4 weeks, birth weight 2 160-3 840 g). All patients required respiratory support. Gentle mechanical ventilation adapted to the degree of pulmonary hypoplasia based on serially measurements of lung function parameters to find appropriate ventilator settings has been performed., Main Results: Functional residual capacity (FRC) and compliance of the respiratory system in all patients were markedly reduced. A FRC between 9.3-10.6 ml/kg and compliance between 1.1-1.8 ml/kPa/kg indicated pronounced hypoplasia of the lungs. Doppler flow patterns through the arterial duct were classified into left-to-right, right-to-left and bidirectional shunting and correlated to the degree of PHT. The additional use of PGE1 to reopen the arterial duct and to stabilize right ventricular function led to an amelioration of severe PHT and preoperative stabilisation in 2 newborns with pronounced pulmonary hypoplasia. All patients underwent successful surgery, and did not show any complications after 2 years follow-up., Conclusion: Measurements of lung function parameters and adaptation of mechanical ventilation to the degree of pulmonary hypoplasia and additional therapy with PGE1 may help to improve the outcome in CDH patients., (© Georg Thieme Verlag KG Stuttgart · New York.)

The IL-10 cytokine family has nine members, four of which are located in the IL10 cluster on chromosome 1q32. These cytokines are the immune regulatory cytokine IL-10 itself, and the IL-20 subfamily members IL-19, IL-20, and IL-24. IL-10 instructs innate and adaptive immune responses and limits pro-inflammatory responses in order to prevent tissue damage. The IL-20 subfamily members are involved in host defense mechanisms, particularly from epithelial cells and seem essential for tissue integrity. Dysregulation of IL-10 family cytokines results in inflammation and autoimmune disease. Here, we discuss cellular source, gene regulation, and receptor complexes of cytokines in the IL10 cluster and their contribution to autoimmune disease and tissue damage., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The IL-10 family of cytokines consists of 9 members, including the immune-regulatory IL-10; Il19 is in close physical relationship with Il10 in the so-called IL-10 cytokine cluster on chromosome 1q32. While IL-10 is ubiquitously expressed, IL-19 expression is restricted to myeloid and epithelial cells. Little is known about molecular mechanisms that control tissue-specific expression of IL-10, and IL-19. Modifications in CpG-DNA methylation are a key mechanism in controlling transcription. Using bisulfite sequencing, we demonstrate that murine Il19 is methylated in CD4+ T lymphocytes. Macrophages display site-specific demethylation of Il19. The ubiquitously expressed Il10 gene is methylated to a lower degree and exhibits tissue-specific methylation patterns. DNA demethylation with 5-azacytidine resulted in an induction of IL-10, and IL-19 expression in CD4+ T cells, and CpG-DNA methylation through DNMT3a resulted in transcriptional silencing in macrophages. Thus, our findings suggest a role of CpG-DNA methylation in the regulation of Il10 and Il19., (© Georg Thieme Verlag KG Stuttgart · New York.)

Chronic nonbacterial osteomyelitis (CNO) with its most severe form chronic recurrent multifocal osteomyelitis (CRMO) is a non-bacterial osteitis of yet unknown origin. Secondary to the absence of both high-titer autoantibodies and autoreactive T lymphocytes, and the association with other autoimmune diseases, it was recently reclassified as an autoinflammatory disorder of the musculoskeletal system. Since its etiology is largely unknown, the diagnosis is based on clinical criteria, and treatment is empiric and not always successful. In this paper, we summarize recent advances in the understanding of possible etiopathogenetic mechanisms in CNO.

Introduction: Idiopathic dilatation of the right atrium (IDRA) is a rare abnormality usually detected by chance at any time between antenatal and adult life. It is defined as isolated enlargement of the right atrium in the absence of other cardiac lesions causing right atrial dilatation. IDRA can be associated with atrial arrhythmia and systemic embolism. The clinical presentation shows high variability ranging from the lack of any symptoms up to cardiac failure., Methods/results: We describe 2 children with antenatally diagnosed IDRA, the intrauterine course in 1 case, the postnatal management and its long-term follow-up. There has been no need for surgical intervention so far because of the lack of arrhythmias and no further progression of right atrial diameters. Thrombus formation in the right atrium, which is a potential risk for pulmonary embolism, led us to initiate anticoagulation in our cases to prevent such complications. Furthermore, we suggest one possible pathomechanism of congenital right atrial dilatation., Conclusion: Optimal management of severe IDRA depends on the individual case. Long-term follow-up of these patients is necessary to monitor a possible further progression of right atrial size and occurrence of arrhythmias. As a possible pathomechanism, a functional partial anomalous pulmonary venous insertion may imitate a structural abnormal pulmonary vein connection in some idiopathic cases of congenital right atrial dilatation., (Copyright © 2012 S. Karger AG, Basel.)

Chronic non-bacterial osteomyelitis (CNO) is an auto-inflammatory disorder that affects the skeletal system. Interleukin (IL-)10 is an immune-modulatory cytokine that controls inflammation, and limits inflammatory cytokine responses. Dysregulation of IL-10 expression has been shown to result in autoimmune and infectious diseases. We investigated IL-10 expression by monocytic cells from CNO patients and controls. In response to stimulation with LPS, IL-10 expression from CNO monocytes was reduced (p<0.001). This was independent of IL10 promoter polymorphisms. Thus, we investigated Sp1 recruitment to the IL10 promoter and saw markedly reduced binding in CNO monocytes. This was accompanied with reduced phosphorylation of histone H3 serine 10 (H3S10), an activating epigenetic mark. Impaired recruitment of Sp1 to the IL10 promoter, and reduced H3S10 phosphorylation, may be a reflection of deficient MAPK signaling in CNO monocytes in response to LPS stimulation. Thus, we have discovered a mechanism that may be central in the pathophysiology of CNO., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Congenital arteriovenous malformations are rare causes of congestive cardiac failure in neonates. The most common sites are in the head and liver, but other sites include the thorax, the abdomen and the limbs. The onset of failure is usually not in the immediate neonatal period, but later on in life, albeit that lesions such as the arteriovenous malformation of the vein of Galen, and other arteriovenous malformations in different locations which produce high flow can present early. We describe here the first case, to the best of our knowledge, of prenatal detection of an intrathoracic arteriovenous malformation producing neonatal cardiac failure, which was successfully treated by surgery postnatally.

Cybr (also known as Cytip, CASP, and PSCDBP) is an interleukin-12-induced gene expressed exclusively in hematopoietic cells and tissues that associates with Arf guanine nucleotide exchange factors known as cytohesins. Cybr levels are dynamically regulated during T-cell development in the thymus and upon activation of peripheral T cells. In addition, Cybr is induced in activated dendritic cells and has been reported to regulate dendritic cell (DC)-T-cell adhesion. Here we report the generation and characterization of Cybr-deficient mice. Despite the selective expression in hematopoietic cells, there was no intrinsic defect in T- or B-cell development or function in Cybr-deficient mice. The adoptive transfer of Cybr-deficient DCs showed that they migrated efficiently and stimulated proliferation and cytokine production by T cells in vivo. However, competitive stem cell repopulation experiments showed a defect in the abilities of Cybr-deficient T cells to develop in the presence of wild-type precursors. These data suggest that Cybr is not absolutely required for hematopoietic cell development or function, but stem cells lacking Cybr are at a developmental disadvantage compared to wild-type cells. Collectively, these data demonstrate that despite its selective expression in hematopoietic cells, the role of Cybr is limited or largely redundant. Previous in vitro studies using overexpression or short interfering RNA inhibition of the levels of Cybr protein appear to have overestimated its immunological role.

The recent elucidation of the multiple molecular mechanisms underlying severe combined immunodeficiency (SCID) is an impressive example of the power of molecular medicine. Analysis of patients and the concomitant generation of animal models mimicking these disorders have quickly provided great insights into the pathophysiology of these potentially devastating illnesses. In this review, we summarize the discoveries that led to the understanding of the role of cytokine receptors and a specific tyrosine kinase, Janus kinase 3 (Jak3), in the pathogenesis of SCID. We discuss how the identification of mutations of Jak3 in autosomal recessive SCID has facilitated the diagnosis of these disorders, offered new insights into the biology of this kinase, permitted new avenues for therapy, and provided the rationale for a generation of a new class of immunosuppressants.

The discovery that Jak3 mutations are a significant cause of severe combined immunodeficiency (SCID), a rare inherited defect characterized by lymphopenia, has provided valuable insights into the functions of Jak3 in lymphoid development and function. The current therapy for patients suffering from Jak3 SCID is hematopoetic stem cell transplantation, although gene therapy trials have also been performed. In lieu of crystal structure data, these patient-derived mutations have aided in the elucidation of the functions of various structural components of Jak3. By virtue of its requirement for lymphoid functions, Jak3 makes a tantalizing target for immunosuppression and anti-cancer therapy. Herein, we discuss the normal actions of the gammac cytokines, the pathogenesis and treatment protocols for SCID, and finally, the production of a new, selective Jak3 inhibitor capable of preventing transplant rejection in two animal models. Further study of Jak3 will hopefully provide insights into the clinical treatment of patients suffering from immune-mediated diseases.

Janus kinases (Jaks) play an essential role in cytokine signaling and have been reported to regulate plasma membrane expression of their cognate receptors. In this study, we examined whether Jak3 and the common gamma chain (gamma(c)) reciprocally regulate their plasma membrane expression. In contrast to interleukin-2Ralpha, gamma(c) localized poorly to the plasma membrane and accumulated in endosomal-lysosomal compartments. However, gamma(c) was expressed at comparable levels on the surface of cells lacking Jak3, and plasma membrane turnover of gamma(c) was independent of Jak3. Nonetheless, overexpression of Jak3 enhanced accumulation of gamma(c) at the plasma membrane. Without gamma(c), Jak3 localized in the cytosol, whereas in the presence of the receptor, it colocalized with gamma(c) in endosomes and at the plasma membrane. Although the Jak FERM domain is necessary and sufficient for receptor binding, the requirement for full-length Jak3 in gamma(c) membrane trafficking was remarkably stringent; using truncation and deletion mutants, we showed that the entire Jak3 molecule was required, although kinase activity was not. Thus, unlike other cytokine receptors, gamma(c) does not require Jak3 for receptor membrane expression. However, full-length Jak3 is required for normal trafficking of this cytokine receptor/Jak pair, a finding that has important structural and clinical implications.

Purpose of Review: The development of lymphoid tissues as well as the ultimate differentiation of naïve and memory T cells are dependent on cytokines. In this review, we will focus on recent advances in the understanding of molecular mechanisms that regulate lymphoid development, homeostasis and tolerance., Recent Findings: Cytokines play a critical role in the development and differentiation of lymphoid cells. In addition, newer data indicate important roles of interleukin-7 and interleukin-15 in lymphoid homeostasis and memory. Furthermore, a new family of heterodimeric cytokines comprising interleukin-12, interleukin-23 and -27 is important for differentiation of helper T cells and cell-mediated immunity. Finally the importance of tumor necrosis factor superfamily members in the development of lymphoid organs has recently been elucidated and will be discussed in detail., Summary: New cytokines and receptors continue to be identified. The discovery and characterization of cytokines, their receptors and signaling molecules will provide a more complete understanding of normal lymphoid development, differentiation and function. In addition, this knowledge should improve our understanding of the pathogenesis of immunological diseases and hopefully will provide new treatment strategies.