Surfactant protein A and D in the reproductive tract of stallion

Dysregulated serum and seminal plasma levels of surfactant protein D and MCP-1 in men with genital tract infection/inflammation

PROBLEM

Surfactant protein D (SP-D), a multimeric collectin expressed by testicular mucosal epithelia and is positively regulated by testosterone. It exerts antimicrobial effects, modulates inflammation and rescued spermatogenesis in a murine model. Various cytokines and chemokines, including MCP-1, play a key role in regulating the inflammation in rat and human testis. The study aimed to investigate the role of SP-D and involvement of chemokines and cytokines in the male infertility associated with urogenital infections or inflammation.

METHOD OF STUDY

The cross-sectional study evaluated levels of SP-D, testosterone, estradiol and the cytokines/chemokines including MCP-1 in the serum and semen samples of fertile and infertile Indian men with and without urogenital infections/inflammation (n = 76).

RESULTS

Both fertile and infertile males with urogenital infection/inflammation had significantly lower levels of SP-D and higher levels of the chemokine, Monocyte chemoattractant protein 1 (MCP-1) in the serum and seminal plasma. Seminal plasma of these males exhibited significantly higher proportion of proteolytically degraded forms of SP-D. The serum SP-D levels positively correlated with testosterone/estradiol (TE) ratio. There was no significant correlation between the SP-D levels in seminal plasma and sperm count/motility. With a significant area under the Receiver Operating Characteristic curves, the serum and seminal plasma SP-D levels exhibited significant potential to predict infertility with high sensitivity and specificity in men with genital infections/inflammation.

CONCLUSIONS

The circulating and seminal plasma SP-D levels were decreased in men with urogenital infection and inflammation. This could be due to their engagement at the site of infection, dysregulated expression owing to the altered hormonal profile and increased proteolytic degradation.

Different expression of circulating microRNA profile and plasma SP-D in Tibetan COPD patients

COPD is the fourth leading cause of mortality, and is predicted to be the third leading cause of death worldwide by 2020. But few studies on Tibetan COPD of China. This study identifies distinctive miRNA signatures in Tibetan COPD patients from Tibetan healthy subjects that could serve as diagnostic biomarkers or describe differential molecular mechanisms with potential therapeutic implications. In this study, a total of 210 differentially expressed miRNAs were screened. Analysis of the functions of target genes of differentially expressed miRNAs via GO enrichment analysis revealed that they mainly influenced guanyl-nucleotide exchange factor activity, cell morphogenesis and the positive regulation of GTPase activity. KEGG pathway enrichment analysis showed that these target genes were mainly enriched in signaling by NGF, Axon guidance, developmental biology, ubiquitin mediated proteolysis, and PDGF signaling pathways. MiR-106-5p and miR-486-5p expression was validated in the complete cohort. Age, plasma miR-106-5p, miR-486-5p, SP-D protein levels, and SP-D mRNA level were also determined to be correlated with FEV1%Pred, and may as the risk factors of Tibetan COPD. The combination of plasma miR-106-5p, miR-486-5p and SP-D mRNA expression may be the best model to assist the diagnosis of Tibetan COPD.

Surfactant protein D inhibits HIV-1 infection of target cells via interference with gp120-CD4 interaction and modulates pro-inflammatory cytokine production

Surfactant Protein SP-D, a member of the collectin family, is a pattern recognition protein, secreted by mucosal epithelial cells and has an important role in innate immunity against various pathogens. In this study, we confirm that native human SP-D and a recombinant fragment of human SP-D (rhSP-D) bind to gp120 of HIV-1 and significantly inhibit viral replication in vitro in a calcium and dose-dependent manner. We show, for the first time, that SP-D and rhSP-D act as potent inhibitors of HIV-1 entry in to target cells and block the interaction between CD4 and gp120 in a dose-dependent manner. The rhSP-D-mediated inhibition of viral replication was examined using three clinical isolates of HIV-1 and three target cells: Jurkat T cells, U937 monocytic cells and PBMCs. HIV-1 induced cytokine storm in the three target cells was significantly suppressed by rhSP-D. Phosphorylation of key kinases p38, Erk1/2 and AKT, which contribute to HIV-1 induced immune activation, was significantly reduced in vitro in the presence of rhSP-D. Notably, anti-HIV-1 activity of rhSP-D was retained in the presence of biological fluids such as cervico-vaginal lavage and seminal plasma. Our study illustrates the multi-faceted role of human SP-D against HIV-1 and potential of rhSP-D for immunotherapy to inhibit viral entry and immune activation in acute HIV infection.

Serum concentration of surfactant protein D in horses with lower airway inflammation

REASONS FOR PERFORMING STUDY

Surfactant protein D (SP-D), mainly synthesised by alveolar type II cells and nonciliated bronchiolar cells, is one important component of innate pulmonary immunity. In man, circulating concentrations of SP-D are routinely used as biomarkers for pulmonary injury. To date, serum SP-D levels have only been investigated in horses in an experimental model of bacterial airway infection.

OBJECTIVES

To compare serum SP-D concentrations at rest and after exercise in horses with and without inflammatory airway disease (IAD).

METHODS

Venous blood samples were collected from 42 Standardbred racehorses at rest and 60 min after performing a standardised treadmill exercise test. Tracheal wash and bronchoalveolar lavage fluid (BALF) samples were collected after exercise. Based on BALF cytology, 22 horses were defined as IAD-affected and 20 classified as controls. Serum SP-D concentrations were assessed using a commercially available ELISA kit and statistically compared between groups of horses and sampling times.

RESULTS

Serum concentrations of SP-D in IAD-affected horses were significantly higher than those of control horses, both at rest and after exercise. Within the IAD-affected group, no significant correlation was found between serum SP-D concentrations and BALF cytology. Within each group of horses (IAD and control), no significant influence of exercise was found on serum SP-D levels.

CONCLUSIONS

This is the first study determining serum SP-D concentrations in a noninfectious, naturally occurring form of lower airway inflammation in horses. The results highlight that IAD is associated with a detectable, though moderate, increase of circulating SP-D levels.

POTENTIAL RELEVANCE

Serum concentration of surfactant protein D could represent a potentially valuable and readily accessible blood biomarker of equine lower airway inflammation.

Identification and comparative analysis of three novel C-type lectins from the silkworm with functional implications in pathogen recognition

C-type lectins can act as pattern recognition receptors (PRRs) in innate immunity. Previously, we identified two C-type lectins from silkworm (Bombyx mori), BmLBP and BmMBP, as PRRs. In the present study, we identified three homologs of these lectins by searching the silkworm genome database. These novel B. mori low-expression lectins were designated BmLEL-1, BmLEL-2, and BmLEL-3. Although Western-blot analysis failed to detect BmLEL-1, -2, or -3 in plasma, affinity precipitation of larval plasma with various microorganisms revealed that BmLEL-1 and -2 bind to rough and smooth strains of Gram-negative bacteria, respectively. BmLEL-1, -2, and -3 were found to be expressed in testis and ovary, where BmLEL-2 expression was up-regulated after bacteria infection. These results indicate that the novel C-type lectins might play a role in the innate immunity in these tissues as PRRs. Here, we discuss the roles and members of the C-type lectins as primary PRRs in B. mori cellular immunity.

Role of lung surfactant in respiratory disease: current knowledge in large animal medicine

Lung surfactant is produced by type II alveolar cells as a mixture of phospholipids, surfactant proteins, and neutral lipids. Surfactant lowers alveolar surface tension and is crucial for the prevention of alveolar collapse. In addition, surfactant contributes to smaller airway patency and improves mucociliary clearance. Surfactant-specific proteins are part of the innate immune defense mechanisms of the lung. Lung surfactant alterations have been described in a number of respiratory diseases. Surfactant deficiency (quantitative deficit of surfactant) in premature animals causes neonatal respiratory distress syndrome. Surfactant dysfunction (qualitative changes in surfactant) has been implicated in the pathophysiology of acute respiratory distress syndrome and asthma. Analysis of surfactant from amniotic fluid allows assessment of fetal lung maturity (FLM) in the human fetus and exogenous surfactant replacement therapy is part of the standard care in premature human infants. In contrast to human medicine, use and success of FLM testing or surfactant replacement therapy remain limited in veterinary medicine. Lung surfactant has been studied in large animal models of human disease. However, only a few reports exist on lung surfactant alterations in naturally occurring respiratory disease in large animals. This article gives a general review on the role of lung surfactant in respiratory disease followed by an overview of our current knowledge on surfactant in large animal veterinary medicine.

Presence and subcellular localizations of surfactant proteins A and D in human spermatozoa

OBJECTIVE

To investigate the presence of surfactant protein-A (SP-A); molecular weight 34 kDa and surfactant protein-D (SP-D); and molecular weight 43 kDa in human spermatozoa.

DESIGN

Prospective, research study.

SETTING

Two universities in Turkey.

PATIENT(S)

Semen specimens (n = 10) were obtained from normozoospermic donors.

INTERVENTION(S)

Human sperm were exposed to an anti-human SP-A polyclonal antibody, and monoclonal antibody, to human SP-D protein.

MAIN OUTCOME MEASURE(S)

Presence of SP-A and SP-D proteins in human beings.

RESULT(S)

Indirect immunofluorescence assays of human sperm indicated the presence of SP-A in the mid piece, the tail, and sometimes at the equatorial region of spermatozoa. A brilliant green light detected SP-D in the tails and acrosome of some sperm. The anti-SP-A antibody detected a single band corresponding to the molecular weight values of 34 kDa in spermatozoa, whereas no band was observed in the negative control. The anti-SP-D antibody showed the expected band at 43 kDa in spermatozoa.

CONCLUSION(S)

This is the first report and a novel finding of the presence of surfactant glycoproteins on human spermatozoa.