Functional Diversity of Memory CD8 T Cells is Spatiotemporally Imprinted

Tissue-resident memory CD8 T cells (TRM) kill infected cells and recruit additional immune cells to limit pathogen invasion at barrier sites. Small intestinal (SI) TRM cells consist of distinct subpopulations with higher expression of effector molecules or greater memory potential. We hypothesized that occupancy of diverse anatomical niches imprints these distinct TRM transcriptional programs. We leveraged human samples and a murine model of acute systemic viral infection to profile the location and transcriptome of pathogen-specific TRM cell differentiation at single-transcript resolution. We developed computational approaches to capture cellular locations along three anatomical axes of the small intestine and to visualize the spatiotemporal distribution of cell types and gene expression. TRM populations were spatially segregated: with more effector- and memory-like TRM preferentially localized at the villus tip or crypt, respectively. Modeling ligand-receptor activity revealed patterns of key cellular interactions and cytokine signaling pathways that initiate and maintain TRM differentiation and functional diversity, including different TGFβ sources. Alterations in the cellular networks induced by loss of TGFβRII expression revealed a model consistent with TGFβ promoting progressive TRM maturation towards the villus tip. Ultimately, we have developed a framework for the study of immune cell interactions with the spectrum of tissue cell types, revealing that T cell location and functional state are fundamentally intertwined.

Diagnostic evaluation of paediatric autoimmune lymphoproliferative immunodeficiencies (ALPID): a prospective cohort study

BACKGROUND

Lymphoproliferation and autoimmune cytopenias characterise autoimmune lymphoproliferative syndrome. Other conditions sharing these manifestations have been termed autoimmune lymphoproliferative syndrome-like diseases, although they are frequently more severe. The aim of this study was to define the genetic, clinical, and immunological features of these disorders to improve their diagnostic classification.

METHODS

In this prospective cohort study, patients were referred to the Center for Chronic Immunodeficiency in Freiburg, Germany, between Jan 1, 2008 and March 5, 2022. We enrolled patients younger than 18 years with lymphoproliferation and autoimmune cytopenia, lymphoproliferation and at least one additional sign of an inborn error of immunity (SoIEI), bilineage autoimmune cytopenia, or autoimmune cytopenia and at least one additional SoIEI. Autoimmune lymphoproliferative syndrome biomarkers were determined in all patients. Sanger sequencing followed by in-depth genetic studies were recommended for patients with biomarkers indicative of autoimmune lymphoproliferative syndrome, while IEI panels, exome sequencing, or genome sequencing were recommended for patients without such biomarkers. Genetic analyses were done as decided by the treating physician. The study was registered on the German Clinical Trials Register, DRKS00011383, and is ongoing.

FINDINGS

We recruited 431 children referred for autoimmune lymphoproliferative syndrome evaluation, of whom 236 (55%) were included on the basis of lymphoproliferation and autoimmune cytopenia, 148 (34%) on the basis of lymphoproliferation and another SoIEI, 33 (8%) on the basis of autoimmune bicytopenia, and 14 (3%) on the basis of autoimmune cytopenia and another SoIEI. Median age at diagnostic evaluation was 9·8 years (IQR 5·5-13·8), and the cohort comprised 279 (65%) boys and 152 (35%) girls. After biomarker and genetic assessments, autoimmune lymphoproliferative syndrome was diagnosed in 71 (16%) patients. Among the remaining 360 patients, 54 (15%) had mostly autosomal-dominant autoimmune lymphoproliferative immunodeficiencies (AD-ALPID), most commonly affecting JAK-STAT (26 patients), CTLA4-LRBA (14), PI3K (six), RAS (five), or NFκB (three) signalling. 19 (5%) patients had other IEIs, 17 (5%) had non-IEI diagnoses, 79 (22%) were unresolved despite extended genetics (ALPID-U), and 191 (53%) had insufficient genetic workup for diagnosis. 16 (10%) of 161 patients with a final diagnosis had somatic mutations. Alternative classification of patients fulfilling common variable immunodeficiency or Evans syndrome criteria did not increase the proportion of genetic diagnoses.

INTERPRETATION

The ALPID phenotype defined in this study is enriched for patients with genetic diseases treatable with targeted therapies. The term ALPID might be useful to focus diagnostic and therapeutic efforts by triggering extended genetic analysis and consideration of targeted therapies, including in some children currently classified as having common variable immunodeficiency or Evans syndrome.

FUNDING

Deutsche Forschungsgemeinschaft under Germany's Excellence Strategy.

TRANSLATION

For the German translation of the abstract see Supplementary Materials section.

Abnormal biomarkers predict complex FAS or FADD defects missed by exome sequencing

BACKGROUND

Elevated TCRαβ+CD4-CD8- double-negative T cells (DNT) and serum biomarkers help identify FAS mutant patients with autoimmune lymphoproliferative syndrome (ALPS). However, in some patients with clinical features and biomarkers consistent with ALPS, germline or somatic FAS mutations cannot be identified on standard exon sequencing (ALPS-undetermined: ALPS-U).

OBJECTIVE

We sought to explore whether complex genetic alterations in the FAS gene escaping standard sequencing or mutations in other FAS pathway-related genes could explain these cases.

METHODS

Genetic analysis included whole FAS gene sequencing, copy number variation analysis, and sequencing of FAS cDNA and other FAS pathway-related genes. It was guided by FAS expression analysis on CD57+DNT, which can predict somatic loss of heterozygosity (sLOH).

RESULTS

Nine of 16 patients with ALPS-U lacked FAS expression on CD57+DNT predicting heterozygous "loss-of-expression" FAS mutations plus acquired somatic second hits in the FAS gene, enriched in DNT. Indeed, 7 of 9 analyzed patients carried deep intronic mutations or large deletions in the FAS gene combined with sLOH detectable in DNT; 1 patient showed a FAS exon duplication. Three patients had reduced FAS expression, and 2 of them harbored mutations in the FAS promoter, which reduced FAS expression in reporter assays. Three of the 4 ALPS-U patients with normal FAS expression carried heterozygous FADD mutations with sLOH.

CONCLUSION

A combination of serum biomarkers and DNT phenotyping is an accurate means to identify patients with ALPS who are missed by routine exome sequencing.

Activated phosphoinositide 3-kinase δ syndrome: Update from the ESID Registry and comparison with other autoimmune-lymphoproliferative inborn errors of immunity

BACKGROUND

Activated phosphoinositide-3-kinase δ syndrome (APDS) is an inborn error of immunity (IEI) with infection susceptibility and immune dysregulation, clinically overlapping with other conditions. Management depends on disease evolution, but predictors of severe disease are lacking.

OBJECTIVES

This study sought to report the extended spectrum of disease manifestations in APDS1 versus APDS2; compare these to CTLA4 deficiency, NFKB1 deficiency, and STAT3 gain-of-function (GOF) disease; and identify predictors of severity in APDS.

METHODS

Data was collected from the ESID (European Society for Immunodeficiencies)-APDS registry and was compared with published cohorts of the other IEIs.

RESULTS

The analysis of 170 patients with APDS outlines high penetrance and early onset of APDS compared to the other IEIs. The large clinical heterogeneity even in individuals with the same PIK3CD variant E1021K illustrates how poorly the genotype predicts the disease phenotype and course. The high clinical overlap between APDS and the other investigated IEIs suggests relevant pathophysiological convergence of the affected pathways. Preferentially affected organ systems indicate specific pathophysiology: bronchiectasis is typical of APDS1; interstitial lung disease and enteropathy are more common in STAT3 GOF and CTLA4 deficiency. Endocrinopathies are most frequent in STAT3 GOF, but growth impairment is also common, particularly in APDS2. Early clinical presentation is a risk factor for severe disease in APDS.

CONCLUSIONS

APDS illustrates how a single genetic variant can result in a diverse autoimmune-lymphoproliferative phenotype. Overlap with other IEIs is substantial. Some specific features distinguish APDS1 from APDS2. Early onset is a risk factor for severe disease course calling for specific treatment studies in younger patients.

The β1-adrenergic receptor links sympathetic nerves to T cell exhaustion

CD8+ T cells are essential components of the immune response against viral infections and tumours, and are capable of eliminating infected and cancerous cells. However, when the antigen cannot be cleared, T cells enter a state known as exhaustion1. Although it is clear that chronic antigen contributes to CD8+ T cell exhaustion, less is known about how stress responses in tissues regulate T cell function. Here we show a new link between the stress-associated catecholamines and the progression of T cell exhaustion through the β1-adrenergic receptor ADRB1. We identify that exhausted CD8+ T cells increase ADRB1 expression and that exposure of ADRB1+ T cells to catecholamines suppresses their cytokine production and proliferation. Exhausted CD8+ T cells cluster around sympathetic nerves in an ADRB1-dependent manner. Ablation of β1-adrenergic signalling limits the progression of T cells towards the exhausted state in chronic infection and improves effector functions when combined with immune checkpoint blockade (ICB) in melanoma. In a pancreatic cancer model resistant to ICB, β-blockers and ICB synergize to boost CD8+ T cell responses and induce the development of tissue-resident memory-like T cells. Malignant disease is associated with increased catecholamine levels in patients2,3, and our results establish a connection between the sympathetic stress response, tissue innervation and T cell exhaustion. Here, we uncover a new mechanism by which blocking β-adrenergic signalling in CD8+ T cells rejuvenates anti-tumour functions.

Metabolic programs of T cell tissue residency empower tumour immunity

Tissue resident memory CD8+ T (TRM) cells offer rapid and long-term protection at sites of reinfection1. Tumour-infiltrating lymphocytes with characteristics of TRM cells maintain enhanced effector functions, predict responses to immunotherapy and accompany better prognoses2,3. Thus, an improved understanding of the metabolic strategies that enable tissue residency by T cells could inform new approaches to empower immune responses in tissues and solid tumours. Here, to systematically define the basis for the metabolic reprogramming supporting TRM cell differentiation, survival and function, we leveraged in vivo functional genomics, untargeted metabolomics and transcriptomics of virus-specific memory CD8+ T cell populations. We found that memory CD8+ T cells deployed a range of adaptations to tissue residency, including reliance on non-steroidal products of the mevalonate-cholesterol pathway, such as coenzyme Q, driven by increased activity of the transcription factor SREBP2. This metabolic adaptation was most pronounced in the small intestine, where TRM cells interface with dietary cholesterol and maintain a heightened state of activation4, and was shared by functional tumour-infiltrating lymphocytes in diverse tumour types in mice and humans. Enforcing synthesis of coenzyme Q through deletion of Fdft1 or overexpression of PDSS2 promoted mitochondrial respiration, memory T cell formation following viral infection and enhanced antitumour immunity. In sum, through a systematic exploration of TRM cell metabolism, we reveal how these programs can be leveraged to fuel memory CD8+ T cell formation in the context of acute infections and enhance antitumour immunity.

Insights into phenotypic and functional CD8+ TRM heterogeneity

Cytotoxic CD8+ T cells recognize and eliminate infected or cancerous cells. A subset of CD8+ memory T cells called tissue-resident memory T cells (TRM ) resides in peripheral tissues, monitors the periphery for pathogen invasion, and offers a rapid and potent first line of defense at potential sites of re-infection. TRM cells are found in almost all tissues and are transcriptionally and epigenetically distinct from circulating memory populations, which shows their ability to acclimate to the tissue environment to allow for long-term survival. Recent work and the broader availability of single-cell profiling have highlighted TRM heterogeneity among different tissues, as well as identified specialized subsets within individual tissues, that are time and infection dependent. TRM cell phenotypic and transcriptional heterogeneity has implications for understanding TRM function and longevity. This review aims to summarize and discuss the latest findings on CD8+ TRM heterogeneity using single-cell molecular profiling and explore the potential implications for immune protection and the design of immune therapies.

Transcriptional programming of CD4+ TRM differentiation in viral infection balances effector- and memory-associated gene expression

After resolution of infection, T cells differentiate into long-lived memory cells that recirculate through secondary lymphoid organs or establish residence in tissues. In contrast to CD8+ tissue-resident memory T cells (TRM), the developmental origins and transcriptional regulation of CD4+ TRM remain largely undefined. Here, we investigated the phenotypic, functional, and transcriptional profiles of CD4+ TRM in the small intestine (SI) responding to acute viral infection, revealing a shared gene expression program and chromatin accessibility profile with circulating TH1 and the progressive acquisition of a mature TRM program. Single-cell RNA sequencing identified heterogeneity among established CD4+ TRM, which were predominantly located in the lamina propria, and revealed a population of cells that coexpressed both effector- and memory-associated genes, including the transcriptional regulators Blimp1, Id2, and Bcl6. TH1-associated Blimp1 and Id2 and TFH-associated Bcl6 were required for early TRM formation and development of a mature TRM population in the SI. These results demonstrate a developmental relationship between TH1 effector cells and the establishment of early TRM, as well as highlighted differences in CD4+ versus CD8+ TRM populations, providing insights into the mechanisms underlying the origins, differentiation, and persistence of CD4+ TRM in response to viral infection.

DNA architectural protein CTCF facilitates subset-specific chromatin interactions to limit the formation of memory CD8+ T cells

Although the importance of genome organization for transcriptional regulation of cell-fate decisions and function is clear, the changes in chromatin architecture and how these impact effector and memory CD8+ T cell differentiation remain unknown. Using Hi-C, we studied how genome configuration is integrated with CD8+ T cell differentiation during infection and investigated the role of CTCF, a key chromatin remodeler, in modulating CD8+ T cell fates through CTCF knockdown approaches and perturbation of specific CTCF-binding sites. We observed subset-specific changes in chromatin organization and CTCF binding and revealed that weak-affinity CTCF binding promotes terminal differentiation of CD8+ T cells through the regulation of transcriptional programs. Further, patients with de novo CTCF mutations had reduced expression of the terminal-effector genes in peripheral blood lymphocytes. Therefore, in addition to establishing genome architecture, CTCF regulates effector CD8+ T cell heterogeneity through altering interactions that regulate the transcription factor landscape and transcriptome.

JAKs and STATs from a Clinical Perspective: Loss-of-Function Mutations, Gain-of-Function Mutations, and Their Multidimensional Consequences

The JAK/STAT signaling pathway plays a key role in cytokine signaling and is involved in development, immunity, and tumorigenesis for nearly any cell. At first glance, the JAK/STAT signaling pathway appears to be straightforward. However, on closer examination, the factors influencing the JAK/STAT signaling activity, such as cytokine diversity, receptor profile, overlapping JAK and STAT specificity among non-redundant functions of the JAK/STAT complexes, positive regulators (e.g., cooperating transcription factors), and negative regulators (e.g., SOCS, PIAS, PTP), demonstrate the complexity of the pathway's architecture, which can be quickly disturbed by mutations. The JAK/STAT signaling pathway has been, and still is, subject of basic research and offers an enormous potential for the development of new methods of personalized medicine and thus the translation of basic molecular research into clinical practice beyond the use of JAK inhibitors. Gain-of-function and loss-of-function mutations in the three immunologically particularly relevant signal transducers STAT1, STAT3, and STAT6 as well as JAK1 and JAK3 present themselves through individual phenotypic clinical pictures. The established, traditional paradigm of loss-of-function mutations leading to immunodeficiency and gain-of-function mutation leading to autoimmunity breaks down and a more differentiated picture of disease patterns evolve. This review is intended to provide an overview of these specific syndromes from a clinical perspective and to summarize current findings on pathomechanism, symptoms, immunological features, and therapeutic options of STAT1, STAT3, STAT6, JAK1, and JAK3 loss-of-function and gain-of-function diseases.

License to kill: Retinoic acid programs T cells for tissue residency

In this issue of JEM, Qiu et al. (2023. J. Exp. Med. https://doi.org/10.1084/jem.20210923) show that retinoic acid signaling during priming in the mesenteric lymph node licenses CD8+ T cells to develop into small intestinal tissue-resident memory cells, a finding that provides key insights into tissue-specific vaccination strategies.

Monogenic early-onset lymphoproliferation and autoimmunity: Natural history of STAT3 gain-of-function syndrome

BACKGROUND

In 2014, germline signal transducer and activator of transcription (STAT) 3 gain-of-function (GOF) mutations were first described to cause a novel multisystem disease of early-onset lymphoproliferation and autoimmunity.

OBJECTIVE

This pivotal cohort study defines the scope, natural history, treatment, and overall survival of a large global cohort of patients with pathogenic STAT3 GOF variants.

METHODS

We identified 191 patients from 33 countries with 72 unique mutations. Inclusion criteria included symptoms of immune dysregulation and a biochemically confirmed germline heterozygous GOF variant in STAT3.

RESULTS

Overall survival was 88%, median age at onset of symptoms was 2.3 years, and median age at diagnosis was 12 years. Immune dysregulatory features were present in all patients: lymphoproliferation was the most common manifestation (73%); increased frequencies of double-negative (CD4-CD8-) T cells were found in 83% of patients tested. Autoimmune cytopenias were the second most common clinical manifestation (67%), followed by growth delay, enteropathy, skin disease, pulmonary disease, endocrinopathy, arthritis, autoimmune hepatitis, neurologic disease, vasculopathy, renal disease, and malignancy. Infections were reported in 72% of the cohort. A cellular and humoral immunodeficiency was observed in 37% and 51% of patients, respectively. Clinical symptoms dramatically improved in patients treated with JAK inhibitors, while a variety of other immunomodulatory treatment modalities were less efficacious. Thus far, 23 patients have undergone bone marrow transplantation, with a 62% survival rate.

CONCLUSION

STAT3 GOF patients present with a wide array of immune-mediated disease including lymphoproliferation, autoimmune cytopenias, and multisystem autoimmunity. Patient care tends to be siloed, without a clear treatment strategy. Thus, early identification and prompt treatment implementation are lifesaving for STAT3 GOF syndrome.

Revisiting autoimmune lymphoproliferative syndrome caused by Fas ligand mutations

BACKGROUND

Fas ligand (FasL) is expressed by activated T cells and induces death in target cells upon binding to Fas. Loss-of-function FAS or FASLG mutations cause autoimmune-lymphoproliferative syndrome (ALPS) characterized by expanded double-negative T cells (DNT) and elevated serum biomarkers. While most ALPS patients carry heterozygous FAS mutations, FASLG mutations are rare and usually biallelic. Only 2 heterozygous variants were reported, associated with an atypical clinical phenotype.

OBJECTIVE

We revisited the significance of heterozygous FASLG mutations as a cause of ALPS.

METHODS

Clinical features and biomarkers were analyzed in 24 individuals with homozygous or heterozygous FASLG variants predicted to be deleterious. Cytotoxicity assays were performed with patient T cells and biochemical assays with recombinant FasL.

RESULTS

Homozygous FASLG variants abrogated cytotoxicity and resulted in early-onset severe ALPS with elevated DNT, raised vitamin B₁₂, and usually no soluble FasL. In contrast, heterozygous variants affected FasL function by reducing expression, impairing trimerization, or preventing Fas binding. However, they were not associated with elevated DNT and vitamin B₁₂, and they did not affect FasL-mediated cytotoxicity. The dominant-negative effects of previously published variants could not be confirmed. Even Y166C, causing loss of Fas binding with a dominant-negative effect in biochemical assays, did not impair cellular cytotoxicity or cause vitamin B₁₂ and DNT elevation.

CONCLUSION

Heterozygous loss-of-function mutations are better tolerated for FASLG than for FAS, which may explain the low frequency of ALPS-FASLG.

Exhaustion of CD39-Expressing CD8+ T Cells in Crohn's Disease Is Linked to Clinical Outcome

BACKGROUND & AIMS

Exhaustion of CD8 T cells has been suggested to inform different clinical outcomes in Crohn's disease, but detailed analyses are lacking. This study aimed to identify the role of exhaustion on a single-cell level and identify relevant CD8 T cell populations in Crohn's disease.

METHODS

Blood and intestinal tissue from 58 patients with Crohn's disease (active disease or remission) were assessed for CD8 T cell expression of exhaustion markers and their cytokine profile by highly multiplexed flow and mass cytometry. Key disease-associated subsets were sorted and analyzed by RNA sequencing. CD39 inhibition assays were performed in vitro.

RESULTS

Activated CD39⁺ and CD39⁺PD-1⁺ CD8 T cell subsets expressing multiple exhaustion markers were enriched at low frequency in active Crohn's disease. Their cytokine production capacity was inversely linked to the Harvey-Bradshaw Index. Subset-level protein and transcriptome profiling revealed co-existence of effector and exhaustion programs in CD39⁺ and CD39⁺ PD-1⁺CD8 T cells, with CD39⁺ cells likely originating from the intestine. CD39 enzymatic activity controlled T cell cytokine production. Importantly, transcriptional exhaustion signatures were enriched in remission in CD39-expressing subsets with up-regulation of TOX. Subset-level transcriptomics revealed a CD39-related gene module that is associated with the clinical course.

CONCLUSIONS

These data showed a role for the exhaustion of peripheral CD39-expressing CD8 T cell subsets in Crohn's disease. Their low frequency illustrated the utility of single-cell cytometry methods for identification of relevant immune populations. Importantly, the link of their exhaustion status to the clinical activity and their specific gene signatures have implications for exhaustion-based personalized medicine approaches.

Evaluation of Laboratory and Sonographic Parameters for Detection of Portal Hypertension in Patients with Common Variable Immunodeficiency

Timely detection of portal hypertension as a manifestation in a subgroup of patients with common variable immunodeficiency (CVID) represents a challenge since it is usually not associated with liver cirrhosis. To identify relevant markers for portal hypertension, we evaluated clinical history, laboratory parameters, and abdominal ultrasound including liver elastography and biomarkers of extracellular matrix formation. Twenty seven (6%) of 479 CVID patients presented with clinically significant portal hypertension as defined by either the presence of esophageal varices or ascites. This manifestation occurred late during the course of the disease (11.8 years after first diagnosis of CVID) and was typically part of a multiorgan disease and associated with a high mortality (11/27 patients died during follow up). The strongest association with portal hypertension was found for splenomegaly with a longitudinal diameter of > 16 cm. Similarly, most patients presented with a liver stiffness measurement (LSM) of above 6.5 kPa, and a LSM above 20 kPa was always indicative of manifest portal hypertension. Additionally, many laboratory parameters including Pro-C4 were significantly altered in patients with portal hypertension without clearly increasing the discriminatory power to detect non-cirrhotic portal hypertension in CVID. Our data suggest that a spleen size above 16 cm and an elevated liver stiffness above 6.5 kPa should prompt further evaluation of portal hypertension and its sequelae, but earlier and better liquid biomarkers of this serious secondary complication in CVID are needed.

STAT3-confusion-of-function: beyond the loss and gain dualism

BACKGROUND

Germline mutations of signal transducer and activator of transcription 3 (STAT3) are responsible for two distinct human diseases: autosomal-dominant hyper-immunoglobulin E syndrome (AD-HIES) caused by STAT3 loss-of-function (STAT3-LOF) mutations and STAT3 gain-of-function (STAT3-GOF) disease. So far, these entities have been regarded as antithetic, with AD-HIES mainly associated with characteristic infections and a connective tissue phenotype and STAT3-GOF characterized by lymphoproliferation and poly-autoimmunity. The R335W substitution in the DNA binding domain of STAT3 was initially described in 2 patients with typical AD-HIES, but paradoxically, recent functional analysis demonstrated a GOF effect of this variant.

OBJECTIVE

We describe a patient with Sjögren syndrome and features of AD-HIES with this mutation and further characterize its molecular consequences.

METHODS

We provide a clinical and immunological description of the patient. We studied STAT phosphorylation in primary patient cells and used A4 cells transfected with the patient allele to study phosphorylation kinetics, transcriptional activity and target-gene induction.

RESULTS

The hybrid clinical features of the patient were associated with normal Th17 cells. We observed enhanced and prolonged STAT3 phosphorylation, an increased STAT3 driven luciferase reporter activity upon interleukin-6 stimulation, but reduced IL-6 induced SOCS3 production.

CONCLUSION

The germline R335W-STAT3 variant displays a mixed behavior in vitro that mainly shows gain-of-function, but also loss-of-function features. This is matched by an ambiguous clinical and immunological phenotype which dismantles the classical antithetic dualism of gain- versus loss-of-function. Germline STAT3 mutation related-disease represents a pathological spectrum with the p.R335W associated phenotype locating between the two recognized clinical disease patterns.

660 Targeting T cell fates: converting exhaustion to memory to improve immunotherapeutic responses to cancer

Background

In cancer, CD8+ T cells have the power to target and kill tumor cells with precision, but often fail due to chronic activation from the immunosuppressive tumor microenvironment (TME). T cells that experience prolonged activation in the TME differentiate into a severely dysfunctional cell state known as exhaustion. In healthy tissues, T cells differentiate into tissue-resident memory cells (TRM) in response to infection, which remain lodged in tissues to provide protection from reinfection. When TRM-like cells are found in patient tumors, they are correlated with improved outcomes and responses to immunotherapy. Understanding how to manipulate T cell fates in an effort to prevent exhaustion and favor TRM-characteristics could benefit cancer immunotherapy.

Methods

To explore differences between these cell states, we screened the core TRM gene-expression signatures for genes downregulated as T cells undergo terminal exhaustion. Targets were then overexpressed in antigen-specific T cells and adoptively transferred into tumor-bearing mice for analysis.

Results

Interestingly, many genes related to protein regulation and processing were identified, including a novel gene called Neuralized E3 Ubiquitin Protein Ligase 3 (Neurl3). Neurl3's function is not well described, however, experimentally mutating the RING domain suggests Neurl3 transfers ubiquitin to target proteins for degradation. When Neurl3 was overexpressed in tumor-specific T cells, we found tumor infiltrating lymphocytes still upregulated inhibitory receptors PD1 and Tim3, but showed enhanced anti-tumor function. Neurl3-overexpressing T cells had increased accumulation in the TME, upregulated canonical TRM markers CD69 and CD103, produced more cytokines, controlled tumor growth, and increased mouse survival in B16 melanoma.

Conclusions

These results highlight the understudied field of negative regulation of T cell function by protein degradation in T cell differentiation fate and uncover a potential gene target for immunocellular therapies to favor functional T cell fates in cancer.

Ethics Approval

The study was approved by UCSD's Institutional Animal Care and Use Committee, protocol number S04105.

A distinct CD38+CD45RA+ population of CD4+, CD8+, and double-negative T cells is controlled by FAS

The identification and characterization of rare immune cell populations in humans can be facilitated by their growth advantage in the context of specific genetic diseases. Here, we use autoimmune lymphoproliferative syndrome to identify a population of FAS-controlled TCRαβ⁺ T cells. They include CD4⁺, CD8⁺, and double-negative T cells and can be defined by a CD38⁺CD45RA⁺T-BET⁻ expression pattern. These unconventional T cells are present in healthy individuals, are generated before birth, are enriched in lymphoid tissue, and do not expand during acute viral infection. They are characterized by a unique molecular signature that is unambiguously different from other known T cell differentiation subsets and independent of CD4 or CD8 expression. Functionally, FAS-controlled T cells represent highly proliferative, noncytotoxic T cells with an IL-10 cytokine bias. Mechanistically, regulation of this physiological population is mediated by FAS and CTLA4 signaling, and its survival is enhanced by mTOR and STAT3 signals. Genetic alterations in these pathways result in expansion of FAS-controlled T cells, which can cause significant lymphoproliferative disease.

Germline STAT3 gain-of-function mutations in primary immunodeficiency: Impact on the cellular and clinical phenotype

Signal transducer and activator of transcription 3 (STAT3) is a key transcription factor involved in regulation of immune cell activation and differentiation. Recent discoveries highlight the role of germline activating STAT3 mutations in inborn errors of immunity characterized by early-onset multi-organ autoimmunity and lymphoproliferation. Much progress has been made in defining the clinical spectrum of STAT3 GOF disease and unraveling the molecular and cellular mechanisms underlying this disease. In this review, we summarize our current understanding of the disease and discuss the clinical phenotype, diagnostic approach, cellular and molecular effects of STAT3 GOF mutations and therapeutic concepts for these patients.

Therapeutic approaches to pediatric COVID-19: an online survey of pediatric rheumatologists

Data on therapy of COVID-19 in immunocompetent and immunosuppressed children are scarce. We aimed to explore management strategies of pediatric rheumatologists. All subscribers to international Pediatric Rheumatology Bulletin Board were invited to take part in an online survey on therapeutic approaches to COVID-19 in healthy children and children with autoimmune/inflammatory diseases (AID). Off-label therapies would be considered by 90.3% of the 93 participating respondents. In stable patients with COVID-19 on oxygen supply (stage I), use of remdesivir (48.3%), azithromycin (26.6%), oral corticosteroids (25.4%) and/or hydroxychloroquine (21.9%) would be recommended. In case of early signs of “cytokine storm” (stage II) or in critically ill patients (stage III) (a) anakinra (79.5% stage II; 83.6% stage III) or tocilizumab (58.0% and 87.0%, respectively); (b) corticosteroids (oral 67.2% stage II, intravenously 81.7% stage III); (c) intravenous immunoglobulins (both stages 56.5%); or (d) remdesivir (both stages 46.7%) were considered. In AID, > 94.2% of the respondents would not support a preventive adaptation of the immunomodulating therapy. In case of mild COVID-19, more than 50% of the respondents would continue pre-existing treatment with immunoglobulins (100%), hydroxychloroquine (94.2%), anakinra (79.2%) or canakinumab (72.5%), or tocilizumab (69.8%). Long-term corticosteroids would be reduced by 26.9% (< = 2 mg/kg/d) and 50.0% (> 2 mg/kg/day), respectively, with only 5.8% of respondents voting to discontinue the therapy. Conversely, more than 75% of respondents would refrain from administering cyclophosphamide and anti-CD20-antibodies. As evidence on management of pediatric COVID-19 is incomplete, continuous and critical expert opinion and knowledge exchange is helpful.

Seletalisib for Activated PI3Kδ Syndromes: Open-Label Phase 1b and Extension Studies

Mutations in two genes can result in activated PI3Kδ syndrome (APDS), a rare immunodeficiency disease with limited therapeutic options. Seletalisib, a potent, selective PI3Kδ inhibitor, was evaluated in patients with APDS1 and APDS2. In the phase 1b study (European Clinical Trials Database 2015-002900-10) patients with genetic and clinical confirmation of APDS1 or APDS2 received 15-25 mg/d seletalisib for 12 wk. Patients could enter an extension study (European Clinical Trials Database 2015-005541). Primary endpoints were safety and tolerability, with exploratory efficacy and immunology endpoints. Seven patients (median age 15 years; APDS1 n = 3; APDS2 n = 4) received seletalisib; five completed the phase 1b study. For the extension study, four patients entered, one withdrew consent (week 24), three completed ≥84 wk of treatment. In the phase 1b study, patients had improved peripheral lymphadenopathy (n = 2), lung function (n = 1), thrombocyte counts (n = 1), and chronic enteropathy (n = 1). Overall, effects were maintained in the extension. In the phase 1b study, percentages of transitional B cells decreased, naive B cells increased, and senescent CD8 T cells decreased (human cells); effects were generally maintained in the extension. Seletalisib-related adverse events occurred in four of seven patients (phase 1b study: hepatic enzyme increased, dizziness, aphthous ulcer, arthralgia, arthritis, increased appetite, increased weight, restlessness, tendon disorder, and potential drug-induced liver injury) and one of four patients had adverse events in the extension (aphthous ulcer). Serious adverse events occurred in three of seven patients (phase 1b study: hospitalization, colitis, and potential drug-induced liver injury) and one of four patients had adverse events in the extension (stomatitis). Patients with APDS receiving seletalisib had improvements in variable clinical and immunological features, and a favorable risk-benefit profile was maintained for ≤96 wk.

Early-onset autoimmunity associated with SOCS1 haploinsufficiency

Autoimmunity can occur when a checkpoint of self-tolerance fails. The study of familial autoimmune diseases can reveal pathophysiological mechanisms involved in more common autoimmune diseases. Here, by whole-exome/genome sequencing we identify heterozygous, autosomal-dominant, germline loss-of-function mutations in the SOCS1 gene in ten patients from five unrelated families with early onset autoimmune manifestations. The intracellular protein SOCS1 is known to downregulate cytokine signaling by inhibiting the JAK-STAT pathway. Accordingly, patient-derived lymphocytes exhibit increased STAT activation in vitro in response to interferon-γ, IL-2 and IL-4 that is reverted by the JAK1/JAK2 inhibitor ruxolitinib. This effect is associated with a series of in vitro and in vivo immune abnormalities consistent with lymphocyte hyperactivity. Hence, SOCS1 haploinsufficiency causes a dominantly inherited predisposition to early onset autoimmune diseases related to cytokine hypersensitivity of immune cells.

[COVID-19: treatment strategies of German-speaking pediatric rheumatologists : Results of an online survey]

Hintergrund

Zuverlässige Daten zu Verlauf und Therapie von COVID-19 („corona virus disease 2019“) bei Kindern mit rheumatischen Erkrankungen unter Immunsuppression fehlen.

Ziel der Arbeit

Abbildung individueller Strategien der Mitglieder der Gesellschaft für Kinder- und Jugendrheumatologie (GKJR) im Umgang mit COVID-19.

Methodik

Mittels Online-Umfrage wurden im Mai 2020 das Meinungsbild der GKJR-Mitglieder zum Umgang mit DMARDs („disease-modifying anti-rheumatic drugs“) bei COVID-19-Erkrankung sowie die Bereitschaft zum Einsatz spezieller Therapieansätze bei Patienten mit unterschiedlicher Schwere von COVID-19 erhoben.

Ergebnisse

Es nahmen 71 Kollegen (27,3 % aller befragten ärztlichen Mitglieder) an der Umfrage teil; davon hatten 28,2 % bereits Patienten mit COVID-19 betreut. Über 95 % der Teilnehmer lehnten eine präventive Anpassung der antirheumatischen Therapie im Rahmen der SARS-CoV-2-Pandemie ab. Bei ambulanten Patienten unter Immunsuppression mit nachgewiesener COVID-19-Erkrankung würden mehr als 50 % der Teilnehmer folgende Therapien aussetzen: intravenöse hoch dosierte Steroide, Cyclophosphamid, Anti-CD20-Antikörper, sowie eine BAFF-, CTLA-4-, TNF-α-Blockade. Hingegen würden nichtsteroidale Antiphlogistika, Hydroxychloroquin (HCQ), orale Steroide, Mycophenolat, IL-1-Blockade sowie Immunglobuline (Ig) von >70 % der Kollegen weiter fortgeführt. Bei stationären Patienten mit COVID-19 würden insgesamt 74,6 % der Kollegen eine COVID-19-gerichtete Therapie erwägen. Bei stabilem Verlauf unter O₂-Therapie (Stufe I) würden am häufigsten HCQ (18,3 %), Azithromycin (16,9 %) und Ig (9,9 %) in Betracht gezogen. Bei drohendem (Stufe II) bzw. manifestem Zytokinsturm (Stufe III) würden am häufigsten Anakinra (40,8 % bei Stufe II bzw. 46,5 % bei Stufe III), Tocilizumab (26,8 % bzw. 40,8 %), Steroide (25,4 % bzw. 33,8 %) und Remdesivir (29,6 % bzw. 38,0 %) eingesetzt. Von vielen Kollegen wurde betont, dass die Therapiestrategie individuell und der klinischen Situation entsprechend angepasst werden soll.

Diskussion

Die Ergebnisse der Online-Umfrage sind vor dem Hintergrund einer aktuell in Deutschland niedrigen Prävalenz von COVID-19 zu sehen und spiegeln somit theoretische Überlegungen der Befragten wider. Da Kinder derzeit nicht im Fokus von prospektiven COVID-19-Studien stehen, scheint der kontinuierliche und kritische kollegiale Fachaustausch bei Therapieentscheidungen umso wichtiger zu sein.

Comprehensive infectious disease screening in a cohort of unaccompanied refugee minors in Germany from 2016 to 2017: A cross-sectional study

BACKGROUND

Information regarding the prevalence of infectious diseases (IDs) in child and adolescent refugees in Europe is scarce. Here, we evaluate a standardized ID screening protocol in a cohort of unaccompanied refugee minors (URMs) in a municipal region of southwest Germany.

METHODS AND FINDINGS

From January 2016 to December 2017, we employed a structured questionnaire to screen a cohort of 890 URMs. Collecting sociodemographic information and medical history, we also performed a standardized diagnostics panel, including complete blood count, urine status, microbial stool testing, tuberculosis (TB) screening, and serologies for hepatitis B virus (HBV) and human immunodeficiency virus (HIV). The mean age was 16.2 years; 94.0% were male, and 93.6% originated from an African country. The most common health complaints were dental problems (66.0%). The single most frequent ID was scabies (14.2%). Of the 776 URMs originating from high-prevalence countries, 7.7% and 0.4% tested positive for HBV and HIV, respectively. Nineteen pathogens were detected in a total of 119 stool samples (16.0% positivity), with intestinal schistosomiasis being the most frequent pathogen (6.7%). Blood eosinophilia proved to be a nonspecific criterion for the detection of parasitic infections. Active pulmonary TB was identified in 1.7% of URMs screened. Of note, clinical warning symptoms (fever, cough >2 weeks, and weight loss) were insensitive parameters for the identification of patients with active TB. Study limitations include the possibility of an incomplete eosinophilia workup (as no parasite serologies or malaria diagnostics were performed), as well as the inherent selection bias in our cohort because refugee populations differ across Europe.

CONCLUSIONS

Our study found that standardized ID screening in a URM cohort was practicable and helped collection of relevant patient data in a thorough and time-effective manner. However, screening practices need to be ameliorated, especially in relation to testing for parasitic infections. Most importantly, we found that only a minority of infections were able to be detected clinically. This underscores the importance of active surveillance of IDs among refugees.

Distinct molecular response patterns of activating STAT3 mutations associate with penetrance of lymphoproliferation and autoimmunity

Germline STAT3 gain-of-function (GOF) mutations have been linked to poly-autoimmunity and lymphoproliferation with variable expressivity and incomplete penetrance. Here we studied the impact of 17 different STAT3 GOF mutations on the canonical STAT3 signaling pathway and correlated the molecular results with clinical manifestations. The mutations clustered in three groups. Group 1 mutants showed altered STAT3 phosphorylation kinetics and strong basal transcriptional activity. They were associated with the highest penetrance of lymphoproliferation and autoimmunity. Group 2 mutants showed a strongly inducible transcriptional reporter activity and were clinically less penetrant. Group 3 mutants were mostly located in the DNA binding domain and showed the strongest DNA binding affinity despite a poor transcriptional reporter response. Thus, the GOF effect of STAT3 mutations is determined by a heterogeneous response pattern at the molecular level. The correlation of response pattern and clinical penetrance indicates a significant contribution of mutation-determined effects on disease manifestations.

The German National Registry of Primary Immunodeficiencies (2012-2017)

Introduction: The German PID-NET registry was founded in 2009, serving as the first national registry of patients with primary immunodeficiencies (PID) in Germany. It is part of the European Society for Immunodeficiencies (ESID) registry. The primary purpose of the registry is to gather data on the epidemiology, diagnostic delay, diagnosis, and treatment of PIDs. Methods: Clinical and laboratory data was collected from 2,453 patients from 36 German PID centres in an online registry. Data was analysed with the software Stata® and Excel. Results: The minimum prevalence of PID in Germany is 2.72 per 100,000 inhabitants. Among patients aged 1-25, there was a clear predominance of males. The median age of living patients ranged between 7 and 40 years, depending on the respective PID. Predominantly antibody disorders were the most prevalent group with 57% of all 2,453 PID patients (including 728 CVID patients). A gene defect was identified in 36% of patients. Familial cases were observed in 21% of patients. The age of onset for presenting symptoms ranged from birth to late adulthood (range 0-88 years). Presenting symptoms comprised infections (74%) and immune dysregulation (22%). Ninety-three patients were diagnosed without prior clinical symptoms. Regarding the general and clinical diagnostic delay, no PID had undergone a slight decrease within the last decade. However, both, SCID and hyper IgE- syndrome showed a substantial improvement in shortening the time between onset of symptoms and genetic diagnosis. Regarding treatment, 49% of all patients received immunoglobulin G (IgG) substitution (70%-subcutaneous; 29%-intravenous; 1%-unknown). Three-hundred patients underwent at least one hematopoietic stem cell transplantation (HSCT). Five patients had gene therapy. Conclusion: The German PID-NET registry is a precious tool for physicians, researchers, the pharmaceutical industry, politicians, and ultimately the patients, for whom the outcomes will eventually lead to a more timely diagnosis and better treatment.

Clinical and Immunological Phenotype of Patients With Primary Immunodeficiency Due to Damaging Mutations in NFKB2

Non-canonical NF-κB-pathway signaling is integral in immunoregulation. Heterozygous mutations in NFKB2 have recently been established as a molecular cause of common variable immunodeficiency (CVID) and DAVID-syndrome, a rare condition combining deficiency of anterior pituitary hormone with CVID. Here, we investigate 15 previously unreported patients with primary immunodeficiency (PID) from eleven unrelated families with heterozygous NFKB2-mutations including eight patients with the common p.Arg853^* nonsense mutation and five patients harboring unique novel C-terminal truncating mutations. In addition, we describe the clinical phenotype of two patients with proximal truncating mutations. Cohort analysis extended to all 35 previously published NFKB2-cases revealed occurrence of early-onset PID in 46/50 patients (mean age of onset 5.9 years, median 4.0 years). ACTH-deficiency occurred in 44%. Three mutation carriers have deceased, four developed malignancies. Only two mutation carriers were clinically asymptomatic. In contrast to typical CVID, most patients suffered from early-onset and severe disease manifestations, including clinical signs of T cell dysfunction e.g., chronic-viral or opportunistic infections. In addition, 80% of patients suffered from (predominately T cell mediated) autoimmune (AI) phenomena (alopecia > various lymphocytic organ-infiltration > diarrhea > arthritis > AI-cytopenia). Unlike in other forms of CVID, auto-antibodies or lymphoproliferation were not common hallmarks of disease. Immunophenotyping showed largely normal or even increased quantities of naïve and memory CD4⁺ or CD8⁺ T-cells and normal T-cell proliferation. NK-cell number and function were also normal. In contrast, impaired B-cell differentiation and hypogammaglobinemia were consistent features of NFKB2-associated disease. In addition, an array of lymphocyte subpopulations, such as regulatory T cell, Th17-, cTFH-, NKT-, and MAIT-cell numbers were decreased. We conclude that heterozygous damaging mutations in NFKB2 represent a distinct PID entity exceeding the usual clinical spectrum of CVID. Impairment of the non-canonical NF-κB pathways affects function and differentiation of numerous lymphocyte-subpopulations and thus causes a heterogeneous, more severe form of PID phenotype with early-onset. Further characteristic features are multifaceted, primarily T cell-mediated autoimmunity, such as alopecia, lymphocytic organ infiltration, and in addition frequently ACTH-deficiency.

Is an infectious trigger always required for primary hemophagocytic lymphohistiocytosis? Lessons from in utero and neonatal disease

In this report, we evaluate the hypothesis that hemophagocytic lymphohistiocytosis in patients with defects of lymphocyte cytotoxicity is usually triggered by infections. We show that in the majority of patients, extensive virus PCR panels performed in addition to routine microbiological investigations remain negative and summarize 25 patients with onset of hemophagocytic lymphohistiocytosis in utero or within the first 10 days of life, in none of which an associated bacterial or viral infection was reported. These observations, even though preliminary, invite to consider a key role of lymphocyte cytotoxicity in controlling T-cell homeostasis also in the absence of apparent infectious stimuli.

Disease Evolution and Response to Rapamycin in Activated Phosphoinositide 3-Kinase δ Syndrome: The European Society for Immunodeficiencies-Activated Phosphoinositide 3-Kinase δ Syndrome Registry

Activated phosphoinositide 3-kinase (PI3K) δ Syndrome (APDS), caused by autosomal dominant mutations in PIK3CD (APDS1) or PIK3R1 (APDS2), is a heterogeneous primary immunodeficiency. While initial cohort-descriptions summarized the spectrum of clinical and immunological manifestations, questions about long-term disease evolution and response to therapy remain. The prospective European Society for Immunodeficiencies (ESID)-APDS registry aims to characterize the disease course, identify outcome predictors, and evaluate treatment responses. So far, 77 patients have been recruited (51 APDS1, 26 APDS2). Analysis of disease evolution in the first 68 patients pinpoints the early occurrence of recurrent respiratory infections followed by chronic lymphoproliferation, gastrointestinal manifestations, and cytopenias. Although most manifestations occur by age 15, adult-onset and asymptomatic courses were documented. Bronchiectasis was observed in 24/40 APDS1 patients who received a CT-scan compared with 4/15 APDS2 patients. By age 20, half of the patients had received at least one immunosuppressant, but 2-3 lines of immunosuppressive therapy were not unusual before age 10. Response to rapamycin was rated by physician visual analog scale as good in 10, moderate in 9, and poor in 7. Lymphoproliferation showed the best response (8 complete, 11 partial, 6 no remission), while bowel inflammation (3 complete, 3 partial, 9 no remission) and cytopenia (3 complete, 2 partial, 9 no remission) responded less well. Hence, non-lymphoproliferative manifestations should be a key target for novel therapies. This report from the ESID-APDS registry provides comprehensive baseline documentation for a growing cohort that will be followed prospectively to establish prognostic factors and identify patients for treatment studies.

Primary and secondary hemophagocytic lymphohistiocytosis have different patterns of T-cell activation, differentiation and repertoire

Hemophagocytic lymphohistiocytosis (HLH) is a life‐threatening inflammatory syndrome characterized by hyperactivation of lymphocytes and histiocytes. T cells play a key role in HLH pathogenesis, but their differentiation pattern is not well characterized in patients with active HLH. We compared T‐cell activation patterns between patients with familial HLH (1°HLH), 2°HLH without apparent infectious trigger (2°HLH) and 2°HLH induced by a viral infection (2°V‐HLH). Polyclonal CD8⁺ T cells are highly activated in 1°HLH and 2°V‐HLH, but less in 2°HLH as assessed by HLA‐DR expression and marker combination with CD45RA, CCR7, CD127, PD‐1 and CD57. Absence of increased HLA‐DR expression on T cells excluded active 1° HLH with high sensitivity and specificity. A high proportion of polyclonal CD127⁻CD4⁺ T cells expressing HLA‐DR, CD57, and perforin is a signature of infants with 1°HLH, much less prominent in virus‐associated 2°HLH. The similar pattern and extent of CD8⁺ T‐cell activation compared to 2° V‐HLH is compatible with a viral trigger of 1°HLH. However, in most 1°HLH patients no triggering infection was documented and the unique activation of cytotoxic CD4⁺ T cells indicates that the overall T‐cell response in 1°HLH is different. This may reflect different pathways of pathogenesis of these two HLH variants.

OX40 facilitates control of a persistent virus infection

During acute viral infections, clearance of the pathogen is followed by the contraction of the anti-viral T cell compartment. In contrast, T cell responses need to be maintained over a longer period of time during chronic viral infections in order to control viral replication and to avoid viral spreading. Much is known about inhibitory signals such as through PD-1 that limit T cell activity during chronic viral infection, but little is known about the stimulatory signals that allow maintenance of anti-viral T cells. Here, we show that the co-stimulatory molecule OX40 (CD134) is critically required in the context of persistent LCMV clone 13 infection. Anti-viral T cells express high levels of OX40 in the presence of their cognate antigen and T cells lacking the OX40 receptor fail to accumulate sufficiently. Moreover, the emergence of T cell dependent germinal center responses and LCMV-specific antibodies are severely impaired. Consequently, OX40-deficient mice fail to control LCMV clone 13 infection over time, highlighting the importance of this signaling pathway during persistent viral infection.

A robust T cell response is the hallmark of an effective immune response to a variety of invading viruses. In many acute infections, the clearance of the viral pathogen is associated with a short and vigorous T cell response followed by development of pathogen-specific immune memory. However, some viruses can establish persistent infection in their respective host, during which an ongoing T cell response is required in order to prevent overwhelming viral replication. Little is known about the factors that sustain the T cell response in the persistent phase of a viral infection. In this report, we demonstrate that ligation of the OX40 molecule, which is expressed on T cells targeting the virus, is critically required in order to sustain the anti-viral immune response. We show that virus-specific, OX40-deficient T cells fail to accumulate sufficiently and consequently, mice lacking the OX40 receptor are incapable of controlling viral replication. Collectively our data establish OX40 as a crucial signaling molecule during a persistent viral infection.

Minimal T-cell-stimulatory sequences and spectrum of HLA restriction of immunodominant CD4+ T-cell epitopes within hepatitis C virus NS3 and NS4 proteins

The hepatitis C virus (HCV)-specific CD4+ T-cell response against nonstructural proteins is strongly associated with successful viral clearance during acute hepatitis C. To further develop these observations into peptide-based vaccines and clinical immunomonitoring tools like HLA class II tetramers, a detailed characterization of immunodominant CD4+ T-cell epitopes is required. We studied peripheral blood mononuclear cells from 20 patients with acute hepatitis C using 83 overlapping 20-mer peptides covering the NS3 helicase and NS4. Eight peptides were recognized by > or = 40% of patients, and specific CD4+ T-cell clones were obtained for seven of these and three additional, subdominant epitopes. Mapping of minimal stimulatory sequences defined epitopes of 8 to 13 amino acids in length, but optimal T-cell stimulation was observed with 10- to 15-mers. While some epitopes were presented by different HLA molecules, others were presented by only a single HLA class II molecule, which has implications for patient selection in clinical trials of peptide-based immunotherapies. In conclusion, using two different approaches we identified and characterized a set of CD4+ T-cell epitopes in the HCV NS3-NS4 region which are immunodominant in patients achieving transient or persistent viral control. This information allows the construction of a valuable panel of HCV-specific HLA class II tetramers for further study of CD4+ T-cell responses in chronic hepatitis C. The finding of immunodominant epitopes with very constrained HLA restriction has implications for patient selection in clinical trials of peptide-based immunotherapies.

[Three patients with hereditary multiple exostoses and malignant degeneration of an osteochondroma located in the pelvis]

In three male patients with hereditary multiple exostoses (HME), aged 50, 29 and 31 years, peripheral low-grade chondrosarcoma in the pelvic region led to swelling or pain. In the first patient, curative resection was not feasible because of the size and extension of the tumour. However, rapid tumour growth and unbearable pain necessitated a debulking procedure 16 months later. Histopathologic examination revealed a highly malignant dedifferentiated chondrosarcoma. The patient died two years after initial presentation as a result of local tumour growth. In the second patient, treatment consisted of wide resection of the tumour. Five years after the surgery the patient was free of disease. The third patient was initially treated by intralesional resection, followed by partial hemipelvectomy because of residual tumour. Thirteen months later, a local recurrence occurred that was treated by wide excision. Four years after the partial hemipelvectomy the patient was both pain-free and disease-free. Patients with HME are at increased risk for malignant degeneration of pelvic osteochondroma to chondrosarcoma. Periodic control of patients with pelvic osteochondromas is advised, preferably once every two years.

Cortical fibroblast culture from human biopsies

BACKGROUND

Tubulointerstitial fibrosis is an integral part of progressive renal disease. Human cortical fibroblasts are believed to be key effector cells in fibrogenesis. Thus, a reliable culture of these cells is necessary for studies of their pathophysiology.

METHODS

Cortical fibroblast culture from routine kidney biopsies were analyzed and the cells were characterized. Indirect immunofluorescence staining was done after the first passage for cytokeratin, vimentin, alpha-smooth muscle actin, CD 44, CD 54, CD 68, collagen types I, III, and HLA-DR. We then assessed the utility of the putative fibroblast markers CD 90, prolyl-4-hydroxylase (P4H) and F1b in simultaneous stainings of tubular epithelial cells.

RESULTS

During the study period, 49 biopsy cores were cultured and cortical fibroblasts could be successfully established in 21 cases (42.9%). There was no relation between the success rate of culture and the degree of interstitial fibrosis, but an association was seen with the time of completion of the first passage. There was a negative correlation between the extent of scarring and the percentage of cytokeratin positive cells (r = -0.66, p < 0.001). All primary fibroblasts were negative for factor VIII, HLA-DR, CD 68, and cytokeratin. They expressed alpha-smooth muscle actin and collagen types I and III to variable degrees. There was a robust correlation between the percentage of alpha-smooth muscle actin positive cells and interstitial scarring but no such association with collagen type I or type III positive cells. The three putative fibroblast markers did not prove useful in differentiating between tubular epithelial cells and fibroblasts. However, since only fibroblasts stained positive for CD 90 and negative for cytokeratin, these two markers may suffice to distinguish fibroblasts from other renal cellular elements.

CONCLUSIONS

Cortical renal fibroblasts can be easily cultured from kidney biopsy cores, though the success rate of pure cultures is below 50%. Staining for CD 90 and cytokeratin may suffice for initial characterization of these cells.

Effects of pentoxifylline, pentifylline and gamma-interferon on proliferation, differentiation, and matrix synthesis of human renal fibroblasts

BACKGROUND

Kidneys that progress to end-stage renal failure are almost invariably characterized by the presence of tubulointerstitial fibrosis. Therapeutic interventions to halt the progressive deterioration of renal function are still limited. Pentoxifylline, pentifylline, and gamma-interferon have shown a potential benefit in the treatment of fibrotic processes in the skin and lung. Thus, the aim of the present study was the analysis of potential anti-fibrotic effects of these substances on human kidney fibroblasts in vitro.

METHODS

Primary renal fibroblasts were established from human kidney biopsies and were studied in addition to two renal fibroblast cell lines. Cells were first growth arrested by withdrawal of fetal calf serum (FCS) and subsequently stimulated with 10% FCS in the presence of different concentrations of pentoxifylline (PTX), pentifylline (PTF), or gamma-interferon (IFN-gamma). Fibroblast proliferation was determined by bromodeoxyuridine incorporation and cell counts. Northern and western blot hybridizations for basic fibroblast growth factor (FGF)-2 and transforming growth factor (TGF)-beta1 were performed to analyse inhibitory effects. The effects of all three substances on matrix synthesis were evaluated by immunoblot analyses and ELISA for collagen type I and fibronectin after stimulation with TGF-beta1. Finally, differentiation into myofibroblasts was examined by double immunofluorescence staining for alpha-smooth-muscle actin and Hoechst dye H33258.

RESULTS

PTX and PTF resulted in a dose- and time-dependent inhibition of proliferation in all fibroblast lines (maximum 78.9+/-6.2% at 500 microg/ml PTX). Conversely, IFN-gamma had only modest effects on fibroblast proliferation, resulting in a maximum of 36.0+/-6.1% inhibition at 500 U/ml. Northern blot hybridizations determined that FGF-2 mRNA levels in fibroblasts were decreased up to 73.7 and 91.5% by PTX (1000 microg/ml) and PTF (100 microg/ml), whereas IFN-gamma led to a reduction of 46.2% at 1000 U/ml, indicating that the inhibitory effects of all three substances may be mediated through inhibition of FGF-2 synthesis. These findings were corroborated by immunoblot analyses where again PTX and PTF had the strongest inhibitory effects. No change in TGF-beta1 mRNA levels was noted. Synthesis of cellular and secreted collagen type I was robustly inhibited by PTX and PTF, whereas IFN-gamma exerted the strongest inhibitory effect on fibronectin synthesis and secretion. In addition, IFN-gamma down-regulated the expression of alpha-smooth-muscle actin up to 73.3% (at 1000 U/ml) whereas PTX and PTF resulted in a down-regulation of up to 49.7+/-1.8 and 80.0+/-4.4% (at 1000 and 100 microg/ml) respectively. PTF was in all experiments about 10 times more potent than equimolar concentrations of PTX.

CONCLUSIONS

PTX and PTF exerted robust inhibitory effects on fibroblast proliferation, extracellular matrix synthesis, and myofibroblastic differentiation. Conversely, IFN-gamma caused strong inhibition of fibronectin synthesis and alpha-smooth-muscle cell actin expression but had only weak inhibitory influences on fibroblast proliferation and collagen type I synthesis. Inhibitory effects of all three substances on proliferation may be mediated through inhibition of FGF-2 synthesis.

Acetabular fractures in children and adolescents

A retrospective study of 29 acetabular fractures in children 2 to 16 years of age with an average followup of 14 years is presented. Nineteen patients had an additional dislocation of the femoral head and 14 patients had an associated neurologic injury. Surgical treatment was performed in 16 patients and consisted of open reduction and internal fixation in 14 patients and a simple arthrotomy in two patients. Thirteen patients were treated nonoperatively with traction or bedrest. The outcome was satisfactory in all patients with undisplaced fractures and fractures with disruption of a small fragment. Eight patients with linear fractures with instability all were treated surgically. All but one of the patients had a satisfactory functional outcome; one patient had early degenerative changes develop after an open pelvic and acetabular fracture. Patients with central fractures and dislocations had a relatively poor outcome, and congruency was achieved in only one of the four patients who were treated surgically. Results may deteriorate with time, as was seen when the results of the current study were compared with those published 10 years previously.

Neonatal infectious spondylitis of the cervical spine presenting with quadriplegia: a case report

STUDY DESIGN

A case report.-

OBJECTIVE

To highlight the evaluation and treatment of neonatal infectious spondylitis of the cervical spine.

SUMMARY OF BACKGROUND DATA

Most authors advise intravenous antibiotics as first-choice treatment. The place of aspiration or operative drainage is debated, as is the position and duration of immobilization.

METHODS

A 3-week-old neonate was presented with intermittent quadriplegia.

RESULTS

Additional investigation demonstrated an osteolytic process in the body of C3 with a large epidural abscess compressing the spinal cord. Because an infectious spondylitis of C3 was suspected, aspiration of the abscess was performed, and antibiotic therapy was started. The patient improved to neurologically normal within 3 weeks and remains asymptomatic throughout a follow-up period of 7 years.

CONCLUSIONS

Neonatal infectious spondylitis should be diagnosed early and treated promptly; otherwise, it may have devastating consequences.

Simultaneous occurrence of a supra- and an infratentorial glioma in a patient with Ollier's disease: more evidence for non-mesodermal tumor predisposition in multiple enchondromatosis

A case is presented in which two neuro-ectodermal tumors, an infra- and a supratentorial glioma, developed in a young man with multiple enchondromatosis of Ollier's disease. This is the third such case of multifocal low-grade glioma in Ollier's disease, suggesting a predisposition for non-mesodermal tumors in Ollier's disease. The related condition of multiple enchondromatosis and hemangiomas (Maffucci's syndrome) is well known for its malignant potential, developing both mesodermal and non-mesodermal tumors. Along with other authors, we support the concept of two variants of the same disease with a predisposition to development of tumors from various germ layers.

Total knee and hip arthroplasty in haemophilic patients

We evaluated the long-term results of three total hip and nine total knee arthroplasties in nine haemophilic patients with disabling pain and end-stage arthropathy. These patients have been followed over a period of 2-12 years (mean 6.9). One patient had a post-operative haematoma, which was evacuated; two patients required manipulation of the knee because of a limited range of motion. There were no infections. At follow-up, all but two patients were completely free of pain; two patients had occasional pain. The functional improvement was impressive with an average increase in the knee score from 37 to 80 points post-operatively. The hip score increased from 36 to 85 points. The range of motion was increased in seven joints, unchanged in two joints and decreased in three. One total hip arthroplasty was revised after 9 years for aseptic loosening. One total knee demonstrated nonprogressive radiographic evidence of aseptic loosening. Median consumption of coagulation factor concentrate in severe haemophiliacs decreased from 47.00 U yr-1 (range 16.000-144.000) before surgery, to 25.000 U yr-1 (range 18.000-132.000) at 2 years after surgery.

CONCLUSION

Hip and knee arthroplasty is a valuable option in symptomatic haemophilic patients with disabling arthropathy, in order to obtain pain relief and functional improvement. It is associated with a low rate of complications and may reduce the need for substitution of factor VIII and IX.

Rotationplasty of the lower limb for childhood osteosarcoma of the femur

BACKGROUND

Surgical management of osteosarcoma of the limb in childhood often involves extensive surgery. Intervention ranges from local resection to amputation depending on the level and the extent of the disease process. However, where the disease is extensive the level of amputation may preclude effective prosthetic use. In these circumstances resection of the diseased segment of the limb, i.e. an intercalary amputation and reconstruction with rotation of the tibial component of the limb can provide function equivalent to a below-knee amputee.

METHODS

To examine the role of rotationplasty of the lower limb for childhood osteosarcoma of the femur, a retrospective study was carried out which examined the function of five patients who had been treated by a tibial rotationplasty. The records of two patients who had died from metastatic disease 2 and 4 years after surgery were examined. The three surviving patients were examined clinically and their clinical records and radiographs were reviewed.

RESULTS

Of the two patients who died from metastatic disease, neither had local recurrence of the tumour, neurovascular complications, late derotations or psychological problems. In the three patients who survived, there had been no local recurrence of tumour or other complication and each has an excellent level of activity with below-knee function using a rotationplasty prosthesis.

CONCLUSIONS

For children with osteosarcoma of the femur and with extensive disease that precludes complete limb preservation, resection and tibial rotationplasty provides function far superior to a high above-knee amputation or a hip disarticulation without the risk of local recurrence.

Bilateral dislocation of the hip in spina bifida: a long-term follow-up study

Nineteen patients with spina bifida and bilateral dislocation of the hips were studied with a minimal follow-up of 10 years. The average age at review was 21 years (range, 10-31). Ten patients had an upper neurologic level (thoracic to L3), and nine had a low lesion (L4 to sacrum). Three patients had no hip surgery. A closed or open reduction was performed in 12 hips, supplemented by one or more surgical procedures. Of these, 10 remained enlocated, and two had redislocated. In all other hips, several surgical procedures were performed, aimed at improvement of hip-flexion deformity or stability. At follow-up, one patient had occasional pain in one hip, which was dysplastic. Of the 10 patients with a high lesion, only two were walkers, but both had bilateral dislocation of the hips at follow-up. In contrast, all nine patients were walkers, but four of these had bilateral dislocation at follow-up. We found that a level pelvis and good range of motion of the hips are more important for ambulation than is reduction of bilateral hip dislocation.

[One hundred years of orthopedics in the Netherlands. II. Treatment of fractures]

The treatment of fractures was originally conservative. Improvements in materials and surgical techniques and new insights into the biological aspects of fracture healing led to an increase of surgical treatment of fractures. The main breakthrough of osteosynthesis took place with the foundation of the Arbeitsgemeinschaft für Osteosynthesefragen (Study Group for Problems in Osteosynthesis) which had as its basic principles anatomical repositioning, stable internal fixation, atraumatic surgical technique and early mobilization. In general, surgical treatment is indicated for periarticular fractures, open fractures, fractures complicated by nervous or vascular lesions, pathological fractures and fractures in multiple injury patients. The question who should practise traumatology, the general or the orthopaedic surgeon, was initially a point of controversy; by now, cooperative teams have been formed based on appreciation of one another's qualities. The trend for the near future appears to be minimally invasive surgery, with indirect repositioning and fixation techniques and biological methods of stimulating fracture healing.

Excision of a haemophilic pseudotumour of the ilium, complicated by fistulation

We report the case of a patient with a haemophilic pseudotumour of the ilium who developed chronic fistulation, 6 months after en-bloc resection. During the initial resection, the large defect in the iliac wing was filled with bone cement, which may have contributed to fistula formation. A second surgical procedure consisted of excision of the fistula and bone cement and the dead space was obliterated by bringing the gluteus medius muscle into the defect. The fistula recurred, however. Reexcision of the fistula and obliteration of the dead space by a pedicled rectus abdominis muscle flap resulted in eradication of the fistula. We emphasize the importance of obliteration of dead space, resulting from large pseudotumour resection. The use of bone cement is not advocated. If a fistula does occur, a pedicled rectus abdominis muscle flap may be considered.

Karsch-Neugebauer syndrome in two sibs with unaffected parents

We report on 2 sisters with Karsch-Neugebauer syndrome comprising split foot and split hand anomalies in association with congenital nystagmus. These sisters share a nearly identical phenotype with the 8 previously reported instances of this disorder. Although genetic heterogeneity can not be formally excluded, most evidence suggests that Karsch-Neugebauer syndrome is an autosomal dominant disorder. If so, then this report of 2 affected sibs born to healthy parents is the second instance of apparent gonadal mosaicism in this disorder. The apparent high frequency of gonadal mosaicism is important to recognize in counseling families with this disorder.

Ambulation with the reciprocating-gait orthosis. Experience in 15 children with myelomeningocele or paraplegia

We reviewed 15 children with spina bifida or paraplegia who have used a reciprocating-gait orthosis between 1985 and 1995. All were nonfunctional ambulators. The level of the spinal lesions ranged from Th10 to L3. The mean age of fitting the orthosis was 5 years. 8 children have stopped using it at an average age of 10 years. The maximum ambulation level with the orthosis was a community ambulator in 4 children, household ambulator in 9 children and 2 remained nonfunctional ambulators. The average daily use was 6 hours by community ambulators to 0.5 hours nonfunctional ambulators. Bilateral dislocations of the hip, mild flexion deformities of the hips and knees and scoliosis were well tolerated with orthotic wear. Since functional ambulation could be achieved in 6 children with no quadriceps power, the use of this orthosis can be advocated for upper lumbar and low thoracic lesions. Strong motivation, realistic goals and expectations, the ability to participate in a training program and journeys for frequent orthosis repairs are of importance for successful use of this orthosis.