Association of SNP-SNP interactions of surfactant protein genes with severity of respiratory syncytial virus infection in children.

The severity of respiratory syncytial virus (RSV) may be linked to host genetic susceptibility. Surfactant protein (SP) genetic variants have been associated with RSV severity, but the impact of single-nucleotide polymorphism (SNP)-SNP interactions remains unexplored. Therefore, we used a novel statistical model to investigate the association of SNP-SNP interactions of SFTP genes with RSV severity in two- and three-interaction models. We analyzed available genotype and clinical data from prospectively enrolled 405 children diagnosed with RSV, categorizing them into moderate or severe RSV groups. Using Wang's statistical model, we studied significant associations of SNP-SNP interactions with RSV severity in a case-control design. We observed, first, association of three interactions with increased risk of severe RSV in a two-SNP model. One intragenic interaction was between SNPs of SFTPA2, and the other two were intergenic, involving SNPs of hydrophilic and hydrophobic SPs alone. We also observed, second, association of 22 interactions with RSV severity in a three-SNP model. Among these, 20 were unique, with 12 and 10 interactions associated with increased or decreased risk of RSV severity, respectively, and included at least one SNP of either SFTPA1 or SFTPA2. All interactions were intergenic except one, among SNPs of SFTPA1. The remaining interactions were either among SNPs of hydrophilic SPs alone (n = 8) or among SNPs of both hydrophilic or hydrophobic SPs (n = 11). Our findings indicate that SNPs of all SFTPs may contribute to genetic susceptibility to RSV severity. However, the predominant involvement of SFTPA1 and/or SFTPA2 SNPs in these interactions underscores their significance in RSV severity.NEW & NOTEWORTHY Although surfactant protein (SP) genetic variants are associated with respiratory syncytial virus (RSV) severity, the impact of single-nucleotide polymorphism (SNP)-SNP interactions of SP genes remained unexplored. Using advanced statistical models, we uncovered 22 SNP-SNP interactions associated with RSV severity, with notable involvement of SFTPA1 and SFTPA2 SNPs. This highlights the comprehensive role of all SPs in genetic susceptibility to RSV severity, shedding light on potential avenues for targeted interventions.

Association of surfactant protein A2 with acute respiratory failure in children.

BACKGROUND: Interactions among single nucleotide polymorphisms (SNPs) of surfactant protein (SP) are associated with acute respiratory failure (ARF) and its short-term outcome, pulmonary dysfunction at discharge (PDAD) in children. However, genetic association studies using individual SNPs have not been conducted before. We hypothesize that SP genetic variants are associated with pediatric ARF and its short-term complications by themselves. METHODS: We used available genotype and clinical data in the Floros biobank consisting of 248 children aged ≤24 months with ARF; 86 developed PDAD. A logistic regression analysis was performed for each of the 14 selected SNPs, SP-A1 and SP-A2 genotypes. A p-value less than the Bonferroni correction threshold was considered significant. A likelihood ratio test was done to compare two models (one with demographic data and another with genetic variants). RESULTS: Before Bonferroni correction, female sex is associated with a decreased risk of ARF. Black race and the rs721917 of the SFTPD are associated with increased risk of ARF. After Bonferroni correction, the 1A0 1A1 genotype of SFTPA2 was associated with decreased risk of ARF. The likelihood ratio test showed that the model of the genotype information with demographic data was a better fit to predict ARF risk. None of the SP SNPs and SP-A1, SP-A2 genotypes were associated with PDAD. CONCLUSION: Our results indicate that SNPs and genotypes of SPs involved in innate immunity and host defense play an important role in ARF and, in the future, may be used as biomarkers.

Degradation of Lung Protective Angiotensin Converting Enzyme-2 by Meconium in Human Alveolar Epithelial Cells: A Potential Pathogenic Mechanism in Meconium Aspiration Syndrome.

BACKGROUND: Pancreatic digestive enzymes present in meconium might be responsible for meconium-induced lung injury. The local Renin Angiotensin System plays an important role in lung injury and inflammation. Particularly, angiotensin converting enzyme-2 (ACE-2) has been identified as a protective lung enzyme against the insult. ACE-2 converts pro-apoptotic Angiotensin II to anti-apoptotic Angiotensin 1-7. However, the effect of meconium on ACE-2 has never been studied before. OBJECTIVE: To study the effect of meconium on ACE-2, and whether inhibition of proteolytic enzymes present in the meconium reverses its effects on ACE-2. METHODS: Alveolar epithelial A549 cells were exposed to F-12 medium, 2.5% meconium, meconium + a protease inhibitor cocktail (PIc) and PIc alone for 16 h. At the end of incubation, apoptosis was measured with a nuclear fragmentation assay and cell lysates were collected for ACE-2 immunoblotting and enzyme activity. RESULTS: Meconium caused a fourfold increase in apoptotic nuclei (p < 0.001). The pro-apoptotic effect of meconium can be reversed by PIc. Meconium reduced ACE-2 enzyme activity by cleaving ACE-2 into a fragment detected at ~ 37 kDa by immunoblot. PIc prevented the degradation of ACE-2 and restored 50% of ACE-2 activity (p < 0.05). CONCLUSION: These data suggest that meconium causes degradation of lung protective ACE-2 by proteolytic enzymes present in meconium, since the effects of meconium can be reversed by PIc.

Prenatal Exposure to Air Pollution and Respiratory Distress in Term Newborns: Results from the MIREC Prospective Pregnancy Cohort.

BACKGROUND: Respiratory distress is the leading cause of neonatal morbidity and mortality worldwide, and prenatal exposure to air pollution is associated with adverse long-term respiratory outcomes; however, the impact of prenatal air pollution exposure on neonatal respiratory distress has not been well studied. OBJECTIVES: We examined associations between prenatal exposures to fine particular matter (PM2.5) and nitrogen dioxide (NO2) with respiratory distress and related neonatal outcomes. METHODS: We used data from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a prospective pregnancy cohort (n=2,001) recruited in the first trimester from 10 Canadian cities. Prenatal exposures to PM2.5 (n=1,321) and NO2 (n=1,064) were estimated using land-use regression and satellite-derived models coupled with ground-level monitoring and linked to participants based on residential location at birth. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) for associations between air pollution and physician-diagnosed respiratory distress in term neonates in hierarchical logistic regression models adjusting for detailed maternal and infant covariates. RESULTS: Approximately 7% of newborns experienced respiratory distress. Neonates received clinical interventions including oxygen therapy (6%), assisted ventilation (2%), and systemic antibiotics (3%). Two percent received multiple interventions and 4% were admitted to the neonatal intensive care unit (NICU). Median PM2.5 and NO2 concentrations during pregnancy were 8.81 µg/m3 and 18.02 ppb, respectively. Prenatal exposures to air pollution were not associated with physician-diagnosed respiratory distress, oxygen therapy, or NICU admissions. However, PM2.5 exposures were strongly associated with assisted ventilation (OR per 1-µg/m3 increase in PM2.5=1.17; 95% CI: 1.02, 1.35), multiple clinical interventions (OR per 1-µg/m3 increase in PM2.5=1.16; 95% CI: 1.07, 1.26), and systemic antibiotics, (OR per 1-µg/m3 increase in PM2.5=1.12; 95% CI: 1.04, 1.21). These associations were consistent across exposure periods-that is, during prepregnancy, individual trimesters, and total pregnancy-and robust to model specification. NO2 exposure was associated with administration of systemic antibiotics (OR per 1-ppb increase in NO2=1.03; 95% CI: 1.00, 1.06). DISCUSSION: Prenatal exposures to PM2.5 increased the risk of severe respiratory distress among term newborns. These findings support the development and prioritization of public health and prenatal care strategies to increase awareness and minimize prenatal exposures to air pollution. https://doi.org/10.1289/EHP12880.

SP-R210 isoforms of Myosin18A modulate endosomal sorting and recognition of influenza A virus infection in macrophages.

Influenza A virus (IAV) infection causes acute and often lethal inflammation in the lung. The role of macrophages in this adverse inflammation is partially understood. The surfactant protein A receptor 210 (SP-R210) consists of two isoforms, a long (L) SP-R210L and a short (S) SP-R210S isoform encoded by alternative splicing of the myosin 18A gene. We reported that disruption of SP-R210L enhances cytosolic and endosomal antiviral response pathways. Here, we report that SP-R210L antagonizes type I interferon ß (IFNß), as depletion of SP-R210L potentiates IFNß secretion. SP-R210 antibodies enhance and attenuate IFNß secretion in SP-R210L replete and deficient macrophages, respectively, indicating that SP-R210 isoform stoichiometry alters macrophage function intrinsically. This reciprocal response is coupled to unopposed and restricted expression of viral genes in control and SP-R210L-deficient macrophages, respectively. Human monocytic cells with sub-stoichiometric expression of SP-R210L resist IAV infection, whereas alveolar macrophages with increased abundance of SP-R210L permit viral gene expression similar to murine macrophages. Uptake and membrane binding studies show that lack of SP-R210 isoforms does not impair IAV binding and internalization. Lack of SP-R210L, however, results in macropinocytic retention of the virus that depends on both SP-R210S and interferon-inducible transmembrane protein-3 (IFITM3). Mass spectrometry and Western blot analyses indicate that SP-R210 isoforms modulate differential recruitment of the Rho-family GTPase RAC1 and guanine nucleotide exchange factors. Our study suggests that SP-R210 isoforms modulate RAC-dependent macropinosomal sorting of IAV to discrete endosomal and lysosomal compartments that either permit or prevent endolysosomal escape and inflammatory sensing of viral genomes in macrophages.

Proposed Screening for Congenital Hyperinsulinism in Newborns: Perspective from a Neonatal-Perinatal Medicine Group.

This perspective work by academic neonatal providers is written specifically for the audience of newborn care providers and neonatologists involved in neonatal hypoglycemia screening. Herein, we propose adding a screen for congenital hyperinsulinism (CHI) by measuring glucose and ketone (i.e., ß-hydroxybutyrate (BOHB)) concentrations just prior to newborn hospital discharge and as close to 48 h after birth as possible, at the same time that the mandated state Newborn Dried Blood Spot Screen is obtained. In the proposed protocol, we do not recommend specific metabolite cutoffs, as our primary objective is to simply highlight the concept of screening for CHI in newborns to newborn caregivers. The premise for our proposed screen is based on the known effect of hyperinsulinism in suppressing ketogenesis, thereby limiting ketone production. We will briefly discuss genetic CHI, other forms of neonatal hypoglycemia, and their shared mechanisms; the mechanism of insulin regulation by functional pancreatic islet cell membrane KATP channels; adverse neurodevelopmental sequelae and brain injury due to missing or delaying the CHI diagnosis; the principles of a good screening test; how current neonatal hypoglycemia screening programs do not fulfill the criteria for being effective screening tests; and our proposed algorithm for screening for CHI in newborns.

Surfactant protein A alters endosomal trafficking of influenza A virus in macrophages.

Influenza A virus infection (IAV) often leads to acute lung injury that impairs breathing and can lead to death, with disproportionate mortality in children and the elderly. Surfactant Protein A (SP-A) is a calcium-dependent opsonin that binds a variety of pathogens to help control pulmonary infections by alveolar macrophages. Alveolar macrophages play critical roles in host resistance and susceptibility to IAV infection. The effect of SP-A on IAV infection and antiviral response of macrophages, however, is not understood. Here, we report that SP-A attenuates IAV infection in a dose-dependent manner at the level of endosomal trafficking, resulting in infection delay in a model macrophage cell line. The ability of SP-A to suppress infection was independent of its glycosylation status. Binding of SP-A to hemagglutinin did not rely on the glycosylation status or sugar binding properties of either protein. Incubation of either macrophages or IAV with SP-A slowed endocytic uptake rate of IAV. SP-A interfered with binding to cell membrane and endosomal exit of the viral genome as indicated by experiments using isolated cell membranes, an antibody recognizing a pH-sensitive conformational epitope on hemagglutinin, and microscopy. Lack of SP-A in mice enhanced IFNß expression, viral clearance and reduced mortality from IAV infection. These findings support the idea that IAV is an opportunistic pathogen that co-opts SP-A to evade host defense by alveolar macrophages. Our study highlights novel aspects of host-pathogen interactions that may lead to better understanding of the local mechanisms that shape activation of antiviral and inflammatory responses to viral infection in the lung.

Corrigendum: Single nucleotide polymorphisms interactions of the surfactant protein genes associated with respiratory distress syndrome susceptibility in preterm infants.

[This corrects the article DOI: 10.3389/fped.2021.682160.].

Single Nucleotide Polymorphisms (SNP) and SNP-SNP Interactions of the Surfactant Protein Genes Are Associated With Idiopathic Pulmonary Fibrosis in a Mexican Study Group; Comparison With Hypersensitivity Pneumonitis.

Surfactant proteins (SPs) are important for normal lung function and innate immunity of the lungs and their genes have been identified with significant genetic variability. Changes in quantity or quality of SPs due to genetic mutations or natural genetic variability may alter their functions and contribute to the host susceptibility for particular diseases. Alternatively, SP single nucleotide polymorphisms (SNPs) can serve as markers to identify disease risk or response to therapies, as shown for other genes in a number of other studies. In the current study, we evaluated associations of SFTP SNPs with idiopathic pulmonary fibrosis (IPF) by studying novel computational models where the epistatic effects (dominant, additive, recessive) of SNP-SNP interactions could be evaluated, and then compared the results with a previously published hypersensitivity pneumonitis (HP) study where the same novel models were used. Mexican Hispanic patients (IPF=84 & HP=75) and 194 healthy control individuals were evaluated. The goal was to identify SP SNPs and SNP-SNP interactions that associate with IPF as well as SNPs and interactions that may be unique to each of these interstitial diseases or common between them. We observed: 1) in terms of IPF, i) three single SFTPA1 SNPs to associate with decreased IPF risk, ii) three SFTPA1 haplotypes to associate with increased IPF risk, and iii) a number of three-SNP interactions to associate with IPF susceptibility. 2) Comparison of IPF and HP, i) three SFTPA1 and one SFTPB SNP associated with decreased risk in IPF but increased risk in HP, and one SFTPA1 SNP associated with decreased risk in both IPF and HP, ii) a number of three-SNP interactions with the same or different effect pattern associated with IPF and/or HP susceptibility, iii) one of the three-SNP interactions that involved SNPs of SFTPA1, SFTPA2, and SFTPD, with the same effect pattern, was associated with a disease-specific outcome, a decreased and increased risk in HP and IPF, respectively. This is the first study that compares the SP gene variants in these two phenotypically similar diseases. Our findings indicate that SNPs of all SFTPs may play an important role in the genetic susceptibility to IPF and HP. Importantly, IPF and HP share some SP genetic variants, suggesting common pathophysiological mechanisms and pathways regarding surfactant biogenesis, but also some differences, highlighting the diverse underlying pathogenic mechanisms between an inflammatory-driven fibrosis (HP) and an epithelial-driven fibrosis (IPF). Alternatively, the significant SNPs identified here, along with SNPs of other genes, could serve as markers to distinguish these two devastating diseases.

Covid-19 vaccine acceptance and associated factors among pregnant women in Pennsylvania 2020.

Data on factors associated with vaccine acceptance among pregnant women are critical to the rapid scale up of interventions to improve vaccine uptake. When COVID-19 vaccines were still in the testing phases of research, we surveyed pregnant women accessing prenatal care at an academic medical institution in Central Pennsylvania, United States to examine factors associated with vaccine acceptance. Willingness to receive a COVID-19 vaccine once a vaccine became available was asked as part of an ongoing study on the COVID-19 pandemic and pregnancy (n = 196). Overall, 65% of women reported they would be willing or somewhat willing to receive the COVID-19 vaccine. Women who had received an influenza vaccine within the past year were more likely to be willing to receive the COVID-19 vaccine than women who had never received an influenza vaccine or those who received it over one year ago (aOR 4.82; 95% CI 2.17, 10.72). Similarly, women who were employed full-time were more willing to receive the COVID-19 vaccine than women who were not employed full time (aOR 2.22; 95% CI 1.02, 4.81), and women who reported feeling overloaded were more willing to receive the COVID-19 vaccine than women who did not feel overloaded (aOR 2.18; 95% CI 1.02, 4.68). Our findings support the need to increase vaccination education among pregnant women before vaccines are rolled out, especially those who have not received an influenza vaccine within the past year. Improved understanding of willingness to vaccinate among pregnant women will improve future pandemic responses and current vaccination efforts.

SNP-SNP Interactions of Surfactant Protein Genes in Persistent Respiratory Morbidity Susceptibility in Previously Healthy Children.

We studied associations of persistent respiratory morbidity (PRM) at 6 and 12 months after acute respiratory failure (ARF) in previously healthy children with single-nucleotide polymorphisms (SNPs) of surfactant protein (SP) genes. Of the 250 enrolled subjects, 155 and 127 were followed at 6 and 12 months after an ARF episode, respectively. Logistic regression analysis and SNP-SNP interaction models were used. We found that 1) in the multivariate analysis, an increased risk at 6 and 12 months was associated with rs1124_A and rs4715_A of SFTPC, respectively; 2) in a single SNP model, increased and decreased risks of PRM at both timepoints were associated with rs1124 of SFTPC and rs721917 of SFTPD, respectively; an increased risk at 6 months was associated with rs1130866 of SFTPB and rs4715 of SFTPC, and increased and decreased risks at 12 months were associated with rs17886395 of SFTPA2 and rs2243639 of SFTPD, respectively; 3) in a two-SNP model, PRM susceptibility at both timepoints was associated with a number of intergenic interactions between SNPs of the studied SP genes. An increased risk at 12 months was associated with one intragenic (rs1965708 and rs113645 of SFTPA2) interaction; 4) in a three-SNP model, decreased and increased risks at 6 and 12 months, respectively, were associated with an interaction among rs1130866 of SFTPB, rs721917 of SFTPD, and rs1059046 of SFTPA2. A decreased risk at 6 months was associated with an interaction among the same SNPs of SFTPB and SFTPD and the rs1136450 of SFTPA1. The findings revealed that SNPs of all SFTPs appear to play a role in long-term outcomes of ARF survivors and may serve as markers for disease susceptibility.

Hydrophilic But Not Hydrophobic Surfactant Protein Genetic Variants Are Associated With Severe Acute Respiratory Syncytial Virus Infection in Children.

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infection-related hospitalization in the first year of life. Surfactant dysfunction is central to pathophysiologic mechanisms of various pulmonary diseases including RSV. We hypothesized that RSV severity is associated with single nucleotide polymorphisms (SNPs) of surfactant proteins (SPs). We prospectively enrolled 405 RSV-positive children and divided them into moderate and severe RSV disease. DNA was extracted and genotyped for sixteen specific SP gene SNPs. SP-A1 and A2 haplotypes were assigned. The association of RSV severity with SP gene SNPs was investigated by multivariate logistic regression. A likelihood ratio test was used to test the goodness of fit between two models (one with clinical and demographic data alone and another that included genetic variants). p ≤ 0.05 denotes statistical significance. A molecular dynamics simulation was done to determine the impact of the SFTPA2 rs1965708 on the SP-A behavior under various conditions. Infants with severe disease were more likely to be younger, of lower weight, and exposed to household pets and smoking, as well as having co-infection on admission. A decreased risk of severe RSV was associated with the rs17886395_C of the SFTPA2 and rs2243639_A of the SFTPD, whereas an increased risk was associated with the rs1059047_C of the SFTPA1. RSV severity was not associated with SNPs of SFTPB and SFTPC. An increased risk of severe RSV was associated with the 1A0 genotype of SFTPA2 in its homozygous or heterozygous form with 1A3. A molecular dynamic simulation study of SP-A variants that differ in amino acid 223, an important amino acid change (Q223K) between 1A0 and 1A3, showed no major impact on the behavior of these two variants except for higher thermodynamic stability of the K223 variant. The likelihood ratio test showed that the model with multi-allelic variants along with clinical and demographic data was a better fit to predict RSV severity. In summary, RSV severity was associated with hydrophilic (but not with hydrophobic) SPs gene variants. Collectively, our findings show that SP gene variants may play a key role in RSV infection and have a potential role in prognostication.

Single Nucleotide Polymorphisms Interactions of the Surfactant Protein Genes Associated With Respiratory Distress Syndrome Susceptibility in Preterm Infants.

Background: Neonatal respiratory distress syndrome (RDS), due to surfactant deficiency in preterm infants, is the most common cause of respiratory morbidity. The surfactant proteins (SFTP) genetic variants have been well-studied in association with RDS; however, the impact of SNP-SNP (single nucleotide polymorphism) interactions on RDS has not been addressed. Therefore, this study utilizes a newer statistical model to determine the association of SFTP single SNP model and SNP-SNP interactions in a two and a three SNP interaction model with RDS susceptibility. Methods: This study used available genotype and clinical data in the Floros biobank at Penn State University. The patients consisted of 848 preterm infants, born <36 weeks of gestation, with 477 infants with RDS and 458 infants without RDS. Seventeen well-studied SFTPA1, SFTPA2, SFTPB, SFTPC, and SFTPD SNPs were investigated. Wang's statistical model was employed to test and identify significant associations in a case-control study. Results: Only the rs17886395 (C allele) of the SFTPA2 was associated with protection for RDS in a single-SNP model (Odd's Ratio 0.16, 95% CI 0.06-0.43, adjusted p = 0.03). The highest number of interactions (n = 27) in the three SNP interactions were among SFTPA1 and SFTPA2. The three SNP models showed intergenic and intragenic interactions among all SFTP SNPs except SFTPC. Conclusion: The single SNP model and SNP interactions using the two and three SNP interactions models identified SFTP-SNP associations with RDS. However, the large number of significant associations containing SFTPA1 and/or SFTPA2 SNPs point to the importance of SFTPA1 and SFTPA2 in RDS susceptibility.

Trends in Costs of Birth Hospitalization and Readmissions for Late Preterm Infants.

Background: The objective is to study previously unexplored trends of birth hospitalization and readmission costs for late preterm infants (LPIs) in the United States between 2005 and 2016. Methods: We conducted a retrospective analysis of claims data to study healthcare costs of birth hospitalization and readmissions for LPIs compared to term infants (TIs) using a large private insurance database. We used a generalized linear regression model to study birth hospitalization and readmission costs. Results: A total of 2,123,143 infants were examined (93.2% TIs; 6.8% LPIs). The proportion of LPIs requiring readmission was 4.2% compared to 2.1% of TIs, (p < 0.001). The readmission rate for TIs decreased during the study period. LPIs had a higher mean cost of birth hospitalization (25,700 vs. 3300 USD; p < 0.001) and readmissions (25,800 vs. 14,300 USD; p < 0.001). For LPIs, birth hospitalization costs increased from 2007 to 2013, and decreased since 2014. Conversely, birth hospitalization costs of TIs steadily increased since 2005. The West region showed higher birth hospitalization costs for LPIs. Conclusions: LPIs continue to have a higher cost of birth hospitalization and readmission compared to TIs, but these costs have decreased since 2014. Standardization of birth hospitalization care for LPIs may reduce costs and improve quality of care and outcomes.

Trend of influenza vaccine Facebook posts in last 4 years: a content analysis.

BACKGROUND: Decreasing immunization rates may be partly due to antivaccine campaigns and other sources of misinformation available on social media, particularly on Facebook. Given the potential impact of this medium for communicating vaccine-related information, it is important to analyze the trend of information available on Facebook. METHODS: We searched Facebook on August 15, 2018 to obtain posts containing relevant health information on influenza vaccine in years 2015-2018. We collected information regarding nature of the post (eg, pro-, antivaccine, and informational), number of shares and likes received, and ease of reading for each post. We evaluated these characteristics by year and type of post in our exploratory analyses. RESULTS: The proportion of pro-vaccine posts has increased compared to antivaccine and informational posts since 2016. There was no correlation between ease of reading and popularity of posts. Although the language of antivaccine posts was complex, they were shared and liked more than pro-vaccine posts. The pro-vaccine personal post by a nurse was the most popular in our study (shared over 46,000 times) in 2018. CONCLUSIONS: Though the number of pro-vaccine posts increased, antivaccine posts remained more popular. The government agency may use an emotive personal family-oriented message to promote vaccination.

Sex-Specific Regulation of Gene Expression Networks by Surfactant Protein A (SP-A) Variants in Alveolar Macrophages in Response to Klebsiella pneumoniae.

Surfactant protein A (SP-A) in addition to its surfactant-related functions interacts with alveolar macrophages (AM), the guardian cells of innate immunity in the lungs, and regulates many of its functions under basal condition and in response to various pressures, such as infection and oxidative stress. The human SP-A locus consists of two functional genes, SFTPA1 and SFTPA2, and one pseudogene. The functional genes encode human SP-A1 and SP-A2 proteins, respectively, and each has been identified with several genetic variants. SP-A variants differ in their ability to regulate lung function mechanics and survival in response to bacterial infection. Here, we investigated the effect of hSP-A variants on the AM gene expression profile in response to Klebsiella pneumoniae infection. We used four humanized transgenic (hTG) mice that each carried SP-A1 (6A2, 6A4) or SP-A2 (1A0, 1A3), and KO. AM gene expression profiling was performed after 6 h post-infection. We found: (a) significant sex differences in the expression of AM genes; (b) in response to infection, 858 (KO), 196 (6A2), 494 (6A4), 276 (1A0), and 397 (1A3) genes were identified (P < 0.05) and some of these were differentially expressed with ≥2 fold, specific to either males or females; (c) significant SP-A1 and SP-A2 variant-specific differences in AM gene expression; (d) via Ingenuity Pathway Analysis (IPA), key pathways and molecules were identified that had direct interaction with TP53, TNF, and cell cycle signaling nodes; (e) of the three pathways (TNF, TP-53, and cell cycle signaling nodes) studied here, all variants except SP-A2 (1A3) female, showed significance for at least 2 of these pathways, and KO male showed significance for all three pathways; (f) validation of key molecules exhibited variant-specific significant differences in the expression between sexes and a similarity in gene expression profile was observed between KO and SP-A1. These results reveal for the first time a large number of biologically relevant functional pathways influenced in a sex-specific manner by SP-A variants in response to infection. These data may assist in studying molecular mechanisms of SP-A-mediated AM gene regulation and potentially identify novel therapeutic targets for K. pneumoniae infection.

Sex and SP-A2 Dependent NAD(H) Redox Alterations in Mouse Alveolar Macrophages in Response to Ozone Exposure: Potential Implications for COVID-19.

Co-enzyme nicotinamide adenine dinucleotide (NAD(H)) redox plays a key role in macrophage function. Surfactant protein (SP-) A modulates the functions of alveolar macrophages (AM) and ozone (O3) exposure in the presence or absence of SP-A and reduces mouse survival in a sex-dependent manner. It is unclear whether and how NAD(H) redox status plays a role in the innate immune response in a sex-dependent manner. We investigated the NAD(H) redox status of AM from SP-A2 and SP-A knockout (KO) mice in response to O3 or filtered air (control) exposure using optical redox imaging technique. We found: (i) In SP-A2 mice, the redox alteration of AM in response to O3 showed sex-dependence with AM from males being significantly more oxidized and having a higher level of mitochondrial reactive oxygen species than females; (ii) AM from KO mice were more oxidized after O3 exposure and showed no sex differences; (iii) AM from female KO mice were more oxidized than female SP-A2 mice; and (iv) Two distinct subpopulations characterized by size and redox status were observed in a mouse AM sample. In conclusions, the NAD(H) redox balance in AM responds to O3 in a sex-dependent manner and the innate immune molecule, SP-A2, contributes to this observed sex-specific redox response.

Impact of Ozone, Sex, and Gonadal Hormones on Bronchoalveolar Lavage Characteristics and Survival in SP-A KO Mice Infected with Klebsiella pneumoniae.

Surfactant protein A (SP-A) plays an important role in innate immunity. The sex-dependent survival of infected SP-A knockout (KO) mice has been observed. Our goal was to study the impact of ozone (O3) and sex, as well as gonadal hormones, on the bronchoalveolar lavage (BAL) readouts and survival, respectively, of Klebsiella pneumoniae-infected SP-A KO mice. Male and female SP-A KO mice were exposed to O3 or filtered air and infected with K. pneumoniae. We studied markers of inflammation and tissue damage at 4, 24, and 48 h, as well as the survival over 14 days, of gonadectomized (Gx) mice implanted with control pellets (CoP) or hormone (5α-dihydrotestosterone (DHT) in female gonadectomized mice (GxF) or 17ß-estradiol (E2) in male gonadectomized mice (GxM)). We observed: (1) an increase in neutrophil and macrophage inflammatory protein-2 levels as time progressed post-infection, and O3 exposure appeared to increase this response; (2) an increase in lactate dehydrogenase, total protein, oxidized protein, and phospholipids in response to O3 with no consistent sex differences in studied parameters; and (3) a reduction in survival of the GxM and CoP mice, the GxM and E2 mice, and the GxF and DHT mice but not for the GxF and CoP mice after O3. Without SP-A, (a) sex was found to have a minimal impact on BAL cellular composition and tissue damage markers, and (b) the impact of gonadal hormones on survival was found to involve different mechanisms than in the presence of SP-A.

SNP and Haplotype Interaction Models Reveal Association of Surfactant Protein Gene Polymorphisms With Hypersensitivity Pneumonitis of Mexican Population.

Background: Hypersensitivity pneumonitis (HP) is an interstitial lung disease caused by inhalation of common environmental organic particles. Surfactant proteins (SPs) play a role in innate immunity and surfactant function. We hypothesized that single nucleotide polymorphisms (SNPs) or haplotypes of the SP genes associate with HP. Methods: Seventy-five HP patients caused by avian antigen and 258 controls, asymptomatic antigen exposed and non-exposed were enrolled. SNP association was performed using logistic regression analysis and SNP-SNP interaction models. Results: Based on odds ratio, regression analyses showed association of (a) rs7316_G, 1A3 (protective) compared to antigen exposed; (b) male sex, smoking, rs721917_T and rs1130866_T (protective) compared to non-exposed controls with HP; (c) compared to antigen exposed, 25 interactions associated with HP in a three-SNP model; (d) compared to non-exposed, (i) rs1136451 associated with increased, whereas rs1136450 and rs1130866 associated with lower HP risk, (ii) 97 interactions associated with HP in a three-SNP model. The majority of SNP-SNP interactions associated with increased HP risk involved SNPs of the hydrophilic SPs, whereas, the majority of interactions associated with lower HP risk involved SNPs of both hydrophilic and hydrophobic SPs; (e) haplotypes of SP genes associated with HP risk. Conclusions: The complexity of SNPs interactions of the SFTP genes observed indicate that the lung inflammatory response to avian antigens is modulated by a complex gene interplay rather than by single SNPs.

Association of SNP-SNP Interactions of Surfactant Protein Genes with Pediatric Acute Respiratory Failure.

The hallmarks of pediatric acute respiratory failure (ARF) are dysregulated inflammation and surfactant dysfunction. The objective is to study association of surfactant protein (SP) genes' single nucleotide polymorphisms (SNPs) with ARF and its morbidity: pulmonary dysfunction at discharge (PDAD), employing a single-, two-, and three-SNP interaction model. We enrolled 468 newborn controls and 248 children aged ≤ 24 months with ARF; 86 developed PDAD. Using quantitative genetic principles, we tested the association of SP genes SNPs with ARF and PDAD. We observed a dominant effect of rs4715 of the SFTPC on ARF risk. In a three-SNP model, we found (a) 34 significant interactions among SNPs of SFTPA1, SFTPA2, and SFTPC associated with ARF (p = 0.000000002-0.05); 15 and 19 of those interactions were associated with increased and decreased risk for ARF, respectively; (b) intergenic SNP-SNP interactions of both hydrophobic and hydrophilic SP genes associated with PDAD (p = 0.00002-0.03). The majority of intra- and intergenic interactions associated with ARF involve the SFTPA2 SNPs, whereas most of the intra- and intergenic interactions associated with PDAD are of SFTPA1 SNPs. We also observed a dominant effect of haplotypes GG of SFTPA1 associated with increased and AA of SFTPC associated with decreased ARF risk (p = 0.02). To the best of our knowledge, this is the first study showing an association of complex interactions of SP genes with ARF and PDAD. Our data indicate that SP genes polymorphisms may contribute to ARF pathogenesis and subsequent PDAD and/or may serve as markers for disease susceptibility in healthy children.