PD1, CTLA4 and TIGIT Expression on T and NK Cells in Granulomatous Diseases: Sarcoidosis and ANCA-Associated Vasculitis

Sarcoidosis is a granulomatous diseases affecting the lungs. Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a histologically granulomatous B-mediated disorder characterized by activated T cells. The expression of immune checkpoint (IC) molecules (PD1, CTLA4, TIGIT) on T- and NK-cells negatively regulate the T-cell immune function. The present study aimed to explore the peripheral distribution of IC molecules to better elucidate their peripheral tolerance failure, which might reflect the development of diseases. Patients referred to Respiratory Diseases and Rheumatology Unit of Siena University Hospital were prospectively and consecutively enrolled. Healthy subjects were also enrolled as a control group. Multicolor flow cytometric analysis was performed to detect IC molecules in the peripheral blood of patients. Twenty-three patients were consecutively and prospectively enrolled in the study: 11 patients had an AAV diagnosis and 12 had sarcoidosis. CD4+PD1+ cells were higher in sarcoidosis and GPA than in HC (p = 0.0250 and p = 0.0253, respectively). CD56+CTLA4+ were higher in sarcoidosis than GPA, MPA and HC (p = 0.0085, p = 0.0042 and p = 0.0004, respectively). CTLA4+NK cells clustered for 100% of sarcoidosis patients according to decision tree analysis, while PD1+CD4 and CD8 cells for clustered for 100% of GPA patients. Our analyses showed substantial differences between sarcoidosis and AAV, further confirming the immunological peculiarity of this disease. Despite these advances, the pathogenesis remains incompletely understood, indicating an urgent need for further research to reveal the distinct immunological events in this process, with the hope to open up new therapeutic avenues and, if possible, to develop preventive measures. © 2022 by the authors

Markers of Bronchiolitis Obliterans Syndrome after Lung Transplant: Between Old Knowledge and Future Perspective

Bronchiolitis obliterans syndrome (BOS) is the most common form of CLAD and is characterized by airflow limitation and an obstructive spirometric pattern without high-resolution computed tomography (HRCT) evidence of parenchymal opacities. Computed tomography and microCT analysis show abundant small airway obstruction, starting from the fifth generation of airway branching and affecting up to 40–70% of airways. The pathogenesis of BOS remains unclear. It is a multifactorial syndrome that leads to pathological tissue changes and clinical manifestations. Because BOS is associated with the worst long-term survival in LTx patients, many studies are focused on the early identification of BOS. Markers may be useful for diagnosis and for understanding the molecular and immunological mechanisms involved in the onset of BOS. Diagnostic and predictive markers of BOS have also been investigated in various biological materials, such as blood, BAL, lung tissue and extracellular vesicles. The aim of this review was to evaluate the scientific literature on markers of BOS after lung transplant. We performed a systematic review to find all available data on potential prognostic and diagnostic markers of BOS

A Comprehensive Review of Sarcoidosis Diagnosis and Monitoring for the Pulmonologist

Sarcoidosis is a systemic granulomatous disease with heterogenous clinical manifestations. Here we review the diagnosis of sarcoidosis and propose a clinically feasible diagnostic work-up and monitoring protocol. As sarcoidosis is a systemic disease, a multidisciplinary approach is recommended for best outcomes. However, since the lungs are frequently involved, the pulmonologist is often the referral physician for diagnosis and management. When sarcoidosis is suspected, diagnosis needs to be confirmed and organ involvement/impairment assessed. This process is also required to establish whether the patient is likely to benefit from treatment, as many cases of sarcoidosis are self-limited and remit spontaneously. Whether or not treatment is started, effective regular follow-up is necessary to monitor changes in the disease, including extension, progression, remissions, flare-ups, and complications

PD1, CTLA4 and TIGIT Expression on T and NK Cells in Granulomatous Diseases: Sarcoidosis and ANCA-Associated Vasculitis

Sarcoidosis is a granulomatous diseases affecting the lungs. Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a histologically granulomatous B-mediated disorder characterized by activated T cells. The expression of immune checkpoint (IC) molecules (PD1, CTLA4, TIGIT) on T- and NK-cells negatively regulate the T-cell immune function. The present study aimed to explore the peripheral distribution of IC molecules to better elucidate their peripheral tolerance failure, which might reflect the development of diseases. Patients referred to Respiratory Diseases and Rheumatology Unit of Siena University Hospital were prospectively and consecutively enrolled. Healthy subjects were also enrolled as a control group. Multicolor flow cytometric analysis was performed to detect IC molecules in the peripheral blood of patients. Twenty-three patients were consecutively and prospectively enrolled in the study: 11 patients had an AAV diagnosis and 12 had sarcoidosis. CD4+PD1+ cells were higher in sarcoidosis and GPA than in HC (p = 0.0250 and p = 0.0253, respectively). CD56+CTLA4+ were higher in sarcoidosis than GPA, MPA and HC (p = 0.0085, p = 0.0042 and p = 0.0004, respectively). CTLA4+NK cells clustered for 100% of sarcoidosis patients according to decision tree analysis, while PD1+CD4 and CD8 cells for clustered for 100% of GPA patients. Our analyses showed substantial differences between sarcoidosis and AAV, further confirming the immunological peculiarity of this disease. Despite these advances, the pathogenesis remains incompletely understood, indicating an urgent need for further research to reveal the distinct immunological events in this process, with the hope to open up new therapeutic avenues and, if possible, to develop preventive measures

Imbalance of Lymphocyte Subsets and CD45RA-Expressing Cells in Intrathoracic Lymph Nodes, Alveolar Compartment and Bloodstream of Pulmonary Sarcoidosis Patients

Sarcoidosis is a systemic granulomatous disease mainly affecting the lungs and hilomediastinal lymph nodes. It is characterized by non-caseating epithelioid cell granulomas in lymph nodes and lungs. Our study aimed to evaluate and compare T, B and NK cell subsets in the alveolar compartment, lymph nodes and the bloodstream simultaneously in the same patients to elucidate the immune responses associated with the development and progression of sarcoidosis. A secondary aim was to evaluate the distribution of CD45RA-expressing cells in the different anatomical compartments. Patients suspected to have sarcoidosis and who underwent bronchoscopy with bronchoalveolar lavage (BAL), lung-draining lymph node (LLN) biopsy by EBUS-TBNA and peripheral blood (PB) sampling were included in the study. They were monitored at the Regional Referral Centre of Siena University Hospital and the Respiratory Diseases Unit of Perugia Hospital. Multicolour flow cytometry analysis through FASCLyric was performed to assess T, B and NK cell subsets. Thirty-two patients (median age (IQR) 57 (52–58) years) were consecutively and prospectively enrolled. Machine learning analysis created a model which selected CD56dim16bright, CD8, Tfc, Th17, Th12, Tfh17, Tfh2, TcemRA, ThemRA, T naïve, Tc naïve, Breg, CD1d+CD5+, Th-reg, Tfh, Th1 and CD4 cells with an accuracy of 0.9500 (kappa 0.8750). Comparative analysis found 18 cell populations that differed significantly between the three anatomical compartments. The bloodstream was enriched in ThemRA (p = 0.0416), Tfh2 (p = 0.0189), Tfh17 (p = 0.0257), Th2 (p = 0.0212), Th17 (p = 0.0177), Th-naïve (p = 0.0368), CD56dimCD16bright (p p = 0.0319), TcemRA (p p = 0.0004) compared with the alveolar compartment, while Th-reg were lower in PB than BAL (p = 0.0329). The alveolar compartment was enriched in Breg (p = 0.0249) and CD1d+CD5+ (p = 0.0013) with respect to LLN samples and PB. Conversely, Tfh (p = 0.0470), Th1 (p = 0.0322), CD4 (p = 0.0486) and Tc-naïve (p = 0.0009) were more abundant in LLN than in BAL and PB. It has been speculated that changes in the relative contents of PB cells could be related to changes in production and to the selective redistribution of PB cells to granulomatous foci. This study further supports the fact that sarcoidosis is multisystemic in nature. However, the low level of immune cells in peripheral blood of patients with sarcoidosis is concerning. A re-expression of CD45RA on CD4+ and CD8+ cells could result in a reduction in peripheral immune activity. Thus, changes in the spectrum of the bloodstream may reflect both pathogenic and compensatory processes