Regulatory T cell monitoring in severe eosinophilic asthma patients treated with mepolizumab

Single-cell RNA sequencing reveals transcriptional changes in circulating immune cells from patients with severe asthma induced by biologics

Patients with severe eosinophilic asthma often require systemic medication, including corticosteroids and anti-type 2 (T2) cytokine biologics, to control the disease. While anti-IL5 and anti-IL4Rα antibodies suppress the effects of IL-4, IL-5 and IL-13, the molecular pathways modified by these biologics that are associated with clinical improvement remain unclear. Therefore, we aimed to describe the effects of T2-targeting biologics on the gene expression of blood immune cells. We conducted single-cell RNA sequencing (scRNA-seq) of peripheral blood mononuclear cells (PBMCs) from eight patients with severe eosinophilic asthma treated with mepolizumab, reslizumab, or dupilumab. PBMCs were obtained before the initiation of biologics and at 1- and 6-month timepoints after the initiation of treatment to elucidate treatment-induced changes. During treatment, the proportions of T cells/natural killer (NK) cells, myeloid cells, and B cells did not change. However, the composition of classical monocytes (CMs) changed: IL1B+ CMs were reduced, and S100A+ CMs were increased. The subsets of T cells also changed, and significant downregulation of the NF-κB pathway was observed. The genes related to the NF-κB pathway were suppressed across T/NK, myeloid, and B cells. The transcriptional landscape did not significantly change after the first month of treatment, but marked changes occurred at six-month intervals. In conclusion, regardless of the type of biologics used, suppression of T2-mediated pathways ultimately reduces the expression of genes related to NF-κB signaling in circulating immune cells. Further studies are warranted to identify potential biomarkers related to treatment response and long-term outcomes.Clinical trial registration number: NCT05164939.

Interleukin-5 as a pleiotropic cytokine orchestrating airway type 2 inflammation: Effects on and beyond eosinophils

Interleukin (IL)-5 is the key cytokine in the maturation, activation, proliferation, migration and survival of eosinophils, which are key effector cells in many upper and lower airway diseases. Through its effects on eosinophils, IL-5 indirectly contributes to various pathophysiological processes including tissue damage, repair and remodelling. Understanding the importance of IL-5 in eosinophil-associated diseases led to the development of anti-IL-5 therapies, which provide clinical benefits across a range of conditions. However, recent evidence suggests that eosinophil-depletion alone may not account for all of the therapeutic effects of anti-IL-5 therapy and that IL-5 may also contribute to disease independently of its effects on eosinophils. Indeed, evidence from ex vivo studies and targeted therapy in vivo demonstrates that IL-5 and its inhibition affects a much broader range of cells beyond eosinophils, including epithelial cells, plasma cells, mast cells, basophils, neutrophils, type 2 innate lymphoid cells, T regulatory cells and fibroblasts. This review will provide an update on the evidence supporting the breadth of IL-5 biology relevant to disease pathogenesis beyond eosinophil-associated inflammation, where there is a need for additional insight, and the clinical implications of a more central role of IL-5 in type 2 inflammation.

CD4+ Foxp3+ Regulatory T-cells in Modulating Inflammatory Microenvironment in Chronic Rhinosinusitis with Nasal Polyps: Progress and Future Prospect

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a subtype of chronic rhinosinusitis (CRS) characterized by the presence of nasal polyps (NP) in the paranasal mucosa. Despite the complex etiology, NP is believed to result from chronic inflammation. The long-term aftermath of the type 2 response is responsible for symptoms seen in NP patients, i.e. rhinorrhea, hyposmia, and nasal obstruction. Immune cellular tolerogenic mechanisms, particularly CD4 + Foxp3 + regulatory T cells (Tregs), are crucial to curtail inflammatory responses. Current evidence suggests impaired Treg activity is the main reason underlying the compromise of self-tolerance, contributing to the onset of CRSwNP. There is compelling evidence that tumor necrosis factor 2 (TNFR2) is preferentially expressed by Tregs, and TNFR2 is able to identify the most potent suppressive subset of Tregs. Tumor necrosis factor (TNF)-TNFR2 interaction plays a decisive role in the activation and expansion of Tregs. This review summarizes current understanding of Tregs biology, focusing on the discussion of the recent advances in the study of TNF-TNFR2 axis in the upregulation of Treg function as a negative feedback mechanism in the control of chronic inflammation. The role of dysregulation of Tregs in the immunopathogenesis of CRSwNP will be analyzed. The future perspective on the harnessing Tregs-mediated self-tolerant mechanism in the management of CRSwNP will be introduced.

The effect of anti-IL5 monoclonal antibodies on regulatory and effector T cells in severe eosinophilic asthma

INTRODUCTION

Biological treatments have redesigned the clinical management of severe eosinophilic asthmatic (SA) patients. Despite emerging evidence supporting the role of natural Killer (NK), and T regulatory cells (Treg) in the pathogenesis of asthma, no data is available on the effects of anti-IL5/IL5R therapies on these cell subsets.

METHODS

We prospectively enrolled fourteen SA patients treated with benralizumab (n = 7) or mepolizumab (n = 7) and compared them with healthy controls (HC) (n = 11) and mild to moderate asthmatic (MM) patients (n = 9). Clinical parameters were collected at baseline (T0) and during follow-up. Cellular analysis, including the analysis of T/NK cell subsets, was determined through multicolor flow cytometry.

RESULTS

At T0, SA patients showed higher percentages of CD4 TEM (33.3 ± 17.9 HC, 42.6 ± 16.6 MM and 66.1 ± 19.7 in SA; p < 0.0001) than HC and MM patients. With different timing, the two drugs induce a reduction of CD4 TEM ( 76 ± 19 T0; 43 ± 14 T1; 45 ± 23 T6; 62 ± 18 at T24; p < 0.0001 for mepolizumab and 55 ± 21 T0; 55 ± 22 T1; 43 ± 14 T6; 27 ± 12 at T24; p < 0.0001 for benralizumab) and an increase of Treg cells (1.2 ± 1.3 T0; 5.1 ± 2.5 T1; 6.3 ± 3.4 T6; 8.4 ± 4.6 at T24; p < 0.0001 for mepolizumab and 3.4 ± 1.7 T0; 1.9 ± 0.8 T1; 1.9 ± 1 T6; 5.1 ± 2.4 at T24; p < 0.0001 for benralizumab). The change of CD56dim PD-1+ significantly correlated with FEV1% (r = - 0.32; p < 0.01), while Treg expressing PD-1 correlates with the use of oral steroids ( r = 0.36 p = 0.0008) and ACT score (r = 0.36 p = 0.0008) p < 0.001) CONCLUSIONS: Beyond the clinical improvement, anti-IL-5 treatment induces a rebalancing of Treg and T effector cells in patients with SA.

Severe asthma remaining well-controlled after mepolizumab discontinuation: A case report and literature review

Mepolizumab, a humanized anti-IL-5 monoclonal antibody used for severe asthma, results in a reduced rate of asthma exacerbation, improved lung function, reduced oral corticosteroid use, and improved quality of life. A 62-year-old man using high-dose inhaled corticosteroid visited our hospital because of poorly-controlled asthma. He had eosinophilia in peripheral blood and sputum, and high levels of fraction of exhaled nitric oxide. Therefore, he was treated with mepolizumab for severe asthma. Mepolizumab treatment resulted in significantly improved pulmonary function and reduced frequencies of asthma exacerbations. Because of his good asthma control, mepolizumab treatment was discontinued after 3 years. Since discontinuing mepolizumab, his asthma control has remained without exacerbation. Previous studies suggest that mepolizumab should be continued to sustain clinical benefits. However, cases of long-term controlled asthma have not been reported after mepolizumab withdrawal, and our case may be instructive.

T-cell responses in asthma exacerbations

OBJECTIVE

Asthma is a chronic lung disease comprising multiple endotypes and characterized by periodic exacerbations. A diverse array of T cells has been found to contribute to all endotypes of asthma in pathogenic and regulatory roles. Here, we review the contributions of CD4+, CD8+, and unconventional T cells in allergic and nonallergic asthma.

DATA SOURCES

Review of published literature pertaining to conventional and unconventional T-cell types in asthma.

STUDY SELECTIONS

Recent peer-reviewed articles pertaining to T cells in asthma, with additional peer-reviewed studies for context.

RESULTS

Much research in asthma has focused on the roles of CD4+ TH cells. Roles for TH2 cells in promoting allergic asthma pathogenesis have been well-described, and the recent description of pathogenic TH2A cells provides additional insight into these responses. Other TH types, notably TH1 and TH17, have been linked to neutrophilic and steroid-resistant asthma phenotypes. Beyond CD4+ T cells, CD8+ Tc2 cells are also strongly associated with allergic asthma. An emerging area for study is unconventional T-cell types, including γδT, invariant natural killer T, and mucosal-associated invariant T cells. Although data in asthma remain limited for these cells, their ability to bridge innate and adaptive responses likely makes them key players in asthma. A number of asthma therapies target T-cell responses, and, although data are limited, they seem to modulate T-cell populations.

CONCLUSION

Given the diversity and heterogeneity of asthma and T-cell responses, there remain many rich avenues for research to better understand the pathogenesis of asthma. Despite the breadth of T cells in asthma, approved therapeutics remain limited to TH2 networks.

Sex Steroids Effects on Asthma: A Network Perspective of Immune and Airway Cells

A multitude of evidence has suggested the differential incidence, prevalence and severity of asthma between males and females. A compilation of recent literature recognized sex differences as a significant non-modifiable risk factor in asthma pathogenesis. Understanding the cellular and mechanistic basis of sex differences remains complex and the pivotal point of this ever elusive quest, which remains to be clarified in the current scenario. Sex steroids are an integral part of human development and evolution while also playing a critical role in the conditioning of the immune system and thereby influencing the function of peripheral organs. Classical perspectives suggest a pre-defined effect of sex steroids, generalizing estrogens popularly under the “estrogen paradox” due to conflicting reports associating estrogen with a pro- and anti-inflammatory role. On the other hand, androgens are classified as “anti-inflammatory,” serving a protective role in mitigating inflammation. Although considered mainstream and simplistic, this observation remains valid for numerous reasons, as elaborated in the current review. Women appear immune-favored with stronger and more responsive immune elements than men. However, the remarkable female predominance of diverse autoimmune and allergic diseases contradicts this observation suggesting that hormonal differences between the sexes might modulate the normal and dysfunctional regulation of the immune system. This review illustrates the potential relationship between key elements of the immune cell system and their interplay with sex steroids, relevant to structural cells in the pathophysiology of asthma and many other lung diseases. Here, we discuss established and emerging paradigms in the clarification of observed sex differences in asthma in the context of the immune system, which will deepen our understanding of asthma etiopathology.

NK and T Cell Immunological Signatures in Hospitalized Patients with COVID-19

Severe acute respiratory syndrome caused by coronavirus 2 emerged in Wuhan (China) in December 2019 and has severely challenged the human population. NK and T cells are involved in the progression of COVID-19 infection through the ability of NK cells to modulate T-cell responses, and by the stimulation of cytokine release. No detailed investigation of the NK cell landscape in clinical SARS-CoV-2 infection has yet been reported. A total of 35 COVID-19 hospitalised patients were stratified for clinical severity and 17 healthy subjects were enrolled. NK cell subsets and T cell subsets were analysed with flow cytometry. Serum cytokines were detected with a bead-based multiplex assay. Fewer CD56dimCD16brightNKG2A+NK cells and a parallel increase in the CD56+CD69+NK, CD56+PD-1+NK, CD56+NKp44+NK subset were reported in COVID-19 than HC. A significantly higher adaptive/memory-like NK cell frequency in patients with severe disease than in those with mild and moderate phenotypes were reported. Moreover, adaptive/memory-like NK cell frequencies were significantly higher in patients who died than in survivors. Severe COVID-19 patients showed higher serum concentrations of IL-6 than mild and control groups. Direct correlation emerged for IL-6 and adaptive/memory-like NK. All these findings provide new insights into the immune response of patients with COVID-19. In particular, they demonstrate activation of NK through overexpression of CD69 and CD25 and show that PD-1 inhibitory signalling maintains an exhausted phenotype in NK cells. These results suggest that adaptive/memory-like NK cells could be the basis of promising targeted therapy for future viral infections.

γδT17/γδTreg cell subsets: a new paradigm for asthma treatment

Bronchial asthma (abbreviated as asthma), is a heterogeneous disease characterized by chronic airway inflammation and airway hyperresponsiveness. The main characteristics of asthma include variable reversible airflow limitation and airway remodeling. The pathogenesis of asthma is still unclear. Th1/Th2 imbalance, Th1 deficiency and Th2 hyperfunction are classic pathophysiological mechanisms of asthma. Some studies have shown that the imbalance of the Th1/Th2 cellular immune model and Th17/Treg imbalance play a key role in the occurrence and development of asthma; however, these imbalances do not fully explain the disease. In recent years, studies have shown that γδT and γδT17 cells are involved in the pathogenesis of asthma. γδTreg has a potential immunosuppressive function, but its regulatory mechanisms have not been fully elucidated. In this paper, we reviewed the role of γδT17/γδTreg cells in bronchial asthma, including the mechanisms of their development and activation. Here we propose that γδT17/Treg cell subsets contribute to the occurrence and development of asthma, constituting a novel potential target for asthma treatment.

Follicular T Helper and Breg Cell Balance in Severe Allergic Asthma Before and After Omalizumab Therapy

BACKGROUND

Severe allergic asthma (SAA) is based on type 2 (T2-high) immune responses to allergens promoting type 2 T helper (Th2) cell cytokine responses and production of IgE antibodies. Omalizumab was the first biological drug licensed for clinical use in the management of IgE-mediated SAA. Despite emerging evidence supporting the prominent role of follicular T cells (Tfh), Breg and Treg subsets, in the development and progression of SAA, no data are available on the impact of omalizumab therapy.

METHODS

Ten SAA patients monitored at the Respiratory Diseases Unit of Siena University Hospital and ten healthy sex- and age-matched controls were enrolled in the study. Clinical and functional parameters were collected at baseline (T0) and after 6 months of therapy (T6). Cellular population analysis was determined through multicolour flow cytometry.

RESULTS

SAA patients showed higher percentages of Th17.1, Tfh and Tfh2 while CD24hiCD27hi Breg cell, Treg and Tfr percentages were significantly lower than in controls. Higher percentages of Tfh2 in patients with nasal polyps than in those without and in controls were observed. At T6, significant decreases in Tfh and Tfh2 compared with T0 were observed. A slightly significant increase in Teffs was reported at T6 compared to T0. ΔIgE levels in serum were correlated with ΔCD19+CD24+CD27+ Breg cell percentages (r = - 0.86, p = 0.0022).

CONCLUSIONS

Our data explored the changes in Tfh cells, Tregs and Bregs in severe asthma. The restoration of immunological imbalance in SAA patients after omalizumab is certainly intriguing and represents a glimpse into the comprehension of immunological effects of treatment.

Regulatory T cell deficiency in patients with eosinophilic asthma

There is a lack of information about regulatory T cells (Tregs) and inflammatory phenotypes in patients with asthma. In this study, we aimed to compare the characteristics of Tregs in patients with eosinophilic asthma. Forty healthy and 120 stable asthmatic patients were recruited. Sputum and airway inflammatory phenotypes were assessed, and all patients were followed for one year. Human peripheral blood mononuclear cells (PBMCs) were collected and stimulated with phytohemagglutinin (PHA) and Dermatophagoides farina (Derp) to detect CD4 + CD25 + FOXP3+ T cells and Foxp3 levels. Interleukin (IL)-13, IL-5, IL-17, IL-9, and interferon (IFN)-γ levels were measured. We found that 38.33% of patients had eosinophilic asthma, 13.33% had neutrophilic asthma, 6.67% had mixed granulocytic asthma, and 41.67% had pauci-granulocytic asthma. The eosinophilic asthma patients had a relatively high Asthma Control Test (ACT) score, an increased prediction and improvement FEV1(%) rate, and elevated total IgE serum levels (P < 0.05). T helper cell 2 (Th2) cytokines IL-13 and IL-5 were predominantly expressed in the eosinophilic phenotype, while the Th1 cytokine IFN-γ and Th17 cytokine were found in the neutrophilic phenotype. IL-10 was significantly lower in eosinophilic asthmatic patients compared to the controls (P < 0.05). CD4 + CD25 + FOXP3+ T cells (%Tregs) and Foxp3 gene expression in the PHA stimulated eosinophilic asthma samples were significantly lower compared to the control samples (P < 0.05). The airway inflammation phenotypes remained stable after one-year of therapy. Asthmatic patients with the eosinophilic phenotype in this study were deficient in Tregs, as characterized by a Th2 cell-biased pattern.

Real-World Multicenter Experience with Mepolizumab and Benralizumab in the Treatment of Uncontrolled Severe Eosinophilic Asthma Over 12 Months

Purpose

Treatment of severe eosinophilic asthma (SEA) has been revolutionized by the development of monoclonal antibodies targeting underlying immunological pathways of eosinophilic asthma. Two of the most frequently used antibodies in clinical practice are mepolizumab, targeting interleukin (IL) 5 and benralizumab, targeting the IL5 receptor alpha. The comparative treatment efficacy of these antibodies remains unclear, particularly regarding long-term outcomes.

Patients and Methods

In this multicenter, retrospective study, we included 123 patients treated with mepolizumab and 64 patients treated with benralizumab for 12 months at one of three study sites in Germany. Data were collected at baseline and after 6 and 12 months of therapy. Endpoints were changes in pulmonary function (PF), exacerbation rate, oral corticosteroid (OCS) use and dose, asthma control test (ACT) score and fractional exhaled nitric oxide (FeNO) levels.

Results

Both mepolizumab and benralizumab led to significant improvements in PF with an increase in median forced expiratory volume (FEV1) after 12 months from 59% to 74% for mepolizumab and 63% to 72% for benralizumab. Treatment also led to significant improvements in ACT scores after 12 months (mepolizumab: 13 [interquartile range (IQR) 9-17] to 19 [IQR 15-23]; benralizumab: 12 [IQR 9-16] to 22 [IQR 16-25]) as well as a reduction of mean OCS dose (mepolizumab 8 mg [IQR 5-12.5 mg] median prednisolone equivalent at baseline to 5 mg [IQR 3-7.5 mg]; benralizumab 7.5 mg [IQR 5-15 mg] to 5 mg [IQR 2-10 mg]). The exacerbation rates were reduced significantly, irrespective of the treatment. Overall, changes were similar after 6 and 12 months of therapy.

Conclusion

Both mepolizumab and benralizumab are highly effective in the long-term treatment of SEA, with no clinically relevant differences in outcomes after 12 months of therapy. In both groups, improvements were similar after 6 and 12 months of therapy, underlining the feasibility of early treatment evaluation.

Adaptive immune system in pulmonary sarcoidosis-Comparison of peripheral and alveolar biomarkers

Sarcoidosis is a multi‐systemic granulomatous disease of unknown origin. Recent research has focused upon the role of autoimmunity in its development and progression. This study aimed to determine and define the disturbance and distribution of T and B cell subsets in the alveolar and peripheral compartments. Thirteen patients were selected for the study [median age, interquartile range (IQR) = 57 years (48–59); 23% were male]. Twelve healthy controls [median age, IQR = 53 years (52–65); 16% male] were also enrolled into the study. Cellular and cytokine patterns were measured using the cytofluorimetric approach. Peripheral CD8 percentages were higher in sarcoidosis patients (SP) than healthy controls (HC) (p = 0.0293), while CD4 percentages were lower (p = 0.0305). SP showed low bronchoalveolar lavage (BAL) percentages of CD19 (p = 0.0004) and CD8 (p = 0.0035), while CD19⁺CD5⁺CD27⁻ percentages were higher (p = 0.0213); the same was found for CD4 (p = 0.0396), follicular regulatory T cells (T_reg) (p = 0.0078) and T_reg (p < 0.0001) cells. Low T helper type 17 (Th17) percentages were observed in BAL (p = 0.0063) of SP. Peripheral CD4⁺ C‐X‐C chemokine receptor (CXCR)5⁺CD45RA⁻) percentages and follicular T helper cells (Tfh)‐like Th1 (Tfh1) percentages (p = 0.0493 and p = 0.0305, respectively) were higher in the SP than HC. Tfh1 percentages and Tfh‐like Th2 percentages were lower in BAL than in peripheral blood (p = 0.0370 and p = 0.0078, respectively), while CD4⁺ C‐X‐C motif CXCR5⁺CD45RA⁻ percentages were higher (p = 0.0011). This is the first study, to our knowledge, to demonstrate a link between an imbalance in circulating and alveolar Tfh cells, especially CCR4‐, CXCR3‐ and CXCR5‐expressing Tfh subsets in the development of sarcoidosis. These findings raise questions about the pathogenesis of sarcoidosis and may provide new directions for future clinical studies and treatment strategies.

Regulatory and Effector Cell Disequilibrium in Patients with Acute Cellular Rejection and Chronic Lung Allograft Dysfunction after Lung Transplantation: Comparison of Peripheral and Alveolar Distribution

Background: The immune mechanisms occurring during acute rejection (AR) and chronic lung allograft dysfunction are a challenge for research and the balance between effector and regulatory cells has not been defined completely. In this study, we aimed to elucidate the interaction of effector cells, mainly Th17, Th1 and Th2, and regulatory cells including (CD4⁺CD25⁺CD127^low/−) T reg cells and phenotypes of B regs, CD19⁺CD24^hiCD38^hi, CD19⁺CD24^hiCD27^hi and CD19⁺CD5⁺CD1d⁺. Methods: Bronchoalveolar lavage cells (BAL) and peripheral blood mononuclear cells (PBMCs) from stable lung transplanted (LTx )subjects (n = 4), AR patients (n = 6) and bronchiolitis obliterans syndrome (BOS) (n = 6) were collected at the same time. Cellular subsets were detected through flow cytometry. Results: A predominance of Th17 cells subtypes in the PBMCs and BAL and a depletion of Tregs, that resulted in decrease Treg/Th17 ratio, was observed in the AR group. CD19⁺CD24^hiCD38^hi Bregs resulted increased in BAL of AR patients. Th1 cells predominance and a reduction of Tregs cells was observed in BAL from AR patients. Moreover, multivariate analysis showed interdependences within studied variables revealing that effector cells and regulatory cells can effectively discriminate patients’ immunological status. Conclusions: In AR, BOS and stable lung transplant, regulatory and effector cells clearly demonstrated different pathways of activation. Understanding of the balance of T cells and T and B regulatory cells can offers insights into rejection.