Current and emerging treatments for neonatal sepsis

ABSTRACT

Introduction

Mortality due to sepsis is still prevalent, peaking at extreme ages of life including infancy. Despite many efforts, the peculiarity of the infant immune system has limited further advances in its treatment. Indeed, neonates experience a dramatic physiological transition from immune tolerance to the maternal antigens to functional maturity. Such a transition is extremely dynamic, as is the pathophysiology of infant sepsis, which is dependent on many infant, maternal, and environmental factors.     

Iron-saturated lactoferrin as a comitogenic substance for neonatal rat hepatocytes in primary culture

We studied the effect of lactoferrin on DNA synthesis in neonatal rat hepatocytes in primary culture to determine if this agent acts as a mitogen in human milk. Thymidine incorporation into the DNA of cultured hepatocytes stimulated by lactoferrin in the presence of insulin and human epidermal growth factor was examined. Iron-saturated lactoferrin increased DNA synthesis of neonatal hepatocytes by 1.5 times and this potency was the same as that of insulin. It significantly enhanced the stimulatory effect of human epidermal growth factor plus insulin; DNA synthesis under these conditions was seven times that of control. Iron-free lactoferrin did not affect DNA synthesis, nor did the exogenous addition of ferric ions. The enhancement of DNA synthesis by iron-saturated lactoferrin was significant for neonatal hepatocytes, but not for adult hepatocytes. These results suggest that iron-saturated lactoferrin, which itself had low mitogenic activity, is a co-mitogenic substance for neonatal hepatocytes in vitro.     

乳铁蛋白治疗牙周炎的炎症免疫机制研究

目的 研究乳铁蛋白调节炎症免疫反应在治疗牙周炎中的作用及其机制。方法 取100只SD大鼠随机分成空白对照组,模型组,乳铁蛋白给药组低、中、高剂量组(1,2,3 g·kg^-1),甲硝唑阳性对照组(0.02 g·kg^-1),PDTC组(200 mg·kg^-1),乳铁蛋白+PDTC组(2 g·kg^-1,200 mg·kg^-1),MCC950组(1 mg·kg^-1),乳铁蛋白+MCC950(2 g·kg^-1,1 mg·kg^-1),每组10只。采用丝线结扎联合10%蔗糖饮水建立模型后开始给药,每天1次口腔给药,空白对照组和模型组口腔给药0.9% NaCl,连续给药1个月后处死各组大鼠。ELISA试剂盒检测IL-1b、IL-8、IL-10的含量;Western blotting检测TLR2-NF-κB通路和NLRP3炎症小体相关蛋白的表达。采用HE染色观察各组大鼠牙周组织的病理变化。结果 与模型组比较,乳铁蛋白各剂量组牙周炎症状得到明显改善,HE染色显示炎症细胞浸润减少,成纤维细胞增生活跃。TLR2、NF-κB、NLRP3、Caspase-1 p20和GSDMD-N蛋白表达降低,促炎因子IL-1b、IL-8的含量降低,抗炎因子IL-10的含量升高。结论 乳铁蛋白在治疗牙周炎中发挥的调节炎症免疫反应可能通过下调TLR2-NF-κB-NLRP3通路的蛋白表达,降低炎症反应的启动和炎症因子的释放,从而达到抗炎的目的。     

Lactoferrin-Loaded Alginate Microparticles to Target Clostridioides difficile Infection

Some forms of bovine lactoferrin (bLf) are effective in delaying Clostridioides difficile growth and preventing toxin production. However, therapeutic use of bLf may be limited by protein stability issues. The objective of this study was to prepare and evaluate colon-targeted, pH-triggered alginate microparticles loaded with bioactive bLf and to evaluate their anti-C difficile defense properties in vitro. Different forms of metal-bound bLf were encapsulated in alginate microparticles using an emulsification or internal gelation method. The microparticles were coated with chitosan to control protein release. In vitro drug release studies were conducted in pH-simulated gastrointestinal conditions to investigate the release kinetics of encapsulated protein. No significant release of metal-bound bLf was observed at acidic pH; however, on reaching simulated colonic pH, most of the encapsulated lactoferrin was released. The application of bLf (5 mg/mL) delivered from alginate microparticles to human intestinal epithelial cells significantly reduced the cytotoxic effects of toxins A and B as well as bacterial supernatant on Caco-2 and Vero cells, respectively. These results are the first to suggest that alginate-bLf microparticles show protective effects against C difficile toxin-mediated epithelial damage and impairment of barrier function in human intestinal epithelial cells. The future potential of lactoferrin-loaded alginate microparticles against C difficile deserves further study.     

Glucocorticoids: regulation of gene expression and apoptosis

Abstract

Previous studies have shown that oral treatment with lactoferrin (LF) restores the immune response in cyclophosphamide (CP) immunocompromised mice. The aim of the present investigation was to determine the regulatory ability of LF on the production of interleukin 6 (IL-6) in peritoneal and alveolar cells, derived from CP-treated mice. CBA mice were injected with a single, intraperitoneal (i.p.) dose of CP (350 mg/kg body weight) followed by LF administered in drinking water (0.5% solution) for 21 days. The control counterparts were given water. Peritoneal and alveolar cells were isolated from mice and the production of IL-6, both spontaneous and lipopolysaccharide (LPS) induced, was determined in 24h cell cultures using a bioassay. The results showed increased production of IL-6 in both CP-treated mice and in mice given, in addition, LF. The administration of LF alone led also to an increase in IL-6 production by the cell cultures. Intravenous (i.v.) administration of LPS resulted in a significant increase in IL-6 serum levels in CP and CP/LF but not in LF-treated mice. Analysis of cell type composition in the peritoneal cavity revealed a strong increase in mastocyte and neutrophil content in CP and CP/LF-treated groups. Our findings suggest that enhanced IL-6 production in CP and CP/LF-treated mice may contribute to reconstitution of immune system function in immunocompromised mice.     

Bovine milk RNases modulate pro-inflammatory responses induced by nucleic acids in cultured immune and epithelial cells

Activation of innate immune receptors by exogenous substances is crucial for the detection of microbial pathogens and a subsequent inflammatory response. The inflammatory response to microbial lipopolysaccharide via Toll-like receptor 4 (TLR4) is facilitated by soluble accessory proteins, but the role of such proteins in the activation of other pathogen recognition receptors for microbial nucleic acid is not well understood. Here we demonstrate that RNase4 and RNase5 purified from bovine milk bind to Salmonella typhimurium DNA and stimulate pro-inflammatory responses induced by nucleic acid mimetics and S. typhimurium DNA in an established mouse macrophage cell culture model, RAW264.7, as well as in primary bovine mammary epithelial cells. RNase4 and 5 also modulated pro-inflammatory signalling in response to nucleic acids in bovine peripheral blood mononuclear cells, although producing a distinct response. These results support a role for RNase4 and RNase5 in mediating inflammatory signals in both immune and epithelial cells, involving mechanisms that are cell-type specific.     

Relationship between salivary immunoglobulin a,lactoferrin and lysozyme flow rates and lifestyle factors in Japanese children: a cross-sectional study

Objective: The antimicrobial substances in saliva contribute to the maintenance of both oral health and overall health of the body. Therefore, the associations among immunoglobulin A (IgA), lactoferrin and lysozyme flow rates in the saliva of children, and their relationships with the physical attributes and lifestyle factors of children, were examined.

Materials and methods: Saliva was collected from 90 children who visited the Kanagawa Dental University Hospital Pediatric Dentistry, and questionnaires were completed by guardians. IgA, lactoferrin and lysozyme concentrations were measured in the saliva samples using enzyme-linked immunosorbent assays (ELISAs).

Results: The IgA flow rate in saliva increased as age, height and weight increased. A correlation was found between lactoferrin and lysozyme flow rates. When the antimicrobial substance flow rates in the saliva were divided into two groups of 22 children each based on the highest and lowest quartiles, children with either a low or high IgA flow rate also had a high or low lactoferrin flow rate, respectively. The same pattern was observed for lactoferrin and lysozyme flow rates.

Conclusions: There is a high probability that the IgA flow rate in the saliva of children reflects and corresponds to the developmental status of immune function as the child ages and increases in height and weight. The flow rates of lactoferrin and lysozyme were correlated in children. In addition, regarding lifestyle factors, the duration of sleep and lactoferrin flow rate were also related.     

Use of bovine lactoferrin for Helicobacter pylori eradication

BACKGROUND: One-week triple therapy is the most frequently recommended treatment for Helicobacter pylori infection. Eradication rate is satisfactory, nevertheless is advisable to look for more effective therapies. AIM: To test the efficacy of a standard triple therapy plus bovine lactoferrin in the eradication of H. pylori infection. PATIENTS AND METHODS: One hundred and fifty consecutive H. pylori positive patients, suffering from dyspeptic symptoms were recruited in a 7-day triple therapy open randomised single centre study with rabeprazole, clarithromycin, tinidazole, bovine lactoferrin (group A) or rabeprazole, clarithromycin, tinidazole (group B), or a 10-day therapy with rabeprazole, clarithromycin, tinidazole (group C). H. pylori status was assessed 8 weeks after the end of the treatment by means of a 13C-urea breath test or a H. pylori stool antigen-test. RESULTS: Eradication rates (intention to treat/per protocol) were: group A (92.2/95.9%), group B (71.2/72.5%) and group C (70.2/75%). The efficacy of triple therapy added with lactoferrin was significantly higher than other two regimens (p=0.01, intention to treat analysis; p=0.005, per protocol analysis). CONCLUSION: These results suggest that lactoferrin tested in the present study was effective in curing H. pylori and could be a new agent to assist the antimicrobials in the eradication of the bacterium.     

Inhibition of HBV infection by bovine lactoferrin and iron-, zinc-saturated lactoferrin

In this study, we investigated the effect of bovine lactoferrin (BLf), lactoferrin hydrolysate, or iron-, zinc-saturated lactoferrin on hepatitis B virus (HBV)-infected HepG2 cells. Fluorescent quantitative polymerase chain reaction (FQ-PCR) was used to quantify HBV-DNA copies. BLf, iron- or zinc-saturated lactoferrin significantly inhibited the amplification of HBV-DNA in a dose-dependent manner in HBV-infected HepG2 cells. However, the inhibitive effect of lactoferrin hydrolysate on HBV-DNA copies was insignificant. These findings suggest that BLf inhibits the function of HBV by integrated structure. In conclusion, BLf, iron- or zinc-saturated BLf is one of the candidates for anti-HBV reagents in treatment of patients with hepatitis.     

Reciprocal Interactions between Lactoferrin and Bacterial Endotoxins and Their Role in the Regulation of the Immune Response

Lactoferrin (Lf), an iron-binding glycoprotein expressed in most biological fluids, represents a major component of the mammalian innate immune system. Lf's multiple activities rely not only on its capacity to bind iron, but also to interact with molecular and cellular components of both host and pathogens. Lf can bind and sequester lipopolysaccharide (LPS), thus preventing pro-inflammatory pathway activation, sepsis and tissue damage. However, Lf-bound LPS may retain the capacity to induce cell activation via Toll-like receptor 4-dependent and -independent mechanisms. This review discusses the complex interplay between Lf and LPS and its relevance in the regulation of the immune response.