A trispecific antibody targeting HER2 and T cells inhibits breast cancer growth via CD4 cells.

Effective antitumour immunity depends on the orchestration of potent T cell responses against malignancies1. Regression of human cancers has been induced by immune checkpoint inhibitors, T cell engagers or chimeric antigen receptor T cell therapies2-4. Although CD8 T cells function as key effectors of these responses, the role of CD4 T cells beyond their helper function has not been defined. Here we demonstrate that a trispecific antibody to HER2, CD3 and CD28 stimulates regression of breast cancers in a humanized mouse model through a mechanism involving CD4-dependent inhibition of tumour cell cycle progression. Although CD8 T cells directly mediated tumour lysis in vitro, CD4 T cells exerted antiproliferative effects by blocking cancer cell cycle progression at G1/S. Furthermore, when T cell subsets were adoptively transferred into a humanized breast cancer tumour mouse model, CD4 T cells alone inhibited HER2+ breast cancer growth in vivo. RNA microarray analysis revealed that CD4 T cells markedly decreased tumour cell cycle progression and proliferation, and also increased pro-inflammatory signalling pathways. Collectively, the trispecific antibody to HER2 induced T cell-dependent tumour regression through direct antitumour and indirect pro-inflammatory/immune effects driven by CD4 T cells.

Nonclassical CD4+CD49b+ Regulatory T Cells as a Better Alternative to Conventional CD4+CD25+ T Cells To Dampen Arthritis Severity.

Promising immunotherapeutic strategies are emerging to restore tolerance in autoimmune diseases by triggering an increase in the number and/or the function of endogenous regulatory T (Treg) cells, which actively control pathological immune responses. Evidence suggests a remarkable heterogeneity in peripheral Treg cells that warrants their better characterization in terms of phenotype and suppressive function, to determine which subset may be optimally suitable for a given clinical situation. We found that repetitive injections of immature dendritic cells expanded Foxp3-negative CD49b(+) Treg cells that displayed an effector memory phenotype. These expanded Treg cells were isolated ex vivo for transcriptome analysis and found to contain multiple transcripts of the canonical Treg signature shared mainly by CD25(+) but also by other subphenotypes. We characterized the CD49b(+) Treg cell phenotype, underscoring its similarities with the CD25(+) Treg cell phenotype and highlighting some differential expression patterns for several markers, including lymphocyte activation gene 3, KLRG1, CD103, ICOS, CTLA-4, and granzyme B. Comparison of the CD25(+) and CD49b(+) Treg cells' suppressive mechanisms, in vitro and in vivo, revealed the latter's potent suppressive activity, which was partly dependent on IL-10 secretion. Altogether, our results strongly suggest that expression of several canonical Treg cell markers and suppressive function could be Foxp3 independent, and underscore the therapeutic potential of IL-10-secreting CD49b(+) Treg cells in arthritis.

Mouse and human CD8(+) CD28(low) regulatory T lymphocytes differentiate in the thymus.

Regulatory T (Treg) lymphocytes play a central role in the control of immune responses and so maintain immune tolerance and homeostasis. In mice, expression of the CD8 co-receptor and low levels of the co-stimulatory molecule CD28 characterizes a Treg cell population that exerts potent suppressive function in vitro and efficiently controls experimental immunopathology in vivo. It has remained unclear if CD8(+) CD28(low) Treg cells develop in the thymus or represent a population of chronically activated conventional T cells differentiating into Treg cells in the periphery, as suggested by their CD28(low) phenotype. We demonstrate that functional CD8(+) CD28(low) Treg cells are present in the thymus and that these cells develop locally and are not recirculating from the periphery. Differentiation of CD8(+) CD28(low) Treg cells requires MHC class I expression on radioresistant but not on haematopoietic thymic stromal cells. In contrast to other Treg cells, CD8(+) CD28(low) Treg cells develop simultaneously with CD8(+) CD28(high) conventional T cells. We also identified a novel homologous naive CD8(+) CD28(low) T-cell population with immunosuppressive properties in human blood and thymus. Combined, our data demonstrate that CD8(+) CD28(low) cells can develop in the thymus of mice and suggest that the same is true in humans.

Intrathymic progenitor cell transplantation across histocompatibility barriers results in the persistence of early thymic progenitors and T-cell differentiation.

Donor hematopoietic stem cells (HSCs) can correct T-cell deficiencies in patients with severe combined immunodeficiency by replacing resident thymus cells. However, as those progenitors that naturally migrate to the thymus are not capable of supporting long-term thymopoiesis, a successful transplant is thought to require the ongoing migration of donor progenitors. We previously showed that the forced intrathymic administration of histocompatible HSCs can sustain long-term thymopoiesis in ZAP-70-immunodeficient mice. However, it is not known whether T-cell reconstitution across histocompatibility barriers is modulated by intrathymic vs intravenous administration of HSCs. In the absence of conditioning, long-term thymopoiesis by semiallogeneic progenitors was detected in mice transplanted via the intrathymic, but not the intravenous, route. In intrathymic-transplanted mice, ongoing thymopoiesis was associated with a 10-fold higher level of early thymic progenitors (ETPs). The enhanced reconstitution capacity of these intrathymic-derived ETPs was corroborated by their significantly augmented myeloid lineage potential compared with endogenous ETPs. Notably, though, myeloablative conditioning resulted in a reduced expansion of intrathymic-administered donor ETPs. Thus, in the absence of conditioning, the forced thymic entry of HSCs results in a sustained T-cell development across histocompatibility barriers, highlighting the capacity of the thymus to support cells with long-term renewal potential.

Increased thymic development of regulatory T cells in NOD mice is functionally dissociated from type I diabetes susceptibility.

Regulatory T (Treg) lymphocytes play a central role in the control of autoimmune pathology. Any alteration in Treg-cell biology in mouse strains used for the study of these disorders therefore raises the question of its direct link with disease susceptibility. Paradoxically, in non-obese diabetic (NOD) mice increased numbers of Treg cells develop in the thymus. In this report we identify a locus of <7 Mbp that quantitatively controls Treg-cell development in the thymus of the NOD mouse. This 'Trd1' region is located centromeric to the H2 complex on chromosome 17 and does not include genes encoding classical MHC molecules. The genomic region identified here contains the Idd16 diabetes susceptibility locus and the use of congenic mouse strains allowed us to investigate the potential link between quantitatively altered thymic Treg cells and diabetes susceptibility. Hybrid mice present similar levels of thymic Treg cells as B6 animals but they developed diabetes with the same kinetics as NOD mice. Therefore, the increased Treg-cell development in NOD mice controlled by Trd1 is functionally dissociated from the susceptibility of NOD to diabetes.

The thymic niche does not limit development of the naturally diverse population of mouse regulatory T lymphocytes.

Thymus-derived CD4(+)Foxp3(+) regulatory T lymphocytes (Tregs) play a central role in the suppression of immune responses to self-antigens and thus avoid autoimmune disorders. It remains unclear if the specialized thymic niche controls the number of differentiating Tregs. We investigated development of murine Tregs from precursors expressing the naturally very large repertoire of TCRs. By analyzing their developmental kinetics, we observed that differentiating Tregs dwell in the thymus ∼1 d longer than their conventional T cell counterparts. By generating hematopoietic chimeras with very low proportions of trackable precursors, we could follow individual waves of developing T cells in the thymus. We observed strongly increased proportions of Tregs at the end of the waves, confirming that these cells are the last to leave the thymus. To assess whether the thymic niche limits Treg development, we generated hematopoietic chimeras in which very few T cell precursors could develop. The substantial increase in the proportion of Tregs we found in these mice suggested a limiting role of the thymic niche; however, this increase was accounted for entirely by the prolonged thymic dwell time of Tregs. We conclude that, when precursors express a naturally diverse TCR repertoire, the thymic niche does not limit differentiation of Tregs.

Molecular and cellular basis of T cell lineage commitment.

The thymus forms as an alymphoid thymic primordium with T cell differentiation requiring the seeding of this anlage. This review will focus on the characteristics of the hematopoietic progenitors which colonize the thymus and their subsequent commitment/differentiation, both in mice and men. Within the thymus, the interplay between Notch1 and IL-7 signals is crucial for the orchestration of T cell development, but the precise requirements for these factors in murine and human thympoeisis are not synonymous. Recent advances in our understanding of the mechanisms regulating precursor entry and their maintenance in the thymus will also be presented.

Autoimmune regulator (AIRE)-deficient CD8+CD28low regulatory T lymphocytes fail to control experimental colitis.

Mutations in the gene encoding the transcription factor autoimmune regulator (AIRE) are responsible for autoimmune polyendocrinopathy candidiasis ectodermal dystrophy syndrome. AIRE directs expression of tissue-restricted antigens in the thymic medulla and in lymph node stromal cells and thereby substantially contributes to induction of immunological tolerance to self-antigens. Data from experimental mouse models showed that AIRE deficiency leads to impaired deletion of autospecific T-cell precursors. However, a potential role for AIRE in the function of regulatory T-cell populations, which are known to play a central role in prevention of immunopathology, has remained elusive. Regulatory T cells of CD8(+)CD28(low) phenotype efficiently control immune responses in experimental autoimmune and colitis models in mice. Here we show that CD8(+)CD28(low) regulatory T lymphocytes from AIRE-deficient mice are transcriptionally and phenotypically normal and exert efficient suppression of in vitro immune responses, but completely fail to prevent experimental colitis in vivo. Our data therefore demonstrate that AIRE plays an important role in the in vivo function of a naturally occurring regulatory T-cell population.

D313Y variant in two related end-stage renal disease patients - Pathogenic or not yet?

Fabry disease is a multisystem lysosomal storage disorder caused by mutations in the GLA gene that result in a deficient or absent activity of alpha-galactosidase A. There is a wide spectrum of GLA gene variants, some of which are described as non-pathogenic. The clinical importance of the D313Y variant is still under debate, although in recent years it has been considered as a variant of unknown significance or a benign variant. Despite this prevailing notion, there are multiple case reports of patients with D313Y variant that presented signs and symptoms consistent with FD without any other etiological explanation. In this article, we present two family members with an important renal phenotype and other typical manifestations of FD (white matter lesions and left ventricular hypertrophy) that only had the D313Y variant. These cases suggest that this variant of unknown significance may contribute to the development of common features of FD and should not be undervalued.

Combined immunodeficiency caused by pathogenic variants in the ZAP70 C-terminal SH2 domain.

Introduction: ZAP-70, a protein tyrosine kinase recruited to the T cell receptor (TCR), initiates a TCR signaling cascade upon antigen stimulation. Mutations in the ZAP70 gene cause a combined immunodeficiency characterized by low or absent CD8+ T cells and nonfunctional CD4+ T cells. Most deleterious missense ZAP70 mutations in patients are located in the kinase domain but the impact of mutations in the SH2 domains, regulating ZAP-70 recruitment to the TCR, are not well understood. Methods: Genetic analyses were performed on four patients with CD8 lymphopenia and a high resolution melting screening for ZAP70 mutations was developed. The impact of SH2 domain mutations was evaluated by biochemical and functional analyses as well as by protein modeling. Results and discussion: Genetic characterization of an infant who presented with pneumocystis pneumonia, mycobacterial infection, and an absence of CD8 T cells revealed a novel homozygous mutation in the C-terminal SH2 domain (SH2-C) of the ZAP70 gene (c.C343T, p.R170C). A distantly related second patient was found to be compound heterozygous for the R170C variant and a 13bp deletion in the ZAP70 kinase domain. While the R170C mutant was highly expressed, there was an absence of TCR-induced proliferation, associated with significantly attenuated TCR-induced ZAP-70 phosphorylation and a lack of binding of ZAP-70 to TCR-ζ. Moreover, a homozygous ZAP-70 R192W variant was identified in 2 siblings with combined immunodeficiency and CD8 lymphopenia, confirming the pathogenicity of this mutation. Structural modeling of this region revealed the critical nature of the arginines at positions 170 and 192, in concert with R190, forming a binding pocket for the phosphorylated TCR-ζ chain. Deleterious mutations in the SH2-C domain result in attenuated ZAP-70 function and clinical manifestations of immunodeficiency.

Intrathymic transplantation of bone marrow-derived progenitors provides long-term thymopoiesis.

The sustained differentiation of T cells in the thymus cannot be maintained by resident intrathymic (IT) precursors and requires that progenitors be replenished from the bone marrow (BM). In patients with severe combined immunodeficiency (SCID) treated by hematopoietic stem cell transplantation, late T-cell differentiation defects are thought to be due to an insufficient entry of donor BM progenitors into the thymus. Indeed, we find that the intravenous injection of BM progenitors into nonconditioned zeta-chain-associated protein kinase 70 (ZAP-70)-deficient mice with SCID supports short- but not long-term thymopoiesis. Remarkably, we now show that the IT administration of these progenitors produces a significant level of donor-derived thymopoiesis for more than 6 months after transplantation. In contrast to physiologic thymopoiesis, long-term donor thymopoiesis was not due to the continued recruitment of progenitors from the BM. Rather, IT transplantation resulted in the unique generation of a large population of early c-Kit(high) donor precursors within the thymus. These ZAP-70-deficient mice that received an IT transplant had a significantly increased prothymocyte niche compared with their untreated counterparts; this phenotype was associated with the generation of a medulla. Thus, IT administration of BM progenitors results in the filling of an expanded precursor niche and may represent a strategy for enhancing T-cell differentiation in patients with SCID.

Atypical presentation of fistula dysfunction due to brachial arterial embolization mimicking stroke.

Vascular access thrombosis is an important complication with great impact on access patency and, consequently, on a patient's quality of life and survival. We report the case of a 73-year-old woman with chronic kidney disease on hemodialysis with a radiocephalic arteriovenous fistula on the right arm that was brought to the emergency department with decreased strength in her right arm, ipsilateral hypoesthesia and facial hemi-hypoesthesia. The patient was given a brain computed tomographic scan that did not confirm suspicion of stroke. On re-examination, the patient had new-onset pain at arteriovenous fistula level, and her right arm was cold and pale. The nephrology department was called for arteriovenous fistula evaluation. On physical examination, her forearm fistula had a decreased thrill and arm elevation exacerbated its paleness. A bedside ultrasound was performed for arteriovenous fistula assessment. Doppler ultrasound revealed: partial thrombosis at brachial bifurcation, a flow of 80-105 mL/min at brachial artery level and a radial artery with a damped waveform. Anastomosis and draining vein were permeable. In this case, the diagnosis of acute embolic brachial artery occlusion was made by a fast bedside ultrasound evaluation. The patient underwent thromboembolectomy with Fogarty technique, recovering fistula thrill, radial and cubital pulses. Thromboembolism of the fistula feeding artery is a rare cause of vascular access thrombosis and it is rarely mentioned in the literature. In this report, failure to recognize the upper limb ischemia would have led to delayed treatment, potentially resulting in the fistula's complete thrombosis and further limb ischemia. We highlight the importance of a diagnosis method like Doppler ultrasound, which allows for rapid evaluation at the patient's bedside.

Lupus-like nephritis with positive anti-neutrophil cytoplasmic antibodies and negative antinuclear antibodies.

Antineutrophil cytoplasmic antibodies (ANCAs) are associated with small vessel vasculitis but their prevalence is not rare in other immune diseases. In lupus nephritis (LN), their pathological role and clinical relevance have been the target of controversial views. We present a case of acute kidney injury and nephrotic syndrome in a young woman with diffuse global proliferative and membranous nephritis on her kidney biopsy, showing a full-house immunofluorescence pattern, very allusive of class IV + V LN, but lacking associated clinical criteria and laboratory findings to support the diagnosis of systemic lupus erythematosus (SLE). Furthermore, the patient presented with high titers of ANCA, steadily decreasing alongside the renal function and proteinuria improvements, with mycophenolate mofetil (MMF) and steroid treatment. The authors believe this is a case of lupus-like nephritis, in which ANCAs are immunological markers, although they are not directly involved in the pathogenesis.

Efficient intrathymic gene transfer following in situ administration of a rAAV serotype 8 vector in mice and nonhuman primates.

The thymus is the primary site of T-cell development and plays a key role in the induction of self-tolerance. We previously showed that the intrathymic (i.t.) injection of a transgene-expressing lentiviral vector (LV) in mice can result in the correction of a T cell-specific genetic defect. Nevertheless, the efficiency of thymocyte transduction did not exceed 0.1-0.3% and we were unable to detect any thymus transduction in macaques. As such, we initiated studies to assess the capacity of recombinant adeno-associated virus (rAAV) vectors to transduce murine and primate thymic cells. In vivo administration of AAV serotype 2-derived single-stranded AAV (ssAAV) and self-complementary AAV (scAAV) vectors pseudotyped with capsid proteins of serotypes 1, 2, 4, 5, and 8 demonstrated that murine thymus transduction was significantly enhanced by scAAV2/8. Transgene expression was detected in 5% of thymocytes and, notably, transduced cells represented 1% of peripheral T lymphocytes. Moreover, i.t. administration of scAAV2/8 particles in macaques, by endoscopic-mediated guidance, resulted in significant gene transfer. Thus, in healthy animals, where thymic gene transfer does not provide a selective advantage, scAAV2/8 is a unique tool promoting the in situ transduction of thymocytes with the subsequent export of gene-modified lymphocytes to the periphery.

Rituximab use in adult glomerulopathies and its rationale.

Glomerulopathies are one of the leading causes of end-stage renal disease. In the last years, clinical research has made significant contributions to the understanding of such conditions. Recently, rituximab (RTX) has appeared as a reasonably safe treatment. The Kidney Disease: Improving Global Outcomes guidelines (KDIGO) recommended RTX only as initial treatment in antineutrophil cytoplasm antibody associated vasculitis (AAV) and in non-responders patients with lupus nephritis (LN), but these guidelines have not been updated since 2012. Nowadays, RTX seems to be at least as effective as other immunosuppressive regimens in idiopathic membranous nephropathy (IMN). In minimal-change disease, (MCD) this drug might allow a long-lasting remission period in steroid-dependent or frequently relapsing patients. Preliminary results support the use of RTX in patients with pure membranous LN and immunoglobulin-mediated membranoproliferative glomerulonephritis (MPGN), but not in patients with class III/IV LN or complement-mediated MPGN. No conclusion can be drawn in idiopathic focal segmental glomerulosclerosis (FSGS) and anti-glomerular basement membrane antibody glomerulonephritis (anti-GBM GN) because studies are small, heterogeneous, and scarce. Lastly, immunosuppression including RTX is not particularly useful in IgA nephropathy. This review presents the general background, outcomes, and safety for RTX treatment in different glomerulopathies. In this regard, we describe randomized controlled trials (RCTs) performed in adults, whenever possible. A literature search was performed using clinicaltrials.gov and PubMed.

Trispecific antibodies enhance the therapeutic efficacy of tumor-directed T cells through T cell receptor co-stimulation.

Despite the significant therapeutic advances provided by immune-checkpoint blockade and chimeric antigen receptor T cell treatments, many malignancies remain unresponsive to immunotherapy. Bispecific antibodies targeting tumor antigens and activating T cell receptor signaling have shown some clinical efficacy; however, providing co-stimulatory signals may improve T cell responses against tumors. Here, we developed a trispecific antibody that interacts with CD38, CD3 and CD28 to enhance both T cell activation and tumor targeting. The engagement of both CD3 and CD28 affords efficient T cell stimulation, whereas the anti-CD38 domain directs T cells to myeloma cells, as well as to certain lymphomas and leukemias. In vivo administration of this antibody suppressed myeloma growth in a humanized mouse model and also stimulated memory/effector T cell proliferation and reduced regulatory T cells in non-human primates at well-tolerated doses. Collectively, trispecific antibodies represent a promising platform for cancer immunotherapy.

In vivo and ex vivo gene transfer in thymocytes and thymocyte precursors.

The thymus provides a specialized environment allowing the differentiation of T lymphocytes from bone marrow-derived progenitor cells. We and others have demonstrated that gene transfer into distinct thymocyte populations can be obtained, both in vivo and ex vivo, using lentiviral vectors. Here, we describe techniques for intrathymic lentiviral transduction in mice, using a surgical approach wherein the thoracic cavity is exposed as well as a significantly less invasive strategy wherein virions are directly injected through the skin. Moreover, thymocyte differentiation from murine and human progenitors is now feasible in vitro, under conditions wherein the Notch and IL-7 signaling pathways are activated. We describe methods allowing transduction of murine and human progenitors and their subsequent differentiation into more mature thymocytes. Conditions for lentiviral gene transfer into more differentiated human thymocyte subsets are also presented. Optimization of technologies for HIV-based gene transfer into murine and human thymocyte progenitors will advance strategies aimed at modulating T-cell differentiation and function in-vivo; approaches potentially targeting patients with genetic and acquired immunodeficiencies as well as immune-sensitive tumors. Furthermore, this technology will foster the progression of basic research aimed at elucidating molecular aspects of T-cell differentiation in mice and humans.

Arthritis sensory and motor scale: predicting functional deficits from the clinical score in collagen-induced arthritis.

BACKGROUND: In the collagen-induced arthritis (CIA) mouse model, inflammation readouts are usually quantified using operator-dependent clinical scoring systems, and no systematic relationship with functional deficits has been detected. In this study, we extensively quantified sensory and motor deficits in CIA mice during natural disease progression and therapeutic treatment. Then, we used these data to build a scale to predict functional deficits on the basis of the classical clinical score. METHODS: Using the CIA mouse model, we longitudinally screened multiple approaches to assess locomotion (open field test, Catwalk™), sensitivity (Von Frey, Hargreaves, static weight-bearing tests), and inflammation (skin temperature), and identified the most accurate tests to correlate sensory and motor deficits with disease severity, measured by clinical score. We then used these tests to characterize functional deficits in control (naïve and mice injected with complete Freund's adjuvant) and CIA mice, either untreated or treated with methotrexate to prevent functional deficits. By mathematical approaches, we finally investigated the relationship between functional deficits and clinical score. RESULTS: We found that the functional disability scores obtained with the open field, Catwalk™, Hargreaves, and skin temperature tests significantly correlated with the clinical score in CIA mice, either untreated or treated with methotrexate. Mathematical correlation showed that motor deficits, robustly characterized by two different tests, were twice more responsive than thermal sensitivity deficits. CONCLUSION: We propose the arthritis sensory and motor (ArthriSM) scale as a new theranostic tool to predict motor and sensory deficit based on the clinical score, in the experimental mouse model of CIA. This ArthriSM scale may facilitate the transfer of knowledge between preclinical and clinical studies.

Cecum perforation associated with a calcium polystyrene sulfonate bezoar - a rare entity.

Hyperkalemia is one of the most common electrolyte disorders, responsible for a high number of adverse outcomes, including life-threatening arrhythmias. Potassium binders are largely prescribed drugs used for hyperkalemia treatment but unfortunately, there are many adverse events associated with its use, mostly gastrointestinal. Identification of patients at highest risk for the serious complications associated with the current potassium binders, such as colon necrosis and perforation, could prevent fatal outcomes. The authors present a case of a 56-year-old man with secondary diabetes and chronic renal disease that was treated for hyperkalemia with Calcium Polystyrene Sulfonate (CPS). He later presented with acute abdomen due to cecum perforation and underwent ileocecal resection but ultimately died from septic shock a week later. During surgery, a solid white mass was isolated in the lumen of the colon. The mass was identified as a CPS bezoar, a rare drug-mass formed in the gastrointestinal tract that contributed to the perforation. A previous history of partial gastrectomy and vagothomy was identified as a probable risk factor for the CPS bezoar development. Hopefully, the two new potassium binders patiromer and (ZS-9) Sodium Zirconium Cyclosilicate will help treat such high-risk patients, in the near future.