No abstract

While lung cancer risk among smokers is dependent on smoking dose, it remains unknown if this increased risk reflects an increased rate of somatic mutation accumulation in normal lung cells. Here we applied single-cell whole genome sequencing of proximal bronchial basal cells from 33 subjects aged between 11 and 86 years with smoking histories varying from never smoking to 116 pack years. We found an increase in the frequency of single-nucleotide variants and small insertions and deletions with chronological age in never-smokers with mutation frequencies significantly elevated among smokers. When plotted against smoking pack-years, mutations followed the linear increase in cancer risk only until about 23 pack years, after which no further increase in mutation frequency was observed, pointing towards individual selection for mutation avoidance. Known lung cancer-defined mutation signatures tracked with both age and smoking. No significant enrichment for somatic mutations in lung cancer driver genes was observed.

531T he serotonin hypothesis of pulmonary arterial hypertension (PAH) emerged . 40 years ago and was reemphasized in the 1990s following the association of pulmonary hypertension (PH) 1 with anorexic agents such as aminorex fumarate and fenfl uramine. [2][3][4][5] Serotonin promotes pulmonary arterial smooth muscle cell and fi broblast proliferation, pulmonary arterial vasoconstriction, and local microthrombosis-all key pathogenic features in PAH. These effects of serotonin are mediated by interactions between serotonin and its transporter and receptors. [6][7][8][9][10] In particular, the serotonin transporter (SERT) plays a key role in the pathogenesis of experimental PH; in animal models, SERT overexpression predisposes to the development of PH, whereas pharmacologic blockade of SERT is protective. 1,[11][12][13][14] In humans, a functional polymorphism in the SERT gene correlates with more severe PH associated with COPD. 15 Selective serotonin reuptake inhibitors (SSRIs) act via blockade of SERT, resulting in an extracellular accumulation of serotonin and increased activation of serotonin receptors. 16 SSRIs have been associated with both protection against and regression of PH in animal models, suggesting a possible role in the treatment of PAH in humans. 1,14,17 Early observational studies have suggested therapeutic effi cacy of SSRIs in patients with Background: Selective serotonin reuptake inhibitors (SSRIs) have been suggested to offer therapeutic benefi t in patients with pulmonary arterial hypertension (PAH). We conducted two analyses to explore the association between SSRI use and PAH outcomes using the Registry to Evaluate Early and Long-term PAH Disease Management (REVEAL Registry). Methods: First, new users (SSRI-naive patients who initiated treatment after enrollment, incident use analysis, n 5 220) were matched (1:2) with non-SSRI users (nonusers, n 5 440) by enrollment center, sex, date of most recent visit, age, and 6-min walk distance. Second, a cross-sectional design was used to compare nonusers (n 5 2,463), high-affi nity SSRI users (n 5 430), and non-high-affi nity SSRI users (n 5 125) at enrollment. Mortality and a composite end point defi ned by events indicative of clinical worsening were evaluated. Results: New users had a higher risk of death (unadjusted hazard ratio [HR], 1.74; 95% CI, 1.19-2.54; P 5 .004) and were less likely to be free from the composite end point 2 years after enrollment vs nonusers (25.7% vs 43.2%, respectively; P , .001). Similarly, among prevalent SSRI users (patients with a history of SSRI use at enrollment), high-affi nity SSRI users were less likely to be free from the composite end point vs nonusers (unadjusted HR, 1.20; 95% CI, 1.07-1.36; P 5 .003). In both analyses, differences in outcome were maintained after adjustment for clinical variables previously associated with PAH outcomes. Conclusions:In a large population of patients with PAH, incident SSRI use was associated with increased mortality and a greater risk of clinical worsening, although we could ...