Disruption of splicing patterns due to mutations of genes coding splicing factors in tumors represents a potential source of tumor neoantigens, which would be both public (shared between patients) ...and tumor-specific (not expressed in normal tissues). In this study, we show that mutations of the splicing factor
in uveal melanoma generate such immunogenic neoantigens. Memory CD8
T cells specific for these neoantigens are preferentially found in 20% of patients with uveal melanoma bearing
-mutated tumors. Single-cell analyses of neoepitope-specific T cells from the blood identified large clonal T-cell expansions, with distinct effector transcription patterns. Some of these expanded T-cell receptors are also present in the corresponding tumors. CD8
T-cell clones specific for the neoepitopes specifically recognize and kill
-mutated tumor cells, supporting the use of this new family of neoantigens as therapeutic targets. SIGNIFICANCE: Mutations of the splicing factor
in uveal melanoma generate shared neoantigens that are uniquely expressed by tumor cells, leading to recognition and killing by specific CD8 T cells. Mutations in splicing factors can be sources of new therapeutic strategies applicable to diverse tumors.
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Uveal melanoma (UM) is the most common cancer of the eye. The loss of chromosome 3 (M3) is associated with a high risk of metastases. M3 tumors are more infiltrated by T-lymphocytes than low-risk ...disomic-3 (D3) tumors, contrasting with other tumor types in which T cell infiltration correlates with better prognosis. Whether these T cells represent an antitumor response and how these T cells would be primed in the eye are both unknown. Herein, we characterized the T cells infiltrating primary UMs. CD8+ and Treg cells were more abundant in M3 than in D3 tumors. CD39+PD-1+CD8+ T cells were enriched in M3 tumors, suggesting specific responses to tumor antigen (Ag) as confirmed using HLA-A2:Melan-A tetramers. scRNAseq-VDJ analysis of T cells evidenced high numbers of proliferating CD39+PD1+CD8+ clonal expansions, suggesting in situ antitumor Ag responses. TCRseq and tumor-Ag tetramer staining characterized the recirculation pattern of the antitumor responses in M3 and D3 tumors. Thus, tumor-Ag responses occur in localized UMs, raising the question of the priming mechanisms in the absence of known lymphatic drainage.
Little is known about the Hox gene complement in parasitic platyhelminthes (Neodermata). With the aim of identifying Hox genes in this group we performed two independent strategies: we performed a ...PCR survey with degenerate primers directed to the Hox homeobox in the cestode Mesocestoides corti, and we searched genomic assemblies of Echinococcus multilocularis and Schistosoma mansoni. We identified two Hox genes in M. corti, seven in E. multilocularis, and nine in S. mansoni (including five previously reported). The affinities of these sequences, and other previously reported Hox sequences from flatworms, were determined according to phylogenetic analysis, presence of characteristic parapeptide sequences, and unusual intron positions. Our results suggest that the last common ancestor of triclads and neodermatans had a Hox gene complement of at least seven genes, and that this was probably derived by gene loss from a larger ancestral Hox complement in lophotrochozoans.
Checkpoint inhibitors have revolutionized cancer treatment. However, only a minority of patients respond to these immunotherapies. Here, we report that blocking the inhibitory NKG2A receptor enhances ...tumor immunity by promoting both natural killer (NK) and CD8+ T cell effector functions in mice and humans. Monalizumab, a humanized anti-NKG2A antibody, enhanced NK cell activity against various tumor cells and rescued CD8+ T cell function in combination with PD-x axis blockade. Monalizumab also stimulated NK cell activity against antibody-coated target cells. Interim results of a phase II trial of monalizumab plus cetuximab in previously treated squamous cell carcinoma of the head and neck showed a 31% objective response rate. Most common adverse events were fatigue (17%), pyrexia (13%), and headache (10%). NKG2A targeting with monalizumab is thus a novel checkpoint inhibitory mechanism promoting anti-tumor immunity by enhancing the activity of both T and NK cells, which may complement first-generation immunotherapies against cancer.
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•Blocking NKG2A unleashes both T and NK cell effector functions•Combined blocking of the NKG2A and the PD-1 axis promotes anti-tumor immunity•Blocking NKG2A and triggering CD16 illustrates the efficacy of dual checkpoint therapy
Blocking of the NKG2A inhibitory receptor unleashes both T and NK cells, and demonstrates anti-tumor efficacy in combination with anti-EGFR or with anti-PD-x antibodies.
Although CD8+ T-cell-mediated autoimmune β cell destruction occurs in type 1 diabetes (T1D), the target epitopes processed and presented by β cells are unknown. To identify them, we combined ...peptidomics and transcriptomics strategies. Inflammatory cytokines increased peptide presentation in vitro, paralleling upregulation of human leukocyte antigen (HLA) class I expression. Peptide sources featured several insulin granule proteins and all known β cell antigens, barring islet-specific glucose-6-phosphatase catalytic subunit-related protein. Preproinsulin yielded HLA-A2-restricted epitopes previously described. Secretogranin V and its mRNA splice isoform SCG5-009, proconvertase-2, urocortin-3, the insulin gene enhancer protein ISL-1, and an islet amyloid polypeptide transpeptidation product emerged as antigens processed into HLA-A2-restricted epitopes, which, as those already described, were recognized by circulating naive CD8+ T cells in T1D and healthy donors and by pancreas-infiltrating cells in T1D donors. This peptidome opens new avenues to understand antigen processing by β cells and for the development of T cell biomarkers and tolerogenic vaccination strategies.
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•Peptide HLA class I presentation by β cells is increased by inflammatory cytokines•Peptide sources feature several insulin granule proteins, e.g., SCG5, PCSK2, UCN3•SCG5-009 mRNA splice products and IAPP fusion peptides are also presented•In type 1 diabetes, peptide-reactive CD8+ T cells are enriched in the pancreas
Mallone et al. use peptidomics and transcriptomics to identify the epitopes presented by β cells that trigger type 1 diabetes (T1D) autoimmunity. Multiple pathways, including conventional processing and mRNA and peptide splicing, are involved in epitope generation and presentation; these epitopes are selectively recognized by pancreas-infiltrating CD8+ T lymphocytes in T1D patients.
Coronavirus disease 2019 (COVID‐19) is often associated with interstitial pneumonia. However, there is insufficient knowledge on the presence of autoimmune serological markers in patients with ...COVID‐19. We analyzed the presence and role of autoantibodies in patients with COVID‐19‐associated pneumonia. We prospectively studied 33 consecutive patients with COVID‐19, 31 (94%) of whom had interstitial pneumonia, and 25 age‐matched and sex‐matched patients with fever and/or pneumonia with etiologies other than COVID‐19 as the pathological control group. All patients were tested for the presence of antinuclear antibodies (ANAs), anti‐antiphospholipid antibodies, and anti‐cytoplasmic neutrophil antibodies (ANCAs). Clinical, biochemical, and radiological parameters were also collected. Fifteen of 33 patients (45%) tested positive for at least one autoantibody, including 11 who tested positive for ANAs (33%), 8 who tested positive for anti‐cardiolipin antibodies (immunoglobulin (Ig)G and/or IgM; 24%), and 3 who tested positive for anti‐β2‐glycoprotein antibodies (IgG and/or IgM; 9%). ANCA reactivity was not detected in any patient. Patients that tested positive for auto‐antibodies had a significantly more severe prognosis than other patients did: 6 of 15 patients (40%) with auto‐antibodies died due to COVID‐19 complications during hospitalization, whereas only 1 of 18 patients (5.5%) who did not have auto‐antibodies died (P = 0.03). Patients with poor prognosis (death due to COVID‐19 complications) had a significantly higher respiratory rate at admission (23 breaths per minute vs. 17 breaths per minute; P = 0.03) and a higher frequency of auto‐antibodies (86% vs. 27%; P = 0.008). In conclusion, auto‐antibodies are frequently detected in patients with COVID‐19 possibly reflecting a pathogenetic role of immune dysregulation. However, given the small number of patients, the association of auto‐antibodies with an unfavorable prognosis requires further multicenter studies.
The human leukocyte antigen-A2 (HLA-A2)-restricted zinc transporter 8
(ZnT8
) and other islet epitopes elicit interferon-γ secretion by CD8
T cells preferentially in type 1 diabetes (T1D) patients ...compared with controls. We show that clonal ZnT8
-reactive CD8
T cells express private T cell receptors and display equivalent functional properties in T1D and healthy individuals. Ex vivo analyses further revealed that CD8
T cells reactive to ZnT8
and other islet epitopes circulate at similar frequencies and exhibit a predominantly naïve phenotype in age-matched T1D and healthy donors. Higher frequencies of ZnT8
-reactive CD8
T cells with a more antigen-experienced phenotype were detected in children versus adults, irrespective of disease status. Moreover, some ZnT8
-reactive CD8
T cell clonotypes were found to cross-recognize a
mimotope. Whereas ZnT8 was poorly expressed in thymic medullary epithelial cells, variable thymic expression levels of islet antigens did not modulate the peripheral frequency of their cognate CD8
T cells. In contrast, ZnT8
-reactive cells were enriched in the pancreata of T1D patients versus nondiabetic and type 2 diabetic individuals. Thus, islet-reactive CD8
T cells circulate in most individuals but home to the pancreas preferentially in T1D patients. We conclude that the activation of this common islet-reactive T cell repertoire and progression to T1D likely require defective peripheral immunoregulation and/or a proinflammatory islet microenvironment.
Some nonpathogenic bacteria were found to have protective effects in mouse models of allergic and autoimmune diseases. These "probiotics" are thought to interact with dendritic cells during Ag ...presentation, at the initiation of adaptive immune responses. Many other myeloid cells are the effector cells of immune responses. They are responsible for inflammation that accounts for symptoms in allergic and autoimmune diseases. We investigated in this study whether probiotics might affect allergic and autoimmune inflammation by acting at the effector phase of adaptive immune responses. The effects of one strain of Lactobacillus casei were investigated in vivo on IgE-induced passive systemic anaphylaxis and IgG-induced passive arthritis, two murine models of acute allergic and autoimmune inflammation, respectively, which bypass the induction phase of immune responses, in vitro on IgE- and IgG-induced mouse mast cell activation and ex vivo on IgE-dependent human basophil activation. L. casei protected from anaphylaxis and arthritis, and inhibited mouse mast cell and human basophil activation. Inhibition required contact between mast cells and bacteria, was reversible, and selectively affected the Lyn/Syk/linker for activation of T cells pathway induced on engagement of IgE receptors, leading to decreased MAPK activation, Ca(2+) mobilization, degranulation, and cytokine secretion. Also, adoptive anaphylaxis induced on Ag challenge in mice injected with IgE-sensitized mast cells was abrogated in mice injected with IgE-sensitized mast cells exposed to bacteria. These results demonstrate that probiotics can influence the effector phase of adaptive immunity in allergic and autoimmune diseases. They might, therefore, prevent inflammation in patients who have already synthesized specific IgE or autoantibodies.
Although the COVID‐19 pandemic peaked in March/April 2020 in France, the prevalence of infection is barely known. Using high‐throughput methods, we assessed herein the serological response against ...the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) of 1847 participants working in three sites of an institution in Paris conurbation.
In May–July 2020, 11% (95% confidence interval CI: 9.7–12.6) of serums were positive for IgG against the SARS‐CoV‐2 N and S proteins, and 9.5% (95% CI: 8.2–11.0) were neutralizer in pseudo‐typed virus assays. The prevalence of seroconversion was 11.6% (95% CI: 10.2–13.2) when considering positivity in at least one assay. In 5% of RT‐qPCR positive individuals, no systemic IgGs were detected. Among immune individuals, 21% had been asymptomatic. Anosmia (loss of smell) and ageusia (loss of taste) occurred in 52% of the IgG‐positive individuals and in 3% of the negative ones. In contrast, 30% of the anosmia–ageusia cases were seronegative, suggesting that the true prevalence of infection may have reached 16.6%. In sera obtained 4–8 weeks after the first sampling, anti‐N and anti‐S IgG titers and neutralization activity in pseudo‐virus assay declined by 31%, 17%, and 53%, resulting thus in half‐life of 35, 87, and 28 days, respectively.
The population studied is representative of active workers in Paris. The short lifespan of the serological systemic responses suggests an underestimation of the true prevalence of infection.
In May 2020, 11% of workers at Institut Curie living in Paris conurbation were seropositive and 9.5% had detectable but short‐lived neutralizing antibodies of SARS‐CoV‐2. Some 21% of these neutralizing sera actually belong to asymptomatic individuals. Only 2% of the PCR‐detected infections had not been followed by humoral immune response.
Congenital erythropoietic porphyria (CEP) is a rare autosomal recessive disorder characterized by uroporphyrinogen III synthase (UROS) deficiency resulting in massive porphyrin accumulation in blood ...cells, which is responsible for hemolytic anemia and skin photosensitivity. Among the missense mutations actually described up to now in CEP patients, the C73R and the P248Q mutations lead to a profound UROS deficiency and are usually associated with a severe clinical phenotype. We previously demonstrated that the UROS C⁷³ᴿ mutant protein conserves intrinsic enzymatic activity but triggers premature degradation in cellular systems that could be prevented by proteasome inhibitors. We show evidence that the reduced kinetic stability of the UROS ᴾ²⁴⁸Q mutant is also responsible for increased protein turnover in human erythroid cells. Through the analysis of EGFP-tagged versions of UROS enzyme, we demonstrate that both UROS C⁷³ᴿ and UROS ᴾ²⁴⁸Q are equally destabilized in mammalian cells and targeted to the proteasomal pathway for degradation. We show that a treatment with proteasomal inhibitors, but not with lysosomal inhibitors, could rescue the expression of both EGFP-UROS mutants. Finally, in CEP mice (Uros ᴾ²⁴⁸Q/ᴾ²⁴⁸Q) treated with bortezomib (Velcade), a clinically approved proteasome inhibitor, we observed reduced porphyrin accumulation in circulating RBCs and urine, as well as reversion of skin photosensitivity on bortezomib treatment. These results of medical importance pave the way for pharmacologic treatment of CEP disease by preventing certain enzymatically active UROS mutants from early degradation by using proteasome inhibitors or chemical chaperones.
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