Surfactant replacement therapy in premature babies with respiratory distress syndrome: factors affecting the response to surfactant and comparison of outcome from 1982-86 and 1987-91

Development of a safe and effective novel synthetic mucosal adjuvant SF-10 derived from physiological metabolic pathways and function of human pulmonary surfactant

A safe and effective mucosal adjuvant is required for vaccination against influenza A virus (IAV) infection. Previously, we described that intranasally administration of surfacten®, a medicine derived from bovine pulmonary surfactant (PS), with IAV vaccine can induce IAV-specific IgA in the respiratory tract mucosa and IgG in serum. PS is secreted by alveolar type II cells and Clara cells and serves to reduce lung surface tension. PS finished its rules is incorporated by antigen presenting cells (APCs), such as alveolar macrophages and dendritic cells, and alveolar type II cells and rapidly metabolized. We focused on the metabolic pathways and rapid metabolic turnover of PS and developed a PS-based mucosal adjuvant. First, we determined the essential components of PS adjuvanticity and found that the complex of three PS lipids and surfactant protein-C can enhance to deliver the vaccine antigen and activate APCs. Later, we improved the safety, efficacy and ease of manufacture and finally succeeded in developing SF-10. The use of SF-10 with influenza split vaccine (HAv) (HAv-SF-10) enhances HAv incorporation into APCs both in vitro and in vivo, and intranasal instillation of HAv-SF-10 induced systemic and mucosal HAv-specific immunities in not only mice but also cynomolgus monkeys. The report that PS has physiological effects on the gastrointestinal mucosa prompted us develop a new SF-10-based vaccine that can be administered orally. In this review, We summarize our work on the development of clinically effective PS-based nasal and oral mucosal adjuvants for influenza vaccine.

Thromboelastometry in Neonates with Respiratory Distress Syndrome: A Pilot Study

BACKGROUND

Although respiratory distress syndrome (RDS) constitutes a postnatal risk factor for bleeding and thromboembolic events in neonates, few studies have addressed this issue. We aimed to evaluate the hemostatic profile of neonates with RDS using rotational thromboelastometry (ROTEM).

METHODS

An observational study was conducted from November 2018 to November 2020 in the NICU of General Hospital of Nikaia "Aghios Panteleimon". Preterm and term neonates with RDS hospitalized in the NICU were included and EXTEM (tissue factor-triggered extrinsic pathway), INTEM (ellagic acid activated intrinsic pathway), and FIBTEM (with platelet inhibitor cytochalasin D) assays were performed at the onset of the disease.

RESULTS

A hypocoagulable profile was noted in neonates with RDS compared to controls, expressed as significant prolongation of EXTEM CT (clotting time) and CFT (clot formation time), lower EXTEM A10 (amplitude at 10 min), MCF (maximum clot firmness), and LI60 (lysis index). Furthermore, prolongation of INTEM CFT and FIBTEM CT, and decreased INTEM and FIBTEM A10 and MCF were found in neonates with RDS. Multivariable logistic regression analysis showed that RDS is an independent factor for the recorded alterations in ROTEM variables.

CONCLUSIONS

RDS is associated with a hypocoagulable profile and greater hyperfibrinolytic potential compared to healthy neonates.

Induction of systemic and mucosal immunity and maintenance of its memory against influenza A virus by nasal vaccination using a new mucosal adjuvant SF-10 derived from pulmonary surfactant in young cynomolgus monkeys

Induction of systemic and mucosal immunity and maintenance of its memory was investigated in 12 young male cynomolgus monkeys after intranasal instillation of flu vaccine using a new mucosal adjuvant SF-10 derived from pulmonary surfactant constituents. Split-product of influenza virus A/California/7/2009(H1N1)pdm hemagglutinin vaccine (HAv) at 15 μg with or without SF-10 and the adjuvant alone were instilled intranasally three times every 2 weeks. SF-10-adjuvanted HAv (SF-10-HAv) elicited significantly higher HAv-specific IgG and hemagglutinin inhibition (HI) titers in serum and HAv-specific secretory IgA and its neutralizing activities in nasal washes compared with HAv antigen and SF-10 alone. Significant cross-neutralizing activities of nasal washes after the third vaccination to several other H1N1 and H3N2 strains were observed. HI titers in serum and neutralizing activities in nasal washes reached peak levels at 6 weeks after initial vaccination, then gradually decreased after 10 weeks and returned to the baseline levels at 36 weeks. A single intranasal revaccination of SF-10-HAv at 36 weeks rapidly and significantly increased both immunity in serum and nasal washes compared with naïve monkeys. Revaccination by one or two doses achieved almost maximal immunity at 2 or 4 weeks after instillation. Statistically significant adverse effects (e.g., body weight loss, elevated body temperature, nasal discharge, change in peripheral blood leukocyte and platelet counts) were not observed for 2 weeks after vaccination of SF-10-HAv, HAv or SF-10 and also during the experimental period. These results in young monkey model suggest the potential of clinical use SF-10 for intranasal flu vaccine.

Surfactant

Exogenous pulmonary surfactant, widely used in neonatal care, is one of the best-studied treatments in neonatology, and its introduction in the 1990s led to a significant improvement in neonatal outcomes in preterm infants, including a decrease in mortality. This chapter provides an overview of surfactant composition and function in health and disease and summarizes the evidence for its clinical use.

Intranasal influenza vaccination using a new synthetic mucosal adjuvant SF-10: induction of potent local and systemic immunity with balanced Th1 and Th2 responses

BACKGROUND

We found previously that bovine pulmonary Surfacten® used in newborns with acute respiratory distress syndrome is a safe and efficacious antigen vehicle for intranasal vaccination.

OBJECTIVES

The objective of this study was to industrially produce a synthetic adjuvant mimicking Surfacten® for clinical use without risk of bovine spongiform encephalopathy.

METHODS

We selected three Surfacten lipids and surfactant protein (SP)-C as essential constituents for adjuvanticity. For replacement of the hydrophobic SP-C, we synthesized SP-related peptides and analyzed their adjuvanticity. We evaluated lyophilization to replace sonication for the binding of influenza virus hemagglutinin (HA) to the synthetic adjuvant. We also added a carboxy vinyl polymer (CVP) to the synthetic adjuvant and named the mixture as SF-10 adjuvant. HA combined with SF-10 was administered intranasally to mice, and induction of nasal-wash HA-specific secretory IgA (s-IgA) and serum IgG with Th1-/Th2-type cytokine responses in nasal cavity and virus challenge test were assessed.

RESULTS AND CONCLUSIONS

Intranasal immunization with HA-SF-10 induced significantly higher levels of anti-HA-specific nasal-wash s-IgA and serum IgG than those induced by HA-poly(I:C), a reported potent mucosal vaccine, and provided highly efficient protection against lethal doses of virus challenge in mice. Anti-HA-specific serum IgG levels induced by HA-SF-10 were almost equivalent to those induced by subcutaneous immunization of HA twice. Intranasal administration of HA-SF-10 induced balanced anti-HA-specific IgG1 and IgG2a in sera and IFN-γ- and IL-4-producing lymphocytes in nasal cavity without any induction of anti-HA IgE. The results suggest that HA-SF-10 is a promising nasal influenza vaccine and that SF-10 can be supplied in large quantities commercially.

Morbidity and mortality of infants born at the threshold of viability: ten years' experience in a single neonatal intensive care unit, 1991-2000

BACKGROUND

The purpose of the present paper was to evaluate the mortality and morbidity of infants born at 22-24 weeks gestation.

METHODS

A total of 78 infants born at 22-24 weeks gestation, who were admitted between January 1991 through December 2000, were retrospectively studied.

RESULTS

Seventy-one of 78 infants were enrolled in the present study. One year survival rates at 22, 23 and 24 weeks were 40.0% (2/5), 61.1% (11/18), and 50.0% (24/48), respectively. Failure of response to surfactant and air leak were associated with death in infants born at 23 weeks gestation. Low Apgar score, intraventricular hemorrhage (> or =III), and sepsis were correlated with death in infants born at 24 weeks gestation. The handicap rates of survivors born at 22, 23, and 24 weeks gestation were 100, 36.4, and 26.1%, respectively.

CONCLUSIONS

The present study indicates that infants born at 22 weeks gestation, in whom pulmonary structure is established, that is, a viable lung that can exchange gas with exogenous surfactant, have a chance to survive, but neurological outcome is still poor. Every possible effort should be made to extend gestation beyond 22 weeks.

Modified Pulmonary Surfactant Is a Potent Adjuvant That Stimulates the Mucosal IgA Production in Response to the Influenza Virus Antigen

The intranasal administration of influenza hemagglutinin (HA) vaccine with Surfacten, a modified pulmonary surfactant free of antigenic c-type lectins, as a mucosal adjuvant induced the highest protective mucosal immunity in the airway. The intranasal immunization of mice with HA vaccine (0.2 microg)-Surfacten (0.2 microg) selectively induced the neutralizing anti-HA IgA, but not IgG, and conferred nearly maximal protection in the airway, without inducing a systemic response. In contrast, intranasal inoculation of vaccine with 0.2 microg of the potent mucosal adjuvant cholera toxin B* (CT-B*), prepared by adding 0.2% native CT to the B subunit of CT, induced both anti-HA IgA and IgG in the airway and in the serum. The intranasal administration of HA vaccine alone induced a limited amount of mucosal IgA against influenza virus. Although the s.c. administration of HA vaccine prominently induced serum IgG and IgA, Surfacten and CT-B* did not enhance their induction, and the concentrations of Abs leaking into the airways were insufficient to prevent viral multiplication. The intranasal administration of HA-Surfacten stimulated the expression of MHC class II, CD40, and CD86 molecules in the CD11c-positive cells isolated from the nasal mucosa, but not the expression of cells from the lungs or spleens. Lymphocytes isolated from the airway mucosa after intranasal HA-Surfacten immunization prominently induced TGF-beta1 which, compared with inoculation without Surfacten, promoted an Ag-specific mucosal IgA response. Surfacten alone, however, did not induce TGF-beta1. Our observations suggest that Surfacten, by mimicking the natural surfactant, is an effective mucosal adjuvant in the process of airway immunization.

Surfactant protein D in newborn infants: factors influencing surfactant protein D levels in umbilical cord blood and capillary blood

Surfactant protein D (SP-D) is a collectin that plays an important role in the innate immune system. The role of SP-D in the metabolism of surfactant is as yet quite unclear. The aims of this study were to establish normal values of SP-D in the umbilical cord blood and capillary blood of mature newborn infants and to assess the influence of perinatal conditions on these levels. A total of 458 infants were enrolled in the present study. Umbilical cord blood was drawn at the time of birth and capillary blood at age 4 to 10 d. The concentration of SP-D in umbilical cord blood and capillary blood was measured by enzyme-linked immunosorbent assay. The median concentration of SP-D in umbilical cord blood was 392.1 ng/mL and was found to be influenced by maternal smoking and labor. The median concentration of SP-D in capillary blood was 777.5 ng/mL and was found to be influenced by the mode of delivery, the highest levels being observed in infants born by cesarean section. It was concluded that SP-D concentrations in umbilical cord blood and capillary blood are highly variable and depend on several perinatal conditions. Further studies are needed to elucidate the effect of respiratory distress and infection on SP-D concentrations.

Comparison of clinical efficacy of Newfactan versus Surfacten for the treatment of respiratory distress syndrome in the newborn infants

Newfactan is a domestically developed, bovine lung-derived, semi-synthetic surfactant. The aim of this study was to compare the clinical efficacy of Newfactan with that of Surfacten in the treatment of respiratory distress syndrome (RDS). Newfactan or Surfacten was randomly allocated to 492 newborn infants who were diagnosed as RDS and required surfactant instillation in four participating hospitals. The comparisons were made individually in two subsets of infants by birth weight (<1,500 g group [n=253] and > or =1,500 g group [n=239]). Short-term responses to surfactant and acute complications, such as the total doses of surfactant instilled, response type, extubation rate, ventilator settings, changes in respiratory parameters, air leak, patent ductus arteriosus, pulmonary hemorrhage, and intraventricular hemorrhage, and mortality during the 96 hr after surfactant instillation were measured. Long-term outcome and complications, such as total duration of intubation, bronchopulmonary dysplasia and periventricular leukomalacia, and ultimate mortality were measured. There were no significant differences in demographic and perinatal variables, shortterm responses to surfactant and acute complications, and long-term outcome and complications between Newfactan and Surfacten in both birth weight groups. We concluded that Newfactan was comparable to Surfacten in the clinical efficacy in the treatment of RDS in both birth weight groups.

Risk factors for the different types of chronic lung diseases of prematurity according to the preceding respiratory distress syndrome

BACKGROUND

Recently, atypical chronic lung disease (CLD) of prematurity that develops in the absence of preceding respiratory distress syndrome (RDS) have been observed frequently. The specific risk factors for atypical CLD that are presumed to be different from those for classical CLD that develops following RDS were assessed.

METHODS

Prospective cohort analysis was done from 115 very low-birthweight infants who were born in Seoul National University Hospital, Seoul, Korea, and survived more than 36 weeks postmenstrual age or 28 days of life. All subjects were classified into either a preceding RDS group (n = 35) or a non-RDS group (n = 80). Logistic regression analysis was done for the multivariate assessment of specific risk factors for CLD in both groups.

RESULTS

The analysis showed that short gestational age (GA; relative risk [RR], 3.1 per 1 week decrement; 95% confidence intervals [CI], 2.7-3.4), of the male gender (RR, 9.8; CI, 0.9-112), and poor response to surfactant (RR, 14; CI, 1.2-156) were significant risk factors for CLD in the preceding RDS group. In the non-RDS group, chorioamnionitis was one of the significant risk factors for CLD (RR, 4.8; CI, 1.1-21) along with short GA and high mean airway pressure (MAP) during the first 3 days of life.

CONCLUSION

Chorioamnionitis was a risk factor for atypical CLD in addition to short GA and high MAP during the early postnatal period, and poor response to surfactant was a risk factor for classical CLD in addition to short GA and being male. Therefore, CLD is considered to have type-specific risk factors.

Clinical characteristics of chronic lung disease without preceding respiratory distress syndrome in preterm infants

BACKGROUND

Recently, the incidence of atypical presentation of chronic lung disease (CLD) that develops in infants without a history of preceding respiratory distress syndrome (RDS) is increasing. Therefore, the clinical characteristics of CLD without RDS in comparison with CLD with RDS were assessed.

METHODS

Prospective cohort analysis was done from 117 very low-birthweight infants who were born in Seoul National University Hospital and survived more than 36 weeks postmenstrual age (PMA).

RESULTS

Of the 117 infants analyzed, CLD developed in 44 infants (38%). Among these 44 infants, CLD with RDS developed in 27 infants (23%) and CLD without RDS developed in 17 infants (15%). Each type of CLD was subgrouped according to the presence of chorioamnionitis (CA): RDS(+)CA(+) CLD (n = 8) and RDS(+)CA(-) CLD (n = 19); and RDS(-)CA(+) CLD (n = 12) and RDS(-)CA(-) CLD (n = 5). There were no significant differences in the demographic characteristics between CLD with RDS and CLD without RDS. Chorioamnionitis was significantly more common in CLD without RDS, while patent ductus arteriosus was more common in CLD with RDS. Although the severity of initial respiratory failure was not greater than that of CLD with RDS, CLD without RDS showed a gradually increasing chronic oxygen requirement pattern. Chronic oxygen requirement pattern showed that infants with RDS(+)CA(+)CLD required the highest concentrations of oxygen not only initially but also thereafter until the 28th day of life and 36 weeks PMA.

CONCLUSIONS

Although CLD without RDS was still less common than CLD with RDS, it comprised over a third of all cases of CLD in our study. Clinical characteristics and chronic oxygen requirement pattern of CLD without RDS seems to be less severe than those of CLD with RDS. Our data suggest that CLD without RDS may be developed by causes other than initial acute lung injury. Chorioamnionitis may be one of antecedents of CLD without RDS.

Current surfactant use in premature infants

Exogenous surfactant therapy has been a significant advance in the management of preterm infants with RDS. It has become established as a standard part of the management of such infants. Both natural and synthetic surfactants lead to clinical improvement and decreased mortality, with natural surfactants having additional advantages over currently available synthetic surfactants. The use of prophylactic surfactant administered after initial stabilization at birth to infants at risk for RDS has benefits compared with rescue surfactant given to treat infants with established RDS. In infants who do not receive prophylaxis, earlier treatment (before 2 hours) has benefits over later treatment. The use of multiple doses of surfactant is a superior strategy to the use of a single dose, whereas the use of a higher threshold for retreatment seems to be as effective as a low threshold. Adverse effects of surfactant therapy are infrequent and usually not serious. Long-term follow-up of infants treated with surfactant in the neonatal period is reassuring. In the future we are likely to see the development of new types of surfactants. Further research is required to determine the optimal use of surfactant in conjunction with other respiratory interventions.

Biophysical properties of protein-free, totally synthetic pulmonary surfactants, ALEC and Exosurf, in comparison with surfactant TA

An artificial pulmonary surfactant prepared from chloroform-methanol extract of bovine pulmonary surfactant (surfactant TA) has been shown to be effective in both the prevention and the treatment of respiratory distress syndrome in premature babies. Recently, two types of protein-free totally synthetic surfactants, artificial lung expanding compound (ALEC) and Exosurf, have been evaluated in clinical trials of surfactant therapy. Artificial lung expanding compound was used initially as a dry powder, but is now prepared as a crystalline suspension in saline at 4 degrees C. In this study we compared the biophysical properties of three different forms of ALEC (dry powder, crystalline suspension at 4 degrees C and 37 degrees C), Exosurf and surfactant TA (Surfacten) using a modified Wilhelmy surface balance and a pulsating bubble surfactometer. Surface activity of a crystalline suspension of ALEC in cold saline was no better than the dry powder of ALEC. Surfactant activity of ALEC was improved by addition of hydrophobic surfactant protein B and C (SP-B, SP-C) which are important constituents of surfactant TA. Surface properties of ALEC in any form and Exosurf were not superior to those of surfactant TA. These results suggest that a surfactant which contains SP-B and SP-C does not necessarily have to be dry or crystalline for an effective exogenous surfactant.