Mesothelin antigen density influences anti-mesothelin chimeric antigen receptor T cell cytotoxicity.

BACKGROUND AIMS: Several anti-mesothelin (MSLN) chimeric antigen receptor (CAR) T cells are in phase 1/2 clinical trials to treat solid-organ malignancies. The effect of MSLN antigen density on MSLN CAR cytotoxicity against tumor cells has not been examined previously, nor are there data regarding the effect of agents that increase MSLN antigen density on anti-MSLN CAR T cell efficacy. METHODS: MSLN antigen density was measured on a panel of pancreatic cancer and mesothelioma cell lines by flow cytometry. In parallel, the cytotoxicity and specificity of two anti-MSLN CAR T cells (m912 and SS1) were compared against these cell lines using a real-time impedance-based assay. The effect of two MSLN 'sheddase' inhibitors (lanabecestat and TMI-1) that increase MSLN surface expression was also tested in combination with CAR T cells. RESULTS: SS1 CAR T cells were more cytotoxic compared with m912 CAR T cells against cell lines that expressed fewer than ∼170 000 MSLN molecules/cell. A comparison of the m912 and amatuximab (humanized SS1) antibodies identified that amatuximab could detect and bind to lower levels of MSLN on pancreatic cancer and mesothelioma cell lines, suggesting that superior antibody/scFv affinity was the reason for the SS1 CAR's superior cytotoxicity. The cytotoxicity of m912 CAR T cells was improved in the presence of sheddase inhibitors, which increased MSLN antigen density. CONCLUSIONS: These data highlight the value of assessing CAR constructs against a panel of cells expressing varying degrees of target tumor antigen as occurs in human tumors. Furthermore, the problem of low antigen density may be overcome by concomitant administration of drugs that inhibit enzymatic shedding of MSLN.

High mesothelin expression by immunohistochemistry predicts improved survival in pleural mesothelioma.

AIMS: Mesothelin (MSLN) is a cancer-associated antigen that is overexpressed in malignancies such as mesothelioma, pancreatic and ovarian cancer. It is also a target for novel personalised therapies, including antibodies, antibody-drug conjugates and chimeric antigen receptor T cells. Immunohistochemistry may predict those who would best respond to anti-mesothelin therapies and guide decisions in therapeutic strategy. This study aimed to assess the intensity and distribution of MSLN immunostaining in mesothelioma, and to determine the prognostic value of MSLN expression by histochemical-score (H-score). METHODS AND RESULTS: The MN1 anti-MSLN antibody was used to stain a formalin-fixed paraffin-embedded tissue microarray of histologically confirmed mesothelioma from 75 consecutive patients who had undergone pleurectomy with or without decortication. MSLN positivity, the staining intensity, distribution of staining and H-score were evaluated. The correlation of H-score with prognosis was investigated. Sixty-six per cent of epithelioid tumours were MSLN-positive (with expression in > 5% tumour cells). Of MSLN-expressing epithelioid tumours, 70.4% had moderate (2+) or strong (3+) intensity MSLN immunostaining, although only 37% of samples had staining in ≥ 50% of tumour cells. In multivariate analysis, MSLN H-score as a continuous variable and an H-score ≥ 33 were independent predictors of improved survival (P = 0.04 and P < 0.001, respectively). CONCLUSIONS: MSLN expression was more heterogenous in epithelioid mesothelioma than reported previously. Therefore, it would be appropriate to perform an immunohistochemical assessment of MSLN expression to stratify and assess patient suitability for mesothelin-targeted personalised therapies, such as chimeric antigen receptor T cells.

The 4-1BBζ costimulatory domain in chimeric antigen receptors enhances CD8+ T-cell functionality following T-cell receptor stimulation.

BACKGROUND: Chimeric antigen receptor (CAR) T-cells have revolutionized the treatment of CD19- and B-cell maturation antigen-positive haematological malignancies. However, the effect of a CAR construct on the function of T-cells stimulated via their endogenous T-cell receptors (TCRs) has yet to be comprehensively investigated. METHODS: Experiments were performed to systematically assess TCR signalling and function in CAR T-cells using anti-mesothelin human CAR T-cells as a model system. CAR T-cells expressing the CD28 or 4-1BB costimulatory endodomains were manufactured and compared to both untransduced T-cells and CAR T-cells with a non-functional endodomain. These cell products were treated with staphylococcal enterotoxin B to stimulate the TCR, and in vitro functional assays were performed by flow cytometry. RESULTS: Increased proliferation, CD69 expression and IFNγ production were identified in CD8+ 4-1BBζ CAR T-cells compared to control untransduced CD8+ T-cells. These functional differences were associated with higher levels of phosphorylated ZAP70 after stimulation. In addition, these functional differences were associated with a differing immunophenotype, with a more than two-fold increase in central memory cells in CD8+ 4-1BBζ CAR T-cell products. CONCLUSION: Our data indicate that the 4-1BBζ CAR enhances CD8+ TCR-mediated function. This could be beneficial if the TCR targets epitopes on malignant tissues or infectious agents, but detrimental if the TCR targets autoantigens.

Baseline Characteristics and Survival of an Australian Interstitial Pneumonia with Autoimmune Features Cohort.

BACKGROUND AND OBJECTIVE: The research term "interstitial pneumonia with autoimmune features" (IPAF) encompasses interstitial lung disease (ILD) patients with autoimmune features not meeting diagnostic criteria for a defined connective tissue disease (CTD). It remains unclear if IPAF is a distinct disease entity with implications for management and prognosis. We describe an Australian IPAF population and compare their baseline characteristics and outcomes with distinct cohorts of idiopathic interstitial pneumonia (IIP), CTD-ILD, and unclassifiable ILD. METHODS: Review of 291 consecutive patients attending a specialist ILD clinic was performed. Patients with a diagnosis of IIP, CTD-ILD, and unclassifiable ILD by ILD-multidisciplinary meeting (ILD-MDM) were included. Patients meeting the IPAF criteria were identified. Baseline clinical data, survival, and progression were compared between ILD groups. RESULTS: 226 patients were included, 36 meeting the IPAF criteria. IPAF patients demonstrated a high prevalence of autoantibodies to tRNA synthetase (35.3%), Ro52 (27.8%), and neutrophilic cytoplasmic antigens (ANCA; 20.0%). IPAF and CTD-ILD patients demonstrated similar clinical characteristics (mean age 66.6 and 63.7 years, respectively, female predominant, frequent CTD-manifestations). Lung function did not differ between ILD groups. Disease severity, pulmonary hypertension (PH), and ILD-MDM diagnosis were strong predictors of worse transplant-free survival (TFS). Meeting the IPAF criteria was not associated with TFS. CONCLUSIONS: We identified IPAF as a heterogeneous phenotype that overlaps considerably with CTD-ILD. Disease severity, PH, and ILD-MDM diagnosis were more powerful predictors of survival outcomes than meeting the IPAF criteria.

IL-27 Directly Enhances Germinal Center B Cell Activity and Potentiates Lupus in Sanroque Mice.

Germinal centers (GC) give rise to high-affinity and long-lived Abs and are critical in immunity and autoimmunity. IL-27 supports GCs by promoting survival and function of T follicular helper cells. We demonstrate that IL-27 also directly enhances GC B cell function. Exposure of naive human B cells to rIL-27 during in vitro activation enhanced their differentiation into CD20+CD38+CD27lowCD95+CD10+ cells, consistent with the surface marker phenotype of GC B cells. This effect was inhibited by loss-of-function mutations in STAT1 but not STAT3 To extend these findings, we studied the in vivo effects of IL-27 signals to B cells in the GC-driven Roquinsan/san lupus mouse model. Il27ra-/-Roquinsan/san mice exhibited significantly reduced GCs, IgG2a(c)+ autoantibodies, and nephritis. Mixed bone marrow chimeras confirmed that IL-27 acts through B cell- and CD4+ T cell-intrinsic mechanisms to support GCs and alter the production of pathogenic Ig isotypes. To our knowledge, our data provide the first evidence that IL-27 signals directly to B cells promote GCs and support the role of IL-27 in lupus.

Monogenic mutations differentially affect the quantity and quality of T follicular helper cells in patients with human primary immunodeficiencies.

BACKGROUND: Follicular helper T (TFH) cells underpin T cell-dependent humoral immunity and the success of most vaccines. TFH cells also contribute to human immune disorders, such as autoimmunity, immunodeficiency, and malignancy. Understanding the molecular requirements for the generation and function of TFH cells will provide strategies for targeting these cells to modulate their behavior in the setting of these immunologic abnormalities. OBJECTIVE: We sought to determine the signaling pathways and cellular interactions required for the development and function of TFH cells in human subjects. METHODS: Human primary immunodeficiencies (PIDs) resulting from monogenic mutations provide a unique opportunity to assess the requirement for particular molecules in regulating human lymphocyte function. Circulating follicular helper T (cTFH) cell subsets, memory B cells, and serum immunoglobulin levels were quantified and functionally assessed in healthy control subjects, as well as in patients with PIDs resulting from mutations in STAT3, STAT1, TYK2, IL21, IL21R, IL10R, IFNGR1/2, IL12RB1, CD40LG, NEMO, ICOS, or BTK. RESULTS: Loss-of-function (LOF) mutations in STAT3, IL10R, CD40LG, NEMO, ICOS, or BTK reduced cTFH cell frequencies. STAT3 and IL21/R LOF and STAT1 gain-of-function mutations skewed cTFH cell differentiation toward a phenotype characterized by overexpression of IFN-γ and programmed death 1. IFN-γ inhibited cTFH cell function in vitro and in vivo, as corroborated by hypergammaglobulinemia in patients with IFNGR1/2, STAT1, and IL12RB1 LOF mutations. CONCLUSION: Specific mutations affect the quantity and quality of cTFH cells, highlighting the need to assess TFH cells in patients by using multiple criteria, including phenotype and function. Furthermore, IFN-γ functions in vivo to restrain TFH cell-induced B-cell differentiation. These findings shed new light on TFH cell biology and the integrated signaling pathways required for their generation, maintenance, and effector function and explain the compromised humoral immunity seen in patients with some PIDs.

IL-21 signalling via STAT3 primes human naive B cells to respond to IL-2 to enhance their differentiation into plasmablasts.

B-cell responses are guided by the integration of signals through the B-cell receptor (BCR), CD40, and cytokine receptors. The common γ chain (γc)-binding cytokine interleukin (IL)-21 drives humoral immune responses via STAT3-dependent induction of transcription factors required for plasma cell generation. We investigated additional mechanisms by which IL-21/STAT3 signaling modulates human B-cell responses by studying patients with STAT3 mutations. IL-21 strongly induced CD25 (IL-2Rα) in normal, but not STAT3-deficient, CD40L-stimulated naïve B cells. Chromatin immunoprecipitation confirmed IL2RA as a direct target of STAT3. IL-21-induced CD25 expression was also impaired on B cells from patients with IL2RG or IL21R mutations, confirming a requirement for intact IL-21R signaling in this process. IL-2 increased plasmablast generation and immunoglobulin secretion from normal, but not CD25-deficient, naïve B cells stimulated with CD40L/IL-21. IL-2 and IL-21 were produced by T follicular helper cells, and neutralizing both cytokines abolished the B-cell helper capacity of these cells. Our results demonstrate that IL-21, via STAT3, sensitizes B cells to the stimulatory effects of IL-2. Thus, IL-2 may play an adjunctive role in IL-21-induced B-cell differentiation. Lack of this secondary effect of IL-21 may amplify the humoral immunodeficiency in patients with mutations in STAT3, IL2RG, or IL21R due to impaired responsiveness to IL-21.

Autoimmunity in primary antibody deficiency is associated with protein tyrosine phosphatase nonreceptor type 22 (PTPN22).

BACKGROUND: The 1858T allele of protein tyrosine phosphatase nonreceptor type 22 (PTPN22; R620W) exhibits one of the strongest and most consistent associations with sporadic autoimmune disease. Although autoimmunity is common in patients with primary antibody deficiency (PAD), it remains unknown whether its pathogenesis is similar when it arises in this context compared with in immunocompetent patients. OBJECTIVE: We set out to determine whether the 1858T allele of PTPN22 was associated with PAD or with autoimmunity in the context of PAD. METHODS: We genotyped rs2476601 (g.1858C>T), a single nucleotide polymorphism encoding substitution of arginine for tryptophan in PTPN22 (R620W), in 193 patients with PAD and 148 control subjects from an Australian cohort. We also performed a subgroup analysis according to the presence of autoimmunity and B-cell phenotypes. RESULTS: C/T and T/T PTPN22 genotypes were more common in patients with PAD than in the matched control subjects (C/T, 18.1% vs 9.5%; T/T, 1.04% vs 0.6%). The T allele was associated with an increased risk of PAD relative to control subjects (odds ratio, 2.10; 95% CI, 1.11-4.00). The distribution of genotypes in control subjects was similar to those reported previously and did not deviate significantly from Hardy-Weinberg equilibrium. We found a strong association between the 1858T allele and PAD with coexistent autoimmune diseases. In patients with PAD and autoimmunity, 16 (43.2%) of 37 had at least one T allele of PTPN22 compared with 27 (17.3%) of 156 with the C/C genotype (P=.0014; odds ratio, 3.64; 95% CI, 1.68-7.88). We found no evidence that this effect was mediated by enrichment of CD21low B cells. CONCLUSION: The 1858T PTPN22 allele is strongly associated with autoimmunity in patients with PAD.

Signal transducer and activator of transcription 3 (STAT3) mutations underlying autosomal dominant hyper-IgE syndrome impair human CD8(+) T-cell memory formation and function.

BACKGROUND: The capacity of CD8(+) T cells to control infections and mediate antitumor immunity requires the development and survival of effector and memory cells. IL-21 has emerged as a potent inducer of CD8(+) T-cell effector function and memory development in mouse models of infectious disease. However, the role of IL-21 and associated signaling pathways in protective CD8(+) T-cell immunity in human subjects is unknown. OBJECTIVE: We sought to determine which signaling pathways mediate the effects of IL-21 on human CD8(+) T cells and whether defects in these pathways contribute to disease pathogenesis in patients with primary immunodeficiencies caused by mutations in components of the IL-21 signaling cascade. METHODS: Human primary immunodeficiencies resulting from monogenic mutations provide a unique opportunity to assess the requirement for particular molecules in regulating human lymphocyte function. Lymphocytes from patients with loss-of-function mutations in signal transducer and activator of transcription 1 (STAT1), STAT3, or IL-21 receptor (IL21R) were used to assess the respective roles of these genes in human CD8(+) T-cell differentiation in vivo and in vitro. RESULTS: Mutations in STAT3 and IL21R, but not STAT1, led to a decrease in multiple memory CD8(+) T-cell subsets in vivo, indicating that STAT3 signaling, possibly downstream of IL-21R, regulates the memory cell pool. Furthermore, STAT3 was important for inducing the lytic machinery in IL-21-stimulated naive CD8(+) T cells. However, this defect was overcome by T-cell receptor engagement. CONCLUSION: The IL-21R/STAT3 pathway is required for many aspects of human CD8(+) T-cell behavior but in some cases can be compensated by other signals. This helps explain the relatively mild susceptibility to viral disease observed in STAT3- and IL-21R-deficient subjects.

Use of adrenaline to manage suspected anaphylaxis following COVID-19 vaccination: An Australian retrospective cohort study.

BACKGROUND: The rate of anaphylaxis following COVID-19 vaccinations is estimated to be 2-11 cases per million doses administered. However, adrenaline is occasionally used in individuals who are later diagnosed with immunisation stress-related responses, as their initial presenting signs and symptoms can appear similar to that of anaphylaxis. This study aims to describe the clinical profile of individuals who had received adrenaline following a COVID-19 vaccine and their subsequent revaccination outcomes. METHODS: We examined notifications of cases who had received adrenaline following a COVID-19 vaccine in New South Wales, Australia. The cases were classified into Brighton Collaboration Case Definition (BCCD) for anaphylaxis, their clinical presentation, management and subsequent revaccination outcomes were compared. RESULTS: From 22 February 2021 to 30 September 2021, there were 222 cases where adrenaline was administered. Of these, 32 (14 %) fulfilled Level 1 BCCD, 59 (27%) Level 2, 2 (1%) Level 3, 97 (44%) Level 4 and 32 (14 %) Level 5. The most commonly reported symptoms were sensation of throat closure (n = 116, 52%), difficulty breathing (n = 82, 37%) and nausea (n = 55, 25 %). Of the 176 (79%) individuals who proceeded to further vaccination, 89 (51%) received the same vaccine formulation and only 14 (8%) experienced another allergic adverse event with 9 (5%) receiving adrenaline. CONCLUSION: Less than one in five individuals who received adrenaline met Level 1 BCCD criteria for anaphylaxis. Many reactions that were treated with adrenaline had little to no diagnostic certainty of anaphylaxis and in such cases repeat vaccination had a high likelihood of being tolerated. Increased awareness and education on objective signs and symptoms of anaphylaxis is required to ensure appropriate use of adrenaline.

A Composite Serum Biomarker Index for the Diagnosis of Systemic Sclerosis-Associated Interstitial Lung Disease: A Multicenter, Observational Cohort Study.

OBJECTIVE: In patients with systemic sclerosis (SSc), we investigated composite serum biomarker panels for the diagnosis and risk stratification of SSc-associated interstitial lung disease (SSc-ILD). METHODS: We analyzed 28 biomarkers in 640 participants: 259 patients with SSc-ILD and 179 SSc patients without ILD (Australian Scleroderma Cohort Study), 172 patients with idiopathic pulmonary fibrosis (IPF-controls) (Australian IPF Registry), and 30 healthy controls. A composite index was developed from biomarkers associated with ILD in multivariable analysis derived at empirical thresholds. We evaluated the performance of the index to identify ILD, and specifically SSc-ILD, and its association with lung function, disease extent on radiography, and patient health-related quality of life in derivation and validation cohorts. Biomarkers to distinguish SSc-ILD from IPF-controls were identified. RESULTS: A composite biomarker index, comprising surfactant protein D (SP-D), Ca15-3, and intercellular adhesion molecule 1 (ICAM-1), was strongly associated with SSc-ILD diagnosis, independent of age, sex, smoking history, and lung function (for biomarker index score 3, pooled adjusted odds ratio was 12.72 (95% confidence interval 4.59-35.21) (P < 0.001). The composite index strengthened the performance of individual biomarkers for SSc-ILD identification. In SSc patients, a higher index was associated with worse baseline disease severity (for biomarker index score 3 relative to biomarker index score 0, the adjusted absolute change in forced vital capacity percent predicted was -17.84% and the diffusing capacity for carbon monoxide percent predicted was -20.16%; both P < 0.001). CONCLUSION: A composite serum biomarker index, comprising SP-D, Ca15-3, and ICAM-1, may improve the identification and risk stratification of ILD in SSc patients at baseline.

Use of cardiac MR imaging to evaluate the presence of myocarditis in autoimmune myositis: three cases.

Cardiac involvement in patients with idiopathic inflammatory myopathies (autoimmune myositis) is important to detect because it confers an increased risk of mortality. However, detection of myocardial involvement is hampered by a lack of sensitivity of traditional non-invasive methods, and the finding of elevated cardiac troponin T levels that may be due to regenerating skeletal muscle, rather than myocardial damage. Here, we describe three cases of inflammatory myositis with elevated troponin T levels, and non-specific echocardiographic and ECG findings. Cardiac MR imaging was useful in the evaluation for the presence of myocarditis or alternative cardiac pathology.

Autoimmune autonomic ganglionopathy: Ganglionic acetylcholine receptor autoantibodies.

Autoimmune Autonomic Ganglionopathy (AAG) is a rare immune-mediated disease of the autonomic nervous system. The incidence of AAG is unknown and diagnosis is often difficult due to the multicompartmental nature of the autonomic nervous system - sympathetic, parasympathetic and enteric components - with variable severity and number of components affected. Diagnostic confidence is increased when ganglionic acetylcholine receptor (gnACHR) autoantibodies are detected. Three gnACHR autoantibody diagnostic assays have been described (two binding assays, one receptor immunomodulation assay), but cross-validation between assays is limited. The prevalence of gnACHR autoantibodies in AAG is not known, with application of different clinical and laboratory criteria in the few studies of AAG cohorts and large retrospective laboratory studies of positive gnACHR autoantibodies lacking adequate clinical characterisation. Furthermore, the rate of unexpected gnACHR autoantibody positivity in conditions without overt autonomic dysfunction (false positive results) adds to the complexity of their interpretation. We review the pathophysiology of gnACHR autoantibodies and assays for their detection, with immunomodulation and high titer radioimmunoprecipitation results likely offering better AAG disease identification.

Subunit-specific autoantibodies in autoimmune autonomic ganglionopathy.

Autoimmune Autonomic Ganglionopathy (AAG) is a disorder that causes autonomic failure and is associated with alpha3-ganglionic acetylcholine-receptor (gnACHR) antibodies. Assays that detect antibodies to whole gnACHR or subunits are available. We compared in-house subunit-specific immunoassays using bacterially-expressed alpha3 and beta4 subunits against an immunomodulation assay to detect antibodies in patients with AAG or control groups in a novel 2-step clinical-characteristic unblinding protocol. Only 1/8 patients with seropositive-AAG had subunit-specific antibodies, with sensitivity, specificity, false-negative and positive rates of 12.5, 85.2, 78.6 and 13.4% respectively. Subunit-specific antibody-derived false-positive results can lead to misdiagnosis, as autonomic failure is not specific to AAG.

Hemophagocytic lymphohistiocytosis (HLH) and cytokine release syndrome (CRS) in a patient with oncogene-addicted metastatic non-small cell lung cancer (NSCLC) following combination chemotherapy-immunotherapy.

Immune checkpoint inhibitors (ICIs) are utilized in a variety of clinical settings for the management of patients with metastatic non-small cell lung cancer (mNSCLC). While any organ may be subject to immune-related adverse events (irAEs) as a consequence of ICI therapy, hematological irAEs are uncommon. We describe a scenario involving a patient with oncogene-addicted mNSCLC who experienced the rare, life-threatening complication of hemophagocytic lymphohistiocytosis (HLH) and cytokine release syndrome following the receipt of the IMPower150 regimen (carboplatin/paclitaxel/atezolizumab/bevacizumab) after progression on initial tyrosine kinase inhibitor therapy. Malignancy-associated HLH, while previously described, is more typically associated with hematological rather than solid cancers and has only very recently been reported among patients receiving ICIs. While identification of hemophagocytosis on bone marrow examination is pathognomonic, this feature is not essential for confirming a diagnosis of HLH. Prompt recognition of suspicious laboratory and clinical features by medical oncologists and engagement with other relevant disciplines is hence critical to ensure optimal management of the condition.

Gluten-free diet adherence and implications for the diagnosis of coeliac disease.

Coeliac disease (CD) is an autoimmune disorder caused by the ingestion of gluten containing foods in genetically susceptible individuals, with a worldwide prevalence of up to 1%. Currently, the only available treatment is a gluten-free diet (GFD). Screening for CD is primarily performed using serum based testing for anti-tissue transglutaminase (tTG) antibodies. Patients must be on a gluten containing diet at the time of testing to ensure an accurate serological result. We investigated the prevalence of a GFD in hospital clinic settings and the general population using survey data to estimate the proportion of CD patients that may be misdiagnosed for CD based on serological tests. Data were collected at clinics of a metropolitan hospital in Sydney, Australia, and the general population. Data from Medicare Benefits Scheme and tTG results from a large Australian private laboratory were reviewed for comparison. Of 778 participants who responded to the survey, 58 (7.5%) were on a GFD. More patients attending the immunology (15.9%) and gastroenterology (12.1%) clinics adopted a GFD than those attending the diabetes (2.6%) or endocrinology (6.1%) clinics, or in the general population (4.3%). More females than males excluded gluten from their diet (p<0.0001). Medicare statistics between 2013 and 2019 demonstrated an increase in CD serological testing; however, tTG data from a private pathology highlighted a stable level of elevated tTG antibodies of 3% of total tests performed. The high number of individuals on a GFD is likely impacting the ability to accurately diagnose CD using serum-based testing.