Surfactant protein-A (SP-A)is a novel marker of lung disorders in patients discharged after COVID-19 pneumonia

The aim: was to estimate role of SP-A in patients (pts) discharged after COVID-19 pneumonia. Material(s) and Method(s): main group was 75 pts (36 (48,0%) men, age - 54,2 (49,3;57,1)) on 46,5 (42,4;53,1) days after the onset of COVID-19. Pts were divided into 3 subgroups: 1 - 27 pts after moderate COVID-19 pneumonia, 2 - 30 pts after severe COVID-19 pneumonia, 3 - 18 pts after critical COVID-19 pneumonia. All pts before COVID-19 had no history of previous lung disease. Control group - 15 healthy persons. Measurements: dyspnea by mMRC, SpO2, SP-A in serum. Result(s): After 1,5 months the onset of COVID-19 74 pts (98,7%) had dyspnea, but level of SpO2 Me 97,5 (96,3;98,8)% was normal. Level of SP-A didn't differ between subgr. 1 and control gr. (p>0,05). But level of SP-A was significantly higher in pts of subgr. 2 and subgr. 3 in comparison with control gr. and subgr. 1 (p<0,01) (Fig.1). At the same time, it was strong direct correlation between the level of SP-A and severity of dyspnea by mMRC (Fig.2). Conclusion(s): 1) the level of SP-A is an independent predictor of lung lesion in early post-COVID-19 period in pts after severe and critical COVID-19 pneumonia;2) damage of the surfactant system of the lungs can be the reason of dyspnea in the early period after COVID-19;2) determination of SP-A is important element to customize the most appropriate therapeutic strategies for pts after severe and critical COVID-19.

IDENTIFYING A NOVEL SURFACTANT PROTEIN MUTATION IN A FAMILY WITH PULMONARY FIBROSIS

SESSION TITLE: Rare Genetic Mutations and Anatomical Variants SESSION TYPE: Rapid Fire Case Reports PRESENTED ON: 10/18/2022 12:25 pm - 01:25 pm INTRODUCTION: Idiopathic pulmonary fibrosis (IPF) is a fatal disease affecting older adults that results in progressive scarring of the lung parenchyma. Familial IPF (FPF), defined by disease in two or more first-degree relatives, is estimated to occur in 2–20% of all IPF cases and can present with varying phenotypes which may be difficult to diagnose. Inherited gene variation as well as environmental factors predispose a patient to disease development. Additionally, rare genetic variants in the genes encoding surfactant A (SFTPA1, and SFTPA2) that affect alveolar stability and endoplasmic reticulum stress have been reported in less than 1% of FPF cases. Understanding these genetic variants is essential in the diagnosis and management of patients with FPF. CASE PRESENTATION: A 47-year-old Hispanic male with a history of COVID-19 one year ago (not requiring hospitalization) presented to the hospital for a two-day history of subjective fever and shortness of breath. He was hypoxic requiring oxygen via high flow nasal cannula. He was admitted four months ago for shortness of breath and treated for pneumonia. Since then, he has had chronic dyspnea with exertion. Computed tomography of the chest showed extensive ground glass opacities, worse in the right lung, with basilar and upper lobe honeycombing, and air bronchograms in the bilateral lower lobes. Family history was significant for a mother, maternal aunt, maternal grandfather, and maternal cousin who all died from pulmonary fibrosis. His maternal cousin was treated at our facility, in which genetic sequencing revealed a mutation in SFTPA2, c.697T>C. Our patient was found to have the same genetic mutation. DISCUSSION: The genetic basis of IPF remains poorly understood. Prior studies suggest only 20-30% of FPF cases harbor an identifiable causative genetic variant. Rare variants in two biologic pathways contribute to the known heritability of FPF including pathologic variants in surfactant related genes which cause improper protein trafficking leading to endoplasmic reticulum stress, defects in autophagy, and type II alveolar cell toxicity. SFTPA1 and SFTPA2 variants have been associated with FPF and lung adenocarcinoma in a small number of families and there are few reported cases. While currently the SFTPA2, c.697T>C mutation, previously reported by our group in 2016, is considered a variant of unknown significance, its occurrence in two relatives with serious progressive interstitial lung diseases suggests that it is indeed pathogenic. CONCLUSIONS: Gene sequencing should be considered for all patients with a family history of pulmonary fibrosis as identification of a rare genetic variant may offer guidance to diagnosis, prognostication, and risk stratification when considering lung transplantation as well as identify additional relatives who may be affected by IPF. Reference #1: Kropski JA, Young LR, Cogan JD, et al. Genetic Evaluation and Testing of Patients and Families with Idiopathic Pulmonary Fibrosis. Am J Respir Crit Care Med. 2017;195(11):1423-1428. doi:10.1164/rccm.201609-1820PP Reference #2: Wang Y, Kuan PJ, Xing C, Cronkhite JT, Torres F, Rosenblatt RL, DiMaio JM, Kinch LN, Grishin NV, Garcia CK. Genetic defects in surfactant protein A2 are associated with pulmonary fibrosis and lung cancer. Am J Hum Genet. 2009 Jan;84(1):52-9. doi: 10.1016/j.ajhg.2008.11.010. Epub 2008 Dec 18. PMID: 19100526;PMCID: PMC2668050. Reference #3: Pulmonary Fibrosis Due to a Novel Surfactant Protein Mutation R.A. Arciniegas Flores, I.A. Vital, K. Medepalli, D. DeMarzo, M.K. Glassberg Csete, R.A. Alvarez. https://doi.org/10.1164/ajrccm-conference.2019.199.1_Meetings.A5437 DISCLOSURES: No relevant relationships by Roger Alvarez No relevant relationships by Eduardo Lopez Gonzalez No relevant relationships by Anita Singh

The role of surfactant proteins SP-A and SP-D in viral infection: a focus on COVID-19

An immune response to invasion of viral pathogens is an integral part of maintaining the physiological functioning of the bronchopulmonary system and effective gas exchange. Collagen-containing C-type lectins (lung collectins) are some of the key proteins in the identification of viral particles. They have image-recognizing receptors that identify pathogen-associated molecular patterns, particularly viral glycoproteins. The surfactant proteins SP-A and SP-D, which are composed of trimerized units, belong to pulmonary collectins and oligomerize into higher-order structures. These proteins play an essential role in recognition and elimination of microbial pathogens (viruses, bacteria, fungi, parasites, nanoparticles, allergens) through a variety of mechanisms. Taking into account the burden of the novel coronavirus infection caused by the SARS-CoV-2 virus, it is important to consider the role of the surfactant proteins SP-A and SP-D in the pathogenesis of the immune response to viral invasion. Currently, there are data on the direct relationship between surfactant proteins and viruses belonging to the Coronaviridae family. The SP-A and SP-D proteins modulate inflammatory responses and cytokine synthesis, but prevent an excessive inflammatory response (cytokine storm). There is also an assumption that SARSCoV-2 directly suppresses and alters the production of surfactant proteins. Thus, the key pathogenetic role of the surfactant proteins SP-A and SP-D in the response to the viral pathogen SARS-CoV-2 is evident. Today, this is a promising area of translational medicine, which will contribute to a profound understanding of the pathogenesis of coronavirus infection for assessing the diagnostic and prognostic potentials of the surfactant proteins SP-A and SP-D in COVID-19. Additionally, it will help evaluate the therapeutic potential of recombinant fragments of human SP-A and SP-D. © 2022 Siberian State Medical University. All rights reserved.

Elucidating the enhanced binding affinity of a double mutant SP-D with trimannose on the influenza A virus using molecular dynamics.

Surfactant protein D (SP-D) is an essential component of the human pulmonary surfactant system, which is crucial in the innate immune response against glycan-containing pathogens, including Influenza A viruses (IAV) and SARS-CoV-2. Previous studies have shown that wild-type (WT) SP-D can bind IAV but exhibits poor antiviral activities. However, a double mutant (DM) SP-D consisting of two point mutations (Asp325Ala and Arg343Val) inhibits IAV more potently. Presently, the structural mechanisms behind the point mutations' effects on SP-D's binding affinity with viral surface glycans are not fully understood. Here we use microsecond-scale, full-atomistic molecular dynamics (MD) simulations to understand the molecular mechanism of mutation-induced SP-D's higher antiviral activity. We find that the Asp325Ala mutation promotes a trimannose conformational change to a more stable state. Arg343Val increases the binding with trimannose by increasing the hydrogen bonding interaction with Glu333. Free energy perturbation (FEP) binding free energy calculations indicate that the Arg343Val mutation contributes more to the increase of SP-D's binding affinity with trimannose than Asp325Ala. This study provides a molecular-level exploration of how the two mutations increase SP-D binding affinity with trimannose, which is vital for further developing preventative strategies for related diseases.

Can Prophylactic High Flow of Humidified and Warmed Filtered Air Improve Survival from Bacterial Pneumonia and SARS-CoV-2 in Elderly Individuals? The Role of Surfactant Protein A.

In this opinion article, we discuss a serendipitous observation we made in a study investigating survival in aged mice after bacterial infection. This observation involved a non-invasive ventilation approach that led to variable and higher survival in male and female mice with different genetic backgrounds for the innate immune molecule, surfactant protein A (SP-A). We suggest that employing the best ventilatory modality, whether that be HFNC or another method, may augment the role of other factors such as SP-A genetics and sex in a personalized approach, and may ultimately improve the outcome.

SP-A and SP-D: Dual Functioning Immune Molecules With Antiviral and Immunomodulatory Properties.

Surfactant proteins A (SP-A) and D (SP-D) are soluble innate immune molecules which maintain lung homeostasis through their dual roles as anti-infectious and immunomodulatory agents. SP-A and SP-D bind numerous viruses including influenza A virus, respiratory syncytial virus (RSV) and human immunodeficiency virus (HIV), enhancing their clearance from mucosal points of entry and modulating the inflammatory response. They also have diverse roles in mediating innate and adaptive cell functions and in clearing apoptotic cells, allergens and other noxious particles. Here, we review how the properties of these first line defense molecules modulate inflammatory responses, as well as host-mediated immunopathology in response to viral infections. Since SP-A and SP-D are known to offer protection from viral and other infections, if their levels are decreased in some disease states as they are in severe asthma and chronic obstructive pulmonary disease (COPD), this may confer an increased risk of viral infection and exacerbations of disease. Recombinant molecules of SP-A and SP-D could be useful in both blocking respiratory viral infection while also modulating the immune system to prevent excessive inflammatory responses seen in, for example, RSV or coronavirus disease 2019 (COVID-19). Recombinant SP-A and SP-D could have therapeutic potential in neutralizing both current and future strains of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus as well as modulating the inflammation-mediated pathology associated with COVID-19. A recombinant fragment of human (rfh)SP-D has recently been shown to neutralize SARS-CoV-2. Further work investigating the potential therapeutic role of SP-A and SP-D in COVID-19 and other infectious and inflammatory diseases is indicated.

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.

The Importance of Redox Status in the Frame of Lifestyle Approaches and the Genetics of the Lung Innate Immune Molecules, SP-A1 and SP-A2, on Differential Outcomes of COVID-19 Infection.

The pandemic of COVID-19 is of great concern to the scientific community. This mainly affects the elderly and people with underlying diseases. People with obesity are more likely to experience unpleasant disease symptoms and increased mortality. The severe oxidative environment that occurs in obesity due to chronic inflammation permits viral activation of further inflammation leading to severe lung disease. Lifestyle affects the levels of inflammation and oxidative stress. It has been shown that a careful diet rich in antioxidants, regular exercise, and fasting regimens, each and/or together, can reduce the levels of inflammation and oxidative stress and strengthen the immune system as they lead to weight loss and activate cellular antioxidant mechanisms and reduce oxidative damage. Thus, a lifestyle change based on the three pillars: antioxidants, exercise, and fasting could act as a proactive preventative measure against the adverse effects of COVID-19 by maintaining redox balance and well-functioning immunity. Moreover, because of the observed diversity in the expression of COVID-19 inflammation, the role of genetics of innate immune molecules, surfactant protein A (SP-A)1 and SP-A2, and their differential impact on the local lung microenvironment and host defense is reviewed as genetics may play a major role in the diverse expression of the disease.