Association of Dual-Task Gait Cost and White Matter Hyperintensity Burden Poststroke: Results From the ONDRI

BACKGROUND

Acute change in gait speed while performing a mental task [dual-task gait cost (DTC)], and hyperintensity magnetic resonance imaging signals in white matter are both important disability predictors in older individuals with history of stroke (poststroke). It is still unclear, however, whether DTC is associated with overall hyperintensity volume from specific major brain regions in poststroke.

METHODS

This is a cohort study with a total of 123 older (69 ± 7 years of age) participants with history of stroke were included from the Ontario Neurodegenerative Disease Research Initiative. Participants were clinically assessed and had gait performance assessed under single- and dual-task conditions. Structural neuroimaging data were analyzed to measure both, white matter hyperintensity (WMH) and normal appearing volumes. Percentage of WMH volume in frontal, parietal, occipital, and temporal lobes as well as subcortical hyperintensities in basal ganglia + thalamus were the main outcomes. Multivariate models investigated associations between DTC and hyperintensity volumes, adjusted for age, sex, years of education, global cognition, vascular risk factors, APOE4 genotype, residual sensorimotor symptoms from previous stroke and brain volume.

RESULTS

There was a significant positive global linear association between DTC and hyperintensity burden (adjusted Wilks' λ = .87, P = .01). Amongst all WMH volumes, hyperintensity burden from basal ganglia + thalamus provided the most significant contribution to the global association (adjusted β = .008, η² = .03; P = .04), independently of brain atrophy.

CONCLUSIONS

In poststroke, increased DTC may be an indicator of larger white matter damages, specifically in subcortical regions, which can potentially affect the overall cognitive processing and decrease gait automaticity by increasing the cortical control over patients' locomotion.

Genetic Variants Associated with Severe Hypertriglyceridemia: LPL, APOC2, APOA5, GPIHBP1, LMF1, and APOE

OBJECTIVE

High triglyceride (TG) levels are associated with an increased risk for atherosclerotic cardiovascular disease (ASCVD) and pancreatitis. The objectives for this study were to evaluate for the coexistence of severe HTG and pancreatitis in two different geographic regions of Turkey and to identify rare variants that cause monogenic HTG in our country.

METHODS

In our study from 2014 to 2019, patients with severe HTG who presented to the endocrinology outpatient clinics with TG levels >500 mg/dL (5.7 mmol/L) were evaluated. The LPL, APOC2, APOA5, GPIHBP1, LMF1, and APOE genes were sequenced using next generation sequencing to screen for potentially pathogenic variants.

RESULTS

Potentially pathogenic variants were identified in 64 (47.1%) of 136 patients. Variants in LPL were seen in 42 (30.9%) cases, APOA5 variants in 10 (7.4%) cases, APOC2 variants in 5 (3.7%) cases, LMF1 variants in 5 (3.7%) cases, and APOE mutations in 2 (1.5%) cases. In the subgroup that experienced pancreatitis (n = 76, 56.3%), LPL variants were seen at higher frequency (P <0.001) than in the subgroup with no history of pancreatitis (n = 60, 43.7%). Patients who developed pancreatitis (56.3%) demonstrated a median TG of 2083 mg/dL (23.5 mmol/L), and patients without pancreatitis (43.7%) demonstrated a median TG of 1244.5 mg/dL (14.1 mmol/L) (P <0.001).

CONCLUSION

Accurate approach to HTG diagnosis is important for the prevention of pancreatitis and ASCVD. Evaluation of variants in primary HTG after excluding secondary causes may help provide a patient-centric precision treatment plan.

Awareness of lipid guideline recommendations for high-risk patients amongst primary care physicians in Canada

Background

Lipid guidelines for cardiovascular (CV) risk reduction have evolved in recent years, particularly since the introduction of PCSK9 inhibitors. In many jurisdictions, CV risk management is provided by primary care physicians (PCPs). We surveyed Canadian PCPs regarding their awareness and implementation of the 2021 Canadian Cardiovascular Society (CCS) lipid guideline recommendations for patients following an acute coronary syndrome (ACS) or for those with diabetes but without CV disease.

Methods and results

From a national database of PCPs with interest and/or experience in CV medicine, we invited PCPs to complete a survey regarding lipid management in high-risk patients. A committee of PCPs and specialists with lipid expertise including several co-authors of the 2021 CCS lipid guidelines had designed the survey to probe awareness and practice patterns. A total of 203 PCPs from across Canada completed the survey between January and March 2022. 23.6% of respondents had previously prescribed a PCSK9 inhibitor. Almost all (96.5%) PCPs concurred that a post-ACS patient should be seen by their PCP within 4 weeks of hospital discharge (79.3% within 2 weeks). Almost half (45.3%) responded that discharge summaries provided inadequate information relevant for PCPs, and 43% felt that lipid management post-ACS was the primary responsibility of specialists. More than half (56%) articulated challenges when seeing a post-ACS patient, related to inadequate discharge information, complexities of polypharmacy and duration of therapies, and managing perceived or real statin intolerance. 62% correctly identified the LDL-C intensification threshold of 1.8 mmol/L in post-ACS patients, while 79% considered that PCSK9 inhibitors were indicated only for those patients who were already receiving statins plus ezetimibe or had substantially elevated LDL-C levels. 55.2% were able to correctly identify clinical features associated with greatest absolute benefit of PCSK9 inhibitors in post-ACS patients. For patients with diabetes but without ASCVD, 80% of PCPs incorrectly believed that PCSK9 inhibitors were indicated for LDL-C levels above threshold despite statin therapy, and only 42% correctly identified the LDL-C threshold for treatment intensification of 2.0 mmol/L.

Conclusion

While PCPs are aware of the urgency regarding lipid management in post-ACS patients, many encounter challenges after hospital discharge, frequently deferring lipid management to specialists. Thus, almost one year following publication of the 2021 CCS lipid guidelines, substantial knowledge gaps remain regarding intensification thresholds and treatment options for patients post-ACS or for those with diabetes. Innovative and effective knowledge translation programs are urgently required.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Amgen Canada

RNAi inhibition of angiopoietin-like protein 3 (ANGPTL3) with ARO-ANG3 mimics the lipid and lipoprotein profile of familial combined hypolipidemia

Background

Elevated LDL-C and triglyceride rich lipoproteins (TRLs) are independent risk factors for cardiovascular disease (CVD). Genetic deficiency of angiopoietin-like protein 3 (ANGPTL3) is associated with reduced circulating levels of LDL-C, triglycerides (TGs), VLDL-C, HDL-C and reduced CVD risk, with no described adverse phenotype. ARO-ANG3 is a RNA interference drug designed to silence expression of ANGPTL3. Single doses of ARO-ANG3 have been shown to reduce ANGPTL3, TGs, VLDL-C and LDL-C in healthy volunteers (HVs, AHA 2019). We report the effects of multiple doses of ARO-ANG3 in HVs with a focus on the duration of action.

Methods

ARO-ANG3 was administered subcutaneously to HVs on days 1 and 29 at doses of 100, 200 or 300 mg (n=4 per group). Measured parameters included ANGPTL3, LDL-C, TGs, VLDL-C and HDL-C. Follow up is ongoing.

Results

All HVs have received both doses and follow-up is currently through week 16 (12 weeks after second dose). Mean nadir for ANGPTL3 levels occurred 2 weeks after the second dose (−83–93%) with minimal change for 200 and 300 mg but 16% recovery for 100 mg at week 16. Mean TGs and VLDL-C reached nadir earlier (3 wks, −61–65%) without apparent dose response and minimal change for any dose at wk 16. LDL-C nadir occurred 4–6 wks after the second dose (−45–54%), again with minimal evidence for dose response or change through wk 16. HDL-C was reduced 14–37% at wk 16. ARO-ANG3 was well tolerated without serious or severe adverse events or dropouts related to drug. The most common adverse events have been headache and upper respiratory infections.

Conclusions

Genetic deficiency of ANGPTL3 is a cause of familial combined hypolipemia and is associated with a decreased risk of CVD. Using RNAi to selectively suppress ANGPTL3 production reproduces these genetic effects with a duration of at least 12 weeks following a second dose and with good tolerability over 16 wks. ANGPTL3 inhibition results in lowering of LDL-C and TRLs which may confer protection against CVD in patients with atherogenic mixed dyslipidemia.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Arrowhead Pharmaceuticals

RNA interference targeting apolipoprotein C-III with ARO-APOC3 in healthy volunteers mimics lipid and lipoprotein findings seen in subjects with inherited apolipoprotein C-III deficiency

Background

Individuals with triglycerides (TGs) ≥1,000 mg/dL (11.1 mmol/L) are at increased risk of acute pancreatitis. Genetic studies indicate that individuals with apolipoprotein C-3 (APOC3) loss-of-function mutations have low TGs, reduced cardiovascular risk and no observed adverse phenotype. RNA interference (RNAi) with ARO-APOC3 has shown deep and durable knockdown (KD) of APOC3 after single doses in healthy volunteers (HVs, presented at AHA 2019) with good tolerability. We report here initial results using multiple doses of ARO-APOC3 to silence APOC3 expression in HVs.

Methods

ARO-APOC3 was administered subcutaneously to HVs on days 1 and 29 at doses of 10, 25 or 50 mg (n=4 per group). Measured parameters included plasma concentrations of APOC3, LDL-C, TGs, VLDL-C and HDL-C.

Results

All HVs have received both doses and follow-up for most parameters is available through week (wk) 14 (10 wks after second dose) for the 10 and 25 mg doses and through wk 10 for 50 mg. Mean nadir for APOC3 levels occurred at wk 3 for 10 mg (−73%) and remained similar at wk 10 (−66%), at wk 6 for 25 mg (−90%) with no change at wk 10 and at wk 2 for 50 mg (−94%) unchanged at wk 8. TGs fell faster in the 50 mg group (wk 1: 10 mg −41%; 25 mg −47%; 50 mg −72%). By wk 6 the 25 and 50 mg results were similar (−68% and −74%, respectively) and remained similar through wk 14. 10 mg was less active with a nadir of −56% and mean reductions between 42% and 56% post-nadir. VLDL-C values mirrored TGs. LDL-C reductions were more modest and did not manifest a dose response. Mean nadirs (−23–26%) occurred 4–6 wks after the first dose, again with minimal change through 10–14 wks of follow-up. Consistent with genetic studies, HDL-C increased to a maximum at approximately wk 8 (10 mg +42%, 25 mg +48%, 50 mg +84%). ARO-APOC3 was well tolerated without serious or severe adverse events or dropouts related to drug. The most common adverse events were mild injection site AEs and headache.

Conclusions

Genetic deficiency of APOC3 is associated with substantial reductions in TGs, VLDL-C and increases in HDL-C without an adverse phenotype. Using RNAi to selectively suppress APOC3 production mimics these lipid and lipoprotein effects, with a duration of at least 10 weeks following a second dose and with good tolerability over 16 wks using doses ranging from 10 to 50 mg. Investigation of optimal dosing regimen is ongoing, especially with respect to dosing interval. This therapeutic approach has potential for treating patients with chylomicronemia at risk of pancreatitis.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Arrowhead Pharmaceuticals

OR21-3 Familial Chylomicronemia Syndrome: Distinguishing the Rare Among the Common in Adults for Appropriate Management

Background: Hypertriglyceridemia (HTG) is common, but familial chylomicronemia syndrome (FCS) is a very rare cause of severe HTG, associated with pancreatitis, which can be fatal. It is due to impaired lipoprotein lipase (LPL) function, typically caused by bi-allelic LPL loss-of-function mutations. Although FCS generally presents in childhood with acute pancreatitis and HTG, it should also be considered as a diagnosis in adults with severe HTG. Unlike polygenic HTG, dietary fat-restriction is the mainstay of treatment in FCS which is critical in preventing pancreatitis since traditional medications are ineffective. Several promising biologics currently under clinical development may provide novel therapeutic approaches in FCS. Clinical Case: 52-year-old fraternal twins and their 55-year-old brother born to consanguineous parents were recruited into an IRB-approved lipid genetic study. LPL activity and genetic analyses were performed to definitively diagnose FCS. Moreover, the twins participated in clinical trials which investigated novel therapies for HTG. The female twin seemed to have had undiagnosed pancreatitis since age 13, and was hospitalized at age 20 with HTG and severe pancreatitis for the first time. The male twin had multiple hospitalizations for pancreatitis and HTG. The older brother also had emergency room visits for pancreatitis. Misguidedly, all siblings had been on low-carbohydrate diet that lead to severe HTG. Their medical and family histories were consistent with FCS. The studies performed identified a previously unreported homozygous LPL variant, c.617T>C, p.V206A, corroborated by reduced LPL activities, and altered molecular dynamics, consistent with dysfunctional LPL and the diagnosis of FCS. A very low-fat diet was prescribed which facilitated in stabilizing their clinical picture with a reduction in TG and pancreatitis episodes. The female twin qualified to enroll in a clinical study for the treatment of HTG, receiving multiple doses of an experimental APOC3 inhibitor, which lowered her TG from 3,447 to 201 mg/dL (~94% reduction) within 90 days which persisted for several months. The result seemed to indicate that inhibiting APOC3 could effectively enhance the residual LPL lipolytic activity and lower TG. In addition, the twins qualified to participate in a double-blinded clinical trial with an experimental ANGPTL3 inhibitor whose results are forthcoming in the near future. Conclusion: Our case demonstrates the importance of elucidating FCS diagnosis even in adults with HTG for selecting the most appropriate therapy. This was the first reported case of this particular homozygous variant causing FCS. Particularly, the clinical trial result was encouraging that novel biologics may become an optional therapy in certain patients with FCS beyond dietary management in the future. Disclosure: permission to present the study result has been obtained.

A truncating mutation in CEP55 is the likely cause of MARCH, a novel syndrome affecting neuronal mitosis

Background

Hydranencephaly is a congenital anomaly leading to replacement of the cerebral hemispheres with a fluid-filled cyst. The goals of this work are to describe a novel autosomal-recessive syndrome that includes hydranencephaly (multinucleated neurons, anhydramnios, renal dysplasia, cerebellar hypoplasia and hydranencephaly (MARCH)); to identify its genetic cause(s) and to provide functional insight into pathomechanism.

Methods

We used homozygosity mapping and exome sequencing to identify recessive mutations in a single family with three affected fetuses. Immunohistochemistry, RT-PCR and imaging in cell lines, and zebrafish models, were used to explore the function of the gene and the effect of the mutation.

Results

We identified a homozygous nonsense mutation in CEP55 segregating with MARCH. Testing the effect of this allele on patient-derived cells indicated both a reduction of the overall CEP55 message and the production of a message that likely gives rise to a truncated protein. Suppression or ablation of cep55l in zebrafish embryos recapitulated key features of MARCH, most notably renal dysplasia, cerebellar hypoplasia and craniofacial abnormalities. These phenotypes could be rescued by full-length but not truncated human CEP55 message. Finally, we expressed the truncated form of CEP55 in human cells, where we observed a failure of truncated protein to localise to the midbody, leading to abscission failure and multinucleated daughter cells.

Conclusions

CEP55 loss of function mutations likely underlie MARCH, a novel multiple congenital anomaly syndrome. This association expands the involvement of centrosomal proteins in human genetic disorders by highlighting a role in midbody function.

Large-scale gene-centric meta-analysis across 39 studies identifies type 2 diabetes loci

To identify genetic factors contributing to type 2 diabetes (T2D), we performed large-scale meta-analyses by using a custom ∼50,000 SNP genotyping array (the ITMAT-Broad-CARe array) with ∼2000 candidate genes in 39 multiethnic population-based studies, case-control studies, and clinical trials totaling 17,418 cases and 70,298 controls. First, meta-analysis of 25 studies comprising 14,073 cases and 57,489 controls of European descent confirmed eight established T2D loci at genome-wide significance. In silico follow-up analysis of putative association signals found in independent genome-wide association studies (including 8,130 cases and 38,987 controls) performed by the DIAGRAM consortium identified a T2D locus at genome-wide significance (GATAD2A/CILP2/PBX4; p = 5.7 × 10(-9)) and two loci exceeding study-wide significance (SREBF1, and TH/INS; p < 2.4 × 10(-6)). Second, meta-analyses of 1,986 cases and 7,695 controls from eight African-American studies identified study-wide-significant (p = 2.4 × 10(-7)) variants in HMGA2 and replicated variants in TCF7L2 (p = 5.1 × 10(-15)). Third, conditional analysis revealed multiple known and novel independent signals within five T2D-associated genes in samples of European ancestry and within HMGA2 in African-American samples. Fourth, a multiethnic meta-analysis of all 39 studies identified T2D-associated variants in BCL2 (p = 2.1 × 10(-8)). Finally, a composite genetic score of SNPs from new and established T2D signals was significantly associated with increased risk of diabetes in African-American, Hispanic, and Asian populations. In summary, large-scale meta-analysis involving a dense gene-centric approach has uncovered additional loci and variants that contribute to T2D risk and suggests substantial overlap of T2D association signals across multiple ethnic groups.

Hepatic lipase deficiency in a Middle-Eastern-Arabic male

Hepatic lipase (HL) deficiency is a rare genetic disorder that has been associated with premature atherosclerosis despite high plasma high-density lipoprotein (HDL) cholesterol concentrations in the affected individuals. The authors describe the clinical and biochemical features of HL deficiency in a young male of Middle-Eastern-Arabic origin. This is the first report of cholesterol ester transfer protein (CETP) activity and mass in HL deficiency in a patient from this ethnic group. While the CETP mass was high, its activity was low, a discrepancy likely due to the abnormal composition of patient's HDL particles.

A genome-wide linkage scan for familial partial lipodystrophy susceptibility genes in a German kindreds

Background: In Dunnigan-type familial partial lipodystrophy (FPLD) patients are born with normal fat distribution, but subcutaneous fat from extremities and gluteal regions are lost during puberty. The abnormal fat distribution leads to the development of metabolic syndrome (MetS), a cluster of phenotypes including hyperglycemia, dyslipidemia, hypertension, and visceral obesity. The study of FPLD as a monogenic model of MetS may uncover genetic risk factors of the common MetS which affects ~30% of adult North Americans. Two molecular forms of FPLD have been identified including FPLD2, resulting from heterozygous mutations in the LMNA gene, and FPLD3, resulting from both heterozygous dominant negative and haploinsufficiency mutations in the PPARG gene. However, many patients with clinically diagnosed FPLD have no mutation in either LMNA or PPARG, suggesting the involvement of additional genes in FPLD etiology. Methods: Here, we report the results of an Affymetrix 10K GeneChip microarray genome-wide linkage analysis study of a German kindred displaying the FPLD phenotype and no known lipodystrophy-causing mutations. Results: The investigation identified three chromosomal loci, namely 1q, 3p, and 9q, with non-parametric logarithm of odds (NPL) scores >2.7. While not meeting the criteria for genome-wide significance, it is interesting to note that the 1q and 3p peaks contain the LMNA and PPARG genes respectively. Conclusions: Three possible conclusions can be drawn from these results: 1) the peaks identified are spurious findings, 2) additional genes physically close to LMNA, PPARG, or within 9q, are involved in FPLD etiology, or 3) alternative disease causing mechanisms not identified by standard exon sequencing approaches, such as promoter mutations, alternative splicing, or epigenetics, are also responsible for FPLD.

Genetic determinants of carotid ultrasound traits

Atherosclerosis is a complex disease with various intermediate phenotypes that are themselves complex and influenced by many factors. Through the use of carotid ultrasound techniques, the intermediate stages of vascular disease can be imaged and studied for association with potential genetic determinants. In this article we review the most recent available data (reports published since 2004) on the genetic determinants of atherosclerosis, as measured by one-, two-, and three-dimensional ultrasonography of the carotid arteries. In general, associations are disparate and modest. For intima-media thickness, promising associations have been found for both TNFRSF1A R92Q and PPARG P12A, but associations also differed in the same individuals depending on the specific ultrasound trait studied (eg, linear intima-media thickness versus total plaque volume in carotid arteries). Some of the challenging issues for future studies include accounting for gene-environment interactions, sex-specific associations, and the distinctiveness of different carotid ultrasound measures.

Biophysical characteristics of a new mutation on the KCNQ1 potassium channel (L251P) causing long QT syndrome

The congenital long QT syndrome (LQTS) is a hereditary cardiac disease characterized by prolonged ventricular repolarization, syncope, and sudden death. Mutations causing LQTS have been identified in various genes that encode for ionic channels or their regulatory subunits. Several of these mutations have been reported on the KCNQ1 gene encoding for a potassium channel or its regulatory subunit (KCNE1). In this study, we report the biophysical characteristics of a new mutation (L251P) in the transmembrane segment 5 (S5) of the KCNQ1 potassium channel. Potassium currents were recorded from CHO cells transfected with either wild type or mutant KCNQ1 in the presence or in the absence of its regulatory subunit (KCNE1), using the whole-cell configuration of the patch clamp technique. Wild-type KCNQ1 current amplitudes are increased particularly by KCNE1 co-expression but no current is observed with the KCNQ1 (L251P) mutant either in the presence or in the absence of KCNE1. Coexpressing KCNE1 with equal amount of cDNAs encoding wild type and mutant KCNQ1 results in an 11-fold reduction in the amplitude of potassium currents. The kinetics of activation and inactivation and the activation curve are minimally affected by this mutation. Our results suggest that the dominant negative effect of the P251L mutation on KCNQ1 channel explains the prolonged repolarization in patients carrying this mutation.

The impact of diabetes on cardiovascular risk factors and outcomes in a native Canadian population

We measured cardiovascular disease (CVD) risk factors and their relationship to glucose intolerance in a Native Canadian population with very high rates of Type 2 diabetes mellitus. Five hundred and twenty five study-eligible Ojibwa-Cree individuals age 18 and over in the community of Sandy Lake, Canada who had participated in a population-based survey were studied. Diabetes status, plasma concentrations of total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL-C), calculated low density lipoprotein-cholesterol (LDL-C), waist/hip ratio (WHR), BMI, systolic and diastolic BP, and history of smoking were compared to a standard national population. Extremely high rates of obesity (BMI and WHR) were identified in the study population and were associated with increasing glucose intolerance for both males and females. Rates of smoking exceeded 70 and 80% in females and males, respectively. Interestingly, despite obesity individuals who had normal glucose tolerance had significantly lower rates of high risk TC, TG, LDL-C, and HDL-C levels compared to a national Canadian population survey. However, with worsening glucose intolerance, TC, TG, LDL-C and HDL-C dramatically deteriorated in comparison to nationally published levels. These changes in cardiovascular risk factors, as a consequence of diabetes, appear to result in increased clinical outcomes. Admission to hospital for Ischemic Heart Disease (IHD) for Sandy Lake residents increased from a rate of 34.8/10,000 to 109.1/10,000 in 15 years. Although this and similar populations have historically reported low rates of CVD, the impact of diabetes on lipid risk factor is having devastating consequences on cardiovascular outcomes. This trend is expected to continue unless the high rates of diabetes can be modified.

Utility of a lung biopsy for the diagnosis of idiopathic pulmonary fibrosis

It is not known if a surgical lung biopsy is necessary in all patients for the diagnosis of idiopathic pulmonary fibrosis (IPF). We conducted a blinded, prospective study at eight referring centers. Initially, cases were evaluated by clinical history and examination, transbronchial biopsy, and high-resolution lung computed tomography scans. Pulmonologists at the referring centers then assessed their certainty of the diagnosis of IPF and provided an overall diagnosis, before surgical lung biopsy. The lung biopsies were reviewed by a pathology core and 54 of 91 patients received a pathologic diagnosis of IPF. The positive predictive value of a confident (certain) clinical diagnosis of IPF by the referring centers was 80%. The positive predictive value of a confident clinical diagnosis was higher, when the cases were reviewed by a core of pulmonologists (87%) or radiologists (96%). Lung biopsy was most important for diagnosis in those patients with an uncertain diagnosis and those thought unlikely to have IPF. These studies suggest that clinical and radiologic data that result in a confident diagnosis of IPF by an experienced pulmonologist or radiologist are sufficient to obviate the need for a lung biopsy. Lung biopsy is most helpful when clinical and radiologic data result in an uncertain diagnosis or when patients are thought not to have IPF.

Substance P (NK1)- and neurokinin A (NK2)-receptor gene expression in inflammatory airway diseases

The tachykinin neuropeptides substance P and neurokinin (NK) A have been postulated to participate in the inflammatory reaction in airways of smokers and asthmatics. We have examined the hypothesis that the expression of one or more of the three cloned tachykinin receptors (NK1, NK2, and NK3) is increased in inflammatory airway disorders, which could result in augmentation of the effect of released tachykinin neuropeptides. NK1 receptor and NK2 receptor but not NK3-receptor mRNA were detected by ribonuclease protection assay in RNA from both cartilaginous and membranous bronchi and subpleural lung. In lung samples containing membranous airways, NK2-receptor mRNA expression was increased fourfold in asthmatics compared with nonsmoking controls, whereas NK1-receptor mRNA levels were similar in the two groups. NK1- and NK2-receptor mRNA expression was increased twofold in smokers without airflow obstruction compared with nonsmokers, whereas NK1-receptor mRNA expression was significantly lower in patients with chronic obstructive pulmonary disease compared with smoking controls. In situ hybridization indicated NK1-receptor mRNA was expressed in submucosal glands and airway epithelial cells, whereas NK2-receptor and NK3-receptor mRNA were not detected. These observations have implications for the pathophysiology and treatment of both asthma and tobacco smoke-induced airway inflammation.