A GPCR-neuropeptide axis dampens hyperactive neutrophils by promoting an alternative-like polarization during bacterial infection

The notion that neutrophils exist as a homogeneous population is being replaced with the knowledge that neutrophils adopt different functional states. Neutrophils can have a pro-inflammatory phenotype or an anti-inflammatory state, but how these states are regulated remains unclear. Here, we demonstrated that the neutrophil-expressed G-protein-coupled receptor (GPCR) Mrgpra1 is a negative regulator of neutrophil bactericidal functions. Mrgpra1-mediated signaling was driven by its ligand, neuropeptide FF (NPFF), which dictated the balance between pro- and anti-inflammatory programming. Specifically, the Mrgpra1-NPFF axis counter-regulated interferon (IFN) γ-mediated neutrophil polarization during acute lung infection by favoring an alternative-like polarization, suggesting that it may act to balance overzealous neutrophilic responses. Distinct, cross-regulated populations of neutrophils were the primary source of NPFF and IFNγ during infection. As a subset of neutrophils at steady state expressed NPFF, these findings could have broad implications in various infectious and inflammatory diseases. Therefore, a neutrophil-intrinsic pathway determines their cellular fate, function, and magnitude of infection.

Anti-Gephyrin Antibodies: A Novel Specificity in Patients With Systemic Sclerosis and Lower Bowel Dysfunction

OBJECTIVE

Autoantibodies are clinically useful in phenotyping patients with systemic sclerosis (SSc). Gastrointestinal (GI) function is regulated by the enteric nervous system (ENS) and commonly impaired in SSc, suggesting that the SSc autoimmune response may target ENS antigens. We sought to identify novel anti-ENS autoantibodies with an aim to clinically phenotype SSc GI dysfunction.

METHODS

Serum from a patient with SSc with GI dysfunction but without defined SSc-associated autoantibodies was used for autoantibody discovery. Immunoprecipitations performed with murine myenteric plexus lysates were on-bead digested, and autoantigens were identified by mass spectrometry. Prevalence was determined, and clinical features associated with novel autoantibodies were evaluated in a SSc cohort using regression analyses. The expression of gephyrin in human GI tract tissue was examined by immunohistochemistry.

RESULTS

We identified gephyrin as a novel SSc autoantigen. Anti-gephyrin antibodies were present in 9% of patients with SSc (16/188) and absent in healthy controls (0/46). Anti-gephyrin antibody-positive patients had higher constipation scores (1.00 vs 0.50, P = 0.02) and were more likely to have severe constipation and severe distention/bloating (46% vs 15%, P = 0.005; 54% vs 25%, P = 0.023, respectively). Anti-gephyrin antibody levels were significantly higher among patients with severe constipation (0.04 vs 0.00; P = 0.001) and severe distention and bloating (0.03 vs 0.004; P = 0.010). Severe constipation was associated with anti-gephyrin antibodies even in the adjusted model. Importantly, gephyrin was expressed in the ENS, which regulates gut motility.

CONCLUSION

Gephyrin is a novel ENS autoantigen that is expressed in human myenteric ganglia. Anti-gephyrin autoantibodies are associated with the presence and severity of constipation in patients with SSc.

Application of machine learning models to identify serological predictors of COVID-19 severity and outcomes

Critically ill people with COVID-19 have greater antibody titers than those with mild to moderate illness, but their association with recovery or death from COVID-19 has not been characterized. In 178 COVID-19 patients, 73 non-hospitalized and 105 hospitalized patients, mucosal swabs and plasma samples were collected at hospital enrollment and up to 3 months post-enrollment (MPE) to measure virus RNA, cytokines/chemokines, binding antibodies, ACE2 binding inhibition, and Fc effector antibody responses against SARS-CoV-2. The association of demographic variables and >20 serological antibody measures with intubation or death due to COVID-19 was determined using machine learning algorithms. Predictive models revealed that IgG binding and ACE2 binding inhibition responses at 1 MPE were positively and C1q complement activity at enrollment was negatively associated with an increased probability of intubation or death from COVID-19 within 3 MPE. Serological antibody measures were more predictive than demographic variables of intubation or death among COVID-19 patients.

Uncoupling interferons and the interferon signature explain clinical and transcriptional subsets in SLE

Interferons (IFN) are thought to be key players in systemic lupus erythematosus (SLE). The unique and interactive roles of the different IFN families in SLE pathogenesis, however, remain poorly understood. Using reporter cells engineered to precisely quantify IFN-I, IFN-II and IFN-III activity levels in serum/plasma, we found that while IFNs play essential role in SLE pathogenesis and disease activity, they are only significant in specific subsets of patients. Interestingly, whereas IFN-I is the main IFN that governs disease activity in SLE, clinical subsets are defined by the co-elevation of IFN-II and IFN-III. Thus, increased IFN-I alone was only associated with cutaneous lupus. In contrast, systemic features, such as nephritis, were linked to co-elevation of IFN-I plus IFN-II and IFN-III, implying a synergistic effect of IFNs in severe SLE. Intriguingly, while increased IFN-I levels were strongly associated with IFN-induced gene expression (93.5%), in up to 64% of cases, the IFN signature was not associated with IFN-I. Importantly, neither IFN-II nor IFN-III explained IFN-induced gene expression in patients with normal IFN-I levels, and not every feature in SLE was associated with elevated IFNs, suggesting IFN-independent subsets in SLE. Together, the data suggest that, unlike the IFN signature, direct quantification of bioactive IFNs can identify pathogenic and clinically relevant SLE subsets amenable for precise anti-IFN therapies. Since IFN-I is only elevated in a subset of SLE patients expressing the IFN signature, this study explains the heterogeneous response in clinical trials targeting IFN-I, where patients were selected based on IFN-induced gene expression rather than IFN-I levels.

Affinity maturation generates pathogenic antibodies with dual reactivity to DNase1L3 and dsDNA in systemic lupus erythematosus

Anti-dsDNA antibodies are pathogenically heterogeneous, implying distinct origins and antigenic properties. Unexpectedly, during the clinical and molecular characterization of autoantibodies to the endonuclease DNase1L3 in patients with systemic lupus erythematosus (SLE), we identified a subset of neutralizing anti-DNase1L3 antibodies previously catalogued as anti-dsDNA. Based on their variable heavy-chain (VH) gene usage, these antibodies can be divided in two groups. One group is encoded by the inherently autoreactive VH4-34 gene segment, derives from anti-DNase1L3 germline-encoded precursors, and gains cross-reactivity to dsDNA - and some additionally to cardiolipin - following somatic hypermutation. The second group, originally defined as nephritogenic anti-dsDNA antibodies, is encoded by diverse VH gene segments. Although affinity maturation results in dual reactivity to DNase1L3 and dsDNA, their binding efficiencies favor DNase1L3 as the primary antigen. Clinical, transcriptional and monoclonal antibody data support that cross-reactive anti-DNase1L3/dsDNA antibodies are more pathogenic than single reactive anti-dsDNA antibodies. These findings point to DNase1L3 as the primary target of a subset of antibodies classified as anti-dsDNA, shedding light on the origin and pathogenic heterogeneity of antibodies reactive to dsDNA in SLE.

An update on autoantibodies in systemic lupus erythematosus

PURPOSE OF REVIEW

Autoantibodies are cornerstone biomarkers in systemic lupus erythematosus (SLE), an autoimmune disease characterized by autoantibody-mediated tissue damage. Autoantibodies can inform about disease susceptibility, clinical course, outcomes and the cause of SLE. Identifying pathogenic autoantibodies in SLE, however, remains a significant challenge. This review summarizes recent advances in the field of autoantibodies in SLE.

RECENT FINDINGS

High-throughput technologies and innovative hypothesis have been applied to identify autoantibodies linked to pathogenic pathways in SLE. This work has led to the discovery of functional autoantibodies targeting key components is SLE pathogenesis (e.g. DNase1L3, cytokines, extracellular immunoregulatory receptors), as well as the identification of endogenous retroelements and interferon-induced proteins as sources of autoantigens in SLE. Others have reinvigorated the study of mitochondria, which has antigenic parallels with bacteria, as a trigger of autoantibodies in SLE, and identified faecal IgA to nuclear antigens as potential biomarkers linking gut permeability and microbial translocation in SLE pathogenesis. Recent studies showed that levels of autoantibodies against dsDNA, C1q, chromatin, Sm and ribosomal P may serve as biomarkers of proliferative lupus nephritis, and identified novel autoantibodies to several unique species of Ro52 overexpressed by SLE neutrophils.

SUMMARY

Autoantibodies hold promise as biomarkers of pathogenic mechanisms in SLE.

Management of early-stage triple-negative breast cancer: recommendations of a panel of experts from the Brazilian Society of Mastology

BACKGROUND

Triple-negative breast cancer (TNBC) is a heterogenous subtype involving different patterns of behavior and clinical course, demanding a complex, individualized sequence of treatment. The knowledge and attitudes of the affiliated members of the Brazilian Society of Mastology regarding TNBC were evaluated and a consensus regarding management and treatment was reached.

METHODS

Affiliates completed a survey involving 44 objective questions. In addition, a specialist meeting was held with 27 experts and 3 ad hoc consultants. The panelists completed the survey before and after brainstorming. Answers achieving 70% of agreement were considered consensual. The chi-square test was used to compare answers between panelists and affiliates and the Kappa coefficient to calculate agreement.

RESULTS

Consensus among the panelists increased from 26 (59.1%) to 32 questions (72.7%) following brainstorming (p = 0.17), including 7/10 questions on systemic treatment. Among the affiliates, consensus was achieved for 24 questions (54.5%), resulting in moderate agreement (κ = 0.445). Neoadjuvant chemotherapy should be indicated for almost all cases (except cT1a-b N0) and should include platinum agents. When indicated, immunotherapy is part of the standard of care. The panel reaffirmed the concept of no ink on tumor as indicative of adequate margins and the possibility of sentinel lymph node biopsy for cN1 patients who become cN0 following neoadjuvant therapy. Controversies remain on combining immunotherapy with capecitabine/olaparib in pertinent cases.

CONCLUSION

Expert consensus was achieved for > 70% of the questions, with moderate agreement between panelists and affiliates. Educational interventions on systemic breast cancer treatment affected decision-making in 60% of the questions.

High rates of SARS-CoV-2 infection in funeral home workers in Ecuador: Is it an occupational risk for COVID-19?

Aim

The COVID-19 outbreak has already caused more than 6.5 million deaths, overwhelming health systems worldwide. The unusual demand for funeral home services could make these workers a potential risk group for occupational exposure to SARS-CoV-2 associated with corpses management for COVID-19 patients.

Methodology

This is a cross-sectional study aimed to describe the infection rate of SARS-CoV-2 in funeral home staff by testing them with RT-qPCR in Quito, Ecuador. A total of 232 funeral home workers, representing more than 40% of funeral home personnel in Quito, were included in the study, in June 2020, immediately after the population lockdown was lifted in Ecuador.

Results

A total of 48 individuals tested positive for SARS-CoV-2, yielding an infection rate of 20.7%. The SARS-CoV-2 infection rate was 18.1 and 20.0% among personnel managing corpses or not managing corpses, respectively. Among the SARS-CoV-2 positive patients, 81.3% reported no symptoms related to COVID-19, and 3 individuals had high viral loads over 10⁸ copies/ml.

Conclusion

The high SARS-CoV-2 infection rate in funeral home staff suggested a potential occupational risk for COVID-19 but not related to corpses management. Public health guidelines for safe corpses management for COVID-19 victims and safe funeral services should be reinforced.

Heavy Chain Constant Region Usage in Antibodies to Peptidylarginine Deiminase 4 as a Marker of Disease Subsets in Rheumatoid Arthritis

OBJECTIVE

The study of autoantibody isotypes in autoimmune diseases is useful for identifying clinically relevant endotypes. This study was undertaken to study the prevalence and clinical significance of different isotypes and IgG subclasses of anti-peptidylarginine deiminase 4 (anti-PAD4) autoantibodies in individuals with rheumatoid arthritis (RA).

METHODS

In 196 RA subjects and 64 healthy controls, anti-PAD4 antibody types were determined using enzyme-linked immunosorbent assay. We investigated associations between anti-PAD4 antibodies and clinical outcomes, and relevant features were confirmed in an independent RA cohort.

RESULTS

Anti-PAD4 IgG1, anti-PAD4 IgG2, anti-PAD4 IgG3, anti-PAD4 IgG4, anti-PAD4 IgA, and anti-PAD4 IgE antibodies were more frequent in RA patients than healthy controls (P < 0.001). Anti-PAD4 IgG1, anti-PAD4 IgG3, and anti-PAD4 IgE were associated with distinct clinical features. Anti-PAD4 IgG1 was predictive of progressive radiographic joint damage (odds ratio [OR] 4.88, P = 0.005), especially in RA patients without baseline joint damage (40% versus 0%, P = 0.003) or in those negative for anti-cyclic citrullinated peptide and/or rheumatoid factor (OR 32; P = 0.009). IgG1 was also associated with higher levels of C-reactive protein (P = 0.006) and interleukin-6 (P = 0.021). RA patients with anti-PAD4 IgG3 had higher baseline joint damage scores (median Sharp/van der Heijde score 13 versus 7, P = 0.046), while those with anti-PAD4 IgE had higher Disease Activity Score in 28 joints (median 4.0 versus 3.5, P = 0.025), more frequent rheumatoid nodules (31% versus 16%, P = 0.025), and more frequent interstitial lung disease (ground-glass opacification) (24% versus 9%, P = 0.014). Anti-PAD4 IgG1 antibody associations with joint damage were corroborated in an independent RA cohort.

CONCLUSION

Anti-PAD4 IgG1, anti-PAD4 IgG3, and anti-PAD4 IgE antibodies identify discrete disease subsets in RA, suggesting that heavy chain usage drives distinct effector mechanisms of anti-PAD4 antibodies in RA.

Autoantibodies targeting LINE-1-encoded ORF1p are associated with systemic lupus erythematosus diagnosis but not disease activity

OBJECTIVES

Long Interspersed Element 1 (LINE-1) is an endogenous retroelement that constitutes a significant portion of the human genome and has been implicated in the pathogenesis of systemic lupus erythematosus (SLE). The LINE-1 RNA chaperone protein ORF1p was recently identified as an SLE autoantigen. Here we analyse ORF1p for qualities underlying SLE autoantigen status, compared anti-ORF1p antibodies to markers of SLE disease activity, and performed screening for antibodies against LINE-1 reverse transcriptase ORF2p.

METHODS

ORF1p was examined in epithelial cell lines treated with cytotoxic lymphocyte granules and UV irradiation. Anti-ORF1p and anti-ORF2p antibodies were assayed by ELISA and analysed in two SLE cohorts.

RESULTS

We found that ORF1p localises to cytoplasmic RNA-containing blebs in apoptotic cells, and is a substrate of the cytotoxic protease granzyme B (GrB). Anti-ORF1p antibodies were present in 4.2% of healthy controls, compared to 15.8% (p=0.0157) and 15.5% (p=0.036) of subjects in the two SLE cohorts. Anti-ORF1p antibodies were not associated with SLE disease activity nor peripheral blood markers of interferon (IFN) activation. Anti-ORF1p titres demonstrated stability over serial time points. Anti-ORF1p antibodies were not associated with anti-DNA, anti-RNP, or other SLE autoantibodies. There was no difference in anti-ORF2p ELISA results in controls versus SLE patients.

CONCLUSIONS

LINE-1 ORF1p is a component of apoptotic blebs and a substrate for GrB. Anti-ORF1p antibodies are enriched in SLE subjects but are not associated with dynamic markers of disease activity. These data support a potential role for LINE-1 dysregulation in SLE pathogenesis.

Alternative exon usage in TRIM21 determines the antigenicity of Ro52/TRIM21 in systemic lupus erythematosus

The origin and mechanisms of autoantigen generation in systemic lupus erythematosus (SLE) are poorly understood. Here, we identified SLE neutrophils activated in vivo by interferon as a prominent source of Ro52/TRIM21 (hereafter Ro52), a critical autoantigen historically thought to be primarily generated by keratinocytes in SLE. Different to mononuclear cells and keratinocytes, SLE neutrophils are enriched in several unique Ro52 species containing a core sequence encoded by exon-4 (Ro52Ex4) in TRIM21. Ro52Ex4 is the main target of anti-Ro52 antibodies and is found in two Ro52 variants (Ro52α and a novel isoform termed Ro52γ) upregulated in SLE neutrophils. Further analysis of Ro52γ revealed a new subset of autoantibodies against a unique C-terminal domain (Ro52γCT) generated from a frameshift due to the lack of exon-6 in Ro52γ. Antibodies to Ro52Ex4 and Ro52γCT distinguish SLE patient subsets characterized by distinct clinical, laboratory, treatment and transcriptional profiles, which are not discerned by the "classical" anti-Ro52 antibodies. Together, these studies uncover interferon-activated neutrophils as a key source of unique immunogenic forms of Ro52 in SLE. Moreover, the finding of Ro52Ex4 and Ro52γCT as core targets of anti-Ro52 antibodies focus interest on Ro52γ as the potential isoform toward which immunological tolerance is initially lost in SLE.

Microbial pathways to subvert host immunity generate citrullinated neoantigens targeted in rheumatoid arthritis

The specific association between antibodies to citrullinated proteins and rheumatoid arthritis (RA) has centered interest on understanding why citrullinated proteins become immunogenic in this disease, which is believed to inform the origins of autoimmunity in RA. Since citrullination is a physiologic post-translational modification (PTM), one theory is that conditions promoting abnormal citrullination are initiators of self-reactive immune responses to citrullinated proteins in RA. Foremost candidates that dysregulate the normal balance of citrullination are microbial agents, which can exploit citrullination as an effector mechanism to subvert host antimicrobial activities and maximize their progeny. Here, we will use the host-pathogen interface as a unifying model to link microbe-induced citrullination and the loss of immunological tolerance to citrullinated antigens in RA.

The relation between Complex PTSD and Borderline Personality Disorder – a review of the literature

Introduction

Adults diagnosed with Borderline Personality Disorder (BPD) likely have a history of psychological trauma. There has been research about the connection between Complex Post-Traumatic Stress Disorder (c-PTSD) and BPD.

Objectives

This paper provides a review of the relationship between complex trauma and key features of BPD.

Methods

Review of the literature from 2015 to present, using search engines such as Pubmed and Google Shoolar, using the following keywords: borderline personality disorder, complex post-traumatic stress disorder, trauma

Results

Traumatic victimisation and compromised primary caregiving relationships have been hypothesized to be key aetiological factors in the subsequent development of BPD. c-PTSD was defined as a syndrome with symptoms of emotional dysregulation, dissociation somatisation and poor self-esteem, with distorted cognition about relationships, following traumatic interpersonal abuse. It was proposed as an alternative for understanding and treating people who had suffered prolonged and severe interpersonal trauma, many of whom were diagnosed with BPD. Although, the boundaries between c-PTSD and BPD remain vague. Currently, the main difference is the assumption that symptoms of c-PTSD are sequelae of exposure to traumatic stress, which is not inherent in the current DSM-5 definition of BPD. Furthermore, to date, the neurochemistry and neurostructural changes seen in c-PTSD, BPD and PTSD do not clearly differentiate the three conditions.

Conclusions

BPD and PTSD are relatively distinct with regard to the precise qualitative definitions of their diagnostic features, but nevertheless have substantial potential overlap in their symptom criteria.

Disclosure

No significant relationships.

The effect of COVID-19 pandemic on admissions for cannabis-induced psychotic disorder

Introduction

Cannabis-induced psychotic disorder (CIPD) is defined by the development of psychotic symptoms during or briefly after intoxication with cannabis or withdrawal from cannabis. The social measures and restrictions implemented following the COVID-19 pandemic might have had an impact on cannabis availability, as suggested by patients from our clinical practice, reporting a shortage of the substance.

Objectives

To compare sociodemographic, clinical characteristics and admission rates of inpatient treatment for cannabis-induced psychotic disorder in COVID-19 pandemic period and pre-pandemic period.

Methods

Retrospective observational study of inpatient admissions for CIPD in a psychiatry inpatient unit of a tertiary hospital. The statistical analysis was performed using SPSS software, version 27.0.

Results

Our sample included 120 inpatient admissions, corresponding to 80 patients. Compared to 2018 and 2019, in 2020 there was an overall reduction of 21.5% in inpatient admissions (n=618, 549 and 458, respectively). The number of admissions for CIPD in 2018, 2019, 2020 and 2021 up to september were, respectively, 29, 32, 10 and 31 (5.2%, 6.1%, 2.2% and 7.2% of respective annual admissions). We found no statistically significant differences regarding sociodemographic and clinical characteristics in patients admitted for CIPD during 2020.

Conclusions

These results suggest a disproportionate reduction of inpatient admissions due to CIPD in 2020, followed by an expressive increase in the number of admissions in 2021up to september. This might be related to cannabis availability returning to regular levels. However other factors must be considered, such as the delay of treatment due to reduced accessibility to health care.

Disclosure

No significant relationships.

Multiple inpatient admissions for cannabis-induced psychotic disorder - sociodemographic, clinical and treatment evaluation

Introduction

Current evidence contradicts the idea that cannabis-induced psychotic disorder (CIPD) has an overall benign prognosis, with up to half of these patients being with a schizophrenia spectrum disorder later in life.

Objectives

To characterize sociodemographic and clinical characteristics and treatment plan of inpatients with multiple admissions for CIPD over a one-year period, compared to those with a single admission.

Methods

Retrospective observational study of inpatient episodes with CIPD between january 1st 2018 and september 30th 2021 in a tertiary psychiatric inpatient unit. Statistical analysis was performed using SPSS software, version 27.0.

Results

Our sample included 80 inpatients, 15 (18.8%) with multiple admissions for CIPE within one year period and 65 (81.3%) with a single admission. The multiple admissions group had a median of 1 ±0,915 admissions within the same year. Being readmitted for CIPE was associated with outpatient compulsory treatment at discharge (OR 3,01 (95% CI 1,27-7,18, p=0,034). These patients had 3.14 higher odds of future admissions to psychiatry unit (CI 95% 1.70-5.78, p<0.001). We found no statistically significant differences regarding the sociodemographic and clinical characteristics, daily vs. occasional use of cannabis in patients with multiple admissions for CIPE.

Conclusions

Patients with multiple admissions for CIPD tend to have more relapses and require assertive treatment measures. However, they did not differ regarding the sociodemographic and clinical characteristics studied from patients with single admissions. This suggests that additional assessment of these patients might be important to predict the course of the disease.

Disclosure

No significant relationships.

Finding meanings in Late onset Post Traumatic Stress Disorder – a review of the literature

Introduction

About a decade ago, the idea of a Late-Onset Post Traumatic Stress Disorder (LO-PTSD) emerged, in order to characterize the later-life emergence of symptoms related to early-life warzone trauma among aging combat Veterans.

Objectives

This paper provides a review of the changes happened during the onset of a late form of PTSD and how can mental health professionals intervene.

Methods

Review of the literature from 2015 to present, using search engines such as Pubmed and Google Schoolar, using the following keywords: Late-Onset Post Traumatic Stress Disorder, triggers, prevention, intervention

Results

At first, there was hypothesized that aging-related challenges (role transition and loss, death of family members and friends, physical and cognitive decline) might lead to increased reminiscence, and possibly distress, among Veterans who had previously dealt successfully with earlier traumatic events. However, recent studies have proposed that in later life many combat Veterans confront and rework their wartime memories in an effort to find meaning and build coherence. Through reminiscence, life review, and wrestling with issues such as integrity versus despair, they intentionally reengage with experiences they avoided or managed successfully earlier in life, perhaps without resolution or integration. This process can lead positively to personal growth or negatively to increased symptomatology.

Conclusions

Therefore the role of preventive intervention in enhancing positive outcomes for Veterans who reengage with their wartime memories in later life should be reconsidered.

Disclosure

No significant relationships.

Intersection Between Large Granular Lymphocyte Leukemia and Rheumatoid Arthritis

Large granular lymphocyte (LGL) leukemia, a rare hematologic malignancy, has long been associated with rheumatoid arthritis (RA), and the diseases share numerous common features. This review aims to outline the parallels and comparisons between the diseases as well as discuss the potential mechanisms for the relationship between LGL leukemia and RA. RA alone and in conjunction with LGL leukemia exhibits cytotoxic T-cell (CTL) expansions, HLA-DR4 enrichment, RA-associated autoantibodies, female bias, and unknown antigen specificity of associated T-cell expansions. Three possible mechanistic links between the pathogenesis of LGL leukemia and RA have been proposed, including LGL leukemia a) as a result of longstanding RA, b) as a consequence of RA treatment, or c) as a driver of RA. Several lines of evidence point towards LGL as a driver of RA. CTL involvement in RA pathogenesis is evidenced by citrullination and granzyme B cleavage that modifies the repertoire of self-protein antigens in target cells, particularly neutrophils, killed by the CTLs. Further investigations of the relationship between LGL leukemia and RA are warranted to better understand causal pathways and target antigens in order to improve the mechanistic understanding and to devise targeted therapeutic approaches for both disorders.

IgM anti-ACE2 autoantibodies in severe COVID-19 activate complement and perturb vascular endothelial function

BackgroundSome clinical features of severe COVID-19 represent blood vessel damage induced by activation of host immune responses initiated by the coronavirus SARS-CoV-2. We hypothesized autoantibodies against angiotensin-converting enzyme 2 (ACE2), the SARS-CoV-2 receptor expressed on vascular endothelium, are generated during COVID-19 and are of mechanistic importance.MethodsIn an opportunity sample of 118 COVID-19 inpatients, autoantibodies recognizing ACE2 were detected by ELISA. Binding properties of anti-ACE2 IgM were analyzed via biolayer interferometry. Effects of anti-ACE2 IgM on complement activation and endothelial function were demonstrated in a tissue-engineered pulmonary microvessel model.ResultsAnti-ACE2 IgM (not IgG) autoantibodies were associated with severe COVID-19 and found in 18/66 (27.2%) patients with severe disease compared with 2/52 (3.8%) of patients with moderate disease (OR 9.38, 95% CI 2.38-42.0; P = 0.0009). Anti-ACE2 IgM autoantibodies were rare (2/50) in non-COVID-19 ventilated patients with acute respiratory distress syndrome. Unexpectedly, ACE2-reactive IgM autoantibodies in COVID-19 did not undergo class-switching to IgG and had apparent KD values of 5.6-21.7 nM, indicating they are T cell independent. Anti-ACE2 IgMs activated complement and initiated complement-binding and functional changes in endothelial cells in microvessels, suggesting they contribute to the angiocentric pathology of COVID-19.ConclusionWe identify anti-ACE2 IgM as a mechanism-based biomarker strongly associated with severe clinical outcomes in SARS-CoV-2 infection, which has therapeutic implications.FUNDINGBill & Melinda Gates Foundation, Gates Philanthropy Partners, Donald B. and Dorothy L. Stabler Foundation, and Jerome L. Greene Foundation; NIH R01 AR073208, R01 AR069569, Institutional Research and Academic Career Development Award (5K12GM123914-03), National Heart, Lung, and Blood Institute R21HL145216, and Division of Intramural Research, National Institute of Allergy and Infectious Diseases; National Science Foundation Graduate Research Fellowship (DGE1746891).

Redox-Mediated Carbamylation As a Hapten Model Applied to the Origin of Antibodies to Modified Proteins in Rheumatoid Arthritis

Significance: The production of antibodies to posttranslationally modified antigens is a hallmark in rheumatoid arthritis (RA). In particular, the presence of citrullination-associated antibodies, targeting both citrullinating enzymes (the peptidylarginine deiminases [PADs]) and citrullinated antigens (anticitrullinated protein antibodies [ACPAs]), has suggested that dysregulated citrullination is relevant for disease pathogenesis. Antibodies to other protein modifications with physicochemical similarities to citrulline, such as carbamylated-lysine and acetylated-lysine, have also gained interest in RA, but their mechanistic relation to ACPAs remains unclear. Recent Advances: Recent studies using RA-derived monoclonal antibodies have found that ACPAs are cross-reactive to carbamylated and acetylated peptides, challenging our understanding of the implications of such cross-reactivity. Critical Issues: Analogous to the classic antibody response to chemically modified proteins, we examine the possibility that antibodies to modified proteins in RA are more likely to resemble antihapten antibodies rather than autoantibodies. This potential shift in the autoantibody paradigm in RA offers the opportunity to explore new mechanisms involved in the origin and cross-reactivity of pathogenic antibodies in RA. In contrast to citrullination, carbamylation is a chemical modification associated with oxidative stress, it is highly immunogenic, and is considered in the group of posttranslational modification-derived products. We discuss the possibility that carbamylated proteins are antigenic drivers of cross-reacting antihapten antibodies that further create the ACPA response, and that ACPAs may direct the production of antibodies to PAD enzymes. Future Directions: Understanding the complexity of autoantibodies in RA is critical to develop tools to clearly define their origin, identify drivers of disease propagation, and develop novel therapeutics. Antioxid. Redox Signal. 36, 389-409.

High SARS-CoV-2 Infection Rates Among Special Forces Police Units During the Early Phase of the COVID-19 Pandemic in Ecuador

Background

At the beginning of the COVID-19 pandemic, health workers and first-responders, such as police officers, were in charge of trying to contain a disease that was unknown at that time. The lack of information and the tremendous need to contain new outbreaks put police officers at higher risk.

Methodology

A cross-sectional study was conducted to describe SARS-CoV-2 infection rates among Police Special Forces Officers in Quito, Ecuador. In this study, 163 community-dwelling police officers from elite divisions voluntarily participated in our SARS-CoV-2 detection program using reverse transcription quantitative real-time PCR (RT-qPCR).

Results

A total of 20 out of 163 police officers tested positive for SARS-CoV-2, yielding an infection rate of 12.3%. Within this cohort, 10% (2/20) of SARS-CoV-2 positive individuals were potentially super spreaders with viral loads over 10⁸ copies/ul. About 85% of the SARS-CoV-2 positive individuals were asymptomatic and 15% reported mild symptoms related to COVID-19.

Conclusions

We found a high SARS-CoV-2 infection rate within the special forces police officers that, beyond a high health risk for themselves, their families, and coworkers. Our results point out the need for permanent SARS-CoV-2 testing among asymptomatic essential workers and first-responders to avoid local outbreaks and to prevent work-place absenteeism among police special units.

Snake antivenom production in Ecuador: Poor implementation, and an unplanned cessation leads to a call for a renaissance

Snakebite envenomation is a global health problem. This health problem asymmetrically affects rural populations in developing countries to such an extent that it recently has been listed as a priority neglected tropical disease (NTD). It is estimated that 5.4 million individuals are bitten by snakes each year, causing at least 2.7 million envenomations and more than 100,000 deaths each year. Ecuador has one of the highest snakebite envenomation incidence rates in Latin America, mostly in the coastal and Amazonian provinces. Envenomations in these regions are the result of bites primarily by species of snakes belonging to the Viperidae family. Ecuador was able to locally produce antivenoms, however serious flaws were revealed in the antivenom production process, leading to the decommissioning of the existing facility. In the interest of public health, we have summarized the political and social setbacks experienced by the antivenom serum production plant in Ecuador, while encouraging resuming local production of snake antivenom to improve the responsiveness of the already overburdened health system.

Bipolar mania with psychosis vs without psychosis: A clinical characterization with indirect measures of severity

Introduction

The presence of psychotic symptoms is highest during acute episodes of bipolar mania. There is no evidence base regarding the implications of psychosis in the prognosis of bipolar disorder, despite common assumption that their occurrence reflects greater disease severity.

Objectives

We aim to compare sociodemographic and clinical characteristics of inpatients admitted for bipolar mania with and without psychotic features.

Methods

Retrospective observational study of inpatients admitted between January 1^st 2017 and 31 October 2020 in a psychiatry inpatient unit of a tertiary hospital. Descriptive analysis of the results was performed using the SPSS software, version 26.0.

Results

Between 2017 and October 2020 there were 103 admissions due to mania bipolar I disorder, 53.4% (n=55) with psychotic symptoms. When compared with mania without psychosis, psychotic mania was associated to male gender (71.1% to 39.7%; c²(1, N = 103) = 10,06; p = 0.02) and younger age (t(103) = -2.43; p = 0.017). The proportion of compulsory admissions and average length of stay were similar between mania with psychosis and mania without psychosis. Also, having a manic bipolar episode with psychotic symptoms was not associated to being prescribed a long-acting injectable antipsychotic.

Conclusions

The presence of psychotic symptoms in bipolar manic episodes were associated to male gender and younger age but not to indirect measures of illness severity.

Disclosure

No significant relationships.

First vs. multiple cannabis-induced psychotic episodes: Is inpatient treatment any different?

Introduction

Recent studies reported very high cumulative risk for a patient who had cannabis-induced psychosis to be diagnosed with a schizophrenia spectrum disorder.

Objectives

We aim to compare sociodemographic and clinical characteristics, treatment and discharge plan in cannabis-induced first psychosis episode (CI-FEP) vs. multiple cannabis-induced psychotic episodes (CI-MEP) inpatients.

Methods

Retrospective observational study of inpatient episodes with a discharge diagnosis of cannabis-induced psychosis between January 1^st, 2018 and December 31^st, 2019 in the Psychiatry Service of CHUSJ. Descriptive analysis of the results was performed using the SPSS software, version 26.0.

Results

Our sample included 61 inpatients, 19 (31.1%) with CI-FEP and 42 (68.9%) with CI-MEP. CI-MEP group had a median of 1±0,234 previous hospital admissions. CI-MEP group has 10,0 higher odds of being discharged in outpatient compulsory treatment (CI 95% 1,21-82,50, p=0,013) and 6.0 odds of being treated with long-acting injectable antipsychotics (LAIAP) (CI 95% 1,79-20,31, p=0,002) when compared to CI-FEP group. Having multiple cannabis-induced psychotic episodes was associated with future admissions to psychiatry unit (OR 4,85 (95% CI 1,23-19,15, p=0,018). We found no statistically significant differences regarding the sociodemographic and clinical characteristics, use habits and discharge plan between the two groups.

Conclusions

Patients with multiple psychotic episodes due to cannabis use are more likely to have a LAIAP prescription, be discharged in compulsory outpatient regimen and be readmitted in to psychiatric inpatient unit. Considering the prevalence of CI-MEP and the risk of chronicity, we need integrative treatment programs to address the specificities of these patients.

Dementia and suicide: What relationship to establish and what risks to consider?

Introduction

Given the marked population aging in the world, the incidence of dementia has significantly increased, becoming a growing health care problem. Suicide is a considerable health issue throughout the life span, being prevalent in older adults, and in many countries the highest suicide rates are found in the elderly. Thus far, the relationship between dementia and suicide remains poorly understood and inconsistent.

Objectives

The aim of this study is to do a non-systematic review of the current literature regarding the association between suicide risk and dementia.

Methods

We conducted a research using the Medline database, through the Pubmed search engine, using the following key-words: “dementia”, “suicide” and “risk factors”.

Results

Overall, the risk of suicide in people with dementia appears to be the same as that of age-matched general population. However, studies point to the existence of a number of factors that can increase this risk, such as: early age of dementia diagnosis, recent diagnosis, disease awareness and depression, hopelessness, male gender, failure to respond to anti-dementia medication, history of inpatient psychiatric hospitalizations, concurrent medical comorbidities.

Conclusions

Studies have reported mixed results as to whether dementia itself is an independent risk factor for suicide. Despite these findings, understanding the risk factors for suicide among people with dementia is crucial and suicide prevention efforts should be carried out in this population.

Inpatient psychiatry care during coronavirus 2019 pandemic lockdown: Results from a department of psychiatry in northern Portugal

Introduction

COVID-19 pandemic and the consequent containment measures have a negative impact on mental health. Simultaneously, the fear of infection can discourage patients from seeking necessary care.

Objectives

We aim to compare sociodemographic and clinical characteristics of inpatients admitted during the COVID-19 confinement period in Portugal vs. inpatients admitted in the same period the previous year.

Methods

Retrospective observational study of inpatients admitted between March 19^th 2020 and May 1^st 2020 and the analog period of 2019 in a psychiatry inpatient unit of a tertiary hospital. Descriptive analysis of the results was performed using the SPSS software, version 26.0.

Results

During the lockdown period, there were 30 admissions to the psychiatry inpatient unit, 55.2% less than the same period last year (n=67). The proportion of compulsory admissions and the average length of stay did not differ between the two periods. Regarding sociodemographic characteristics, in the confinement period inpatients were similar to the ones in the same period of 2019. In both periods, the majority of patients had previous psychiatric history (lockdown vs. same period last year: 95.5% and 90.0%) and a similar proportion of readmissions rate (previous year) was similar in the two groups (49.9% vs 47.6%). At discharge, the most frequent diagnostic groups were mood disorders (33.3% (n=10) and 34.3% (n=23)) and schizophrenia, schizotypal and delusional disorders (26,7% (n=8) and 31.3% (n=21)).

Conclusions

Although there was an expressive reduction of admissions to the psychiatry inpatient unit during lockdown, the clinical characteristics of these patients were analogous to the same period in the previous year.

Associations of Antibodies Targeting Periodontal Pathogens With Subclinical Coronary, Carotid, and Peripheral Arterial Atherosclerosis in Rheumatoid Arthritis

OBJECTIVE

Both periodontal disease and cardiovascular disease (CVD) are overrepresented in rheumatoid arthritis (RA). This study was undertaken to investigate the contribution of periodontal pathogens to CVD in RA.

METHODS

RA patients underwent assessments of coronary artery calcification (CAC), carotid intima-media thickness and plaque, and ankle-brachial index via computed tomography, ultrasound, and Doppler ultrasound, respectively. Sera were assayed for antibodies targeting Porphyromonas gingivalis (Pg), Aggregatibacter actinomycetemcomitans serotype B (Aa), and Aa-derived leukotoxin A (LtxA). Associations of antibodies against these periodontal pathogens with measures of atherosclerosis were explored using generalized linear models.

RESULTS

Among 197 RA patients, anti-Pg was detected in 72 patients (37%), anti-Aa in 41 patients (21%), and anti-LtxA in 84 patients (43%). Adjusting for relevant confounders and reported tooth loss, the mean CAC score was 90% higher in those with anti-Aa and/or anti-LtxA compared with those without either antibody (19 units versus 10 units; P = 0.033). The adjusted odds of CAC ≥100 units were 2.23-fold higher in those with anti-Aa and/or anti-LtxA compared with those without either antibody (P = 0.040). Anti-Aa and/or anti-LtxA seropositivity was significantly associated with all other assessed measures of atherosclerosis except carotid plaque. Anti-Pg was not associated with any measure of atherosclerosis. Higher swollen joint count was associated with CAC exclusively in the group with anti-Aa and/or anti-LtxA.

CONCLUSION

Immunoreactivity against Aa and/or its major virulence factor LtxA was associated with atherosclerosis in multiple vascular beds of RA patients and amplified the effect of swollen joints on coronary atherosclerosis, suggesting a role for treatment/prevention of periodontal disease in the prevention of CVD in RA.

Granzyme B Induces IRF-3 Phosphorylation through a Perforin-Independent Proteolysis-Dependent Signaling Cascade without Inducing Cell Death

Granzyme B (GrB) is an immune protease implicated in the pathogenesis of several human diseases. In the current model of GrB activity, perforin determines whether the downstream actions of GrB occur intracellularly or extracellularly, producing apoptotic cytotoxicity or nonapoptotic effects, respectively. In the current study, we demonstrate the existence of a broad range of GrB-dependent signaling activities that 1) do not require perforin, 2) occur intracellularly, and 3) for which cell death is not the dominant outcome. In the absence of perforin, we show that GrB enzymatic activity still induces substoichiometric activation of caspases, which through nonlethal DNA damage response signals then leads to activity-associated phosphorylation of IFN regulatory factor-3. These findings illustrate an unexpected potential interface between GrB and innate immunity separate from the traditional role of GrB in perforin-dependent GrB-mediated apoptosis that could have mechanistic implications for human disease.

IgM autoantibodies recognizing ACE2 are associated with severe COVID-19

SARS-CoV-2 infection induces severe disease in a subpopulation of patients, but the underlying mechanisms remain unclear. We demonstrate robust IgM autoantibodies that recognize angiotensin converting enzyme-2 (ACE2) in 18/66 (27%) patients with severe COVID-19, which are rare (2/52; 3.8%) in hospitalized patients who are not ventilated. The antibodies do not undergo class-switching to IgG, suggesting a T-independent antibody response. Purified IgM from anti-ACE2 patients activates complement. Pathological analysis of lung obtained at autopsy shows endothelial cell staining for IgM in blood vessels in some patients. We propose that vascular endothelial ACE2 expression focuses the pathogenic effects of these autoantibodies on blood vessels, and contributes to the angiocentric pathology observed in some severe COVID-19 patients. These findings may have predictive and therapeutic implications.

Pulse oximetry curves in healthy children living at moderate altitude: a cross-sectional study from the Ecuadorian Andes

Background

In populations above 3,000 meters above sea level (m.a.s.l.) normal values of oxygen saturation (SpO2) above 90% have been reported. Few studies have been conducted in cities of moderate altitude (between 2,500 and 3,000 m a.s.l). We set out to describe the range of SpO2 values measured with a pulse oximeter in healthy children between 1 month and 12 years of age living in an Ecuadorian Andean city.

Methods

A cross-sectional study was carried out in Quito, Ecuador, located at 2,810 m a.s.l. SpO2 measurement in healthy children of ages ranging from 1 month to 12 years of age residents in the city were recorded by pulse oximetry. Age and gender were recorded, and median and 2.5th and 5th percentile were drawn. Non parametric tests were used to compare differences in SpO2 values by age and gender.

Results

1,378 healthy children were included for the study, 719 (52.2%) males. The median SpO2 for the entire population was 94.5%. No differences were observed between SpO2 median values by age and gender. The 2.5th percentile for global SpO2 measurements was 90%, in children under 5 years of age was 91% and it was 90% in children older than 7.

Conclusions

Our results provide SpO2 values for healthy children from 1 to 12 years old residents in Quito, a city of moderate altitude. The SpO2 percentile curve could contribute as a healthy range for the clinical evaluation of children residing at this altitude.

Lower predicted probabilities of attained Lifés Simple 7 factors in the presence of sleep problems

Background

Given that sleep disturbances seem to be increasing in Brazil, this may have serious implications on Cardiovascular Health and mortality.

Objective

To examine the predicted probabilities of attained Lifés Simple 7 factors (LS7) in the presence of sleep problems among Brazilian adults.

Methods

We used data from the 2013 Brazilian National Health Survey (PNS), a nationally representative cross-sectional household survey of adults in Brazil. Cardiovascular Health was assessed by the sum of Lifés Simple 7 factors (LS7), which includes four behaviors (smoking, physical activity, body mass index and diet) and three biological factors (hypercholesterolemia, hypertension and diabetes). We analyzed self-reported data from 36,480 Brazilian adults aged 18 and over, including the sleep problems. We estimated predicted probabilities after multivariate Poisson regression.

Results

Mean CVH scores was higher among those who did not report sleep disturbances [4.2 (95% CI: 4.1; 4.2)], than those with sleep disturbances [3.8 (95% CI: 3.7; 3.8)]. Predicted probabilities of attained LS7 and CVH score was lower in the presence of sleep complaints, with a dose response for blood pressure, glucose, smoking and CVH score in both unadjusted and adjusted analyses, for age, sex, schooling, depression and night work shift.

Conclusions

Brazilian adults with sleep disturbances are less likely to achieve LS7 and consequently ideal cardiovascular health. Given that sleep disturbances seem to be increasingly more common in Brazil, recent gains in CVH mortality may be affected.

Key messages

Sleep disturbances may potentially affect metabolic outcomes and modifiable lifestyles behaviors as decreased physical activity and smoking. Sleep disturbances is novel risk factor for metabolic diseases.

Citrulline Not a Major Determinant in the Recognition of Peptidylarginine Deiminase 2 and 4 by Autoantibodies in Rheumatoid Arthritis

OBJECTIVE

Citrullinated proteins are hallmark targets of autoantibodies in rheumatoid arthritis (RA). Our study was undertaken to determine the effect of autocitrullination on the recognition of peptidylarginine deiminases (PADs) 2 and 4 by autoantibodies in RA.

METHODS

Autocitrullination sites in PAD2 and PAD4 were determined by mass spectrometry and literature review. Antibodies against native and autocitrullinated PADs in 184 patients with RA were detected by enzyme-linked immunosorbent assay. Linear regression analysis, outlier calculations, and competition assays were performed to evaluate antibody reactivity to native and citrullinated PADs.

RESULTS

Autocitrullination of PAD2 and PAD4 was detected in 16 (48%) of 33 arginine residues and 7 (26%) of 27 arginine residues, respectively. Despite robust autocitrullination, autoantibodies bound similarly to native and citrullinated PAD2 or PAD4 (ρ = 0.927 and ρ = 0.903, respectively; each P < 0.0001). Although subsets of anti-PAD-positive sera were identified as exhibiting preferential recognition of native or citrullinated PAD2 (40.5% or 4.8%, respectively) or PAD4 (11.7% or 10.4%, respectively), competition assays confirmed that the majority of anti-PAD reactivity was attributed to a pool of autoantibodies that bound irrespective of citrullination status.

CONCLUSION

Autocitrullination does not affect autoantibody reactivity to PADs in the majority of patients with RA, demonstrating that anti-PAD antibodies are distinct from anti-citrullinated protein antibodies in their dependence on citrullination for binding.

Current trends for biosimilars in the Latin American market

The number of approved biological medicines in the global pharmaceutical market has increased in recent decades. However, their high costs have also promoted the development of biosimilar medicines, following the expiry of the patent of the reference drug. Biosimilars are approved medicines of biological origin which have no statistically significant differences in terms of quality, safety and therapeutic efficacy in comparison with the reference biological. Drugs marketed as biomimics meanwhile are copies of monoclonal antibodies and fusion proteins that have not demonstrated bioequivalence to their reference biologicals. Across the world, regulations have been developed to ensure the safety and efficacy of biosimilar products, which can reduce public health expenditure and improve patient access to biological medicines. As a result, Latin America has begun to invest in the development of these drugs. The objective of this literature review is to describe the development of the biosimilar and biomimic market in Latin America.

Impact of preoperative magnetic resonance imaging (MRI) on conservative surgery (CSur) among curable breast cancer (BC) patients treated in a specialized center in Latin America

e12595

Background: Preoperative breast MRI can provide important clinical information on the surgical management of BC patients (pts). However, there is no evidence that it can produce a statistical impact on surgical outcomes in the early BC setting. This retrospective study sought to evaluate whether preoperative MRI was significantly correlated with CSur among early BC pts. Methods: Digital and physical records from 532 pts treated in a specialized BC center in Brazil from 2005 to 2018 were analyzed. The institutional database registered pathological, radiological and clinical information. The categorical variables CSur and MRI were analyzed by Chi-squared coefficient of correlation, whereas significant correlations were included in a multivariate logistic regression model. All statistical analysis were performed in STATA version 15.1C. Results: The present analysis included 532 pts. The diagnosis was suspected through suspicious self-exam in 380 pts (71%), while 129 pts (24%) had altered mammary screening tests. Clinical T and N stages were: T0-1=154pts (29%); T2=179 pts (33%); T3=135 pts (25%); T4=49 pts (9%); N0=267 pts (50%); N1=172 pts (32%); N2=80 pts (15%). Neoadjuvant treatment was performed in 223 pts (42%). MRI was indicated in 248 pts (46%). CSur was performed in 149 pts (28%). Margins were positive in 15 cases. This study found a statistically significant correlation between CSur and MRI ( X2 = 8.07; p=0.018). Although, when controlled for neoadjuvant treatment, T, N, and age, the independent variable MRI was not a statistical predictor of CSur (R=0.008; t=0.25; p=0.8; 95%CI -0.57 – 0.74). Advanced T and neoadjuvant treatment were inversely correlated with CSur in the multivariate analysis (R= -0.11; t= -7.8; p<0.001 and R= -0.11; t= -2.88; p=0.004, respectively). One multivariate analysis to evaluate predictors of T stages showed that suspicious self-exam and N stage had a significant linear relationship with T stages when controlled for age (R=0.70; t=7.9; p<0.001; and R=0.76; t=15; p<0.001, respectively). Conclusions: Preoperative MRI can have impact on the conservative surgical management of curable BC patients and the present analysis showed a positive correlation. In the logistic regression model, MRI was not identified as a predictor of CSur, however the proportion of locally advanced BC may have influenced the results. Further studies must be strengthened for identifying in which subgroup of patients MRI may be a predictor of surgical outcomes.

Generation of Distinct Patterns of Rheumatoid Arthritis Autoantigens by Peptidylarginine Deiminase Types 2 and 4 During Perforin-Induced Cell Damage

OBJECTIVE

To address the independent roles of peptidylarginine deiminase type 2 (PAD2) and PAD4 in generating rheumatoid arthritis (RA) autoantigens by using a system that mimics intracellular citrullination in the RA joint.

METHODS

PAD2- or PAD4-expressing 293T cells and mock-transfected cells were used as targets in cytotoxic assays using lymphokine-activated killer cells, cytotoxic YT cell granule contents, or purified human perforin. Protein citrullination and autoantigen production were determined by immunoblotting using the anti-modified citrulline-Senshu method and RA sera (n = 30), respectively.

RESULTS

RA sera recognized at least 3 categories of autoantigens in PAD-expressing target cells killed by the cytotoxic lymphocyte granule-induced death pathway. These included: 1) autoantigens targeted in their native form, 2) citrullinated antigens, and 3) antigens cleaved by cytotoxic proteases (e.g., granzymes). Interestingly, although target cells expressing PAD2 or PAD4 showed prominent hypercitrullination of a broad range of proteins during cytotoxic granule-induced cell damage, autoantibodies in RA sera targeted only a very limited number of antigens in hypercitrullinated cells. Furthermore, RA sera showed distinct reactivities to autoantigens generated by PAD2 or PAD4.

CONCLUSION

The cytotoxic granule-induced death pathway has the capacity to modify antigens by inducing hypercitrullination and antigen cleavage in target cells. Interestingly, among a large number of citrullinated proteins generated by PAD2 and PAD4 in cells, only a few are likely involved in the production of autoantibodies in RA.

Insights into the study and origin of the citrullinome in rheumatoid arthritis

The presence of autoantibodies and autoreactive T cells to citrullinated proteins and citrullinating enzymes in patients with rheumatoid arthritis (RA), together with the accumulation of citrullinated proteins in rheumatoid joints, provides substantial evidence that dysregulated citrullination is a hallmark feature of RA. However, understanding mechanisms that dysregulate citrullination in RA has important challenges. Citrullination is a normal process in immune and non-immune cells, which is likely activated by different conditions (eg, inflammation) with no pathogenic consequences. In a complex inflammatory environment such as the RA joint, unique strategies are therefore required to dissect specific mechanisms involved in the abnormal production of citrullinated proteins. Here, we will review current models of citrullination in RA and discuss critical components that, in our view, are relevant to understanding the accumulation of citrullinated proteins in the RA joint, collectively referred to as the RA citrullinome. In particular, we will focus on potential caveats in the study of citrullination in RA and will highlight methods to precisely detect citrullinated proteins in complex biological samples, which is a confirmatory approach to mechanistically link the RA citrullinome with unique pathogenic pathways in RA.

Individuals at risk of seropositive rheumatoid arthritis: the evolving story

The aetiology of the autoimmune disease rheumatoid arthritis (RA) involves a complex interplay between genetic and environmental factors that initiate many years before the onset of clinical symptoms. These interactions likely include both protective and susceptibility factors which together determine the risk of developing RA. More than 100 susceptibility loci have been linked to RA. The strongest association is with HLA-DRB1 alleles encoding antigen presenting molecules containing a unique sequence in the peptide-binding grove called the 'shared epitope'. Female sex, infections during childhood, lifestyle habits (e.g. smoking and diet) and distinct microbial agents, amongst many others, are interacting risk factors thought to contribute to RA pathogenesis by dysregulating the immune system in individuals with genetic susceptibility. Interestingly, patients with RA develop autoantibodies many years before the clinical onset of disease, providing strong evidence that the lack of tolerance to arthritogenic antigens is amongst the earliest events in the initiation of seropositive RA. Here, we will discuss the clinical and mechanistic evidence surrounding the role of different environmental and genetic factors in the phases leading to the production of autoantibodies and the initiation of symptomatic RA. Understanding this complexity is critical in order to develop tools to identify drivers of disease initiation and propagation and to develop preventive therapeutics.

Rheumatoid Arthritis-Associated Mechanisms of Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans

Rheumatoid arthritis (RA) is an autoimmune disease of unknown etiology characterized by immune-mediated damage of synovial joints and antibodies to citrullinated antigens. Periodontal disease, a bacterial-induced inflammatory disease of the periodontium, is commonly observed in RA and has implicated periodontal pathogens as potential triggers of the disease. In particular, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans have gained interest as microbial candidates involved in RA pathogenesis by inducing the production of citrullinated antigens. Here, we will discuss the clinical and mechanistic evidence surrounding the role of these periodontal bacteria in RA pathogenesis, which highlights a key area for the treatment and preventive interventions in RA.

Response to comment on "Aggregatibacter actinomycetemcomitans-induced hypercitrullination links periodontal infection to autoimmunity in rheumatoid arthritis"

Antibodies to leukotoxin A are markers that link Aggregatibacter actinomycetemcomitans-associated periodontitis and rheumatoid arthritis.

To NET or not to NET:current opinions and state of the science regarding the formation of neutrophil extracellular traps

Since the discovery and definition of neutrophil extracellular traps (NETs) 14 years ago, numerous characteristics and physiological functions of NETs have been uncovered. Nowadays, the field continues to expand and novel mechanisms that orchestrate formation of NETs, their previously unknown properties, and novel implications in disease continue to emerge. The abundance of available data has also led to some confusion in the NET research community due to contradictory results and divergent scientific concepts, such as pro- and anti-inflammatory roles in pathologic conditions, demarcation from other forms of cell death, or the origin of the DNA that forms the NET scaffold. Here, we present prevailing concepts and state of the science in NET-related research and elaborate on open questions and areas of dispute.

Comment on "Synovial fibroblast-neutrophil interactions promote pathogenic adaptive immunity in rheumatoid arthritis"

Discrepancies on the role of citrullination in the induction of experimental arthritis by neutrophils extracellular traps.

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.

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.

Non-invasive evaluation of portal hypertension using shear-wave elastography: analysis of two algorithms combining liver and spleen stiffness in 191 patients with cirrhosis

BACKGROUND

Two algorithms based on sequential measurements of liver and spleen stiffness using two-dimensional shearwave elastography (2D-SWE) have been recently proposed to estimate clinically significant portal hypertension (hepatic venous pressure gradient [HVPG] ≥10 mm Hg) in patients with cirrhosis, with excellent diagnostic accuracy.

AIM

To validate externally these algorithms in a large cohort of patients with cirrhosis.

METHODS

One hundred and ninety-one patients with stable cirrhosis (Child-Pugh class A 39%, B 29% and C 31%) who underwent liver and spleen stiffness measurements using 2D-SWE at the time of HVPG measurement were included. Diagnostic accuracy of the 2 algorithms was assessed by calculating sensitivity, specificity, positive and negative predictive values.

RESULTS

The first algorithm, using liver stiffness <16.0 kilopascals (kPa) and then spleen stiffness <26.6 kPa, was used to rule-out HVPG ≥10 mm Hg. In our population, its sensitivity and negative predictive value were 95% and 63% respectively. The second algorithm, using liver stiffness >38.0 kPa, or liver stiffness ≤38.0 kPa but spleen stiffness >27.9 kPa, was used to rule-in HVPG ≥10 mm Hg. In our population, its specificity and positive predictive value were 52% and 83% respectively. Restricting the analyses to the 74 patients without any history of decompensation of cirrhosis or to the 65 patients with highly reliable liver stiffness measurement did not improve the results.

CONCLUSION

In our population, diagnostic accuracies of non-invasive algorithms based on sequential measurements of liver and spleen stiffness using 2D-SWE were acceptable, but not good enough to replace HVPG measurement or to base clinical decisions.