Direct control of B cells by Tregs: An opportunity for long-term modulation of the humoral response.

Tregs are believed to be important for maintaining self-tolerance and immune homeostasis. It is well established that Tregs maintain self-tolerance and immune homeostasis by directly suppressing and modulating the effector function of T cells. However, there are a small number of studies that suggest Tregs also directly suppress and modulate B cells. Herein we review the literature that has investigated direct action of Tregs on B cell effector function. This area of study is intriguing because it suggests Tregs may influence long-lived humoral immunity.

Oligodeoxynucleotides stabilize Helios-expressing Foxp3+ human T regulatory cells during in vitro expansion.

Foxp3(+) regulatory T cells (Tregs) maintain self-tolerance and adoptive therapy, and using Foxp3(+) Tregs has been proposed as treatment for autoimmune diseases. The clinical use of Tregs will require large numbers of cells and methods for in vitro expansion of Tregs are being developed. Foxp3(+) Tregs can be divided into 2 subpopulations based on expression of the transcription factor, Helios. Foxp3(+)Helios(+) Tregs (70%) are thymic-derived, whereas Foxp3(+)Helios(-) Tregs (30%) are induced in the periphery. Foxp3(+)Helios(+) Tregs differ from Foxp3(+)Helios(-) Tregs in terms of epigenetic changes at the Foxp3 locus, their capacity to produce effector cytokines, and their stability of Foxp3 expression on days to weeks of expansion in vitro. Addition of a 25 mer DNA oligonucleotide of random composition for a short period during the expansion of Foxp3(+) Tregs in vitro results in prolonged stabilization of the Foxp3(+)Helios(+) subpopulation and yields an optimal population for use in cellular biotherapy.

The percentage of FoxP3+Helios+ Treg cells correlates positively with disease activity in systemic lupus erythematosus.

OBJECTIVE: To assess the use of Helios in combination with FoxP3 as a superior method for identifying non-cytokine-producing human Treg cells in patients with systemic lupus erythematosus (SLE) and to determine if FoxP3+Helios+ Treg cells are maintained at normal levels in patients with clinically active disease. METHODS: Peripheral blood mononuclear cells (PBMCs) were purified from the blood of healthy volunteer donors and from 52 consecutive patients with SLE of varying clinical activity (Systemic Lupus Erythematosus Disease Activity Index scores of 0, 2-4, and ≥ 5). PBMCs (either fresh or after 4 hours of stimulation for cytokine production) were then analyzed by flow cytometry for the expression of cell surface markers (CD4, CD25, CD127, and CD45RA) and transcription factors (FoxP3 and Helios), as well as for the production of cytokines (interleukin-2 and interferon-γ). RESULTS: FoxP3+Helios+ Treg cells were found to be non-cytokine producing in both SLE patients and healthy controls. Patients with clinically active SLE had higher percentages of FoxP3+Helios+ Treg cells than did patients with inactive SLE or healthy controls. When corrected for the total CD4 cell count, the absolute numbers of FoxP3+Helios+ Treg cells in patients with moderately-to-highly active SLE were normal. CONCLUSION: Previous reports of a deficiency in Treg cell number or function in SLE are limited by their use of CD25, either alone or in combination with other markers, to identify human Treg cells. Helios in combination with FoxP3 is a superior method for detecting all non-cytokine-producing Treg cells, irrespective of CD25 or CD45RA expression. Using this method, we showed that FoxP3+Helios+ Treg cell numbers are not reduced in patients with clinically active SLE.

Model-Informed Drug Development-Based Approval of Intravenous Secukinumab for the Treatment of Adult Patients with Active Psoriatic Arthritis, Active Ankylosing Spondylitis, and Active Non-Radiographic Axial Spondyloarthritis.

On October 6, 2023, the US Food and Drug Administration (FDA) approved an intravenous (IV) formulation and dosage of Cosentyx® (secukinumab), for the treatment of adult patients with active psoriatic arthritis (PsA), active ankylosing spondylitis (AS), and active non-radiographic axial spondyloarthritis (nr-axSpA) with objective signs of inflammation. Clinical pharmacokinetics (PK), efficacy, and short-term placebo-controlled safety data were available from clinical studies (NCT04156620 and NCT04209205) with the to-be-marketed IV formulation using a maintenance dosage 3 mg/kg every 4 weeks (q4w), which was different from the dose approved (1.75 mg/kg q4w). The IV dosage of 3 mg/kg utilized in these two trials resulted in exposures (Cmax,ss) significantly higher than those for the approved subcutaneous (SC) regimens. Further, there is limited long-term safety information available for this 3 mg/kg q4w IV dose. To address this important limitation, a model-informed drug development (MIDD) approach was employed to leverage available clinical PK, efficacy, and safety data from the secukinumab development program to identify a maintenance IV dosing regimen, 1.75 mg/kg IV q4w, that better approximated the relevant SC secukinumab exposures for which efficacy and safety have been established. The MIDD analyses were used to support approval of this IV dosing regimen not directly studied in the indications sought for licensure, PsA, AS, and nr-AxSpA.

Targeted Delivery of Chloroquine to Antigen-Presenting Cells Enhances Inhibition of the Type I Interferon Response.

Systemic lupus erythematosus (SLE) causes damaging inflammation in multiple organs via the accumulation of immune complexes. These complexes activate plasmacytoid dendritic cells (pDCs) via toll-like receptors (TLRs), contributing to disease pathogenesis by driving the secretion of inflammatory type I interferons (IFNs). Antimalarial drugs, such as chloroquine (CQ), are TLR antagonists used to alleviate inflammation in SLE. However, they require ∼3 months of continuous use before achieving therapeutic efficacy and can accumulate in the retinal pigment epithelium with chronic use, resulting in retinopathy. We hypothesized that poly(ethylene glycol)-b-poly(propylene sulfide) filamentous nanocarriers, filomicelles (FMs), could directly deliver CQ to pDCs via passive, morphology-based targeting to concentrate drug delivery to specific immune cells, improve drug activity by increased inhibition of type I IFN, and enhance efficacy per dose. Healthy human peripheral blood mononuclear cells were treated with soluble CQ or CQ-loaded FMs, stimulated with TLR agonists or SLE patient sera, and type I IFN secretion was quantified via multi-subtype IFN-α ELISA and MX1 gene expression using real-time reverse transcription-quantitative polymerase chain reaction. Our results showed that 50 µg CQ/mg FM decreased MX1 expression and IFN-α production after TLR activation with either synthetic nucleic acid agonists or immune complex-rich sera from SLE patients. Cellular uptake and biodistribution studies showed that FMs preferentially accumulate in human pDCs and monocytes in vitro and in tissues frequently damaged in SLE patients (i.e., kidneys), while sparing the eye in vivo. These results showed that nanocarrier morphology enables drug delivery, and CQ-FMs may be equally effective and more targeted than soluble CQ at inhibiting SLE-relevant pathways.

T-cell activation under hypoxic conditions enhances IFN-gamma secretion.

Secondary lymphoid organs and peripheral tissues are characterized by hypoxic microenvironments, both in the steady state and during inflammation. Although hypoxia regulates T-cell metabolism and survival, very little is known about whether or how hypoxia influences T-cell activation. We stimulated mouse CD4(+) T cells in vitro with antibodies directed against the T-cell receptor (CD3) and CD28 under normoxic (20% O(2)) and hypoxic (1% O(2)) conditions. Here we report that stimulation under hypoxic conditions augments the secretion of effector CD4(+) T-cell cytokines, especially IFN-gamma. The enhancing effects of hypoxia on IFN-gamma secretion were independent of mouse strain, and were also unaffected using CD4(+) T cells from mice lacking one copy of the gene encoding hypoxia-inducible factor-1alpha. Using T cells from IFN-gamma receptor-deficient mice and promoter reporter studies in transiently transfected Jurkat T cells, we found that the enhancing effects of hypoxia on IFN-gamma expression were not due to effects on IFN-gamma consumption or proximal promoter activity. In contrast, deletion of the transcription factor, nuclear erythroid 2 p45-related factor 2 attenuated the enhancing effect of hypoxia on IFN-gamma secretion and other cytokines. We conclude that hypoxia is a previously underappreciated modulator of effector cytokine secretion in CD4(+) T cells.

Interferon-alpha regulates the dynamic balance between human activated regulatory and effector T cells: implications for antiviral and autoimmune responses.

An adequate effector response against pathogens and its subsequent inactivation after pathogen clearance are critical for the maintenance of immune homeostasis. This process involves an initial phase of T-cell effector (Teff) activation followed by the expansion of regulatory T cells (Tregs), a unique cell population that limits Teff functions. However, significant questions remain unanswered about the mechanisms that regulate the balance between these cell populations. Using an in vitro system to mimic T-cell activation in human peripheral blood mononuclear cells (PBMC), we analysed the patterns of Treg and Teff activation, with special attention to the role of type I interferon (IFN-I). Interestingly, we found that IFN-alpha, either exogenously added or endogenously induced, suppressed the generation of CD4(+) FoxP3(HI )IFN-gamma(Neg) activated Tregs (aTregs) while simultaneously promoting propagation of CD4(+) FoxP3(Low/Neg )IFN-gamma(Pos) activated Teffs (aTeffs). We also showed that IFN-alpha-mediated inhibition of interleukin (IL)-2 production may play an essential role in IFN-alpha-induced suppression of aTregs. In order to test our findings in a disease state with chronically elevated IFN-alpha, we investigated systemic lupus erythematosus (SLE). Plasma from patients with SLE was found to contain IFN-I activity that suppressed aTreg generation. Furthermore, anti-CD3 activated SLE PBMCs exhibited preferential expansion of aTeffs with a very limited increase in aTreg numbers. Together, these observations support a model whereby a transient production of IFN-alpha (such as is seen in an early antiviral response) may promote CD4 effector functions by delaying aTreg generation, but a chronic elevation of IFN-alpha may tip the aTeff:aTreg balance towards aTeffs and autoimmunity.

Immunomodulatory Therapeutic Proteins in COVID-19: Current Clinical Development and Clinical Pharmacology Considerations.

The coronavirus disease 2019 (COVID-19) pandemic caused by infection with SARS-CoV-2 has led to more than 600 000 deaths worldwide. Patients with severe disease often experience acute respiratory distress characterized by upregulation of multiple cytokines. Immunomodulatory biological therapies are being evaluated in clinical trials for the management of the systemic inflammatory response and pulmonary complications in patients with advanced stages of COVID-19. In this review, we summarize the clinical pharmacology considerations in the development of immunomodulatory therapeutic proteins for mitigating the heightened inflammatory response identified in COVID-19.

A Comprehensive Updated Review on SARS-CoV-2 and COVID-19.

This literature review aims to provide a comprehensive current summary of the pathogenesis, clinical features, disease course, host immune responses, and current investigational antiviral and immunomodulatory pharmacotherapies to facilitate the development of future therapies and measures for prevention and control.

Antiphospholipid antibody syndrome with thrombotic splenic infarcts associated with acute cytomegalovirus infection.

INTRODUCTION: We describe a case of acute cytomegalovirus (CMV) infection complicated by acquired antiphospholipid antibodies and splenic thrombi. We discuss the associations between CMV infection and thrombosis risk and correlation with antiphospolipid antibodies. CASE PRESENTATION: A previously healthy 32-year-old woman is hospitalized for acute abdominal pain and fever and found to have multiple splenic infarcts on an abdominal computed tomography (CT) scan. An infectious work-up is negative except for acute CMV, and a hypercoagulable work-up is only positive for antiphospholipid antibodies. The patient is discharged and placed on anti-coagulation therapy for 6 months. CONCLUSION: Co-incident thrombosis and antiphospholipid antibody syndrome can occur with acute viral infections, including CMV. We discuss the viral infection-associated increased risk of developing blood clots and antiphospholipid antibodies as being either correlative with or causative of viral-induced thrombosis.

Semaphorin 4A Stabilizes Human Regulatory T Cell Phenotype via Plexin B1.

We previously reported that neuroimmune semaphorin (Sema) 4A regulates the severity of experimental allergic asthma and increases regulatory T (Treg) cell numbers in vivo; however, the mechanisms of Sema4A action remain unknown. It was also reported that Sema4A controls murine Treg cell function and survival acting through neuropilin 1 (NRP-1) receptor. To clarify Sema4A action on human T cells, we employed T cell lines (HuT78 and HuT102), human PBMCs, and CD4+ T cells in phenotypic and functional assays. We found that HuT78 demonstrated a T effector-like phenotype (CD4+CD25lowFoxp3-), whereas HuT102 expressed a Treg-like phenotype (CD4+CD25hi Foxp3+). Neither cell line expressed NRP-1. HuT102 cells expressed Sema4A counter receptor Plexin B1, whereas HuT78 cells were Sema4A+. All human peripheral blood CD4+ T cells, including Treg cells, expressed PlexinB1 and lacked both NRP-1 and -2. However, NRP-1 and Sema4A were detected on CD3negativeCD4intermediate human monocytes. Culture of HuT cells with soluble Sema4A led to an upregulation of CD25 and Foxp3 markers on HuT102 cells. Addition of Sema4A increased the relative numbers of CD4+CD25+Foxp3+ cells in PBMCs and CD4+ T cells, which were NRP-1negative but PlexinB1+, suggesting the role of this receptor in Treg cell stability. The inclusion of anti-PlexinB1 blocking Ab in cultures before recombinant Sema4A addition significantly decreased Treg cell numbers as compared with cultures with recombinant Sema4A alone. Sema4A was as effective as TGF-ß in inducible Treg cell induction from CD4+CD25depleted cells but did not enhance Treg cell suppressive activity in vitro. These results suggest strategies for the development of new Sema4A-based therapeutic measures to combat allergic inflammatory diseases. ImmunoHorizons, 2019, 3: 71-87.

Cytoplasmic FOXO1 identifies a novel disease-activity associated B cell phenotype in SLE.

Systemic lupus erythematosus (SLE) is a manifestation of hyperactivated lymphocytes and results, in part, from the loss of normal tolerance checkpoints. FOXO1 is a transcription factor involved at critical early and late B cell development checkpoints; however, its role in regulating peripheral B cell tolerance is not fully understood. We have applied our published approach for using imaging flow cytometry to study native FOXO1 localisation in human lymphocytes to peripheral blood samples from healthy individuals versus patients with SLE. We report, here, on dramatic cytoplasmic localisation of FOXO1 in two peripheral B cell SLE subsets: IgD-CD27+ (class-switched memory) B cells and IgD-CD27- (atypical memory) B cells. The latter, so-called 'Double Negative' (DN) B cells have previously been shown to be increased in SLE and enriched in autoreactive clones. Cytoplasmic-predominant FOXO1 (CytoFOX) B cells are significantly increased in patients with SLE as compared to healthy controls, and the levels of CytoFoOX DN B cells correlate directly with SLE disease activity. The highest abundance of CytoFox DN B cells was observed in African American females with SLE Disease Activity Index (SLEDAI)≥6. The phenotype of CytoFOX DN B cells in SLE includes uniquely low CD20 expression and high granularity/side scatter. As FOXO1 phosphorylation downstream of B cell receptor-dependent signalling is required for nuclear exclusion, CytoFOX B cells likely represent a high state of B cell activation with excess signalling and/or loss of phosphatase activity. We hypothesise that CytoFOX B cells in lupus represent a novel biomarker for the expansion of pathological, autoreactive B cells which may provide new insights into the pathophysiology of SLE.

Imaging flow cytometry: A method for examining dynamic native FOXO1 localization in human lymphocytes.

While flow cytometry can reliably assess surface and intracellular marker expression within small cell populations, it does not provide any information on protein localization. Several key transcription factors (TF) downstream of lymphocyte surface receptors are regulated by nuclear versus cytoplasmic localization, and one such TF is Forkhead box O1 (FOXO1). FOXO1 integrates antigen-binding, co-receptor activation and metabolic signals in lymphocytes, leading to proliferation and differentiation. Importantly, the nuclear or cytoplasmic localization of FOXO1 is key for gene expression leading to different lymphocyte phenotypes. In effector lymphocytes (Teff), for example, lymphocyte receptor (TCR) signaling leads to an Akt-dependent phosphorylation of FOXO1. Phosphorylated FOXO1 is excluded from the nucleus, promoting proliferation and effector functions. In contrast, nuclear retention of FOXO1 is essential for early and late development of T and B cells and for the thymic development and stability of regulatory T cells. Given the critical role of FOXO1 localization as an indicator and determinant of function, quantification of FOXO1 cellular localization in human lymphocytes can help determine immune cell activation and activity in experimental and clinical scenarios. The standard method used to determine subcellular protein localization is the analysis of nuclear and cytoplasmic protein extracts by Western blotting (WB). However, available techniques, such as WB, are limited by a requirement for a large number of cells and inability to determine FOXO1 localization in individual cells or sub-populations. In contrast, a standardized method using an imaging flow cytometer (IFC) such as the Amnis ImagestreamX Mark II, would provide both qualitative, per-cell localization information, as well as quantitative data on gated sub-populations. To this end, we report the development and optimization of an IFC protocol to examine native FOXO1 localization in human lymphocytes. A human CD4+ lymphocyte line, HuT102, as well as primary human T cells, were assessed for dynamic FOXO1 localization after treatment with a lymphocyte receptor signaling mimic (PMA/Ionomycin). IFC nuclear translocation analysis permitted us to precisely quantify the alterations over time in nuclear and cytoplasmic localization of native FOXO1 on a per cell basis, including within specific, user-defined sub-populations of cells. For human lymphocytes, using IFC to assess and quantify dynamic FOXO1 localization allows the user to simultaneously study multiple lymphocyte subpopulations as well as to delineate differing effects of dynamic FOXO1 localization that may be lost when other available methods are used.

Barriers and Facilitators of Mentoring for Trainees and Early Career Investigators in Rheumatology Research: Current State, Identification of Needs, and Road Map to an Inter-Institutional Adult Rheumatology Mentoring Program.

OBJECTIVE: To determine perceived barriers and facilitators to effective mentoring for early career rheumatology investigators and to develop a framework for an inter-institutional mentoring program. METHODS: Focus groups or interviews with rheumatology fellows, junior faculty, and mentors were conducted, audiorecorded, and transcribed. Content analysis was performed using NVivo software. Themes were grouped into categories (e.g., mentor-mentee relationship, barriers, and facilitators of a productive relationship). Rheumatology fellows and early career investigators were also surveyed nationwide to identify specific needs to be addressed through an inter-institutional mentoring program. RESULTS: Twenty-five individuals participated in focus groups or interviews. Attributes of the ideal mentee-mentor relationship included communication, accessibility, regular meetings, shared interests, aligned goals, and mutual respect. The mentee should be proactive, efficient, engaged, committed, focused, accountable, and respectful of the mentor's time. The mentor should support/promote the mentee, shape the mentee's goals and career plan, address day-to-day questions, provide critical feedback, be available, and have team leadership skills. Barriers included difficulty with career path navigation, gaining independence, internal competition, authorship, time demands, funding, and work-life balance. Facilitators of a successful relationship included having a diverse network of mentors filling different roles, mentor-mentee relationship management, and confidence. Among 187 survey respondents, the primary uses of an inter-institutional mentoring program were career development planning and oversight, goal-setting, and networking. CONCLUSIONS: In this mixed-methods study, tangible factors for optimizing the mentor-mentee relationship were identified and will inform the development of an adult rheumatology inter-institutional mentoring program.

Rheumatoid arthritis and reproduction.

Additional research is needed to establish the safety of biologic agents in pregnancy and lactation. The practitioner should convey information regarding the natural history of rheumatoid arthritis during pregnancy and safety issues related to pharmacotherapies to every woman of childbearing age with RA, well before conception and pregnancy, to ensure optimal outcomes.

A novel method for assaying human regulatory T cell direct suppression of B cell effector function.

We have established a highly reproducible and reliable protocol for testing human regulatory T cell function in suppressing IgM production from an immature human B cell line. The autoreactive Ramos B cell line provides a stable reporter of B cell effector function that can be tested by a straight-forward IgM ELISA. Tregs from healthy volunteers display a range of ability for suppressing baseline IgM production in a contact- and death-independent manner. Having established the normal range for human Treg direct suppression of B cell effector function, it will now be possible to efficiently test Tregs from various autoimmune conditions in which B cell hyperactivity and secretion of auto-antibodies are a hallmark of disease.

Barriers to and Facilitators of a Career as a Physician-Scientist Among Rheumatologists in the US.

OBJECTIVE: To determine perceived barriers to and facilitators of a career in rheumatology research, examine factors leading rheumatologists to leave an academic research career, and solicit ways to best support young physician-scientists. METHODS: A web-based survey was conducted among the domestic American College of Rheumatology (ACR) membership from January through March 2014. Inclusion criteria were ACR membership and an available e-mail address. Non-rheumatologists were excluded. The survey assessed demographics, research participation, barriers to and facilitators of a career in research, reasons for leaving a research career (when applicable), and ways in which the ACR could support junior investigators. Content analysis was used to extract relevant themes. RESULTS: Among 5,448 domestic ACR members, 502 responses were obtained (9.2% response rate). After exclusions (38 incomplete, 2 duplicates, 32 non-rheumatologists), 430 responses were analyzed. Participants included fellows, young investigators, established investigators, mentors, clinicians, and those who previously pursued a research career but have chosen a different career path. Funding and mentoring were the most highly ranked barriers and facilitators. Protection from clinical and administrative duties, institutional support, and personal characteristics such as resilience and persistence were also ranked highly. The most commonly cited reasons for leaving an academic research career were difficulty obtaining funding and lack of department or division support. CONCLUSION: This is the first study to examine barriers to and facilitators of a career in rheumatology research from the perspectives of diverse groups of rheumatologists. Knowledge of such barriers and facilitators may assist in designing interventions to support investigators during vulnerable points in their career development.