Clarifying Chronic Obstructive Pulmonary Disease Genetic Associations Observed in Biobanks via Mediation Analysis of Smoking.

Varying case definitions of COPD have heterogenous genetic risk profiles, potentially reflective of disease subtypes or classification bias (e.g., smokers more likely to be diagnosed with COPD). To better understand differences in genetic loci associated with ICD-defined versus spirometry-defined COPD we contrasted their GWAS results with those for heavy smoking among 337,138 UK Biobank participants. Overlapping risk loci were found in/near the genes ZEB2, FAM136B, CHRNA3, and CHRNA4, with the CHRNA3 locus shared across all three traits. Mediation analysis to estimate the effects of lead genotyped variants mediated by smoking found significant indirect effects for the FAM136B, CHRNA3, and CHRNA4 loci for both COPD definitions. Adjustment for mediator-outcome confounders modestly attenuated indirect effects, though in the CHRNA4 locus for spirometry-defined COPD the proportion mediated increased an additional 8.47%. Our results suggest that differences between ICD-defined and spirometry-defined COPD associated genetic loci are not a result of smoking biasing classification.

Multi-ancestry genome-wide meta-analysis of 56,241 individuals identifies LRRC4C, LHX5-AS1 and nominates ancestry-specific loci PTPRK , GRB14 , and KIAA0825 as novel risk loci for Alzheimer's disease: the Alzheimer's Disease Genetics Consortium.

Limited ancestral diversity has impaired our ability to detect risk variants more prevalent in non-European ancestry groups in genome-wide association studies (GWAS). We constructed and analyzed a multi-ancestry GWAS dataset in the Alzheimer's Disease (AD) Genetics Consortium (ADGC) to test for novel shared and ancestry-specific AD susceptibility loci and evaluate underlying genetic architecture in 37,382 non-Hispanic White (NHW), 6,728 African American, 8,899 Hispanic (HIS), and 3,232 East Asian individuals, performing within-ancestry fixed-effects meta-analysis followed by a cross-ancestry random-effects meta-analysis. We identified 13 loci with cross-ancestry associations including known loci at/near CR1 , BIN1 , TREM2 , CD2AP , PTK2B , CLU , SHARPIN , MS4A6A , PICALM , ABCA7 , APOE and two novel loci not previously reported at 11p12 ( LRRC4C ) and 12q24.13 ( LHX5-AS1 ). Reflecting the power of diverse ancestry in GWAS, we observed the SHARPIN locus using 7.1% the sample size of the original discovering single-ancestry GWAS (n=788,989). We additionally identified three GWS ancestry-specific loci at/near ( PTPRK ( P =2.4×10 -8 ) and GRB14 ( P =1.7×10 -8 ) in HIS), and KIAA0825 ( P =2.9×10 -8 in NHW). Pathway analysis implicated multiple amyloid regulation pathways (strongest with P adjusted =1.6×10 -4 ) and the classical complement pathway ( P adjusted =1.3×10 -3 ). Genes at/near our novel loci have known roles in neuronal development ( LRRC4C, LHX5-AS1 , and PTPRK ) and insulin receptor activity regulation ( GRB14 ). These findings provide compelling support for using traditionally-underrepresented populations for gene discovery, even with smaller sample sizes.

Invasive fungal infections after respiratory viral infections in lung transplant recipients are associated with lung allograft failure and chronic lung allograft dysfunction within 1 year.

BACKGROUND: Respiratory viral infections (RVI) are associated with chronic lung allograft dysfunction (CLAD) and mortality in lung transplant recipients (LTRs). However, the prevalence and impact of secondary invasive fungal infections (IFIs) post RVIs in LTRs have not been investigated. METHODS: We performed a single center retrospective study including LTRs diagnosed with 5 different respiratory viral pathogens between January 2010 to May 2021 and evaluated their clinical outcomes in 1 year. The risk factors of IFIs were evaluated by logistic regression. The impact of IFIs on CLAD stage progression/death was examined by Cox regression. RESULTS: A total of 202 RVI episodes (50 influenza, 31 severe acute respiratory syndrome coronavirus-2, 30 metapneumovirus, 44 parainfluenza, and 47 respiratory syncytial virus) in 132 patients was included for analysis. Thirty-one episodes (15%) were associated with secondary IFIs, and 27 occurred in LTRs with lower respiratory tract infection (LRTI; 28% from 96 LRTI episodes). Aspergillosis was the most common IFI (80%). LTRs with IFIs had higher disease severity during RVI episodes. In multivariable analysis, RVI with LTRI was associated with IFI (adjusted odds ratio [95% confidence interval (CI)] of 7.85 (2.48-24.9). Secondary IFIs were associated with CLAD stage progression/death after accounting for LRTI, pre-existing CLAD, intensive care unit admission, secondary bacterial pneumonia and underlying lung diseases pre-transplant with adjusted hazard ratio (95%CI) of 2.45 (1.29-4.64). CONCLUSIONS: This cohort demonstrated 15% secondary IFI prevalence in LTRs with RVIs. Importantly, secondary IFIs were associated with CLAD stage progression/death, underscoring the importance of screening for fungal infections in this setting.

Elevated cell-free DNA in respiratory viral infection and associated lung allograft dysfunction.

Respiratory viral infection (RVI) in lung transplant recipients (LTRs) is a risk for chronic lung allograft dysfunction (CLAD). We hypothesize that donor-derived cell-free DNA (%ddcfDNA), at the time of RVI predicts CLAD progression. We followed 39 LTRs with RVI enrolled in the Genomic Research Alliance for Transplantation for 1 year. Plasma %ddcfDNA was measured by shotgun sequencing, with high %ddcfDNA as ≥1% within 7 days of RVI. We examined %ddcfDNA, spirometry, and a composite (progression/failure) of CLAD stage progression, re-transplant, and death from respiratory failure. Fifty-nine RVI episodes, 38 low and 21 high %ddcfDNA were analyzed. High %ddcfDNA subjects had a greater median %FEV1 decline at RVI (-13.83 vs. -1.83, p = .007), day 90 (-7.97 vs. 0.91, p = .04), and 365 (-20.05 vs. 1.09, p = .047), compared to those with low %ddcfDNA and experienced greater progression/failure within 365 days (52.4% vs. 21.6%, p = .01). Elevated %ddcfDNA at RVI was associated with an increased risk of progression/failure adjusting for symptoms and days post-transplant (HR = 1.11, p = .04). No difference in %FEV1 decline was seen at any time point when RVIs were grouped by histopathology result at RVI. %ddcfDNA delineates LTRs with RVI who will recover lung function and who will experience sustained decline, a utility not seen with histopathology.

Donor derived cell free DNA% is elevated with pathogens that are risk factors for acute and chronic lung allograft injury.

BACKGROUND: Acute and chronic forms of lung allograft injury are associated with specific respiratory pathogens. Donor-derived cell free DNA (ddcfDNA) has been shown to be elevated with acute lung allograft injury and predictive of long-term outcomes. We examined the %ddcfDNA values at times of microbial isolation from bronchoalveolar lavage (BAL). METHODS: Two hundred and six BAL samples from 51 Lung Transplant Recipients (LTRs) with concurrently available plasma %ddcfDNA were analyzed along with microbiology and histopathology. Microbial species were grouped into bacterial, fungal, and viral and "higher risk" and "lower risk" cohorts based on historical association with downstream allograft dysfunction. Analyses were performed to determine pathogen category association with %ddcfDNA, independent of inter-subject variability. RESULTS: Presence of microbial isolates in BAL was not associated with elevated %ddcfDNA compared to samples without isolates. However, "higher risk" bacterial and viral microbes showed greater %ddcfDNA values than lower risk species (1.19% vs. 0.65%, p < 0.01), independent of inter-subject variability. Histopathologic abnormalities concurrent with pathogen isolation were associated with higher %ddcfDNA compared to isolation episodes with normal histopathology (medians 1.23% and 0.66%, p = 0.05). Assessments showed no evidence of correlation between histopathology or bronchoscopy indication and presence of higher risk vs. lower risk pathogens. CONCLUSION: %ddcfDNA is higher among cases of microbial isolation with concurrent abnormal histopathology and with isolation of higher risk pathogens known to increase risk of allograft dysfunction. Future studies should assess if %ddcfDNA can be used to stratify pathogens for risk of CLAD and identify pathogen associated injury prior to histopathology.

Impact of COVID-19 on Lung Allograft and Clinical Outcomes in Lung Transplant Recipients: A Case-control Study.

BACKGROUND: The impacts of COVID-19 on lung allograft function, rejection, secondary infection, and clinical outcomes in lung transplant recipients (LTRs) remain unknown. METHODS: A 1:2 matched case-control study was performed to evaluate rehospitalization, lung allograft function, and secondary infections up to 90 d after COVID-19 diagnosis (or index dates for controls). RESULTS: Twenty-four LTRs with COVID-19 (cases) and 48 controls were identified. Cases and controls had similar baseline characteristics and lung allograft function. LTRs with COVID-19 had higher incidence of secondary bacterial infection (29.2% versus 6.3%, P = 0.008), readmission (29.2% versus 10.4%, P = 0.04), and for-cause bronchoscopy (33.3% versus 12.5%, P = 0.04) compared with controls. At d 90, mortality in cases versus controls was 8.3% versus 2.1% (P = 0.21), incidence of invasive fungal infections in cases versus controls was 20.8% versus 8.3% (P = 0.13) and forced expiratory volume in 1 s (FEV1) decline ≥10% from baseline occurred in 19% of cases versus 12.2% of controls (P = 0.46). No acute cellular rejection, acute antibody-mediated rejection, or new donor-specific anti-HLA antibodies were observed among cases or controls within 90 d post index date. CONCLUSIONS: We found LTRs with COVID-19 were at risk to develop secondary infections and rehospitalization post COVID-19, compared with controls. While we did not observe post viral acute cellular rejection or antibody-mediated rejection, further studies are needed to understand if LTRs with COVID-19 who did not recover baseline lung function within 90 d have developed chronic lung allograft dysfunction stage progression.

Human Metapneumovirus and Parainfluenza Virus Infections in Lung Transplant Recipients: The Effects on Lung Allograft and Clinical Outcomes.

BACKGROUND: Human metapneumovirus (HMPVi) and parainfluenza virus (PIVi) infections are common community-acquired infections in lung transplant recipients (LTRs), but data are extremely limited. METHODS: A retrospective study including all LTRs at the Johns Hopkins Hospital during July 2010-June 2019 with positive HMPV and PIV polymerase chain reaction respiratory specimens was performed. RESULTS: Thirty-one HMPV- and 53 PIV-infected LTRs were identified. LTRs with HMPVi and PIVi had similar baseline characteristics, infection parameters, treatment allocation, and allograft function outcomes. Among entire cohort, 31.6% had chronic allograft dysfunction (CLAD) stage progression within 1 y postinfections (29.2% versus 35.5% for PIVi versus HMPVi, respectively, P = 0.56). In forced expiratory volume in 1 s percent (FEV1%) trajectory analysis showed steadily decline of FEV1 across time among CLAD stage progressors from both viruses. FEV1% decline ≥10% at 90 d had adjusted hazard ratio for CLAD stage progression of 18.4 (4.98-67.76) and 4.6 (1.36-15.34) for PIVi and HMPVi, respectively. PIVi caused higher donor-specific antigen development (11.8% versus 3.2%, P = 0.18) and 1-y mortality (9.4% versus 0%, P = 0.11), compared with HMPVi, even though the results were not statistically significant. Ribavirin did not show protective effect, and mycophenolate discontinuation during infection did not increase risk of CLAD stage progression. CONCLUSIONS: One-third of HMPV- and PIV-infected LTRs developed CLAD stage progression within 1 y. The lack of early lung function recovery may predict long-term CLAD progression.