SFTA3, a novel protein of the lung: three-dimensional structure, characterisation and immune activation

Abstract

The lung constantly interacts with numerous pathogens. Thus, complex local immune defence mechanisms are essential to recognise and dispose of these intruders. This work describes the detection, characterisation and three-dimensional structure of a novel protein of the lung (surfactantassociated protein 3 (SFTA3/SP-H)) with putative immunological features.Bioinformatics, biochemical and immunological methods were combined to elucidate the structure and function of SFTA3. The tissue-specific detection and characterisation was performed by using electron microscopy as well as fluorescence imaging.Three-dimensional structure generation and analysis led to the development of specific antibodies and, as a consequence, to the localisation of a novel protein in human lung under consideration of cystic fibrosis, asthma and sepsis. In vitro experiments revealed that lipopolysaccharide induces expression of SFTA3 in the human lung alveolar type II cell line A549. By contrast, the inflammatory cytokines interleukin (IL)-1b and IL-23 inhibit expression of SFTA3 in A549. Sequence-and structure-based prediction analysis indicated that the novel protein is likely to belong to the family of lung surfactant proteins.The results suggest that SFTA3 is an immunoregulatory protein of the lung with relevant protective functions during inflammation at the mucosal sites. @ERSpublications SFTA3: a novel lung protein with putative protective and immunological functions during inflammation in lung diseases

The distribution of human surfactant proteins within the oral cavity and their role during infectious diseases of the gingiva

“…As described by Rausch et al and by Schicht et al, SP-G and SP-H seem to play an important role during inflammation processes and immune defense (Rausch et al, 2012;Schicht et al, 2014). As the oral cavity is exposed to a variety of intruders amongst them also pathogens, a functional and effective first barrier is necessary to sustain physiological stability of the oral cavity and its flora.…”

“…Scale bar = 10 mm. Schicht et al, 2014). Lung tissue (4) served as positive control and was treated and incubated using the same conditions.…”

“…Immunohistochemical staining was performed with the polyclonal antibody against SP-G and SP-H (Rausch et al, 2012;Schicht et al, 2014). Antigen retrieval was performed by microwave pretreatment for 10 min and non-specific binding was inhibited by incubation with porcine normal serum (Dako) 1:5 in Tris-buffered saline (TBS).…”

“…So the aim of this study was to further investigate possible differences in the quantity of the SPs in healthy saliva compared to saliva from patients with pathologically altered periodontal tissues. Recent studies revealed two novel proteins belonging to the family of surfactant proteins namely SP-G and SP-H that have been detected in different tissues amongst them in human lung (Rausch et al, 2012;Schicht et al, 2014). In this context one further objective of the study was to investigate salivary glands and saliva for the possible presence of SP-G and SP-H.…”

Structure, genetics and function of the pulmonary associated surfactant proteins A and D: The extra-pulmonary role of these C type lectins

“…Surfactant protein H (SP-H) or surfactant associated protein 3 (SFTA3) is encoded on chromosome 14. The primary translation product of SP-H consists of 94 amino acids with a molecular weight of ∼10 kDa (Schicht et al, 2014). …”