Diffuse alveolar hemorrhage in coumarin users: a fibrosing interstitial pneumonia trigger?

Drug-Gene Risk Stratification in Patients with Suspected Drug-Induced Interstitial Lung Disease

BACKGROUND

Pulmonary toxicity has been associated with drug use. This is often not recognized in clinical practice, and underestimated.

OBJECTIVE

We aimed to establish whether polymorphisms in certain genes corresponding with a metabolic pathway of drug(s) used are associated with pulmonary toxicity in patients with suspected drug-induced interstitial lung disease (DI-ILD).

METHODS

This retrospective observational study explored genetic variations in three clinically relevant cytochrome P450 (CYP) iso-enzymes (i.e., CYP2D6, CYP2C9, and CYP2C19) in a group of patients with a fibroticinterstitial lung disease, either non-specific interstitial pneumonia (n = 211) or idiopathic pulmonary fibrosis (n = 256), with a suspected drug-induced origin.

RESULTS

Of the 467 patients, 79.0% showed one or more polymorphisms in the tested genes accompanied by the use of drug(s) metabolized by a corresponding affected metabolic pathway (60.0% poor metabolizers and/or using two or more drugs [likely DI-ILD], 37.5% using three or more [highly likely DI-ILD]). Most commonly used drugs were statins (63.1%) with a predominance among men (69.4 vs 47.1%, p < 0.0001). Nitrofurantoin, not metabolized by the tested pathways, was prescribed more frequently among women (51.9 vs 4.5%, p < 0.00001).

CONCLUSIONS

In our cohort with suspected DI-ILD, 79% carried one or more genetic variants accompanied by the use of drugs metabolized by a corresponding affected pathway. In 60%, the diagnosis of DI-ILD was likely, whereas in 37.5%, it was highly likely, based on CYP analyses. This study underlines the importance of considering both drug use and genetic make-up as a possible cause, or at least a contributing factor, in the development and/or progression of fibrotic lung diseases.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT00267800, registered in 2005.

Altered pharmacology and toxicology during ageing: implications for lung disease

PURPOSE OF REVIEW

Drug use in elderly people is high compared to younger people. Simultaneously, elderly are at greater risk when exposed to environmental substances. It is puzzling therefore, that ageing, as a variable in pharmacological and toxicological processes is not investigated in more depth. Moreover, recent data suggest that molecular manifestations of the ageing process also hallmark the pathogenesis of chronic lung diseases, which may impact pharmacology and toxicology.

RECENT FINDINGS

In particular, absorption, distribution, metabolism and excretion (ADME) processes of drugs and toxins alter because of ageing. Polypharmacy, which is quite usual with increasing age, increases the risk of drug-drug interactions. Individual differences in combination of drugs use in conjunction with individual variations in drug metabolizing enzymes can influence lung function.

SUMMARY

Exploring exposure throughout life (i.e. during ageing) to potential triggers, including polypharmacy, may avoid lung disease or unexplained cases of lung damage. Understanding of the ageing process further unravels critical features of chronic lung disease and helps to define new protective targets and therapies. Optimizing resilience can be key in pharmacology and toxicology and helps in maintaining healthy lungs for a longer period.

Drug-induced interstitial lung disease: role of pharmacogenetics in predicting cytotoxic mechanisms and risks of side effects

PURPOSE OF REVIEW

The diagnosis of drug-induced interstitial lung disease (DI-ILD) is challenging and mainly made by exclusion of other possible causes. Toxicity can occur as a cause of drug(s) or drug-drug interactions. In this review, we summarize the possible role of pharmacogenetics of metabolizing enzymes in DI-ILD.

RECENT FINDINGS

Knowledge of the genetic predispositions of enzymes involved in drug metabolization and their relation with proposed cytotoxic mechanisms of DI-ILD, in particular direct cell toxicity and free oxygen radical production is increasing. The cytochrome P450 enzyme family and other enzymes play an important role in the metabolism of all sorts of ingested, injected, or inhaled xenobiotic substances. The liver is the major site for metabolism. Metabolic cytotoxic mechanisms have however also been detected in lung tissue. Polymorphisms in genes coding for enzymes that influence metabolic activity may lead to localized (toxic) reactions and tissue damage. This knowledge may be helpful in preventing the risk of DI-ILD.

SUMMARY

Drug toxicity can be the consequence of absence or very poor enzyme activity, especially if no other metabolic route is available. In the case of reduced enzyme activity, it is recommended to reduce the dose or to prescribe an alternative drug, which is metabolized by a different, unaffected enzyme system to prevent toxic side effects. However, enhanced enzyme activity may lead to excessive formation of toxic and sometimes reactive metabolites. Therefore, knowing a patient's drug-metabolizing profile before drug prescription is a promising way to prevent or explain DI-ILD.

VKORC1 and CYP2C9 Polymorphisms: A Case Report in a Dutch Family with Pulmonary Fibrosis

Here, we describe a Dutch family with idiopathic pulmonary fibrosis (IPF). We hypothesized that there might be an association between the presence of Vitamin K epoxide reductase complex 1 (VKORC1) and/or cytochrome P450 2C9 (CYP2C9) variant alleles and the early onset of IPF in the members of this family. VKORC1 (rs9923231 and rs9934438) and CYP2C9 (rs1799853 and rs1057910) were genotyped in this family, which includes a significant number of pulmonary fibrosis patients. In all family members, at least one of the variant alleles tested was present. The presence of the VKORC1 variant alleles in all of the IPF cases and CYP2C9 variants in all but one, which likely leads to a phenotype that is characterized by the early onset and progressive course of IPF. Our findings indicate a role of these allelic variants in (familial) IPF. Therefore, we suggest that the presence of these variants, in association with other pathogenic mutations, should be evaluated during genetic counselling. Our findings might have consequences for the lifestyle of patients with familial IPF in order to prevent the disease from becoming manifest.

Bronchoalveolar lavage (BAL) cells in idiopathic pulmonary fibrosis express a complex pro-inflammatory, pro-repair, angiogenic activation pattern, likely associated with macrophage iron accumulation

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease of unknown cause characterized by alveolar epithelial damage, patchy interstitial fibrosis and diffuse microvascular abnormalities. In IPF, alveolar clustering of iron-laden alveolar macrophages—a common sign of microhemorrhage, has been associated with vascular abnormalities and worsening of pulmonary hypertension. As iron-dependent ROS generation has been shown to induce unrestrained macrophage activation in disease models of vascular damage, we explored alveolar macrophage activation phenotype in IPF patients (n = 16) and healthy controls (CTR, n = 7) by RNA sequencing of bronchoalveolar lavage (BAL) cells. The frequencies of macrophages in BAL cells were 86+4% and 83.4+8% in IPF and CTR groups, respectively (p-value = 0.41). In IPF patients, BAL cells showed increased iron-dependent ROS generation (p-value<0.05 vs CTR). Gene expression analysis showed overrepresentation of Gene Ontology processes/functions and KEGG pathways enriched in upregulated M1-type inflammatory (p-value<0.01), M2-type anti-inflammatory/tissue remodeling (p-value<0.0001), and MTPP-type chronic inflammatory/angiogenic (p-value<0.0001) chemokine and cytokine genes. The ex vivo finding was confirmed by the induction of iron-dependent ROS generation and chemokine/cytokine overexpression of Ccl4, Cxcl10 (M1), Il1rn (M2), Cxcl2, and Cxcl7 (MTPP) in MH-S murine immortalized alveolar macrophages exposed to ferric ammonium citrate in culture (p-value<0.05 vs CTR). The data show alveolar macrophage expression of a pro-inflammatory, tissue remodeling and angiogenic complex activation pattern, suggesting that iron accumulation may play a role in macrophage activation.

Unfavourable effects of medically indicated oral anticoagulants on survival in idiopathic pulmonary fibrosis

Procoagulant and antifibrinolytic activity has been associated with idiopathic pulmonary fibrosis (IPF); however, investigation of anticoagulant therapy in IPF has suggested deleterious effects. This post hoc analysis evaluated the effect of medically indicated anticoagulation on mortality and other clinical outcomes in IPF.Patients randomised to placebo (n=624) from three controlled trials in IPF were analysed by oral anticoagulant use. End-points included all-cause and IPF-related mortality, disease progression, hospitalisation, and adverse events, over 1 year.At baseline, 32 (5.1%) patients randomised to placebo were prescribed anticoagulants for non-IPF indications, 29 (90.6%) of whom received warfarin. Unadjusted analyses demonstrated significantly higher all-cause and IPF-related mortality at 1 year in baseline anticoagulant users versus nonusers (15.6% versus 6.3%, p=0.039 and 15.6% versus 3.9%, p=0.002, respectively). In multivariate analyses, baseline use of anticoagulants was an independent predictor of IPF-related mortality (hazard ratio 4.7, p=0.034), but not other end-points. Rates of bleeding and cardiac events did not differ significantly between groups. In an exploratory analysis, anticoagulant use at any time during the study was an independent predictor of all end-points.This post hoc analysis suggests that anticoagulants used for non-IPF indications may have unfavourable effects in IPF patients. Future studies are needed to explore this relationship further.