MicroRNAs in inflammasomopathies

microRNAs (miRNAs) are small non-coding RNA sequences that negatively regulate the expression of protein-encoding genes at the post-transcriptional level. They play a role in the regulation of inflammatory responses by controlling the proliferation and activation of immune cells and their expression is disrupted in several immune-mediated inflammatory disorders. Among these, autoinflammatory diseases (AID) are a group of rare hereditary disorders caused by abnormal activation of the innate immune system and characterized by recurrent fevers. Major groups of AID are inflammasomopathies, which are associated with hereditary defects in the activation of inflammasomes, cytosolic multiprotein signaling complexes regulating IL-1 family cytokine maturation and pyroptosis. The study of the role of miRNAs in AID is only recently emerging and remains scarce in inflammasomopathies. In this review, we describe the AID and inflammasomopathies, and the current knowledge on the role of miRNAs in disease processes.

Specific targeting of inflammatory osteoclastogenesis by the probiotic yeast S. boulardii CNCM I-745 reduces bone loss in osteoporosis

Bone destruction is a hallmark of chronic inflammation, and bone-resorbing osteoclasts arising under such a condition differ from steady-state ones. However, osteoclast diversity remains poorly explored. Here, we combined transcriptomic profiling, differentiation assays and in vivo analysis in mouse to decipher specific traits for inflammatory and steady-state osteoclasts. We identified and validated the pattern-recognition receptors (PRR) Tlr2, Dectin-1, and Mincle, all involved in yeast recognition as major regulators of inflammatory osteoclasts. We showed that administration of the yeast probiotic Saccharomyces boulardii CNCM I-745 (Sb) in vivo reduced bone loss in ovariectomized but not sham mice by reducing inflammatory osteoclastogenesis. This beneficial impact of Sb is mediated by the regulation of the inflammatory environment required for the generation of inflammatory osteoclasts. We also showed that Sb derivatives as well as agonists of Tlr2, Dectin-1, and Mincle specifically inhibited directly the differentiation of inflammatory but not steady-state osteoclasts in vitro. These findings demonstrate a preferential use of the PRR-associated costimulatory differentiation pathway by inflammatory osteoclasts, thus enabling their specific inhibition, which opens new therapeutic perspectives for inflammatory bone loss.

miRNA profile at diagnosis predicts treatment outcome in patients with B-chronic lymphocytic leukemia: A FILO study

During many years, chemo-immunotherapy fludarabine-cyclophosphamide-rituximab (FCR) was the gold standard for first line treatment of medically fit patients with symptomatic B-chronic lymphocytic leukemia (CLL). Over the last decade, targeted biotherapies have revolutionized the treatment of B-CLL patients and almost entirely supplanted FCR. However, no biomarker still exists to predict the complete remission (CR) with undetectable minimal residual disease (uMRD) in bone marrow (BM), which remains the best predictive factor for survival. MicroRNAs represent a class of molecular biomarkers which expression is altered in B-CLL. Our study aimed at identifying before treatment blood miRNAs that predict treatment outcome in previously untreated B-CLL patients (NCT 01370772, https://clinicaltrials.gov/ct2/show/NCT01370772). Using hierarchical clustering of miRNA expression profiles discriminating 8 patients who achieved CR with BM uMRD from 8 patients who did not achieve CR and displayed detectable BM MRD, we identified 25 miRNAs differentially expressed before treatment. The expression of 11 miRNAs was further validated on a larger cohort (n=123). Based on the dosage of 5 miRNAs at diagnosis, a decision tree was constructed to predict treatment outcome. We identified 6 groups of patients with a distinct probability of being CR with BM uMRD to FCR treatment, ranging from 72% (miR-125b, miR-15b and miR-181c high) to 4% (miR-125b and miR-193b low). None of the patients displaying high expression levels of miR-125b, miR-15b and miR-181c relapsed during study follow-up. In contrast, patients with low miR-15b and high miR-412, or with low miR-125b and miR-193b, demonstrated significant low PFS. RNA sequencing of blood at diagnosis identified that patients relapsing after treatment are characterized by significant enrichment of gene signatures related to cell cycle, MYC target genes, metabolism and translation regulation. Conversely, patients achieving CR with BM uMRD displayed significant enrichment in genes related to communication between CLL cells and the microenvironment, immune system activation and upregulation of polycomb PRC2 complex target genes. Our results suggest that blood miRNAs are potent predictive biomarkers for FCR treatment efficacy and might be implicated in the FCR efficacy in B-CLL patients, providing new insight into unmet need for the treatment of B-CLL patients and identifying pathways predictive of patients’ remission.

Gender equity in academic rheumatology, current status and potential for improvement: a cross-sectional study to inform an EULAR task force

OBJECTIVES

Evidence on the current status of gender equity in academic rheumatology in Europe and potential for its improvement is limited. The EULAR convened a task force to obtain empirical evidence on the potential unmet need for support of female rheumatologists, health professionals and non-clinical scientists in academic rheumatology.

METHODS

This cross-sectional study comprised three web-based surveys conducted in 2020 among: (1) EULAR scientific member society leaders, (2) EULAR and Emerging EULAR Network (EMEUNET) members and (3) EULAR Council members. Statistics were descriptive with significance testing for male/female responses assessed by χ² test and t-test.

RESULTS

Data from EULAR scientific member societies in 13 countries indicated that there were disproportionately fewer women in academic rheumatology than in clinical rheumatology, and they tended to be under-represented in senior academic roles. From 324 responses of EULAR and EMEUNET members (24 countries), we detected no gender differences in leadership aspirations, self-efficacy in career advancement and work-life integration as well as the share of time spent on research, but there were gender differences in working hours and the levels of perceived gender discrimination and sexual harassment. There were gender differences in the ranking of 7 of 26 factors impacting career advancement and of 8 of 24 potential interventions to aid career advancement.

CONCLUSIONS

There are gender differences in career advancement in academic rheumatology. The study informs a EULAR task force developing a framework of potential interventions to accelerate gender-equitable career advancement in academic rheumatology.

Mitochondrial MicroRNAs Contribute to Macrophage Immune Functions Including Differentiation, Polarization, and Activation

A subset of microRNA (miRNA) has been shown to play an important role in mitochondrial (mt) functions and are named MitomiR. They are present within or associated with mitochondria. Most of the mitochondrial miRNAs originate from the nucleus, while a very limited number is encoded by mtDNA. Moreover, the miRNA machinery including the Dicer and Argonaute has also been detected within mitochondria. Recent, literature has established a close relationship between miRNAs and inflammation. Indeed, specific miRNA signatures are associated with macrophage differentiation, polarization and functions. Nevertheless, the regulation of macrophage inflammatory pathways governed specifically by MitomiR and their implication in immune-mediated inflammatory disorders remain poorly studied. Here, we propose a hypothesis in which MitomiR play a key role in triggering macrophage differentiation and modulating their downstream activation and immune functions. We sustain this proposition by bioinformatic data obtained from either the human monocytic THP1 cell line or the purified mitochondrial fraction of PMA-induced human macrophages. Interestingly, 22% of the 754 assayed miRNAs were detected in the mitochondrial fraction and are either exclusively or highly enriched cellular miRNA. Furthermore, the in silico analysis performed in this study, identified a specific MitomiR signature associated with macrophage differentiation that was correlated with gene targets within the mitochondria genome or with mitochondrial pathways. Overall, our hypothesis and data suggest a previously unrecognized link between MitomiR and macrophage function and fate. We also suggest that the MitomiR-dependent control could be further enhanced through the transfer of mitochondria from donor to target cells, as a new strategy for MitomiR delivery.

Integrative Analysis of Human Macrophage Inflammatory Response Related to Mycobacterium tuberculosis Virulence

Mycobacterium tuberculosis (Mtb), the etiological agent of tuberculosis, kills 1.5 to 1.7 million people every year. Macrophages are Mtb's main host cells and their inflammatory response is an essential component of the host defense against Mtb. However, Mtb is able to circumvent the macrophages' defenses by triggering an inappropriate inflammatory response. The ability of Mtb to hinder phagolysosome maturation and acidification, and to escape the phagosome into the cytosol, is closely linked to its virulence. The modulation of the host inflammatory response relies on Mtb virulence factors, but remains poorly studied. Understanding macrophage interactions with Mtb is crucial to develop strategies to control tuberculosis. The present study aims to determine the inflammatory response transcriptome and miRNome of human macrophages infected with the virulent H37Rv Mtb strain, to identify macrophage genetic networks specifically modulated by Mtb virulence. Using human macrophages infected with two different live strains of mycobacteria (live or heat-inactivated Mtb H37Rv and M. marinum), we quantified and analyzed 184 inflammatory mRNAs and 765 micro(mi)RNAs. Transcripts and miRNAs differently modulated by H37Rv in comparison with the two other conditions were analyzed using in silico approaches. We identified 30 host inflammatory response genes and 37 miRNAs specific for H37Rv virulence, and highlight evidence suggesting that Mtb intracellular-linked virulence depends on the inhibition of IL-1β-dependent pro-inflammatory response, the repression of apoptosis and the delay of the recruitment and activation of adaptive immune cells. Our findings provide new potential targets for the development of macrophage-based therapeutic strategies against TB.

OP0074 A FRAMEWORK OF POTENTIAL INTERVENTIONS TO ACCELERATE GENDER-EQUITABLE CAREER ADVANCEMENT IN ACADEMIC RHEUMATOLOGY

Background:

A growing number of professional societies in clinical and medically related disciplines investigate evidence, make recommendations, and take action to advance gender equity. Evidence on women’s advancement and leadership in the context of the European Alliance of Associations for Rheumatology, EULAR, is limited [1].

Objectives:

The objective of the EULAR Task Force on Gender Equity in Academic Rheumatology was to establish the extent of the unmet need for support of female rheumatologists, health professionals and non-clinical scientists in academic rheumatology and develop a framework to address this through EULAR and Emerging EULAR Network (EMEUNET).

Methods:

Potential interventions to accelerate gender-equitable career advancement in academic rheumatology were gathered from a narrative review of the relevant literature, expert opinion of a multi-disciplinary Task Force (comprised of 23 members from 11 countries), data from the surveys of EULAR scientific member society leaders, EULAR and EMEUNET members, and EULAR Executive Committee members. These interventions were rated by Task Force members, who ranked each according to perceived priority on a five-point numeric scale from 1 = very low to 5 = very high.

Results:

A framework of 29 potential interventions was formulated, which covers six thematic areas, namely, EULAR policies, advocacy and communication, EULAR Congress and associated symposia, training courses, mentoring/peer support, and EULAR funding (Figure 1).

Figure 1.

A framework of potential interventions with the levels of priority, mean and standard deviation (SD)

Conclusion:

The framework provides structured interventions for accelerating gender-equitable career advancement in academic rheumatology.

References:

[1]Andreoli L, Ovseiko PV, Hassan N, et al. Gender equity in clinical practice, research and training: Where do we stand in rheumatology? Joint Bone Spine 2019;86(6):669-72.

Acknowledgements:

The task force is grateful to EULAR for funding this activity under project number EPI 024.

Disclosure of Interests:

None declared

Synovial macrophages: from ordinary eaters to extraordinary multitaskers

Like other tissues, joints contain resident macrophages, and their diversity is only beginning to be characterized. Based on the highlights of recent studies, we discuss where current challenges lie and propose new avenues for future research in the osteoarticular field.

Novel insights into macrophage diversity in rheumatoid arthritis synovium

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease affecting joints and causing progressive damage and disability. Macrophages are of critical importance in the initiation and perpetuation of synovitis in RA, they can function as antigen presenting cells leading to T-cell dependent B-cell activation, assume a variety of inflammatory cell states with the production of destructive cytokines, but also contribute to tissue homeostasis/repair. The recent development of high-throughput technologies, including bulk and single cells RNA-sequencing, has broadened our understanding of synovial cell diversity, and opened novel perspectives to the discovery of new potential therapeutic targets in RA. In this review, we will focus on the relationship between the synovial macrophage infiltration and clinical disease severity and response to treatment. We will then provide a state-of-the-art picture of the biological roles of synovial macrophages and distinct macrophage subsets described in RA. Finally, we will review the effects of approved conventional and biologic drugs on the synovial macrophage component and highlight the therapeutic potential of future strategies to re-program macrophage phenotypes in RA.

'SMASH' recommendations for standardised microscopic arthritis scoring of histological sections from inflammatory arthritis animal models

Animal models for inflammatory arthritides such as rheumatoid arthritis (RA) and psoriatic arthritis are widely accepted and frequently used to identify pathological mechanisms and validate novel therapeutic strategies. Unfortunately, many publications reporting on these animal studies lack detailed description and appropriate assessment of the distinct histopathological features of arthritis: joint inflammation, cartilage damage and bone erosion. Therefore, the European consortium BeTheCure, consisting of 38 academic and industrial partners from 15 countries, set as goal to standardise the histological evaluation of joint sections from animal models of inflammatory arthritis. The consensual approach of a task force including 16 academic and industrial scientists as well as laboratory technicians has resulted in the development of the Standardised Microscopic Arthritis Scoring of Histological sections (‘SMASH’) recommendations for a standardised processing and microscopic scoring of the characteristic histopathological features of arthritis, exemplified by four different rodent models for arthritis: murine collagen-induced arthritis, collagen–antibody-induced arthritis, human tumour necrosis factor transgenic Tg197 mice and rat pristane-induced arthritis, applicable to any other inflammatory arthritis model. Through standardisation, the SMASH recommendations are designed to improve and maximise the information derived from in vivo arthritis experiments and to promote reproducibility and transparent reporting on such studies. In this manuscript, we will discuss and provide recommendations for analysis of histological joint sections: identification of the regions of interest, sample preparation, staining procedures and quantitative scoring methods. In conclusion, awareness of the different features of the arthritis pathology in animal models of inflammatory arthritis is of utmost importance for reliable research outcome, and the standardised histological processing and scoring methods in these SMASH recommendations will help increase uniformity and reproducibility in preclinical research on inflammatory arthritis.

New insights into macrophage heterogeneity in rheumatoid arthritis

Rheumatoid arthritis (RA) is a prototypic autoimmune disease that primarily affects joints. Clinical studies and animal models evidenced that mononuclear phagocytes including monocytes and macrophages are crucial to RA pathogenesis, contributing to inflammation and destruction of cartilage and bone. The last decade of research has tremendously changed our view on the origin of tissue-resident macrophages. In light of the recent publications that reveal important phenotypic and functional heterogeneity among macrophages, it is of paramount importance to identify the synovial macrophage subsets that might amplify the inflammatory response or promote the restoration of tissue homeostasis. In this review, we highlight latest studies applying single-cell RNA sequencing that provide deeper insights in macrophage subsets and their putative functions within both human and mouse synovial joint tissue.

Clinical and Molecular Spectrum of Nonsyndromic Early-Onset Osteoarthritis

OBJECTIVE

Osteoarthritis (OA) is the most common joint disease worldwide. The etiology of OA is varied, ranging from multifactorial to environmental to monogenic. In a condition called early-onset OA, OA occurs at an earlier age than is typical in the general population. To our knowledge, there have been no large-scale genetic studies of individuals with early-onset OA. The present study was undertaken to investigate causes of monogenic OA in individuals with nonsyndromic early-onset OA.

METHODS

The study probands were 45 patients with nonsyndromic early-onset OA who were referred to our skeletal disease center by skeletal dysplasia experts between 2013 and 2019. Criteria for early-onset OA included radiographic evidence, body mass index ≤30 kg/m² , age at onset ≤50 years, and involvement of ≥1 joint site. Molecular analysis was performed with a next-generation sequencing panel.

RESULTS

We identified a genetic variant in 13 probands (29%); the affected gene was COL2A1 in 11, ACAN in 1, and SLC26A2 in 1. After familial segregation analysis, 20 additional individuals were identified. The mean ± SD age at onset of joint pain was 19.5 ± 3.9 years (95% confidence interval 3-47). Eighteen of 33 subjects (55%) with nonsyndromic early-onset OA and a genetic variant had had at least 1 joint replacement (mean ± SD age at first joint replacement 41 ± 4.2 years; mean number of joint replacements 2.6 per individual), and 21 (45%) of the joint replacement surgeries were performed when the patient was <45 years old. Of the 20 patients age >40 years, 17 (85%) had had at least 1 joint replacement.

CONCLUSION

We confirmed that COL2A1 is the main monogenic cause of nonsyndromic early-onset OA. However, on the basis of genetic heterogeneity of early-onset OA, we recommend next-generation sequencing for all individuals who undergo joint replacement prior to the age of 45 years. Lifestyle recommendations for prevention should be implemented.

Differential Accumulation and Activation of Monocyte and Dendritic Cell Subsets in Inflamed Synovial Fluid Discriminates Between Juvenile Idiopathic Arthritis and Septic Arthritis

Despite their distinct etiology, several lines of evidence suggest that innate immunity plays a pivotal role in both juvenile idiopathic arthritis (JIA) and septic arthritis (SA) pathophysiology. Indeed, monocytes and dendritic cells (DC) are involved in the first line of defense against pathogens and play a critical role in initiating and orchestrating the immune response. The aim of this study was to compare the number and phenotype of monocytes and DCs in peripheral blood (PB) and synovial fluid (SF) from patients with JIA and SA to identify specific cell subsets and activation markers associated with pathophysiological mechanisms and that could be used as biomarkers to discriminate both diseases. The proportion of intermediate and non-classical monocytes in the SF and PB, respectively, were significantly higher in JIA than in SA patients. In contrast the proportion of classical monocytes and their absolute numbers were higher in the SF from SA compared with JIA patients. Higher expression of CD64 on non-classical monocyte was observed in PB from SA compared with JIA patients. In SF, higher expression of CD64 on classical and intermediate monocyte as well as higher CD163 expression on intermediate monocytes was observed in SA compared with JIA patients. Moreover, whereas the number of conventional (cDC), plasmacytoid (pDC) and inflammatory (infDC) DCs was comparable between groups in PB, the number of CD141⁺ cDCs and CD123⁺ pDCs in the SF was significantly higher in JIA than in SA patients. CD14⁺ infDCs represented the major DC subset in the SF of both groups with potent activation assessed by high expression of HLA-DR and CD86 and significant up-regulation of HLA-DR expression in SA compared with JIA patients. Finally, higher activation of SF DC subsets was monitored in SA compared with JIA with significant up-regulation of CD86 and PDL2 expression on several DC subsets. Our results show the differential accumulation and activation of innate immune cells between septic and inflammatory arthritis. They strongly indicate that the relative high numbers of CD141⁺ cDC and CD123⁺ pDCs in SF are specific for JIA while the over-activation of DC and monocyte subsets is specific for SA.

THU0580 EULAR TASK FORCE ON GENDER EQUITY IN ACADEMIC RHEUMATOLOGY: PRELIMINARY SURVEY FINDINGS

Background:

Women represent an increasing proportion of the overall rheumatology workforce, but are underrepresented in academic rheumatology, especially in leadership roles [1].

Objectives:

The EULAR Task Force on Gender Equity in Academic Rheumatology has been convened to establish the extent of the unmet need for support of female rheumatologists, health professionals and non-clinical scientists in academic rheumatology and develop a framework to address this through EULAR and EMEUNET.

Methods:

To investigate gender equity in academic rheumatology, an anonymous web-based survey was targeted at the membership of EULAR and Emerging EULAR Network (EMEUNET) and their wider networks. The survey was developed based on a narrative literature review [1], best practice from The Association of Women in Rheumatology, a survey of task force members and face-to-face task force discussions. Personal experiences were explored and 24 potential interventions to aid career advancement were ranked. Statistics were descriptive with significance testing for male/female responses compared using chi-squared/t-tests. The level of significance was set at p<0.001.

Results:

A total of 301 respondents from 24 countries fully completed the survey. By profession, 290 (86.4%) were rheumatologists, 19 (6.3%) health professionals, and 22 (7.3%) non-clinical scientists. By gender, 217 (72.1%) were women, 83 (27.6%) men, and 1 (0.3%) third gender. By age, 203 (67.5%) were 40 or under. By ethnicity, 30 (10.0%) identified themselves as ethnic minority. A high proportion of respondents reported having experienced gender discrimination (47.2% total: 58.1% for women and 18.1% for men) and sexual harassment (26.2%: 31.8% and 10.8% respectively) (Figure 1). Chi-squared tests on the numbers on which these proportions were based showed statistically significant differences between women and men in having experienced gender discrimination (Χ2=36.959 (df=1), p <0.001) and sexual harassment (Χ2=12.633 (df=1), p <0.001). The highest-ranked interventions for career advancement regardless of respondents’ gender included: leadership skills training; speaking/presentation/communication skills training; information on training/career pathways; effective career planning training; support on grant writing applications; and high-impact scientific writing master-classes (Figure 2). Only 8 of 24 proposed interventions showed a significantly higher ranking (p<0.001) by female respondents and these typically related to promotion of female role models and gender-balance in committees, editorial boards and research funding (Figure 2).

Figure 1.

Perceived gender discrimination and sexual harassment, 301 responses

Figure 2.

Mean perceived utility of potential interventions for career advancement by gender and statistically significant gender differences (p<.001), 300 responses

Conclusion:

The results of the survey will inform the development of task force policy proposals for interventions to support career advancement among EULAR and EMEUNET members. The identified interventions have potential to support career advancement of all rheumatologists, health professionals and non-clinical scientists regardless of gender.

References:

[1]Andreoli L, Ovseiko PV, Hassan N, Kiltz U, van Mens L, Gossec L, et al. Gender equity in clinical practice, research and training: Where do we stand in rheumatology? Joint, Bone, Spine: Revue du Rhumatisme. 2019;86(6):669-672.

Acknowledgments:

We gratefully acknowledge the rheumatologists, health professionals and non-clinical scientists who responded to the survey.

Disclosure of Interests:

Pavel V Ovseiko: None declared, Laure Gossec Grant/research support from: Lilly, Mylan, Pfizer, Sandoz, Consultant of: AbbVie, Amgen, Biogen, Celgene, Janssen, Lilly, Novartis, Pfizer, Sandoz, Sanofi-Aventis, UCB, Laura Andreoli: None declared, Uta Kiltz Grant/research support from: AbbVie, Amgen, Biogen, Novartis, Pfizer, Consultant of: AbbVie, Biocad, Eli Lilly and Company, Grünenthal, Janssen, Novartis, Pfizer, UCB, Speakers bureau: AbbVie, MSD, Novartis, Pfizer, Roche, UCB, Leonieke van Mens: None declared, Neelam Hassan: None declared, Marike van der Leeden: None declared, Heidi J Siddle: None declared, Alessia Alunno: None declared, Iain McInnes Grant/research support from: Bristol-Myers Squibb, Celgene, Eli Lilly and Company, Janssen, and UCB, Consultant of: AbbVie, Bristol-Myers Squibb, Celgene, Eli Lilly and Company, Gilead, Janssen, Novartis, Pfizer, and UCB, Nemanja Damjanov Grant/research support from: from AbbVie, Pfizer, and Roche, Consultant of: AbbVie, Gedeon Richter, Merck, Novartis, Pfizer, and Roche, Speakers bureau: AbbVie, Gedeon Richter, Merck, Novartis, Pfizer, and Roche, Florence Apparailly: None declared, Caroline Ospelt Consultant of: Consultancy fees from Gilead Sciences., Irene van der Horst-Bruinsma Grant/research support from: AbbVie, Novartis, Eli Lilly, Bristol-Myers Squibb, MSD, Pfizer, UCB Pharma, Consultant of: AbbVie, Novartis, Eli Lilly, Bristol-Myers Squibb, MSD, Pfizer, UCB Pharma, Elena Nikiphorou: None declared, Katie Druce Speakers bureau: Pfizer and Lilly, Zoltán Szekanecz Grant/research support from: Pfizer, UCB, Consultant of: Sanofi, MSD, Abbvie, Pfizer, Roche, Novertis, Lilly, Gedeon Richter, Amgen, Alexandre Sepriano: None declared, Tadej Avcin: None declared, George Bertsias Grant/research support from: GSK, Consultant of: Novartis, Georg Schett Speakers bureau: AbbVie, BMS, Celgene, Janssen, Eli Lilly, Novartis, Roche and UCB, Anne Maree Keenan: None declared, Laura C Coates: None declared

Dissecting the phenotypic and functional heterogeneity of mouse inflammatory osteoclasts by the expression of Cx3cr1

Bone destruction relies on interactions between bone and immune cells. Bone-resorbing osteoclasts (OCLs) were recently identified as innate immune cells activating T cells toward tolerance or inflammation. Thus, pathological bone destruction not only relies on increased osteoclast differentiation, but also on the presence of inflammatory OCLs (i-OCLs), part of which express Cx3cr1. Here, we investigated the contribution of mouse Cx3cr1⁺ and Cx3cr1^neg i-OCLs to bone loss. We showed that Cx3cr1⁺ and Cx3cr1^neg i-OCLs differ considerably in transcriptional and functional aspects. Cx3cr1^neg i-OCLs have a high ability to resorb bone and activate inflammatory CD4⁺ T cells. Although Cx3cr1⁺ i-OCLs are associated with inflammation, they resorb less and have in vitro an immune-suppressive effect on Cx3cr1^neg i-OCLs, mediated by PD-L1. Our results provide new insights into i-OCL heterogeneity. They also reveal that different i-OCL subsets may interact to regulate inflammation. This contributes to a better understanding and prevention of inflammatory bone destruction.

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

Background

In the collagen-induced arthritis (CIA) mouse model, inflammation readouts are usually quantified using operator-dependent clinical scoring systems, and no systematic relationship with functional deficits has been detected. In this study, we extensively quantified sensory and motor deficits in CIA mice during natural disease progression and therapeutic treatment. Then, we used these data to build a scale to predict functional deficits on the basis of the classical clinical score.

Methods

Using the CIA mouse model, we longitudinally screened multiple approaches to assess locomotion (open field test, Catwalk™), sensitivity (Von Frey, Hargreaves, static weight-bearing tests), and inflammation (skin temperature), and identified the most accurate tests to correlate sensory and motor deficits with disease severity, measured by clinical score. We then used these tests to characterize functional deficits in control (naïve and mice injected with complete Freund’s adjuvant) and CIA mice, either untreated or treated with methotrexate to prevent functional deficits. By mathematical approaches, we finally investigated the relationship between functional deficits and clinical score.

Results

We found that the functional disability scores obtained with the open field, Catwalk™, Hargreaves, and skin temperature tests significantly correlated with the clinical score in CIA mice, either untreated or treated with methotrexate. Mathematical correlation showed that motor deficits, robustly characterized by two different tests, were twice more responsive than thermal sensitivity deficits.

Conclusion

We propose the arthritis sensory and motor (ArthriSM) scale as a new theranostic tool to predict motor and sensory deficit based on the clinical score, in the experimental mouse model of CIA. This ArthriSM scale may facilitate the transfer of knowledge between preclinical and clinical studies.

MicroRNAs: Fine Tuners of Monocyte Heterogeneity

Small non-coding microRNAs (miRNAs) have been found to play critical roles in many biological processes by controlling gene expression at the post-transcriptional level. They appear to fine-tune the immune response by targeting key regulatory molecules, and their abnormal expression is associated with immune-mediated inflammatory disorders. Monocytes actively contribute to tissue homeostasis by triggering acute inflammatory reactions as well as the resolution of inflammation and tissue regeneration, in case of injury or pathogen invasion. Their contribution to tissue homeostasis can have many aspects because they are able to differentiate into different cell types including macrophages, dendritic cells, and osteoclasts, which fulfill functions as different as bone remodeling and immune response. Monocytes consist of different subsets with subset-specific expression of miRNAs linked to distinct biological processes dedicated to specific roles. Therefore, understanding the role of miRNAs in the context of monocyte heterogeneity may provide clues as to which subset gives rise to which cell type in tissues. In addition, because monocytes are involved in the pathogenesis of chronic inflammation, associated with loss of tissue homeostasis and function, identifying subset-specific miRNAs might help in developing therapeutic strategies that target one subset while sparing the others. Here, we give an overview of the state-of-the-art research regarding miRNAs that are differentially expressed between monocyte subsets and how they influence monocyte functional heterogeneity in health and disease, with descriptions of specific miRNAs. We also revisit the existing miRNome data to propose a canonical signature for each subset.

Immune Function and Diversity of Osteoclasts in Normal and Pathological Conditions

Osteoclasts (OCLs) are key players in controlling bone remodeling. Modifications in their differentiation or bone resorbing activity are associated with a number of pathologies ranging from osteopetrosis to osteoporosis, chronic inflammation and cancer, that are all characterized by immunological alterations. Therefore, the 2000s were marked by the emergence of osteoimmunology and by a growing number of studies focused on the control of OCL differentiation and function by the immune system. At the same time, it was discovered that OCLs are much more than bone resorbing cells. As monocytic lineage-derived cells, they belong to a family of cells that displays a wide heterogeneity and plasticity and that is involved in phagocytosis and innate immune responses. However, while OCLs have been extensively studied for their bone resorption capacity, their implication as immune cells was neglected for a long time. In recent years, new evidence pointed out that OCLs play important roles in the modulation of immune responses toward immune suppression or inflammation. They unlocked their capacity to modulate T cell activation, to efficiently process and present antigens as well as their ability to activate T cell responses in an antigen-dependent manner. Moreover, similar to other monocytic lineage cells such as macrophages, monocytes and dendritic cells, OCLs display a phenotypic and functional plasticity participating to their anti-inflammatory or pro-inflammatory effect depending on their cell origin and environment. This review will address this novel vision of the OCL, not only as a phagocyte specialized in bone resorption, but also as innate immune cell participating in the control of immune responses.

MicroRNAs: Key Regulators to Understand Osteoclast Differentiation?

MicroRNAs (miRNAs) are small non-coding single-stranded RNAs that represent important posttranscriptional regulators of protein-encoding genes. In particular, miRNAs play key roles in regulating cellular processes such as proliferation, migration, and cell differentiation. Recently, miRNAs emerged as critical regulators of osteoclasts (OCs) biology and have been involved in OCs pathogenic role in several disorders. OCs are multinucleated cells generated from myeloid precursors in the bone marrow, specialized in bone resorption. While there is a growing number of information on the cytokines and signaling pathways that are critical to control the differentiation of osteoclast precursors (OCPs) into mature OCs, the connection between OC differentiation steps and miRNAs is less well-understood. The present review will first summarize our current understanding of the miRNA-regulated pathways in the sequential steps required for OC formation, from the motility and migration of OCPs to the cell-cell fusion and the final formation of the actin ring and ruffled border in the functionally resorbing multinucleated OCs. Then, considering the difficulty of working on primary OCs and on the generation of robust data we will give an update on the most recent advances in the detection technologies for miRNAs quantification and how these are of particular interest for the understanding of OC biology and their use as potential biomarkers.

Advanced microRNA-based cancer diagnostics using amplified time-gated FRET

MicroRNAs (miRNAs) play an important role in cellular functions and in the development and progression of cancer. Precise quantification of endogenous miRNAs from different clinical patient and control samples combined with a one-to-one comparison to standard technologies is a challenging but necessary endeavor that is largely neglected by many emerging fluorescence technologies. Here, we present a simple, precise, sensitive, and specific ratiometric assay for absolute quantification of miRNAs. Isothermally amplified time-gated Förster resonance energy transfer (TG-FRET) between Tb donors and dye acceptors resulted in miRNA assays with single-nucleotide variant specificity and detection limits down to 4.2 ± 0.5 attomoles. Quantification of miR-21 from human tissues and plasma samples revealed the relevance for breast and ovarian cancer diagnostics. Analysis of miR-132 and miR-146a from acute monocytic leukemia cells (THP-1) demonstrated the broad applicability to different miRNAs and other types of clinical samples. Direct comparison to the gold standard RT-qPCR showed advantages of amplified TG-FRET concerning precision and specificity when quantifying low concentrations of miRNAs as required for diagnostic applications. Our results demonstrate that a careful implementation of rolling circle amplification and TG-FRET into one straightforward nucleic acid detection method can significantly advance the possibilities of miRNA-based cancer diagnostics and research.

Delivery of miR-146a to Ly6Chigh Monocytes Inhibits Pathogenic Bone Erosion in Inflammatory Arthritis

Rationale: Monocytes play critical roles in the pathogenesis of arthritis by contributing to the inflammatory response and bone erosion. Among genes involved in regulating monocyte functions, miR-146a negatively regulates the inflammatory response and osteoclast differentiation of monocytes. It is also the only miRNA reported to differentially regulate the cytokine response of the two classical Ly6C^high and non-classical Ly6C^low monocyte subsets upon bacterial challenge. Although miR-146a is overexpressed in many tissues of arthritic patients, its specific role in monocyte subsets under arthritic conditions remains to be explored. Methods: We analyzed the monocyte subsets during collagen-induced arthritis (CIA) development by flow cytometry. We quantified the expression of miR-146a in classical and non-classical monocytes sorted from healthy and CIA mice, as well as patients with rheumatoid arthritis (RA). We monitored arthritis features in miR-146a^-/- mice and assessed in vivo the therapeutic potential of miR-146a mimics delivery to Ly6C^high monocytes. We performed transcriptomic and pathway enrichment analyses on both monocyte subsets sorted from wild type and miR-146a^-/- mice. Results: We showed that the expression of miR-146a is reduced in the Ly6C^high subset of CIA mice and in the analogous monocyte subset (CD14⁺CD16^-) in humans with RA as compared with healthy controls. The ablation of miR-146a in mice worsened arthritis severity, increased osteoclast differentiation in vitro and bone erosion in vivo. In vivo delivery of miR-146a to Ly6C^high monocytes, and not to Ly6C^low monocytes, rescues bone erosion in miR-146a^-/- arthritic mice and reduces osteoclast differentiation and pathogenic bone erosion in CIA joints of miR-146a^+/+ mice, with no effect on inflammation. Silencing of the non-canonical NF-κB family member RelB in miR-146a^-/- Ly6C^high monocytes uncovers a role for miR-146a as a key regulator of the differentiation of Ly6C^high, and not Ly6C^low, monocytes into osteoclasts under arthritic conditions. Conclusion: Our results show that classical monocytes play a critical role in arthritis bone erosion. They demonstrate the theranostics potential of manipulating miR-146a expression in Ly6C^high monocytes to prevent joint destruction while sparing inflammation in arthritis.

LARP7 variants and further delineation of the Alazami syndrome phenotypic spectrum among primordial dwarfisms: 2 sisters

Alazami syndrome (AS) (MIM# 615071) is an autosomal recessive microcephalic primordial dwarfism (PD) with recognizable facial features and severe intellectual disability due to depletion or loss of function variants in LARP7. To date, 15 patients with AS have been reported. Here we describe two consanguineous Algerian sisters with Alazami PD due to LARP7 homozygous pathogenic variants detected by whole exome sequencing. By comparing these two additional cases with those previously reported, we strengthen the key features of AS: severe growth restriction, severe intellectual disability and some distinguishing facial features such as broad nose, malar hypoplasia, wide mouth, full lips and abnormally set teeth. We also report significant new findings enabling further delineation of this syndrome: disproportionately mild microcephaly, stereotypic hand wringing and severe anxiety, thickened skin over the hands and feet, and skeletal, eye and heart malformations. From previous reviews, we summarize the main etiologies of PD according to the involved mechanisms and cellular pathways, highlighting their clinical core features.

Beneficial Effect of Alcohol Withdrawal on Gut Permeability and Microbial Translocation in Patients with Alcohol Use Disorder

BACKGROUND

The human intestinal microbiota exerts beneficial or harmful effects in several disorders. Many factors, including alcohol consumption, may influence its composition and trigger bacterial translocation. Excessive alcohol consumption increases gut permeability and translocation of endotoxin into peripheral circulation. Although plasma endotoxin concentrations have been measured often, quantitative changes following alcohol withdrawal have never been described in subjects with alcohol use disorder (AUD). The aim of this study was to measure microbial translocation (MT) and gut permeability markers in patients with AUD, to compare these markers to healthy controls (HC) and to monitor markers during the first 6 weeks of abstinence.

METHODS

Sixty-five patients with AUD and hospitalized for alcohol withdrawal were included. Epidemiological, clinical, biological, and addictological data were gathered. Blood samples were collected at baseline, then 3 and 6 weeks after alcohol withdrawal. A hundred healthy volunteers were used as controls. Three markers of MT were monitored in plasma samples: sCD14 and lipopolysaccharide-binding protein (LBP) were quantified using ELISA, and 16S rDNA was quantified using real-time polymerase chain reaction. Zonulin and intestinal fatty acid binding protein (I-FABP) blood levels were also monitored as indirect markers of gut permeability, using ELISA.

RESULTS

At baseline, LBP, 16S rDNA, sCD14 and I-FABP markers were significantly higher in patients with AUD than in HC. Six weeks after alcohol withdrawal plasma levels of sCD14 and LBP decreased significantly. Cannabis consumption and body mass index (BMI) before alcohol withdrawal influenced baseline MT levels and the decrease in MT markers after 6 weeks. Finally, markers of MT and gut permeability did not correlate with each other before and after alcohol withdrawal.

CONCLUSIONS

Before alcohol withdrawal, MT markers were higher in patients with AUD than in HC. After 6 weeks of abstinence, an improvement in MT markers was observed. Our data suggest that there is a link between MT, its improvement, BMI, and cannabis consumption.

miR-125b and miR-532-3p predict the efficiency of rituximab-mediated lymphodepletion in chronic lymphocytic leukemia patients. A French Innovative Leukemia Organization study

The underlying in vivo mechanisms of rituximab action remain incompletely understood in chronic lymphocytic leukemia. Recent data suggest that circulating micro-ribonucleic acids correlate with chronic lymphocytic leukemia progression and response to rituximab. Our study aimed at identifying circulating micro-ribonucleic acids that predict response to rituximab monotherapy in chronic lymphocytic leukemia patients. Using a hierarchical clustering of micro-ribonucleic acid expression profiles discriminating 10 untreated patients with low or high lymphocyte counts, we found 26 micro-ribonucleic acids significantly deregulated. Using individual real-time reverse transcription polymerase chain reaction, the expression levels of micro-ribonucleic acids representative of these two clusters were further validated in a larger cohort (n=61). MiR-125b and miR-532-3p were inversely correlated with rituximab-induced lymphodepletion (P=0.020 and P=0.001, respectively) and with the CD20 expression on CD19⁺ cells (P=0.0007 and P<0.0001, respectively). In silico analyses of genes putatively targeted by both micro-ribonucleic acids revealed a central role of the interleukin-10 pathway and CD20 (MS4A1) family members. Interestingly, both micro-ribonucleic acids were negatively correlated with MS4A1 expression, while they were positively correlated with MS4A3 and MSA47 Our results identify novel circulating predictive biomarkers for rituximab-mediated lymphodepletion efficacy in chronic lymphocytic leukemia, and suggest a novel molecular mechanism responsible for the rituximab mode of action that bridges miR-125b and miR-532-3p and CD20 family members. (clinicaltrials.gov Identifier: 01370772).

microRNA target prediction programs predict many false positives

According to the current view, each microRNA regulates hundreds of genes. Computational tools aim at identifying microRNA targets, usually selecting evolutionarily conserved microRNA binding sites. While the false positive rates have been evaluated for some prediction programs, that information is rarely put forward in studies making use of their predictions. Here, we provide evidence that such predictions are often biologically irrelevant. Focusing on miR-223-guided repression, we observed that it is often smaller than inter-individual variability in gene expression among wild-type mice, suggesting that most predicted targets are functionally insensitive to that microRNA. Furthermore, we found that human haplo-insufficient genes tend to bear the most highly conserved microRNA binding sites. It thus appears that biological functionality of microRNA binding sites depends on the dose-sensitivity of their host gene and that, conversely, it is unlikely that every predicted microRNA target is dose-sensitive enough to be functionally regulated by microRNAs. We also observed that some mRNAs can efficiently titrate microRNAs, providing a reason for microRNA binding site conservation for inefficiently repressed targets. Finally, many conserved microRNA binding sites are conserved in a microRNA-independent fashion: Sequence elements may be conserved for other reasons, while being fortuitously complementary to microRNAs. Collectively, our data suggest that the role of microRNAs in normal and pathological conditions has been overestimated due to the frequent overlooking of false positive rates.

Effects of alcohol withdrawal on monocyte subset defects in chronic alcohol users

Excessive alcohol consumption has a modulating effect on immune functions that may contribute to decreased immunity and host defense. It is associated with increased intestinal permeability to endotoxins that is normalized after 14 d of abstinence. Whether and how blood monocyte subsets are impaired in patients with an AUD and what their evolution is after alcohol withdrawal are the paper's objectives. With the use of flow cytometry, blood monocyte subsets were quantified in AUDs before (n = 40) and 2 wk after (n = 33) alcohol withdrawal and compared with HC donors (n = 20). Expression of TLR2 and TLR4 on monocyte subsets was also quantified. Cytokine response of monocytes was monitored following PGN and LPS stimulation. The CD14⁺CD16^- subset was decreased, whereas the CD14^dimCD16⁺ subset was expanded (P < 0.001) in AUD compared with HC. The frequencies of TLR2- and TLR4-expressing monocytes were reduced in AUD compared with HC. Although the basal production of IL-1, IL-6, and TNF by monocytes in AUD was compared with HC, the PGN- and LPS-mediated IL-6 and TNF production was increased in AUD. Frequencies of IL-6-expressing monocytes were higher in AUD than HC. Alcohol withdrawal partially restored the distribution of monocyte subsets and the frequency of IL-6-producing monocytes and increased the frequency of TNF-producing cells in response to LPS and PGN stimulation to levels compared with those in HC. Our findings indicate that chronic alcohol use alters the distribution as well as the phenotypic and functional characteristics of blood monocyte subsets, which are partially restored following 2 wk of alcohol withdrawal.

MicroRNA Profiling of B Cell Subsets from Systemic Lupus Erythematosus Patients Reveals Promising Novel Biomarkers

MicroRNAs control the differentiation and function of B cells, which are considered key elements in the pathogenesis of systemic lupus erythematosus (SLE). However, a common micro(mi)RNA signature has not emerged since published data includes patients of variable ethnic background, type of disease, and organ involvement, as well as heterogeneous cell populations. Here, we aimed at identifying a miRNA signature of purified B cells from renal and non-renal severe SLE patients of Latin American background, a population known to express severe disease. Genome-wide miRNA expression analyses were performed on naive and memory B cells and revealed two categories of miRNA signatures. The first signature represents B cell subset-specific miRNAs deregulated in SLE: 11 and six miRNAs discriminating naive and memory B cells of SLE patients from healthy controls (HC), respectively. Whether the miRNA was up or down-regulated in memory B cells as compared with naive B cells in HC, this difference was abolished in SLE patients, and vice versa. The second signature identifies six miRNAs associated with specific pathologic features affecting renal outcome, providing a further understanding for SLE pathogenesis. Overall, the present work provided promising biomarkers in molecular diagnostics for disease severity as well as potential new targets for therapeutic intervention in SLE.

Transcriptomic network support distinct roles of classical and non-classical monocytes in human

Classical and non-classical monocytes are two well-defined subsets of monocytes displaying distinct roles. They differentially express numerous genes relevant to their primary role. Using five independent transcriptomic microarray datasets, we ruled out several inconsistent genes and identified common genes consistently overexpressed either in classical or non-classical monocytes. One hundred and eight genes were significantly increased in classical monocytes and are involved in bacterial defense, inflammation and atherosclerosis. Whereas the 74 genes overexpressed in non-classical monocytes are involved in cytoskeletal dynamics and invasive properties for enhanced motility and infiltration. These signatures unravel the biological functions of monocyte subsets. HIGHLIGHTS We compared five transcriptomic GEO datasets of human monocyte subsets. 108 genes in classical and 74 genes in non-classical monocytes are upregulated. Upregulated genes in classical monocytes support anti-bacterial and inflammatory responses. Upregulated genes in non-classical monocytes support patrolling and infiltration functions.

Targeting monocytes/macrophages in the treatment of rheumatoid arthritis

Biotherapies have revolutionized the treatment of RA. However, much work is needed to understand all the mechanisms of these biotherapies, and alternatives are needed to circumvent adverse effects and the high cost of these long-lasting treatments. In this article we outline some of the approaches we have used to target monocytes/macrophages as major components of inflammation and bone homeostasis. We also discuss how anti-TNF-α antibodies target monocytes/macrophages in the complex mechanisms contributing to inhibition of inflammation.

PLGA microspheres encapsulating siRNA anti-TNFalpha: efficient RNAi-mediated treatment of arthritic joints

The aim of this study was to investigate potentialities of poly(dl-lactide-co-glycolide) (PLGA) microspheres for the delivery of small interfering RNAs (siRNAs) against tumor necrosis factor α (TNF-α) to achieve prolonged and efficient inhibition of TNF-α for the treatment of rheumatoid arthritis (RA). PLGA microspheres were prepared by a modified multiple emulsion-solvent evaporation method. The formulations were characterized in terms of morphology, mean diameter and siRNAs distribution, encapsulation efficiency, and in vitro release kinetics. The efficiency of this system was then evaluated both in vitro and in vivo using the murine monocytic cell line J774 and a pre-clinical model of RA, respectively. siRNA-encapsulating PLGA microspheres were characterized by a high encapsulation efficiency and a slow and prolonged anti-TNF-α siRNAs. Our results provide evidence that, upon intra-articular administration, PLGA microspheres slowly releasing siRNAs effectively inhibited the expression of TNF-α in arthritic joints. Our system might represent an alternative strategy for the design of novel anti-rheumatic therapies based on the use of RNA interference in RA.