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BackgroundLung involvement in primary Sjögren’s syndrome (pSS) may vary from 9 to 90%. Interstitial lung disease and tracheobronchial alterations are the most typical findings. The evidence of primarily emphysematous changes at computed tomography of the chest of pSS patients has occasionally been described but poorly characterized. This study aims to assess pulmonary involvement and the impact on respiratory function in a cohort of pSS patients.Materials and methodsA total of 22 consecutive patients diagnosed with pSS underwent pulmonary function tests to investigate the presence of ventilatory impairment and evaluate the exchanges of alveolar gases. All patients underwent a chest high-resolution computed tomography (HRTC).ResultsDynamic volumes were within the normal range in 21 patients (95.4%). A reduction in the diffusing capacity of the lung for carbon monoxide (DLCO) was observed in 18 patients (81.8%). Ten (45.5%) patients showed a mild degree deficit, while 8 patients (36%) showed a moderate degree deficit. Analysis of DLCO revealed a significant difference between pSS patients and controls [t(30.98) = −10.77; p < 0.001], showing a higher DLCO value for the healthy controls (mean ± SE; 101.27 ± 6.08) compared to pSS patients (mean ± SE; 65.95 ± 12.78). Emphysema was found in 21 (94.5%) patients and was the most widespread pulmonary injury. Tracheal thickness was reduced in 15 (67%) patients. Micronodules were observed in 10 (45%) patients in all the pulmonary fields. Bronchial wall thickening and bronchiectasis were observed in 8 (36%) patients, mainly in the lower lobes. Ground glass was found in 5 (22.5%) patients in lower and higher lobes. Cysts were observed in two patients (9%).ConclusionThe reduction of the DLCO could be related to early emphysematous alterations in the absence of spirometric alterations and relevant respiratory symptoms. In conclusion, emphysema might be seen as an early pulmonary involvement mark in patients suffering from pSS.

Severe acute respiratory syndrome-coronavirus-2 (SARS‐CoV‐2), responsible for COVID-19, has caused a global pandemic. Observational studies revealed a condition, herein called as Long-COVID syndrome (PC), that affects both moderately and severely infected patients, reducing quality-of-life. The mechanism/s underlying the onset of fibrotic-like changes in PC are still not well defined. The goal of this study was to understand the involvement of the Absent in melanoma-2 (AIM2) inflammasome in PC-associated lung fibrosis-like changes revealed by chest CT scans. Peripheral blood mononuclear cells (PBMCs) obtained from PC patients who did not develop signs of lung fibrosis were not responsive to AIM2 activation by Poly dA:dT. In sharp contrast, PBMCs from PC patients with signs of lung fibrosis were highly responsive to AIM2 activation, which induced the release of IL-1α, IFN-α and TGF-β. The recognition of Poly dA:dT was not due to the activation of cyclic GMP-AMP (cGAMP) synthase, a stimulator of interferon response (cGAS-STING) pathways, implying a role for AIM2 in PC conditions. The release of IFN-α was caspase-1- and caspase-4-dependent when AIM2 was triggered. Instead, the release of pro-inflammatory IL-1α and pro-fibrogenic TGF-β were inflammasome independent because the inhibition of caspase-1 and caspase-4 did not alter the levels of the two cytokines. Moreover, the responsiveness of AIM2 correlated with higher expression of the receptor in circulating CD14+ cells in PBMCs from patients with signs of lung fibrosis.

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