Immunotherapeutic Concepts to Target Acute Myeloid Leukemia: Focusing on the Role of Monoclonal Antibodies, Hypomethylating Agents and the Leukemic Microenvironment

Intensive chemotherapeutic protocols and allogeneic stem cell transplantation continue to represent the mainstay of acute myeloid leukemia (AML) treatment. Although this approach leads to remissions in the majority of patients, long-term disease control remains unsatisfactory as mirrored by overall survival rates of approximately 30%. The reason for this poor outcome is, in part, due to various toxicities associated with traditional AML therapy and the limited ability of most patients to tolerate such treatment. More effective and less toxic therapies therefore represent an unmet need in the management of AML, a disease for which therapeutic progress has been traditionally slow when compared to other cancers. Several studies have shown that leukemic blasts elicit immune responses that could be exploited for the development of novel treatment concepts. To this end, early phase studies of immune-based therapies in AML have delivered encouraging results and demonstrated safety and feasibility. In this review, we discuss opportunities for immunotherapeutic interventions to enhance the potential to achieve a cure in AML, thereby focusing on the role of monoclonal antibodies, hypomethylating agents and the leukemic microenvironment

Smoking is not linked to the development of anti-peptidylarginine deiminase 4 autoantibodies in rheumatoid arthritis

Background: Defining environmental factors responsible for development of autoimmunity in rheumatoid arthritis (RA) is critical for understanding mechanisms of disease initiation and propagation. Notably, a history of cigarette smoking has been implicated in the genesis of RA and is associated with worse disease outcomes. Antibodies to peptidylarginine deiminase 4 (PAD4) are also associated with more severe RA. A subset of patients who have PAD4 autoantibodies that cross-react with PAD3 (anti-PAD3/4) are at the highest risk for interstitial lung disease, and this risk is augmented by a history of cigarette smoking. It is unclear, however, if smoking is etiologically linked to the development of anti-PAD4 antibodies. Methods: Patients were included in this study if they had physician-diagnosed RA as well as DNA, serum, and a date-matched clinical assessment (n = 274). Anti-PAD4 and anti-CCP antibodies were measured by immunoprecipitation and ELISA, respectively; shared epitope (SE) status was determined by HLA-DRβ1 genotyping. Logistic regression analysis was used to evaluate associations of smoking with PAD4 antibodies, with adjustment for relevant demographic and clinical features. Stratified analyses by disease duration and shared epitope status were also performed. Results: Anti-PAD4 antibodies were present in 25% of RA patients, with 50% of these individuals having anti-PAD3/4 cross-reactive antibodies. Anti-PAD4 antibodies were significantly associated with a longer disease duration, SE alleles, and anti-CCP antibodies. Importantly, there were no significant differences in smoking history between anti-PAD4 positive and negative groups in univariate analyses, stratified analyses, or multivariable models. However, an inverse relationship between smoking and anti-PAD4 antibodies was suggested by a lower prevalence of current smokers among patients with anti-PAD3/4 antibodies compared to antibody negative individuals (p = 0.04). Further, the lowest levels of anti-PAD4 antibodies were observed in current smokers (p = 0.14), and a significant association of SE and anti-PAD4 antibodies was only present among never smokers (p = 0.01). Conclusions: Smoking history was not associated with anti-PAD4 antibodies in patients with RA. The finding that anti-PAD4 antibodies were not associated with smoking suggests that other environmental factors may contribute to the development of autoimmunity to PAD4 in these patients

Aggregatibacter actinomycetemcomitans-induced hypercitrullination links periodontal infection to autoimmunity in rheumatoid arthritis

A bacterial etiology of rheumatoid arthritis (RA) has been suspected since the beginnings of modern germ theory. Recent studies implicate mucosal surfaces as sites of disease initiation. The common occurrence of periodontal dysbiosis in RA suggests that oral pathogens may trigger the production of disease-specific autoantibodies and arthritis in susceptible individuals. We used mass spectrometry to define the microbial composition and antigenic repertoire of gingival crevicular fluid in patients with periodontal disease and healthy controls. Periodontitis was characterized by the presence of citrullinated autoantigens that are primary immune targets in RA. The citrullinome in periodontitis mirrored patterns of hypercitrullination observed in the rheumatoid joint, implicating this mucosal site in RA pathogenesis. Proteomic signatures of several microbial species were detected in hypercitrullinated periodontitis samples. Among these, Aggregatibacter actinomycetemcomitans (Aa), but not other candidate pathogens, induced hypercitrullination in host neutrophils. We identified the pore-forming toxin leukotoxin-A (LtxA) as the molecular mechanism by which Aa triggers dysregulated activation of citrullinating enzymes in neutrophils, mimicking membranolytic pathways that sustain autoantigen citrullination in the RA joint. Moreover, LtxA induced changes in neutrophil morphology mimicking extracellular trap formation, thereby releasing the hypercitrullinated cargo. Exposure to leukotoxic Aa strains was confirmed in patients with RA and was associated with both anti-citrullinated protein antibodies (ACPAs) and rheumatoid factor (RF). The effect of HLA-DRB1 shared epitope alleles on autoantibody positivity was limited to RA patients that were exposed to Aa. These studies identify the periodontal pathogen Aa as a candidate bacterial trigger of autoimmunity in RA

Rheumatoid Arthritis-Associated Autoimmunity Due to Aggregatibacter actinomycetemcomitans and Its Resolution With Antibiotic Therapy

Background:Aggregatibacter actinomycetemcomitans (Aa) is a Gram-negative coccobacillus recognized as a pathogen in periodontitis and infective endocarditis. By producing a toxin (leukotoxin A, LtxA) that triggers global hypercitrullination in neutrophils, Aa has been recently linked to rheumatoid arthritis (RA) pathogenesis. Although mechanistic and clinical association studies implicate Aa infection in the initiation of autoimmunity in RA, direct evidence in humans is lacking.Case:We describe a 59-year-old man with anti-citrullinated protein antibody (ACPA)-positive RA who presented for evaluation of refractory disease. He was found to have Aa endocarditis. Following antibiotic treatment, joint symptoms resolved and ACPAs normalized. Given the implications for RA immunopathogenesis, we further investigated the bacterial, genetic and immune factors that may have contributed to the patient's clinical and autoimmune phenotypes.Methods:DNA was extracted from serum and used to amplify the Aa leukotoxin (ltx) promoter region by PCR, which was further analyzed by Sanger sequencing. High-resolution identification of HLA alleles was performed by sequenced based typing (SBT). TNF-α, IFN-γ, GM-CSF, IL-1β, IL-6, IL-8, IL-17A, IL-18, IL-21, and IL-22 were quantified in serum by a multiplex immunoassay. IgG and IgA antibodies to Aa LtxA were assayed by ELISA.Results:Aa genotyping confirmed infection with a highly leukotoxic strain carrying a 530-bp ltx promoter deletion, shown to result in 10- to 20-fold higher bacterial expression of LtxA. Immuno-phenotyping showed high anti-LtxA antibodies, elevated cytokines implicated in RA pathogenesis (Th1/Th17), and specific host susceptibility conferred by three HLA alleles strongly linked to ACPAs and RA (DRB1*04:04, DRB1*15:01, and DPB1*04:01). One year after eradication of Aa, the patient remained free of arthritis and anti-CCP antibodies.Conclusion: In the context of genetic risk for RA, systemic subacute infection with a leukotoxic strain of Aa can drive ACPA production and a clinical phenotype similar to RA

Autoantibodies to Peptidylarginine Deiminase 2 Are Associated With Less Severe Disease in Rheumatoid Arthritis

Objective: Peptidylarginine deiminases (PAD) 2 and 4 are key enzymes in rheumatoid arthritis (RA) pathogenesis due to their ability to generate the protein targets of anti-citrullinated protein antibodies (ACPA). Anti-PAD4 antibodies that cross-react with PAD3 (anti-PAD3/4) have been identified and are associated with severe joint and lung disease. Here, we examined whether anti-PAD2 antibodies were present in patients with RA and defined their clinical significance.Patients and Methods: A PAD2 ELISA was established to screen for anti-PAD2 IgG in sera from RA patients from a prospective observational cohort study (n = 184) and healthy controls (n = 100). RA patient characteristics were compared according to anti-PAD2 antibody status. Multivariable models were constructed to explore the independent associations of anti-PAD2 antibodies with clinical variables.Results: Anti-PAD2 antibodies were found in 18.5% of RA patients and 3% of healthy controls (p < 0.001). Among RA patients, anti-PAD2 antibodies were not associated with traditional genetic or serologic RA risk factors, including HLA-DRβ1 shared epitope alleles, ACPA, rheumatoid factor (RF), or anti-PAD3/4 antibodies. In addition, antibodies to PAD2 were associated with fewer swollen joints, a lower prevalence of interstitial lung disease, and less progression of joint damage. In subset analyses in which patients were stratified by the baseline presence of ACPA/RF or anti-PAD3/4 antibodies, anti-PAD2 antibodies provided additional value in identifying patients with the least progressive joint disease.Conclusions: Anti-PAD2 antibodies represent a novel serologic marker in RA that identifies a genetically and clinically unique subset of patients with less severe joint and lung disease

The impact of COVID-19 on rheumatology training—results from the COVID-19 Global Rheumatology Alliance trainee survey

Objective: The aim was to evaluate the impact of the coronavirus disease 2019 (COVID-19) pandemic on the clinical experiences, research opportunities and well-being of rheumatology trainees. / Methods: A voluntary, anonymous, Web-based survey was administered in English, Spanish or French from 19 August 2020 to 5 October 2020. Adult and paediatric rheumatology trainees were invited to participate via social media and email. Using multiple-choice questions and Likert scales, the perceptions of trainees regarding the impact of the COVID-19 pandemic on patient care and redeployment, learning and supervision, research and well-being were assessed. / Results: There were 302 respondents from 33 countries, with 83% in adult rheumatology training. An increase in non-rheumatology clinical work was reported by 45%, with 68% of these having been redeployed to COVID-19. Overall, trainees reported a negative impact on their learning opportunities during rheumatology training, including outpatient clinics (79%), inpatient consultations (59%), didactic teaching (55%), procedures (53%), teaching opportunities (52%) and ultrasonography (36%). Impacts on research experiences were reported by 46% of respondents, with 39% of these reporting that COVID-19 negatively affected their ability to continue their pre-pandemic research. Burnout and increases in stress were reported by 50% and 68%, respectively. Physical health was negatively impacted by training programme changes in 25% of respondents. / Conclusion: The COVID-19 pandemic has had a substantial impact on rheumatology training and trainee well-being. Our study highlights the extent of this impact on research opportunities and clinical care, which are highly relevant to future curriculum planning and the clinical learning environment

Special considerations in the management of adult patients with acute leukaemias and myeloid neoplasms in the COVID-19 era: recommendations from a panel of international experts

This article is made available for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.The ongoing COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 is a global public health crisis. Multiple observations indicate poorer post-infection outcomes for patients with cancer than for the general population. Herein, we highlight the challenges in caring for patients with acute leukaemias and myeloid neoplasms amid the COVID-19 pandemic. We summarise key changes related to service allocation, clinical and supportive care, clinical trial participation, and ethical considerations regarding the use of lifesaving measures for these patients. We recognise that these recommendations might be more applicable to high-income countries and might not be generalisable because of regional differences in health-care infrastructure, individual circumstances, and a complex and highly fluid health-care environment. Despite these limitations, we aim to provide a general framework for the care of patients with acute leukaemias and myeloid neoplasms during the COVID-19 pandemic on the basis of recommendations from international experts

Association between solar insolation and a history of suicide attempts in bipolar I disorder

In many international studies, rates of completed suicide and suicide attempts have a seasonal pattern that peaks in spring or summer. This exploratory study investigated the association between solar insolation and a history of suicide attempt in patients with bipolar I disorder. Solar insolation is the amount of electromagnetic energy from the Sun striking a surface area on Earth. Data were collected previously from 5536 patients with bipolar I disorder at 50 collection sites in 32 countries at a wide range of latitudes in both hemispheres. Suicide related data were available for 3365 patients from 310 onset locations in 51 countries. 1047 (31.1%) had a history of suicide attempt. There was a significant inverse association between a history of suicide attempt and the ratio of mean winter solar insolation/mean summer solar insolation. This ratio is smallest near the poles where the winter insolation is very small compared to the summer insolation. This ratio is largest near the equator where there is relatively little variation in the insolation over the year. Other variables in the model that were positively associated with suicide attempt were being female, a history of alcohol or substance abuse, and being in a younger birth cohort. Living in a country with a state-sponsored religion decreased the association. (All estimated coefficients p <0.01). In summary, living in locations with large changes in solar insolation between winter and summer may be associated with increased suicide attempts in patients with bipolar disorder. Further investigation of the impacts of solar insolation on the course of bipolar disorder is needed.Peer reviewe

A critical reappraisal of neutrophil extracellular traps (NETs) and NETosis mimics based on differential requirements for protein citrullination

NETosis, an antimicrobial form of neutrophil cell death, is considered a primary source of citrullinated autoantigens in rheumatoid arthritis (RA) and immunogenic DNA in systemic lupus erythematosus (SLE). Activation of the citrullinating enzyme peptidylarginine deiminase type 4 (PAD4) is believed to be essential for neutrophil extracellular trap (NET) formation and NETosis. PAD4 is therefore viewed as a promising therapeutic target to inhibit the formation of NETs in both diseases. In this review, we examine the evidence for PAD4 activation during NETosis and provide experimental data to suggest that protein citrullination is not a universal feature of NETs. We delineate two distinct biological processes, leukotoxic hypercitrullination (LTH) and defective mitophagy, that have been erroneously classified as NETosis. While these NETosis mimics share morphological similarities with NETosis (i.e. extracellular DNA release), they are biologically distinct. As such, these processes can be readily classified by their stimuli, activation of distinct biochemical pathways, the presence of hypercitrullination, and antimicrobial effector function. NETosis is an antimicrobial form of cell death that is NADPH oxidase-dependent and not associated with hypercitrullination. In contrast, LTH is NADPH oxidase-independent and not bactericidal. Rather, LTH represents a bacterial strategy to achieve immune evasion. It is triggered by pore-forming pathways and equivalent signals that cumulate in calcium-dependent hyperactivation of PADs, protein hypercitrullination, and neutrophil death. The generation of citrullinated autoantigens in RA is likely driven by LTH, but not NETosis. Mitochondrial DNA (mtDNA) expulsion, the result of a constitutive defect in mitophagy, represents a second NETosis mimic. In the presence of interferon-α and immune complexes, this process can generate highly interferogenic oxidized mtDNA, which has previously been mistaken for NETosis in SLE. Distinguishing NETosis from LTH and defective mitophagy is paramount to understanding the role of neutrophil damage in immunity and the pathogenesis of human diseases. This provides a framework to design specific inhibitors of these distinct biological processes in human disease