Orally administered lactoferrin restores humoral immune response in immunocompromised mice

Colostrum Proteins in Protection against Therapy-Induced Injuries in Cancer Chemo- and Radiotherapy: A Comprehensive Review

In this article, we review the benefits of application of colostrum and colostrum-derived proteins in animal models and clinical trials that include chemotherapy with antimetabolic drugs, radiotherapy and surgical interventions. A majority of the reported investigations was performed with bovine colostrum (BC) and native bovine or recombinant human lactoferrin (LF), applied alone, in nutraceutics or in combination with probiotics. Apart from reducing side effects of the applied therapeutics, radiation and surgical procedures, BC and LF augmented their efficacy and improved the wellness of patients. In conclusion, colostrum and colostrum proteins, preferably administered with probiotic bacteria, are highly recommended for inclusion to therapeutic protocols in cancer chemo- and radiotherapy as well as during the surgical treatment of cancer patients.

Immune-Enhancing Effects of Co-treatment With Kalopanax pictus Nakai Bark and Nelumbo nucifera Gaertner Leaf Extract in a Cyclophosphamide-Induced Immunosuppressed Rat Model

Objective

Immune system disorders can result in various pathological conditions, such as infections and cancer. Identifying therapies that enhance the immune response might be crucial for immunocompromised individuals. Therefore, we assessed the immune-enhancing effect of co-treatment with Kalopanax pictus Nakai Bark and Nelumbo nucifera Gaertner leaf extract (KPNN) in a cyclophosphamide (Cy)-induced immunosuppressed rat model.

Materials and Methods

For in vitro studies, macrophages and splenocytes were treated with various KPNN doses in the presence or absence of Cy. Macrophage viability, nitric oxide production, splenocyte viability, cytokine production and natural killer (NK) cell activity were analyzed. For in vivo studies, analysis of weekly body weight, dietary intake, tissue weight, immune-related blood cell count, cytokine levels, and spleen biopsy was performed in a Cy-induced immunocompromised animal model.

Results

KPNN significantly increased phospho-NF-κB and phospho-ERK protein levels and cell viability in macrophages. KPNN significantly increased the NK cell activity in splenocytes compared to that in the control. Cy treatment decreased tumor necrosis factor (TNF)-α, interleukin (IL)-6, and interferon-γ production. In the Cy-induced immunosuppression rat model, KPNN-treated rats had significantly higher body weights and tissue weights than the Cy-treated rats. Additionally, KPNN treatment restored the immune-related factors, such as total leukocyte, lymphocyte, and intermediate cell contents, to their normal levels in the blood. The blood cytokines (TNF-α and IL-6) were increased, and spleen tissue damage was significantly alleviated.

Conclusions

Collectively, KPNN exerts an immune-enhancing effect suggesting their potential as an immunostimulatory agent or functional food.

Host defense peptides as immunomodulators: The other side of the coin

Host defense peptides (HDPs) exhibit a broad range of antimicrobial and immunomodulatory activities. In this sense, both functions are like different sides of the same coin. The direct antimicrobial side was discovered first, and widely studied for the development of anti-infective therapies. In contrast, the immunomodulatory side was recognized later and in the last 20 years the interest in this field has been continuously growing. Different to their antimicrobial activities, the immunomodulatory activities of host defense peptides are more effective in vivo. They offer a great opportunity for new therapeutic applications in the fields of anti-infective therapy, chronic inflammatory diseases treatment, novel vaccine adjuvants development and anticancer immunotherapy. These immune related functions of HDPs includes chemoattraction of leukocytes, modulation of inflammation, enhancement of antigen presentation and polarization of adaptive immune responses. Our attempt with this review is to make a careful evaluation of different aspects of the less explored, but attractive immunomodulatory side of the HDP functional coin.

Lactoferrin: Cytokine Modulation and Application in Clinical Practice

Multiple properties of lactoferrin have been reported in the literature so far. Decades of in vitro and in vivo studies have demonstrated the important antimicrobial, anti-inflammatory, anti-oxidant, and immunomodulating properties. It suggests the use of lactoferrin as an effective and safe option for the treatment of several common disorders. Herein, we show the applications of lactoferrin in clinical practice, highlighting its evidence-based capacities for the treatment of heterogeneous disorders, such as allergic, gastrointestinal, and respiratory diseases, and hematologic, oncologic, gynecologic, dermatologic, and dental disorders. Moreover, the widespread use of lactoferrin in neonatology is summarized here. As a result of its antiviral properties, lactoferrin has also been proposed as a valid option for the treatment for COVID-19 patients. Here, the uses of lactoferrin in clinical practice as a new, safe, and evidence-based treatment for many types of disorders are summarized.

Development of a Machine Learning-Based Autophagy-Related lncRNA Signature to Improve Prognosis Prediction in Osteosarcoma Patients

Background

Osteosarcoma is a frequent bone malignancy in children and young adults. Despite the availability of some prognostic biomarkers, most of them fail to accurately predict prognosis in osteosarcoma patients. In this study, we used bioinformatics tools and machine learning algorithms to establish an autophagy-related long non-coding RNA (lncRNA) signature to predict the prognosis of osteosarcoma patients.

Methods

We obtained expression and clinical data from osteosarcoma patients in the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) and Gene Expression Omnibus (GEO) databases. We acquired an autophagy gene list from the Human Autophagy Database (HADb) and identified autophagy-related lncRNAs by co-expression analyses. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of the autophagy-related lncRNAs were conducted. Univariate and multivariate Cox regression analyses were performed to assess the prognostic value of the autophagy-related lncRNA signature and validate the relationship between the signature and osteosarcoma patient survival in an independent cohort. We also investigated the relationship between the signature and immune cell infiltration.

Results

We initially identified 69 autophagy-related lncRNAs, 13 of which were significant predictors of overall survival in osteosarcoma patients. Kaplan-Meier analyses revealed that the 13 autophagy-related lncRNAs could stratify patients based on their outcomes. Receiver operating characteristic curve analyses confirmed the superior prognostic value of the lncRNA signature compared to clinically used prognostic biomarkers. Importantly, the autophagy-related lncRNA signature predicted patient prognosis independently of clinicopathological characteristics. Furthermore, we found that the expression levels of the autophagy-related lncRNA signature were significantly associated with the infiltration levels of different immune cell subsets, including T cells, NK cells, and dendritic cells.

Conclusion

The autophagy-related lncRNA signature established here is an independent and robust predictor of osteosarcoma patient survival. Our findings also suggest that the expression of these 13 autophagy-related lncRNAs may promote osteosarcoma progression by regulating immune cell infiltration in the tumor microenvironment.

Sustained release of curcumin from fibrin matrix induces cancer cell death and immunomodulation

Despite the role of curcumin in controlling inflammation, angiogenesis, and cancer in human cells, its therapeutic use is limited. The reasons are quick metabolic breakdown, low aqueous solubility, and bioavailability. This study describes the advantages of clinical-grade curcumin-incorporated fibrin matrix either in lyophilized off-the-shelf wafer or injectable hydrogel forms, as a biodegradable local delivery system. To produce the curcumin-fibrin wafer, used clinical-grade fibrin sealant in a modified composition. To fabricate wafer, we premixed the curcumin with either fibrinogen or thrombin, before clotting into a hydrogel. Sustained release of active curcumin from fibrin wafer, suspended in culture medium at 37 °C lasted for seven days. Upon premixing albumin with thrombin and subsequently adding curcumin into the mixture improved the loading concentration and stability. Dose- and time-dependent apoptotic function of curcumin on cancer cell lines upon release from fibrin wafer, were demonstrated in vitro. In vivo immuno-modulation and a nontoxic response to curcumin released from fibrin into the peritoneal cavity of mice were established. The cytotoxic effect of released curcumin was demonstrated; showing both a preventive and therapeutic role against tumor growth. In vivo studies used Dalton's Lymphoma Ascites (DLA) mice model. Both implanted fibrin wafer and injected hydrogel can breakdown by a physiological process and get cleared by the fibrinolytic mechanism. The lyophilized fibrin wafer could function as a hemostat, adhere to surgical cancer tissues, and arrest bleeding. The potential of curcumin in preventing solid tumor metastasis may be explored upon the sustained delivery of the molecule from the fibrin wafer.

Furosine Posed Toxic Effects on Primary Sertoli Cells through Regulating Cep55/NF-κB/PI3K/Akt/FOX01/TNF-α Pathway

As one of the Maillard reaction products, furosine has been widely reported in a variety of heat-processed foods, while the toxicity of furosine on the reproductive system and related mechanisms are unclear. Here, we constructed an intragastric gavage male mice model (42-day administration, 0.1/0.25/0.5 g furosine/Kg body weight per day) to investigate its effects on mice testicle index, hormones in serum, and mice sperm quality. Besides, the lipid metabonomics analysis was performed to screen out the special metabolites and relatively altered pathways in mice testicle tissue. Mice primary sertoli cells were separated from male mice testicle to validate the role of special metabolites in regulating pathways. We found that furosine affected testicle index, hormones expression level and sperm quality, as well as caused pathological damages in testicle tissue. Phosphatidylethanolamine (PE) (18:0/16:1) was upregulated by furosine both in mice testicle tissue and in primary sertoli cells, meanwhile, PE(18:0/16:1) was proved to activate Cep55/NF-κB/PI3K/Akt/FOX01/TNF-α pathway, and as a functional protein in dairy products, lactoferrin could inhibit expression of this pathway when combined with furosine. In conclusion, for the first time we validated that furosine posed toxic effects on mice sperms and testicle tissue through upregulating PE(18:0/16:1) and activating Cep55/NF-κB/PI3K/Akt/FOX01/TNF-α pathway.

Lactoferrin Induces the Synthesis of Vitamin B6 and Protects HUVEC Functions by Activating PDXP and the PI3K/AKT/ERK1/2 Pathway

As a nutritional active protein in foods, multiple studies of the biological activities of lactoferrin had been undertaken, including antioxidant, antiviral, anti-inflammatory, antitumor, antibiosis, and antiparasitic effects, while the mechanism related with its protection of cardiovascular system remained elusive. In the present work, the effect of lactoferrin on the viability of HUVECs (human umbilical vein endothelial cells) was detected to select the proper doses. Moreover, transcriptomics detection and data analysis were performed to screen out the special genes and the related pathways. Meanwhile, the regulation of lactoferrin in the functional factors thromboxane A₂ (TXA₂) and prostacyclin (PGI₂) was detected. Then, the small interfering RNA (SiRNA) fragment of the selected gene pyridoxal phosphatase (PDXP) was transfected into HUVECs to validate its role in protecting HUVECs function. Results showed that lactoferrin inhibited the expression of TXA2 and activated expression of PGI₂, as well as activated expression of PDXP, which significantly up-regulated the synthesis of vitamin B6 (VB6) and the phosphoinositide 3-kinase (PI3K)/ serine/threonine-protein kinase (AKT)/ extracellular regulated protein kinases (ERK) 1/2 pathway. For the first time, we revealed that lactoferrin could induce the synthesis of VB6 and protect HUVECs function through activating PDXP gene and the related pathway.

Effect of Heat Treatment on the Antitumor Activity of Lactoferrin in Human Colon Tumor (HT29) Model

To investigate the effect of heat treatment on the antitumor activity of lactoferrin in colon cancer cells and colon tumors, the HT-29 (human intestinal epithelial tumor cell) cell line was exposed to lactoferrin and various heat treatments. The impacts on cell proliferation, invasion, and migration were observed in vitro, and nude mice bearing HT29 tumors were administered lactoferrin and underwent various heat treatments in vivo. In the HT29 cell proliferation test using transwell and scratch analyses, lactoferrin (20 mg/mL) without or with heat treatment (50 and 70 °C) significantly inhibited cell proliferation, migration, and invasion (compared with the control, p < 0.05), while lactoferrin with heat treatment (100 °C) did not affect these parameters. In vivo, HT29 tumor weight was significantly reduced in the lactoferrin (without heat treatment and with 50 and 70 °C treatment) groups (1.59 ± 0.20, 1.67 ± 0.25, and 2.41 ± 0.42 g, compared with the control, p < 0.05), and there was no significant difference between the control (3.73 ± 0.33 g) and the 100 °C treatment group (3.58 ± 0.29 g). Moreover, 100 °C heat treatment reduced inhibition of the VEGFR2/VEGFA/PI3K/Akt/Erk1/2 angiogenesis pathway by lactoferrin. In summary, HT29 tumors were effectively suppressed by lactoferrin via inhibition of VEGFR2/VEGFA/PI3K/Akt/Erk1/2 pathway, and heat treatment affected the antitumor activity of lactoferrin in a temperature-dependent manner.

Oral Administration of Silk Peptide Enhances the Maturation and Cytolytic Activity of Natural Killer Cells

Silk peptide, the hydrolysate of silk protein derived from cocoons, has been employed as a biomedical material and is believed to be safe for human use. Silk peptide display various bioactivities, including anti-inflammatory, immune-regulatory, anti-tumor, anti-viral, and anti-bacterial. Although earlier investigations demonstrated that silk peptide stimulates macrophages and the production of pro-inflammatory cytokines, its effect on natural killer (NK) cell function has not yet been explored. In this study, we initially confirmed that silk peptide enhances NK cell activity in vitro and ex vivo. To assess the modulatory activity of silk peptide on NK cells, mice were fed various amounts of a silk peptide-supplemented diet for 2 months and the effects on immune stimulation, including NK cell activation, were evaluated. Oral administration of silk peptide significantly enhanced the proliferation of mitogen- or IL-2-stimulated splenocytes. In addition, oral silk peptide treatment enhanced the frequency and degree of maturation of NK cells in splenocytes. The same treatment also significantly enhanced the target cell cytolytic activity of NK cells, which was determined by cell surface CD107a expression and intracellular interferon-γ expression. Finally, oral administration of silk peptide stimulated T helper 1-type cytokine expression from splenic lymphocytes. Collectively, our results suggest that silk peptide potentiates NK cell activity in vivo and could be used as a compound for immune-modulating anti-tumor treatment.

Lactoferrin Exerts Antitumor Effects by Inhibiting Angiogenesis in a HT29 Human Colon Tumor Model

To investigate the effect and potential mechanisms of lactoferrin on colon cancer cells and tumors, HT29 and HCT8 cells were exposed to varying concentrations of lactoferrin, and the impacts on cell proliferation, migration, and invasion were observed. Cell proliferation test showed that high dosage of lactoferrin (5-100 mg/mL) inhibited cell viability in a dose-dependent manner, with the 50% concentration of inhibition at 81.3 ± 16.7 mg/mL and 101 ± 23.8 mg/mL for HT29 and HCT8 cells, respectively. Interestingly, migration and invasion of the cells were inhibited dramatically by 20 mg/mL lactoferrin, consistent with the significant down regulation of VEGFR2, VEGFA, pPI3K, pAkt, and pErk1/2 proteins. HT29 was chosen as the sensitive cell line to construct a tumor-bearing nude mice model. Notably, HT29 tumor weight was greatly reduced in both the lactoferrin group (26.5 ± 6.7 mg) and the lactoferrin/5-Fu group (14.5 ± 5.1 mg), compared with the control one (39.3 ± 6.5 mg), indicating that lactoferrin functioned as a tumor growth inhibitor. Considering lactoferrin also reduced the growth of blood vessels and the degree of malignancy, we concluded that HT29 tumors were effectively suppressed by lactoferrin, which might be achieved by regulation of phosphorylation from various kinases and activation of the VEGFR2-PI3K/Akt-Erk1/2 pathway.

Lactoferrin and prematurity: a promising milk protein?

Lactoferrin (Lf) is the major whey protein in milk, with multiple beneficial health effects including direct antimicrobial activities, anti-inflammatory effects, and iron homeostasis. Oral Lf supplementation in human preterm infants has been shown to reduce the incidence of sepsis and necrotizing enterocolitis. In preclinical models of antenatal stress and perinatal brain injury, bovine Lf protected the developing brain from neuronal loss, improved connectivity, increased neurotrophic factors, and decreased inflammation. It also supported brain development and cognition. Further, Lf can prevent preterm delivery by reducing proinflammatory factors and inhibiting premature cervix maturation. We review here the latest research on Lf in the field of neonatology.

Lactoferrin, a Pleiotropic Protein in Health and Disease

SIGNIFICANCE

Lactoferrin (Lf) is a nonheme iron-binding glycoprotein strongly expressed in human and bovine milk and it plays many functions during infancy such as iron homeostasis and defense against microorganisms. In humans, Lf is mainly expressed in mucosal epithelial and immune cells. Growing evidence suggests multiple physiological roles for Lf after weaning.

RECENT ADVANCES

The aim of this review is to highlight the recent advances concerning multifunctional Lf activities.

CRITICAL ISSUES

First, we will provide an overview of the mechanisms related to Lf intrinsic synthesis or intestinal absorption as well as its interaction with a wide spectrum of mammalian receptors and distribution in organs and cell types. Second, we will discuss the large variety of its physiological functions such as iron homeostasis, transportation, immune regulation, oxidative stress, inflammation, and apoptosis while specifying the mechanisms of action. Third, we will focus on its recent physiopathology implication in metabolic disorders, including obesity, type 2 diabetes, and cardiovascular diseases. Additional efforts are necessary before suggesting the potential use of Lf as a diagnostic marker or as a therapeutic tool.

FUTURE DIRECTIONS

The main sources of Lf in human cardiometabolic disorders should be clarified to identify new perspectives for future research and develop new strategies using Lf in therapeutics. Antioxid. Redox Signal. 24, 813-836.

Anticancer effects of lactoferrin: underlying mechanisms and future trends in cancer therapy

Lactoferrin has been widely studied over the last 70 years, and its role in diverse biological functions is now well known and generally accepted by the scientific community. Usually, alterations of the lactoferrin gene in cells are associated with an increased incidence of cancer. Several studies suggest that exogenous treatment with lactoferrin and its derivatives can efficiently inhibit the growth of tumors and reduce susceptibility to cancer. None of these studies, however, reported a consistent outcome with regard to the mechanisms underlying the anticancer effects of lactoferrin. In this review, the association of lactoferrin with cancer is thoroughly discussed, from lactoferrin gene expression to the potential use of lactoferrin in cancer therapy. Lactoferrin cytotoxicity against several cancers is reported to occur in distinct ways under different conditions, namely by cell membrane disruption, apoptosis induction, cell cycle arrest, and cell immunoreaction. Based on these mechanisms, new strategies to improve the anticancer effects of the lactoferrin protein and/or its derivatives are proposed. The potential for lactoferrin in the field of cancer research (including as a chemotherapeutic agent in cancer therapy) is also discussed.

The effect of carbohydrate moiety structure on the immunoregulatory activity of lactoferrin in vitro

The aim of this study was to evaluate the immunoregulatory effects of recombinant human lactoferrin (rhLF) in two in vitro models: (1) the secondary humoral immune response to sheep erythrocytes (SRBC); and (2) the mixed lymphocyte reaction (MLR). We compared the non-sialylated glycoform of rhLF as expressed by glycoengineered Pichia pastoris with one that was further chemically sialylated. In an earlier study, we showed that sialylated rhLF could reverse methotrexate-induced suppression of the secondary immune response of mouse splenocytes to SRBC, and that the phenomenon is dependent on the interaction of lactoferrin (LF) with sialoadhesin (CD169). We found that the immunorestorative activity of sialylated rhLF is also dependent on its interaction with the CD22 antigen, a member of the immunoglobulin superfamily that is expressed by B lymphocytes. We also demonstrated that only sialylated rhLF was able to inhibit the MLR reaction. MLR was inhibited by bovine lactoferrin (bLF), a glycoform that has a more complex glycan structure. Desialylated bLF and lactoferricin, a bLF-derived peptide devoid of carbohydrates, did not express such inhibitory activity. We showed that the interaction of LF with sialic acid receptors is essential for at least some of the immunoregulatory activity of this glycoprotein.

Effects of Lactoferrin on IL-6 Production by Peritoneal and Alveolar Cells in Cyclophosphamide-Treated Mice

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.

Restoration of immune system function is accelerated in immunocompromised mice by the B-cell-tropic isoxazole R-11

BACKGROUND

Restoration of impaired immune response in immunocompromised patients is a crucial problem. In this study we evaluated the efficacy of isoxazole R-11 in reconstitution of the immune response in immunosuppressed mice.

METHODS

Mice were given a sublethal dose (250 mg/kg b.w.) of cyclophosphamide (CP). The cellular immune response to ovalbumin (OVA) and the humoral immune response to sheep erythrocytes (SRBC) were generated. R-11 was administered at repetitive, intraperitoneal doses (20 μg/mouse) until determination of the immune responses: 7 and 15 doses on alternate days for cellular and humoral immune response, respectively. For phenotypic studies R-11 was given per os, at a single dose of 20 μg/mouse. The ability of R-11 to affect interleukin- 6 (IL-6) production was determined in the whole human blood cell culture.

RESULTS

R-11 increased the content of CD19+ cells in the spleens and lymph nodes with a concomitant decrease of CD3+ and CD4+ cells. The compound significantly accelerated restoration of both cellular and humoral immune responses, elevated the numbers of circulating leukocytes and splenocytes and normalized the blood cell picture. Supplementary experiments showed that R-11 was not toxic with regard to human peripheral blood mononuclear cells (PBMC) and that it upregulated IL-6 production in blood cell culture stimulated with lipopolysaccharide (LPS).

CONCLUSIONS

We demonstrated that R-11 is likely a B-cell tropic agent which can restore both cellular and humoral immune responses in immunocompromised mice and may have a potential to be applied in therapy of immunocompromised patients.

Intestinal receptor targeting for peptide delivery: an expert's personal perspective on reasons for failure and new opportunities

The technology has been available more than 25 years that would enable the oral delivery of vaccines, proteins and peptides, thus avoiding the need for injection. To this day, injection is still the mode of delivery, yet not the main mode of choice. This review focuses on several of the potential modes for oral delivery of peptides, proteins and vaccines. Additionally, the review will provide the reader with an insight into the problems and potential solutions for several of these modes of oral delivery of peptides and proteins.

Antitumor and immunopotentiating activity of polysaccharide PST001 isolated from the seed kernel of Tamarindus indica: an in vivo study in mice

Antitumor activity of polysaccharide PST001 isolated from the seed kernel of Tamarindus indica was evaluated using different cancer cell lines. Human cancer cell lines A549, KB, and MCF-7 and murine cancer cell lines DLA and EAC were treated with PST001 and cell growth inhibition was assessed by MTT assay. In vivo studies were carried out for toxicity, tumor reduction and immunomodulation. The respective IC₅₀ of PST001 in A549, KB, and DLA was at 80.72, 190.99, and 91.14 μg/mL. Significant tumor reduction was obtained in both DLA and EAC tumors on treatment with PST001 which was more prominent when PST001 was administered with CTX/5-fluorouracil. Increase in total WBC, CD4⁺ T-cell population, and bone marrow cellularity suggested strong immunomodulatory activity for this compound. No significant abnormality was observed in toxicity studies. Thus the results of the present study suggest that PST001 has immunomodulatory and tumor inhibitory activities and has the potential to be developed as an anticancer agent and immunomodulator either as a sole agent or as an adjuvant to other chemotherapeutic drugs.

Clinical studies of lactoferrin in children

Much has been learned in recent years about the mechanisms by which breastfeeding improves child health and survival. However, there has been little progress in using these insights to improve pediatric care. The aim of this study was to review all clinical studies of lactoferrin (LF) in children in an effort to determine which interventions may improve pediatric care or require further research. We conducted a systematic and critical review of published literature and found 19 clinical studies that have used human or bovine LF for different outcomes: iron metabolisms and anemia (6 studies), fecal flora (5 studies), enteric infections (3 studies), common pediatric illnesses (1 study), immunomodulation (3 studies), and neonatal sepsis (1 study). Although the efficacies have varied in each trial, the main finding of all published studies is the safety of the intervention. Protection against enteric infections and neonatal sepsis are the most likely biologically relevant activities of LF in children. Future studies on neonatal sepsis should answer critically important questions. If the data from these sepsis studies are proven to be correct, it will profoundly affect the treatment of low birth weight neonates and will aid in the reduction of child mortality worldwide.

Recombination adenovirus-mediated human lactoferrin cDNA inhibits the growth of human MCF-7 breast cancer cells

OBJECTIVES

Human lactoferrin, an 80 kDa iron-binding glycoprotein, has antitumour effects. We have explored the potential therapeutic role of re-expressing human lactoferrin gene product in human breast cancer.

METHODS

A recombinant adenovirus expressing the human lactoferrin cDNA (ad-hLTF) was constructed and used to infect breast cancer cells.

KEY FINDINGS

Seventy-two hours after infection, ad-hLTF had considerable cytotoxicity on MCF-7 cells. A time-course study showed that ad-hLTF infection of MCF-7 cells at 100 plaque-forming units per cell increased the number of cells in G(0) /G(1) phase and appeared markedly at Sub-G(1) apoptotic peak. The presence of apoptotic cells was confirmed using Annexin V-fluoresecein isothiocyanate apoptosis detection by flow cytometry. Ad-hLTF also resulted in a decrease of Bcl-2 protein and an increase in Bax protein.

CONCLUSIONS

Ad-hLTF plays an important role in the induction of cell cycle arrest and apoptosis in MCF-7 cells. The results demonstrated that ad-hLTF could have potential benefits in the treatment of breast cancer.

Resistance to Toxoplasma gondii infection in mice treated with silk protein by enhanced immune responses

This study investigated whether elevated host immune capacity can inhibit T. gondii infection. For this purpose, we used silk protein extracted from Bombyx mori cocoons as a natural supplement to augment immune capacity. After silk protein administration to BALB/c mice for 6 weeks, ratios of T lymphocytes (CD4⁺ and CD8⁺ T-cells) and splenocyte proliferative capacities in response to Con A or T. gondii lysate antigen (TLA) were increased. Of various cytokines, which regulate immune systems, Th1 cytokines, such as IFN-γ, IL-2, and IL-12, were obviously increased in splenocyte primary cell cultures. Furthermore, the survival of T. gondii (RH strain)-infected mice increased from 2 days to 5 or more days. In a state of immunosuppression induced by methylprednisolone acetate, silk protein-administered mice were resistant to reduction in T-lymphocyte (CD4⁺ and CD8⁺ T-cells) numbers and the splenocyte proliferative capacity induced by Con A or TLA with a statistical significance. Taken together, our results suggest that silk protein augments immune capacity in mice and the increased cellular immunity by silk protein administration increases host protection against acute T. gondii infection.

Inhibition of tumor growth by recombinant adenovirus containing human lactoferrin through inducing tumor cell apoptosis in mice bearing EMT6 breast cancer

Human lactoferrin (hLTF), an 80-kDa iron-binding glycoprotein, has antitumor activity. In this study, a recombinant adenovirus containing the human lactoferrin cDNA (ad-rhLTF) was constructed and its effect on tumor growth was investigated in mice bearing EMT6 breast cancer. Ad-rhLTF was injected seven times within 14 days into the tumor site at two concentrations (10(8) and 5 × 10(8) pfu/mL) in mice bearing EMT6 breast cancer. Injected ad-rhLTF had considerable cytotoxicity on mice breast cancer, and significantly reducing the weight of tumor produced and increasing the tumor inhibition rate up to 52.64%. The presence of apoptotic cells was confirmed using TUNEL staining and flow cytometry assays. At the same time, RTPCR and Western blot analyses demonstrated that ad-rhLTF also decreased expression of Bcl-2 and increased Bax and caspase 3 expressions. Therefore, we conclude that ad-rhLTF inhibits tumor growth by inducing tumor cell apoptosis in mice with breast cancer by triggering the mitochondrial-dependent pathway and activation of caspase 3. The results indicate that ad-rhLTF might be a promising drug for breast cancer gene therapy.

Lactoferrin Augmentation of the BCG Vaccine Leads to Increased Pulmonary Integrity

The goal of vaccination to prevent tuberculosis disease (TB) is to offer long-term protection to the individual and the community. In addition, the success of any protective TB vaccine should include the ability to limit cavitary formation and disease progression. The current BCG vaccine protects against disseminated TB disease in children by promoting development of antigenic-specific responses. However, its efficacy is limited in preventing postprimary pulmonary disease in adults that is responsible for the majority of disease and transmission. This paper illustrates the use of lactoferrin as an adjuvant to boost efficacy of the BCG vaccine to control organism growth and limit severe manifestation of pulmonary disease. This resulting limitation in pathology may ultimately, limit spread of bacilli and subsequent transmission of organisms between individuals. The current literature is reviewed, and data is presented to support molecular mechanisms underlying lactoferrin's utility as an adjuvant for the BCG vaccine.

A critical review of the roles of host lactoferrin in immunity

Lactoferrin (Lf) is an essential element of innate immunity, which refers to antigen-nonspecific defense mechanisms that a host uses immediately or within hours after exposure to an antigen. Following infection, Lf is released from neutrophils (PMNs) in blood and inflamed tissues and, such as other soluble pattern-recognition receptors of the innate immunity, Lf recognizes unique microbial molecules called pathogen-associated molecular patterns (PAMPs): LPS from the gram-negative cell wall and bacterial unmethylated CpG DNA. However, unlike classical PAMPs receptors involved in the activation of immune cells, Lf may act either as a competitor for these receptors or as a partner molecule, depending on the physiological status of the organism. These immunomodulatory properties are explained by the ability of Lf to interact with proteoglycans and receptors on the surface of mammalian cells: cells of the innate (NK cells, neutrophils, macrophages, basophils, neutrophils and mast cells) and adaptive [lymphocytes and antigen-presenting cells (APCs)] immune systems, and also epithelial and endothelial cells. Through these interactions, Lf is able to modulate the migration, maturation and functions of immune cells, and thus to influence both adaptive and innate immunities. The understanding of the roles of the host-expressed Lf in immunity comes from in vivo and in vitro studies with exogenous Lf which, although informative, rarely reflect the pathological, or non-pathological, conditions in the organism. In this review, the data from the literature will be critically analyzed in order to present a real picture of the regulatory roles of host Lf in immunity.

A novel immunoregulatory protein in human colostrum, syntenin-1, for promoting the development of IgA-producing cells from cord blood B cells

Human colostrum contains many bioactive factors that must promote the development of intestinal mucosal immunity in infants. Especially, the presence of certain cytokines such as transforming growth factor (TGF)-beta or IL-10 has been of great interest for IgA production as a function of mucosal immune response. In the present study, we attempted to investigate whether unidentified factors inducing generation of IgA-producing cells from naive B cells might exist in colostrum. For this purpose, colostrum samples were directly added to a culture consisting of naive B cells and dendritic cells from cord blood and CD40 ligand-transfected L cells, comparing with recombinant IL-10 (rIL-10) and/or rTGF-beta. It was noted that most colostrum samples alone were able to induce IgA-secreting cells at higher levels than rIL-10 and/or rTGF-beta. IgA-inducing activity of colostrum was abolished by neither anti-neutralizing mAbs against IL-10 nor TGF-beta, though partially by anti-IL-6 mAb. We prepared partially purified fractions from both pooled colostrums with and without IgA-inducing activity and comparatively performed quantitative proteomic analysis by two-dimensional difference gel electrophoresis followed by liquid chromatography-mass spectrometry. As a result, syntenin-1 was identified as a candidate for IgA-inducing protein in colostrum. Western blot analysis indicated that levels of syntenin-1 in colostrum samples were correlated with their IgA-inducing activities. Moreover, we demonstrated that recombinant syntenin-1 could induce preferentially IgA production from naive B cells. These results suggest that syntenin-1 serves as one of IgA-inducing factors for B cells.

Effects of prophylactic administration of bacteriophages to immunosuppressed mice infected with Staphylococcus aureus

BACKGROUND

Bacteriophages can be successfully applied to treat infections caused by antibiotic-resistant bacteria. Until now no attempts have been undertaken to treat infections in immunosuppressed patients with phages. In this work we investigated the prophylactic efficacy of specific bacteriophages in CBA mice treated with cyclophosphamide (CP) and infected with Staphylococcus aureus.

RESULTS

High numbers of bacterial colony-forming units in the organs as well as elevated tumor necrosis factor and interleukin-6 serum concentrations in CP-treated and S. aureus-infected mice were significantly lowered upon application of phages. The phages markedly increased the percentage of circulating neutrophils and immature cells from the myelocytic and lymphocytic lineages in CP-treated, S. aureus-infected mice as well as of myelocytes and immature neutrophils in the bone marrow. In addition, phages stimulated in such mice generation of specific agglutinins against S. aureus.

CONCLUSION

Application of specific phages to immunosuppressed mice prior to infection with S. aureus proved very effective, suggesting a potential benefit of phage therapy in immunocompromised patients experiencing bacterial infections.

Histological and immunohistochemical evaluation of duodenal and colonic biopsies after oral bovine lactoferrin supplementation in beagle puppies

Lactoferrin is a natural compound in the milk of mammals and was shown to influence the intestinal micro-flora and the immune system in mice, calves, dogs and man. The present study was carried out to investigate the effect of orally administered bovine lactoferrin (0, 30, 60 and 120 mg/kg DM feed) on the intestinal morphology and lymphocyte colonization in 36 motherless raised puppies. Endoscopic biopsies from duodenum and colon, taken in week 14, were scored histologically after staining with haematoxylin and eosin (H&E) and lymphocytes (CD3+, CD4+, CD8+) and plasma cells (IgA+, IgG+, IgM+) were enumerated after immunohistochemical staining by computer-aided quantification. Histological scoring revealed no significant differences amongst the groups. IgG+ plasma cells were reduced (p < 0.05) in the lamina propria of the colon of the 30 and the 60 mg group. The number of CD8+ lymphocytes was higher (p < 0.05) in the epithelium of the colon of the lactoferrin groups. In conclusion, this study indicated only minimal effects of bovine lactoferrin on the population of selected immune cells in the gut mucosa of puppies. More investigations are needed to describe the impact of lactoferrin on the digestive physiology of puppies.

Soybean protein fraction digested with neutral protease preparation, "Peptidase R", produced by Rhizopus oryzae, stimulates innate cellular immune system in mouse

A soybean protein fraction was prepared from defatted soybean seed flour and digested with 29 kinds of commercially available protease originating from preparations of animals, plants, and microorganisms. Some digests, in particular, Ro-digest prepared using a Rhizopus oryzae neutral protease preparation (Peptidase R), displayed strong mitogenic activity toward C3H/HeN mouse spleen cells. The number of spleen CD11b+, CD49b+, interleukin (IL)-12+CD11b+, and interferon (IFN)-gamma+CD49b+ cells significantly increased when cultured with Ro-digest. Similarly, the number of spleen IFN-gamma+CD4+ cells significantly increased in the presence of Ro-digest while that of spleen IL-4+CD4+ cells was largely unchanged. Additionally, 5-week-old male C3H/HeN mice were given diets consisting of ovalbumin (OVA) alone (control diet) or a mixture of OVA and Ro-digest (Ro-digest-added diet) as a protein source for 5 weeks, and the immune properties of the mice were investigated. The number of IL-12+CD11b+ cells was greater in spleens from mice given the Ro-digest-added diet than in those given the control diet. The cytotoxic activity of spleen cells toward the human erythroleukemia cell line, K562, was significantly higher in mice given the Ro-digest-added diet than in those given the control diet. Furthermore, in a microarray analysis of mRNAs extracted from mice Peyer's patch cells, gene expression related to innate immune responses was increased in mice given the Ro-digest-added diet. These results indicate that the Ro-digest might stimulate cellular immune systems, in particular, an innate immunity in mice.

Effect of bovine lactoferrin on functions of activated feline peripheral blood mononuclear cells during chronic feline immunodeficiency virus infection

Feline immunodeficiency virus (FIV) infection is characterized by chronic overactivation of immune and inflammatory system, resulting in anergic state and dysfunction of immune cells. Lactoferrin (LF), a glycoprotein present in exocrine secretions and neutrophils, plays an important role in host defense system. Our previous study showed that oral administration of bovine LF (bLF) suppressed oral inflammation, improved the clinical symptoms and decreased serum gamma-globulin as a marker of inflammation in FIV-infected cats with intractable stomatitis. The anti-inflammatory effect was partly involved in regulation of neutrophil function by bLF. In this study, to clarify the relationship between anti-inflammatory effects of bLF and peripheral blood mononuclear cells (PBMC), we examined the effect of bLF on proliferation, cell cycle progression and cytokine expression in mitogen-activated PBMC. MTT [3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyl tetrazolium bromide] assay showed that bLF inhibited the concanavalin A (ConA)-induced cell proliferation in FIV-infected cats with the asymptomatic carrier and AIDS-related complex (ARC) phase. Bovine LF restored ConA-induced cell cycle progression and resulted in suppression of the induced apoptosis in feline PBMC. Real-time RT-PCR showed that bLF suppressed ConA-induced expression of interferon-gamma and interleukin-2 in cells of the ARC group regardless of the time of its addition to the medium. These results suggest the hypothesis that therapy with bLF may have the potential to improve and protect functions of overactivated lymphocytes by modulating the cell proliferation, cell cycle and cytokines expression in cats in terminal stage of FIV infection.

Emerging health properties of whey proteins and their clinical implications

The nursery rhyme "Little Miss Muffet sat on a tuffet (small stool) eating her curds and whey. ..." is recognition of the fact that over the centuries "curds and whey", the two major components of cow's milk, have been widely accepted as part of a healthy diet. Milk provides complete nourishment for the neonate for six months from birth, containing factors that help develop various organ systems including the brain, immune system, and the intestine. Importantly it provides immune protection at a time when the neonates own immune system, though fully developed, is albeit immature. Many adult consumers include cow's milk as part of a healthy diet as it provides protein and essential nutrients, vitamins, and minerals, in particular calcium for strong bones. There is a growing appreciation that milk, and in particular whey, contains components that not only provide nutrition, but can also prevent and attenuate disease, or augment conventional therapies, when delivered in amounts that exceed normal dietary intakes. This paper reviews the emerging health properties of whey proteins and their clinical implications.

[Lactoferrin reduces physiological dysfunctions of goldfish induced by chemotherapeutic agents]

We investigated whether the deleterious side effects of chemotherapeutic agents on the physiologic functions of fish could be modulated by lactoferrin (LF). Goldfish, weighing about 25 g, were treated intramuscularly with methotrexate (MTX: 2.5 mg/kg body weight) and fluorouracil (FU: 15 or 50 mg/kg body weight) three times every other day. In control fish fed a commercial diet, MTX induced severe immunosuppression, increased the number of total bacteria and Enterobacteriaceae in the intestinal tract, and caused intestinal damage such as lowered and thickened mucosa and thinned muscularis externa, with moderate renal dysfunction. A few fish treated with MTX died. In fish injected with FU or FU plus MTX, the side effects were slightly less in comparison with those in the MTX group. Pretreatment with LF (oral administration at 200 mg/kg body weight/day) for 3 weeks reduced the deleterious side effects of MTX and FU. One intraperitoneal injection of LF (200 mg/kg body weight) immediately after the first MTX injection also reduced the side effects. These results show that LF reduces the physiologic dysfunction of fish treated with chemotherapeutic agents.

Effect of dietary lactoferrin on the immune functions and serum iron level of weanling piglets

A total of 90 weanling female pigs (Duroc x Landrace x Yorkshire) were used in a 30-d growth experiment to investigate the effect of lactoferrin (LF) on growth performance, immune function, and serum iron concentrations. The pigs were allocated on the basis of BW and litter to 3 dietary treatments in a randomized complete block design. The dietary treatments were: control group (basal diet), antibiotics group (basal diet + 20 mg/kg of flavomycin + 110 mg/kg of aureomycin), and LF group (basal diet + 1.0 g/kg of LF). There were 3 replicate pens per treatment, and pigs were grouped with 10 pigs per pen. Six pigs, randomly selected from each treatment (2 pigs/pen), were slaughtered for serum and spleen samples on d 15 and 30. Supplementation with LF improved the phytohemagglutinin (PHA)-stimulated peripheral lymphocyte proliferation by 36% (P < 0.01), increased concanavalin A (ConA)- and PHA-induced spleen lymphocyte proliferation by 332% (P < 0.01) and 258% (P < 0.01), enhanced serum IgG by 20% (P < 0.05), IgA by 13% (P < 0.05), IgM by 15% (P < 0.05), complement 4 (C4) by 29% (P < 0.05), IL-2 by 12% (P < 0.01), and serum iron values by 22% (P < 0.05) on d 15 compared with the control. Lactoferrin supplementation increased PHA-stimulated lymphocyte proliferation (P < 0.01), serum IgG by 16% (P < 0.05), IgA by 17% (P < 0.05), C4 by 11% (P < 0.05), IL-2 by 14% (P < 0.05), and serum iron values by 23% (P < 0.01), and decreased the diarrhea ratio (P < 0.05) relative to the control on d 30. Compared with the controls, supplementation with antibiotic increased ConA- and PHA-induced spleen lymphocyte proliferation (P < 0.05) on d 15, decreased the diarrhea ratio (P < 0.05), and increased the PHA-induced spleen lymphocyte proliferation (P < 0.05) and serum iron values (P < 0.01) on d 30. These results support the possible use LF as an immunostimulant to improve immune functions and strengthen host defenses and would seem to be a good method for defending weanling piglets from infections and weanling stress.

A double-blind, placebo-controlled, pilot study of bovine lactoferrin supplementation in bottle-fed infants

BACKGROUND

Lactoferrin has an array of biological activities that include growth, immune modulation, and antimicrobial effects. The aim of this randomized, placebo-controlled, double-blind study was to examine the impact of bovine lactoferrin supplementation in infants.

PATIENTS AND METHODS

Healthy, formula-fed infants, > or =34 weeks' gestation and < or =4 weeks of age, enrolled in a pediatric clinic. Infants received either formula supplemented with lactoferrin (850 mg/L) or commercial cow milk-based formula (102 mg/L) for 12 months. Growth parameters and information on gastrointestinal, respiratory, and colic illnesses were collected for the infants' first year. Antibodies to immunizations and hematologic parameters were measured at 9 and 12 months.

RESULTS

The lactoferrin-enhanced formula was well tolerated. There were significantly fewer lower respiratory tract illnesses, primarily wheezing, in the 26 lactoferrin-fed (0.15 episodes/y) compared with the 26 regular formula-fed (0.5 episodes/y) infants (P < 0.05). Significantly higher hematocrit levels at 9 months (37.1% vs 35.4%; P < 0.05) occurred in the lactoferrin-supplemented group compared with the control formula group.

CONCLUSIONS

Lactoferrin supplementation was associated with potentially beneficial outcomes such as significantly fewer lower respiratory tract illnesses and higher hematocrits. Larger, more focused studies in infants are warranted.

Effects of bovine colostrum supplementation on immune variables in highly trained cyclists

The aim of this study was to investigate the influence of low-dose bovine colostrum protein concentrate (CPC) supplementation on selected immune variables in cyclists. Twenty-nine highly trained male road cyclists completed an initial 40-km time trial (TT(40)) and were then randomly assigned to either a supplement (n = 14, 10 g bovine CPC/day) or placebo group (n = 15, 10 g whey protein concentrate/day). After 5 wk of supplementation, the cyclists completed a second TT(40). They then completed 5 consecutive days of high-intensity training (HIT) that included a TT(40), followed by a final TT(40) in the following week. Venous blood and saliva samples were collected immediately before and after each TT(40), and upper respiratory illness symptoms were recorded over the experimental period. Compared with the placebo group, bovine CPC supplementation significantly increased preexercise serum soluble TNF receptor 1 during the HIT period (bovine CPC = 882 +/- 233 pg/ml, placebo = 468 +/- 139 pg/ml; P = 0.039). Supplementation also suppressed the postexercise decrease in cytotoxic/suppressor T cells during the HIT period (bovine CPC = -1.0 +/- 2.7%, placebo = -9.2 +/- 2.8%; P = 0.017) and during the following week (bovine CPC = 1.4 +/- 2.9%, placebo = -8.2 +/- 2.8%; P = 0.004). Bovine CPC supplementation prevented a postexercise decrease in serum IgG(2) concentration at the end of the HIT period (bovine CPC = 4.8 +/- 6.8%, P = 0.88; placebo = -9.7 +/- 6.9%, P = 0.013). There was a trend toward reduced incidence of upper respiratory illness symptoms in the bovine CPC group (P = 0.055). In summary, low-dose bovine CPC supplementation modulates immune parameters during normal training and after an acute period of intense exercise, which may have contributed to the trend toward reduced upper respiratory illness in the bovine CPC group.

Interactions of lactoferrin with cells involved in immune function

The antimicrobial activities of lactoferrin (Lf) depend on its capacity to bind iron and on its direct interaction with the surface of microorganisms. Its protective effect also extends to the regulation of the host response to infections. Depending on the immune status of an individual, Lf can have anti-inflammatory properties that downregulate the immune response and prevent septic shock and damage to tissues. It also acts as a promoter of the activation, differentiation, and (or) proliferation of immune cells. Although most of the anti-inflammatory activities are correlated with the neutralization of proinflammatory molecules by Lf, the promoting activity seems to be related to a direct effect of Lf on immune cells. Although the mechanisms that govern these activities are not clearly defined, and probably differ from cell to cell, several cellular targets and possible mechanisms of action are highlighted. The majority of the molecular targets at the surface of cells are multiligand receptors but, interestingly, most of them have been reported as signaling, endocytosis, and nuclear-targeting molecules. This review focuses on the known and putative mechanisms that allow the immunoregulating effect of Lf in its interactions with immune cells.

Lactoferrin activates macrophages via TLR4-dependent and -independent signaling pathways

Lactoferrin (LF) is a component of innate immunity and is known to interact with accessory molecules involved in the TLR4 pathway, including CD14 and LPS binding protein, suggesting that LF may activate components of the TLR4 pathway. In the present study, we have asked whether bovine LF (bLF)-induced macrophage activation is TLR4-dependent. Both bLF and LPS stimulated IL-6 production and CD40 expression in RAW 264.7 macrophages and in BALB/cJ peritoneal exudate macrophages. However, in macrophages from congenic TLR4(-/-) C.C3-Tlr4(lps-d) mice, CD40 was not expressed while IL-6 secretion was increased relative to wild-type cells. The signaling components NF-kappaB, p38, ERK and JNK were activated in RAW 264.7 cells and BALB/cJ macrophages after bLF or LPS stimulation, demonstrating that the TLR4-dependent bLF activation pathway utilizes signaling components common to LPS activation. In TLR4 deficient macrophages, bLF-induced activation of NF-kappaB, p38, ERK and JNK whereas LPS-induced cell signaling was absent. We conclude from these studies that bLF induces limited and defined macrophage activation and cell signaling events via TLR4-dependent and -independent mechanisms. bLF-induced CD40 expression was TLR4-dependent whereas bLF-induced IL-6 secretion was TLR4-independent, indicating potentially separate pathways for bLF mediated macrophage activation events in innate immunity.

A complex of lactoferrin with monophosphoryl lipid A is an efficient adjuvant of the humoral and cellular immune response in mice

Our recent investigations demonstrated adjuvant properties of lactoferrin (LF). Other studies proved efficacy and safety of monophosphoryl lipid A (MPL) as an adjuvant in humans. In an attempt to construct more efficient and safer adjuvants, we evaluated the activity of LF-MPL complex, formed by incubation of LF and MPL from Hafnia alvei at 20:1 w/w ratio, and verified its characteristics by SDS-PAGE analysis. Binding kinetics was determined by surface plasmon resonance analysis using a BIAcore 1000 biosensor system. The efficiency of the complex in enhancing the humoral and cellular immune responses was analyzed in BALB/c mice. The complex stimulated the humoral immune response to ovalbumin (OVA) and sheep red blood cells significantly stronger than both components separately, used at respective doses. In addition, the complex increased the serum levels of IgG, IgG2a and IgG1 OVA-specific antibodies as compared to the actions of LF or MPL alone. In the model of delayed type hypersensitivity (DTH) the strongest immune response was demonstrated with OVA administered subcutaneously, admixed with the complex. Administration of the complex in incomplete Freund's adjuvant, together with a sensitizing dose of antigen, was similarly effective as immunization with complete Freund's adjuvant. The complex also significantly enhanced the DTH response to orally administered Calmette-Guérin bacilli. In summary, the new type of adjuvant, the LF-MPL complex, was described. Its activity surpassed the adjuvant action of both constituents tested separately in the humoral and cellular immune responses in mice. The plausible mode of action of the new adjuvant is discussed.

Lactoferrin accelerates reconstitution of the humoral and cellular immune response during chemotherapy-induced immunosuppression and bone marrow transplant in mice

Experimental evidence from previous studies supports the conclusion that orally administered lactoferrin (LF) restores the immune response in mice treated with a sublethal dose of cyclophosphamide (CP). The aim of this study was to elucidate potential benefit of LF in mice undergoing chemotherapy with busulfan (BU) and CP, followed by intravenous (i.v.) injection of bone marrow cells. CBA mice were treated orally with busulfan (4 mg/kg) for 4 consecutive days, followed by two daily doses of CP delivered intraperitoneally (i.p.) at a dose of 100 mg/kg and reconstituted next day with i.v. injection of 10(7) syngeneic bone marrow cells. One group of these mice was given LF in drinking water (0.5% solution). After treatment, mice were immunized with ovalbumin (OVA) to subsequently measure delayed type hypersensitivity responsiveness and with sheep red blood cells to determine humoral immunity by evaluation of splenic antibody-forming cells. As expected, both humoral and cellular immune responses of mice that were treated with these chemotherapeutic agents was markedly impaired. Here we report that this impairment was remarkably attenuated by oral administration of LF. Humoral immunity fell to levels that were 66-88% lower than that of untreated animals. Humoral immunity of LF-treated animals was equivalent to that of untreated mice within 1 month. Cellular immune responses were inhibited by chemotherapy treatment to a lesser degree, reaching levels that were approximately 50% lower than those of untreated animals. Again, LF mitigated this decrease, resulting in responses that were only slightly lower than those observed in untreated animals. Furthermore, when mice were given a lethal dose of BU (4 x 25 mg daily doses, i.p.) followed by a bone marrow transplant, LF caused enhanced lympho-, erythro-, and myelopoiesis in the bone marrow and appearance of transforming splenic lymphoblasts, similar to effects caused by administration of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF). In summary, our study suggests that LF may be a useful agent to accelerate restoration of immune responsiveness induced by chemotherapy in bone marrow transplant recipients.

Enhanced clearance of Escherichia coli and Staphylococcus aureus in mice treated with cyclophosphamide and lactoferrin

Previous studies on cyclophosphamide (CP)-immunocompromised mice showed accelerated reconstitution of immune system function following oral treatment with lactoferrin (LF). The aim of this investigation was to evaluate the ability of mice, treated with a sublethal dose of CP and given LF, to combat bacterial infections. Mice were injected with a single, intraperitoneal dose of CP (350 mg/kg body weight). One group of CP-treated mice was also given LF in drinking water (0.5% solution) for 14 days. Untreated and LF-treated mice served as controls. On day 15 following CP administration, mice were infected intravenously with 10(8) Escherichia coli or 5 x 10(7) Staphylococcus aureus. Twenty-four hours later, the number of colony-forming units (CFU) in spleens and livers were determined. Phenotypic analysis of blood leukocytes was determined, as well as the ability of splenic and peritoneal cells to produce IL-6 spontaneously and in the presence of lipopolysaccharide (LPS). Treatment with CP, or with CP and LF, led to profound reduction of E. coli CFU in the liver and the spleen; treatment with LF alone had significant inhibitory effects on organ enumerated CFU. S. aureus CFUs were also significantly reduced in spleens of mice treated with CP or CP/LF and, to a lesser degree, after LF alone. These effects were also significantly reduced in the livers. Analysis of blood cellular phenotype revealed total number of peripheral leukocytes was lower in the CP-treated group (52.6%) but not significantly different from control values in CP/LF and LF-treated groups (90.7% and 104.6%, respectively). Conversely, percentage of blood neutrophils was markedly elevated in CP and CP/LF groups--62% and 42.5% vs. 18.4% in controls. These findings were accompanied by production of IL-6 by splenic and peritoneal cells which was significantly increased in CP- and CP/LF-treated groups. It was concluded that the increased clearance of bacteria in the organs of mice treated with CP and CP/LF may result from a rise in the number of neutrophils infiltrating the organs and contributing to accelerated clearance of bacteria. The study also suggests that the ability of cells from CP- and CP/LF-treated mice to produce significantly more IL-6 may also contribute to increased resistance to infections. Lastly, together with our previous data, this study indicates that LF used to reconstitute the antigen-specific immune response in CP-treated mice does not impair their resistance to infection.

Effects of lactoferrin on non-specific immune responses of gilthead seabream (Sparus auratus L.)

The main innate cellular immune responses of gilthead seabream (Sparus auratus L.) leucocytes were evaluated after in vitro incubation with human lactoferrin (Lf). Isolated head-kidney leucocytes were incubated with 0 (control) to 1 mg ml(-1) Lf-supplemented culture medium for 30, 120, 240 or 360 min and assayed for viability, peroxidase content, and respiratory burst, phagocytic and cytotoxic activities. Only respiratory burst activity was found to increase when using the highest Lf concentration (1 mg ml(-1)) and long incubation times (more than 120 min). Seabream were fed Lf-supplemented diets (0, control, 50, 100 or 200 mg kg(-1) diet). After 1 or 2 weeks of administration the leucocyte peroxidase content, respiratory burst, phagocytic and cytotoxic activities as a measure of cellular immune responses, as well as serum peroxidase and complement activity as a measure of humoral immune responses were evaluated. The results showed that Lf feeding at 100 mg kg(-1) diet for 1 week enhanced the cellular innate immune responses although only the cytotoxic activity did so significantly. The humoral immune response was not influenced by Lf feeding. In conclusion, Lf seems to affect innate immune cellular activity, mainly respiratory burst and natural cytotoxic activity. The possible use of Lf as an immunostimulant for farmed gilthead seabream is discussed.

Role of endogenous macrophage inflammatory protein-2 in regulating fever induced by bacterial endotoxin in normal and immunosuppressed rats

During myelosuppressive chemotherapy, Gram-negative bacterial infection with consequent exposure to lipopolysaccharide (LPS) is one of the most important causes of persistent fever. The classical model of the pathogenesis of fever suggests that pro-inflammatory cytokines, produced by leucocytes in the bloodstream in response to exogenous pyrogens such as bacterial LPS, represent the distal mediators of the febrile response. Neutrophils are the first effectors cells and the most prominent leucocyte population involved in acute bacterial infection. Macrophage inflammatory protein (MIP)-2 plays a crucial role in influencing early cell trafficking and neutrophil activation during pathophysiological processes and serves the same chemotactic function as human interleukin-8. In the present study, we investigated the role of MIP-2 in the development of a febrile response induced by LPS in immunocompetent and leukopenic rats. Intraperitoneal injection of LPS in leukopenic rats elicited a biphasic febrile response of rapid onset, the magnitude and duration of which were significantly greater than in immunocompetent animals. The febrile responses to LPS were accompanied by a pronounced induction of serum MIP-2 levels at 1, 2 and 4 h compared with their respective controls. In both normal and leukopenic rats, neutralization of endogenous MIP-2 bioactivity by systemic administration of antirat MIP-2 antibody caused a significant attenuation of the early phase of LPS fever. However, in contrast with normal rats, the second phase of fever was unimpaired by anti-MIP-2 in leukopenic rats. These findings suggest that circulating MIP-2 is involved in the generation of the early phase of LPS fever that contributes to the maintenance of the later phase of fever in immunocompetent, but not leukopenic, rats. Our data support a regulatory role for endogenous MIP-2 in initiating the fever responses to LPS. Furthermore, these results provide evidence that different cellular and humoral mechanisms are implicated in the development of a febrile response triggered by Gram-negative bacterial infections in leukopenic hosts.