Oral administration of lactoferrin reduces colitis in rats via modulation of the immune system and correction of cytokine imbalance

Lactoferrin as a therapeutic agent for attenuating hepatic stellate cell activation in thioacetamide-induced liver fibrosis

Liver fibrosis is a chronic liver disease caused by prolonged liver injuries. Excessive accumulation of extracellular matrix replaces the damaged hepatocytes, leading to fibrous scar formation and fibrosis induction. Lactoferrin (LF) is a glycoprotein with a conserved, monomeric signal polypeptide chain, exhibiting diverse physiological functions, including antioxidant, anti-inflammatory, antibacterial, antifungal, antiviral, and antitumoral activities. Previous study has shown LF's protective role against chemically-induced liver fibrosis in rats. However, the mechanisms of LF in liver fibrosis are still unclear. In this study, we investigated LF's mechanisms in thioacetamide (TAA)-induced liver fibrosis in rats and TGF-β1-treated HSC-T6 cells. Using ultrasonic imaging, H&E, Masson's, and Sirius Red staining, we demonstrated LF's ability to improve liver tissue damage and fibrosis induced by TAA. LF reduced the levels of ALT, AST, and hydroxyproline in TAA-treated liver tissues, while increasing catalase levels. Additionally, LF treatment decreased mRNA expression of inflammatory factors such as Il-1β and Icam-1, as well as fibrogenic factors including α-Sma, Collagen I, and Ctgf in TAA-treated liver tissues. Furthermore, LF reduced TAA-induced ROS production and cell death in FL83B cells, and decreased α-SMA, Collagen I, and p-Smad2/3 productions in TGF-β1-treated HSC-T6 cells. Our study highlights LF's ability to ameliorate TAA-induced hepatocyte damage, oxidative stress, and liver fibrosis in rats, potentially through its inhibitory effect on HSC activation. These findings suggest LF's potential as a therapeutic agent for protecting against liver injuries and fibrosis.

Synergistic Effect of Retinoic Acid and Lactoferrin in the Maintenance of Gut Homeostasis

Lactoferrin (LF) is a glycoprotein that binds to iron ions (Fe2+) and other metallic ions, such as Mg2+, Zn2+, and Cu2+, and has antibacterial and immunomodulatory properties. The antibacterial properties of LF are due to its ability to sequester iron. The immunomodulatory capability of LF promotes homeostasis in the enteric environment, acting directly on the beneficial microbiota. LF can modulate antigen-presenting cell (APC) biology, including migration and cell activation. Nonetheless, some gut microbiota strains produce toxic metabolites, and APCs are responsible for initiating the process that inhibits the inflammatory response against them. Thus, eliminating harmful strains lowers the risk of inducing chronic inflammation, and consequently, metabolic disease, which can progress to type 2 diabetes mellitus (T2DM). LF and retinoic acid (RA) exhibit immunomodulatory properties such as decreasing cytokine production, thus modifying the inflammatory response. Their activities have been observed both in vitro and in vivo. The combined, simultaneous effect of these molecules has not been studied; however, the synergistic effect of LF and RA may be employed for enhancing the secretion of humoral factors, such as IgA. We speculate that the combination of LF and RA could be a potential prophylactic alternative for the treatment of metabolic dysregulations such as T2DM. The present review focuses on the importance of a healthy diet for a balanced gut and describes how probiotics and prebiotics with immunomodulatory activity as well as inductors of differentiation and cell proliferation could be acquired directly from the diet or indirectly through the oral administration of formulations aimed to maintain gut health or restore a eubiotic state in an intestinal environment that has been dysregulated by external factors such as stress and a high-fat diet.

Hen egg white bovine colostrum supplement reduces symptoms of mild/moderate COVID-19: a randomized control trial

Aim

The ability of a hen egg white bovine colostrum supplement to prevent severe COVID-19 was tested in a double-blind randomized control study.

Methods

Adults with mild/moderate COVID-19, risk factors for severe disease, and within 5 days of symptom onset were assigned to the intervention (n = 77) or placebo (n = 79) arms. Symptoms were documented until day 42 post-enrollment and viral clearance was assessed at 11-13 days post-symptom onset.

Results

One participant developed severe COVID-19. The severe-type symptom score was lower in the active arm at 11-13 days post-symptom onset (p = 0.049). Chest pain, fever/chills, joint pain/malaise, and sore throat were significantly less frequent in the active arm. No differences in viral clearance were observed.

Conclusion

The intervention reduced symptoms of mild/moderate COVID-19.

Clinical Trial Registration

DOH-27-062021-9191 (South African National Clinical Trials Register).

The Role of Lactoferrin in Intestinal Health

The intestine represents one of the first barriers where microorganisms and environmental antigens come into tight contact with the host immune system. A healthy intestine is essential for the well-being of humans and animals. The period after birth is a very important phase of development, as the infant moves from a protected environment in the uterus to one with many of unknown antigens and pathogens. In that period, mother's milk plays an important role, as it contains an abundance of biologically active components. Among these components, the iron-binding glycoprotein, lactoferrin (LF), has demonstrated a variety of important benefits in infants and adults, including the promotion of intestinal health. This review article aims to provide a compilation of all the information related to LF and intestinal health, in infants and adults.

Role of Lactoferrin in Treatment of Bile Duct Ligation-Induced Hepatic Fibrosis in Rats: Impact on Inflammation and TGF-β1/Smad2/α SMA Signaling Pathway

Background

Hepatic fibrosis is a major health issue that might lead to hepatic cirrhosis and cancer. One of its main causes is cholestasis, which has been stimulated by bile duct ligation (BDL) to block the bile flow from the liver. As for the treatment, lactoferrin (LF), the iron-binding glycoprotein, has been evaluated in various studies for the treatment of infections, inflammation, and cancer. The current study aims to investigate the curative effects of LF on BDL-induced hepatic fibrosis in rats.

Methods

Rats were randomly allocated into 4 groups: (1) Control sham, (2) BDL: that have been subjected to a surgery of BDL, (3) BDL + LF: 14 days later after surgery; they have been subjected to LF treatment (300 mg/kg/day, po) for two weeks, and (4) LF group has been administered (300 mg/kg/day, po) for two weeks.

Results

BDL elevated inflammatory markers (tumor necrosis factor-alpha and interleukin -1beta (IL-1β) by 635% and 250% (P ≤ 0.05), respectively, as sham group), beside it decreased the anti-inflammatory cytokine, interleukin- 10 (IL-10) by 47.7% (P ≤ 0.05) as sham group, causing inflammation, and fibrosis of the liver by the up-regulation of transforming growth factor-beta 1 (TGF-β1)/Smad2/α-smooth muscle actin (SMA) signaling pathway. LF treatment ameliorated these effects through its anti-inflammatory action (it significantly decreased tumor necrosis factor-alpha and IL-1β by 166% and 159% (P ≤ 0.05), respectively, as sham group, while increased IL-10 by 86.8% (P ≤ 0.05), as sham group) and anti-fibrotic effect by the down-regulation of TGF-β1/Smad2/α-SMA signaling pathway. These results were confirmed by histopathological examination.

Conclusion

lactoferrin shows promising results for the treatment of hepatic fibrosis via attenuating the TGF-β1/Smad2/α-SMA pathway and through its properties.

Lactoferrin alleviates cyclophosphamide induced-nephropathy through suppressing the orchestration between Wnt4/β-catenin and ERK1/2/NF-κB signaling and modulating klotho and Nrf2/HO-1 pathway

AIMS

Cyclophosphamide is an alkylating agent with vast arrays of therapeutic activity. Currently, its medical use is limited due to its numerous adverse events, including nephrotoxicity. This study aimed to follow the molecular mechanisms behind the potential renoprotective action of lactoferrin (LF) against cyclophosphamide (CP)-induced renal injury.

MATERIALS AND METHODS

For fulfillment of our aim, Spragw-Dwaly rats were orally administrated LF (300 mg/kg) for seven consecutive days, followed by a single intraperitoneal injection of CP (150 mg/kg).

KEY FINDINGS

Treatment of CP-injured rats with LF significantly reduced the elevated creatinine and blood urea nitrogen (BUN), markedly upregulated Nrf2/HO-1 signaling with consequent increase in renal total antioxidant capacity (TAC) and decrease in renal malondialdehyde (MDA) level. Furthermore, LF treatment significantly reduced the elevated renal p-ERK1/2 expression, tumor necrosis factor-α (TNFα), interleukin-6 (IL-6), nuclear factor-kappa B (NF-κB) levels in CP-treated animals. Interestingly, LF treatment downregulated Wnt4/β-catenin signaling and increased both renal klotho gene expression and serum klotho level. Furthermore, LF treatment reduced apoptosis in kidney tissue via suppressing GSK-3β expression and modulating caspase-3 and Bcl2 levels. Histopathological examination of kidney tissue confirmed the protective effect of LF against CP-induced renal injury.

SIGNIFICANCE

The present findings document the renoprotective effect of LF against CP-induced nephropathy, which may be mediated via suppressing ERK1/2/ NF-κB and Wnt4/β-catenin trajectories and enhancing klotho expression and Nrf2/HO-1 signaling.

Possible Curative Effects of Boric Acid and Bacillus clausii Treatments on TNBS-Induced Ulcerative Colitis in Rats

Crohn's disease (CD) and ulcerative colitis (UC) are two chronic relapsing inflammatory bowel diseases (IBD). Although there are several treatment options available to improve the symptoms of IBD patients, there is no effective treatment that provides a definitive solution. In the present study, we aim to investigate the antioxidative/anti-inflammatory effects of oral administration of boric acid and Bacillus clausii in a rat trinitrobenzenesulfonic acid (TNBS)-induced colitis model. The effects of boric acid and B. clausii were examined in serum and colon tissues with the help of some biochemical and histological analyses. Elevated inflammation and oxidative damage were found in the blood and colon tissue samples in the TNBS-induced group according to the complete blood count (CBC), tumor necrosis factor (TNF) alpha, interleukin-35 (IL-35), malondialdehyde (MDA), glutathione peroxidase (GPx), myeloperoxidase (MPO), nitric oxide (NO), and histological findings. Particularly, the highest IL-35 level (70.09 ± 12.62 ng/mL) in the combined treatment group, highest catalase activity (5322 ± 668.1 U/mg protein) in the TNBS-induced group, and lower relative expression of inducible nitric oxide synthase in the TNBS-induced group than the control group were striking findings. According to our results, it can be concluded that boric acid showed more curative effects, even if B. clausii probiotics was partially ameliorative.

Effect of Cheese Intake on Cardiovascular Diseases and Cardiovascular Biomarkers

Background: A growing number of cohort studies revealed an inverse association between cheese intake and cardiovascular diseases, yet the causal relationship is unclear. Objective: To assess the causal relationship between cheese intake, and cardiovascular diseases and cardiovascular biomarkers. Methods: A two-sample Mendelian randomization (MR) analysis based on publicly available genome-wide association studies was employed to infer the causal relationship. The effect estimates were calculated using the random-effects inverse-variance-weighted method. Results: Cheese intake per standard deviation increase causally reduced the risks of type 2 diabetes (odds ratio (OR) = 0.46; 95% confidence interval (CI), 0.34–0.63; p = 1.02 × 10⁻⁶), heart failure (OR = 0.62; 95% CI, 0.49–0.79; p = 0.0001), coronary heart disease (OR = 0.65; 95% CI, 0.53–0.79; p = 2.01 × 10⁻⁵), hypertension (OR = 0.67; 95% CI, 0.53–0.84; p = 0.001), and ischemic stroke (OR = 0.76; 95% CI, 0.63–0.91; p = 0.003). Suggestive evidence of an inverse association between cheese intake and peripheral artery disease was also observed. No associations were observed for atrial fibrillation, cardiac death, pulmonary embolism, or transient ischemic attack. The better prognosis associated with cheese intake may be explained by lower body mass index (BMI; effect estimate = −0.58; 95% CI, from −0.88 to −0.27; p = 0.0002), waist circumference (effect estimate = −0.49; 95% CI, from −0.76 to −0.23; p = 0.0003), triglycerides (effect estimate = −0.33; 95% CI, from −0.50 to −0.17; p = 4.91 × 10⁻⁵), and fasting glucose (effect estimate = −0.20; 95% CI, from −0.33 to −0.07; p = 0.0003). There was suggestive evidence of a positive association between cheese intake and high-density lipoprotein. No influences were observed for blood pressure or inflammation biomarkers. Conclusions: This two-sample MR analysis found causally inverse associations between cheese intake and type 2 diabetes, heart failure, coronary heart disease, hypertension, and ischemic stroke.

The cross-talk between soluble "Find me" and "Keep out" signals as an initial step in regulating efferocytosis

The rapid clearance of apoptotic cells (ACs), known as efferocytosis, prompts the inhibition of inflammatory responses and autoimmunity and maintains homeostatic cell turnover by controlling the release of intracellular contents. The fast clearance of ACs requires professional and nonprofessional phagocytic cells that can accurately and promptly recognize ACs and migrate towards them. Cells undergoing apoptosis alarm their presence by releasing special soluble chemotactic factors, such as lactoferrin, that act as "Find me," "Keep out," or "Stay away" signals to recruit phagocytic cells, such as macrophages or prevent granulocyte migration. Efferocytosis effectively serves to prevent damage-associated molecular pattern release and secondary necrosis and inhibit inflammation/autoimmunity at the very first step. Since less attention has been given to the cross-talk and balance of "Find me" and "Keep out" signals released from ACs in efferocytosis, we set out to investigate the current knowledge of the roles of "Find me" and "Keep out" signals in the efferocytosis process.

Genetically engineered pH-responsive silk sericin nanospheres with efficient therapeutic effect on ulcerative colitis

Ulcerative colitis (UC) is one type of inflammatory bowel disease (IBD) and lactoferrin (LF) is a promising protein drug to treat UC. However, targeted LF delivery to optimize bioavailability, targeting and effectiveness remains a challenge. Here, we report an effective strategy to fabricate silk sericin nanospheres systems for the delivery of recombinant human lactoferrin (SS-NS-rhLF). The system is based on the use of optimized transgenic silkworms to generate genetically engineered silk fibers (rhLF-silks). The rhLF silks were used for fabricating SS-NS-rhLF by ethanol precipitation. The SS-NS-rhLF were stable with a spherical morphology with an average diameter of 123 nm. The negatively charged sericins in a pH ≥ 5.5 environment achieved specific targeting of the SS-NS-rhLF to positively charged colonic sites. The SS-NS-rhLF achieved efficient uptake by cells in the inflamed colon of mice when compared to free lactoferrin in solution (SOL-rhLF). Furthermore, oral administration of the SS-NS-rhLF with low dose of rhLF significantly relived symptoms of UC in mice and achieved comparable therapeutic effect to the high dose of SOL-rhLF by supporting the reformation of cell structure and length of colon tissue, reducing the release of inflammatory factors, inhibiting the activation of the NF-κB inflammatory pathway, and maintaining a stable intestinal microbial population in mice. These results showed that the SS-NS-rhLF is a promising system for colitis treatment. STATEMENT OF SIGNIFICANCE: Targeting and effective delivery of multiple biological functional protein human lactoferrin (rhLF) is a promising strategy to treat ulcerative colitis in the clinic. Here, rhLF-transgenic silk cocoons were used to fabricate a rhLF-sericin nanosphere delivery system (SS-NS-rhLF). The fabricated SS-NS-rhLF showed identical spherical morphology, stable structure, sustainable rhLF release, efficient cell uptake and negative charge in an environment of pH above 5.5, thus realized the specific targeting to the positively charged colonic sites to treat UC mice through oral administration. The therapeutic effect of SS-NS-rhLF with a low rhLF dose in the UC mice was comparable to the high dose of free rhLF treatment in solution form, suggesting that the SS-NS-rhLF is a promising system for colitis treatment.

Lactoferrin as Immune-Enhancement Strategy for SARS-CoV-2 Infection in Alzheimer's Disease Patients

Coronavirus 2 (SARS-CoV2) (COVID-19) causes severe acute respiratory syndrome. Severe illness of COVID-19 largely occurs in older people and recent evidence indicates that demented patients have higher risk for COVID-19. Additionally, COVID-19 further enhances the vulnerability of older adults with cognitive damage. A balance between the immune and inflammatory response is necessary to control the infection. Thus, antimicrobial and anti-inflammatory drugs are hopeful therapeutic agents for the treatment of COVID-19. Accumulating evidence suggests that lactoferrin (Lf) is active against SARS-CoV-2, likely due to its potent antiviral and anti-inflammatory actions that ultimately improves immune system responses. Remarkably, salivary Lf levels are significantly reduced in different Alzheimer's disease (AD) stages, which may reflect AD-related immunological disturbances, leading to reduced defense mechanisms against viral pathogens and an increase of the COVID-19 susceptibility. Overall, there is an urgent necessity to protect AD patients against COVID-19, decreasing the risk of viral infections. In this context, we propose bovine Lf (bLf) as a promising preventive therapeutic tool to minimize COVID-19 risk in patients with dementia or AD.

Nutraceuticals and Diet Supplements in Crohn's Disease: A General Overview of the Most Promising Approaches in the Clinic

Crohn's disease (CD) is a chronic inflammatory gastrointestinal disorder requiring lifelong medications. The currently approved drugs for CD are associated with relevant side effects and several studies suggest an increased use of nutraceuticals among CD patients, seeking for what is perceived as a more "natural" approach in controlling this highly morbid condition. Nutraceuticals are foods or foods' components with beneficial health properties that could aid in CD treatment for their anti-inflammatory, analgesic and immunoregulatory activities that come along with safety, high tolerability, easy availability and affordability. Depending on their biological effect, nutraceuticals' support could be employed in different subsets of CD patients, both those with active disease, as adjunctive immunomodulatory therapies, and/or in quiescent disease to provide symptomatic relief in patients with residual functional symptoms. Despite the increasing interest of the general public, both limited research and lack of education from healthcare professionals regarding their real clinical effectiveness account for the increasing number of patients turning to unconventional sources. Professionals should recognize their widespread use and the evidence base for or against their efficacy to properly counsel IBD patients. Overall, nutraceuticals appear to be safe complements to conventional therapies; nonetheless, little quality evidence supports a positive impact on underlying inflammatory activity.

Lactoferrin Prevents Hepatic Injury and Fibrosis via the Inhibition of NF-κB Signaling in a Rat Non-Alcoholic Steatohepatitis Model

Non-alcoholic steatohepatitis (NASH) can cause liver cirrhosis and hepatocellular carcinoma (HCC), with cases increasing worldwide. To reduce the incidence of liver cirrhosis and HCC, NASH is targeted for the development of treatments, along with viral hepatitis and alcoholic hepatitis. Lactoferrin (LF) has antioxidant, anti-cancer, and anti-inflammatory activities. However, whether LF affects NASH and fibrosis remains unelucidated. We aimed to clarify the chemopreventive effect of LF on NASH progression. We used a NASH model with metabolic syndrome established using connexin 32 (Cx32) dominant negative transgenic (Cx32ΔTg) rats. Cx32ΔTg rats (7 weeks old) were fed a high-fat diet and intraperitoneally injected with dimethylnitrosamine (DMN). Rats were divided into three groups for LF treatment at 0, 100, or 500 mg/kg/day for 17 weeks. Lactoferrin significantly protected steatosis and lobular inflammation in Cx32ΔTg rat livers and attenuated bridging fibrosis or liver cirrhosis induced by DMN. By quantitative RT-PCR, LF significantly down-regulated inflammatory (Tnf-α, Il-6, Il-18, and Il-1β) and fibrosis-related (Tgf-β1, Timp2, and Col1a1) cytokine mRNAs. Phosphorylated nuclear factor (NF)-κB protein decreased in response to LF, while phosphorylated JNK protein was unaffected. These results indicate that LF might act as a chemopreventive agent to prevent hepatic injury, inflammation, and fibrosis in NASH via NF-κB inactivation.

The Functional Role of Lactoferrin in Intestine Mucosal Immune System and Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), encompassing ulcerative colitis (UC) and Crohn's disease (CD), is one of the main types of intestinal inflammatory diseases with intestine mucosal immune disorder. Intestine mucosal immune system plays a remarkable and important role in the etiology and pathogenesis of IBD. Therefore, understanding the intestine mucosal immune mechanism is a key step to develop therapeutic interventions for IBD. Intestine mucosal immune system and IBD are influenced by various factors, such as inflammation, gut permeability, gut microbiota, and nutrients. Among these factors, emerging evidence show that nutrients play a key role in inflammation activation, integrity of intestinal barrier, and immune cell modulation. Lactoferrin (LF), an iron-binding glycoprotein belonging to transferrin family, is a dietary bioactive component abundantly found in mammalian milk. Notably, LF has been reported to perform diverse biological functions including antibacterial activity, anti-inflammatory activity, intestinal barrier protection, and immune cell modulation, and is involved in maintaining intestine mucosal immune homeostasis. The improved understanding of the properties of LF in intestine mucosal immune system and IBD will facilitate its application in nutrition, clinical medicine, and health. Herein, this review outlines the recent advancements on LF as a potential therapeutic intervention for IBD associated with intestine mucosal immune system dysfunction. We hope this review will provide a reference for future studies and lay a theoretical foundation for LF-based therapeutic interventions for IBD by understanding the particular effects of LF on intestine mucosal immune system.

Antimicrobial peptides and the gut microbiome in inflammatory bowel disease

Antimicrobial peptides (AMP) are highly diverse and dynamic molecules that are expressed by specific intestinal epithelial cells, Paneth cells, as well as immune cells in the gastrointestinal (GI) tract. They play critical roles in maintaining tolerance to gut microbiota and protecting against enteric infections. Given that disruptions in tolerance to commensal microbiota and loss of barrier function play major roles in the pathogenesis of inflammatory bowel disease (IBD) and converge on the function of AMP, the significance of AMP as potential biomarkers and novel therapeutic targets in IBD have been increasingly recognized in recent years. In this frontier article, we discuss the function and mechanisms of AMP in the GI tract, examine the interaction of AMP with the gut microbiome, explore the role of AMP in the pathogenesis of IBD, and review translational applications of AMP in patients with IBD.

Lactoferrin Potentiates Inducible Regulatory T Cell Differentiation through TGF-β Receptor III Binding and Activation of Membrane-Bound TGF-β

Lactoferrin (LF) is known to possess anti-inflammatory activity, although its mechanisms of action are not well-understood. The present study asked whether LF affects the commitment of inducible regulatory T cells (Tregs). LF substantially promoted Foxp3 expression by mouse activated CD4+T cells, and this activity was further enhanced by TGF-β1. Interestingly, blocking TGF-β with anti-TGF-β Ab completely abolished LF-induced Foxp3 expression. However, no significant amount of soluble TGF-β was released by LF-stimulated T cells, suggesting that membrane TGF-β (mTGF-β) is associated. Subsequently, it was found that LF binds to TGF-β receptor III, which induces reactive oxygen species production and diminishes the expression of mTGF-β-bound latency-associated peptide, leading to the activation of mTGF-β. It was followed by phosphorylation of Smad3 and enhanced Foxp3 expression. These results suggest that LF induces Foxp3+ Tregs through TGF-β receptor III/reactive oxygen species-mediated mTGF-β activation, triggering canonical Smad3-dependent signaling. Finally, we found that the suppressive activity of LF-induced Tregs is facilitated mainly by CD39/CD73-induced adenosine generation and that this suppressor activity alleviates inflammatory bowel disease.

Exploring the Links between Diet and Inflammation: Dairy Foods as Case Studies

Systemic chronic inflammation may be a contributing factor to many noncommunicable diseases, including diabetes, cardiovascular disease, and obesity. With the rapid rise of these conditions, identifying the causes of and treatment for chronic inflammation is an important research priority, especially with regard to modifiable lifestyle factors such as diet. An emerging body of evidence indicates that consuming certain foods, including dairy foods like milk, cheese, and yogurt, may be linked to a decreased risk for inflammation. To discuss both broader research on diet and inflammation as well as research on links between individual foods and inflammation, the National Dairy Council sponsored a satellite session entitled "Exploring the Links between Diet and Inflammation: Dairy Foods as Case Studies" at the American Society for Nutrition's 2020 LIVE ONLINE Conference. This article, a review based on the topics discussed during that session, explores the links between diet and inflammation, focusing most closely on the relations between intake of dairy fat and dairy foods like milk, cheese, and yogurt, and biomarkers of inflammation from clinical trials. While there is currently insufficient evidence to prove an "anti-inflammatory" effect of dairy foods, the substantial body of clinical research discussed in this review indicates that dairy foods do not increase concentrations of biomarkers of chronic systemic inflammation.

Bovine Lactoferrin Protects Dextran Sulfate Sodium Salt Mice Against Inflammation and Impairment of Colonic Epithelial Barrier by Regulating Gut Microbial Structure and Metabolites

Background: Ulcerative colitis is characterized by relapsing and remitting mucosal inflammation. Bovine lactoferrin (BL) is a multifunctional protein that could regulate the intestinal flora and has anti-inflammatory effects. The aim of this study was to investigate the therapeutic effect of BL on colitis.

Methods: Dextran sulfate sodium salt (DSS) was utilized to establish a mouse model of colitis. BL was administered to treat DSS mice. The weight, the activity, and fecal status of the mice were recorded every day. Disease activity index was calculated. After the mice were euthanized, the colon length was measured. Hematoxylin and eosin staining was used to observe the pathological changes of the colon, and histological activity index was calculated. The myeloperoxidase (MPO) activity of colon tissue was measured. Western blot and immunohistochemistry were used to detect the expressions of Claudin-1, Occludin, and ZO-1. The expressions of IL-1β, IL-6, IL-10, TNF-α, and TGF-β in colon tissue were detected by ELISA. The protein expressions of MUC2, Reg3γ, β-defensin (HBD-2), and cAMP were detected by immunofluorescence (IF). 16S rDNA sequencing determined the type and structure of intestinal flora. Liquid chromatography–tandem mass spectrometry (LC-MS/MS) measured the metabolites of the intestinal flora.

Results: Compared with the DSS group, the mice's weight in the BL group was higher and the length of the colon was longer. At the 14th day, MPO activity was higher in the BL group. The expressions of Claudin-1, Occludin, and ZO-1 in the colon were up-regulated in the BL group compared with the DSS group. The expressions of IL-1β, IL-6, and TNF-α were lower. The expressions of IL-10 and TGF-β were higher. IF showed that the expressions of MUC2 and β-defensin (HBD-2) were down-regulated, and the expressions of Reg3γ and cAMP were up-regulated. The 16S rDNA sequencing results showed that the alpha diversity and beta diversity were notably changed in the DSS mice treated with BL. Metabolomics results showed that BL changed purine metabolism in the DSS mice.

Conclusion: BL alleviated colitis in mice by improving the inflammatory response and the structure of the colon barrier in the colon. BL changed the composition and metabolites of the intestinal flora. Thus, BL might be an effective nutritional supplement for colitis treatment.

Lactoferrin: an overview of its main functions, immunomodulatory and antimicrobial role, and clinical significance

Lactoferrin (LF), a glycoprotein found in mucosal secretions, is characterized by a wide range of functions, including immunomodulatory and anti-inflammatory activities. Moreover, several investigations confirmed that LF displays high effectiveness against multiple bacteria and viruses and may be regarded as a potential inhibitor of enveloped viruses, such as presently prevailing SARS-CoV-2. In our review, we discuss available studies about LF functions and bioavailability of different LF forms in in vitro and in vivo models. Moreover, we characterize the potential benefits and side effects of LF use; we also briefly summarize the latest clinical trials examining LF application. Finally, we point potential role of LF in inflammatory bowel disease and indicate its use as a marker for disease severity.

Lactoferrin in the Prevention and Treatment of Intestinal Inflammatory Pathologies Associated with Colorectal Cancer Development

The connection between inflammation and cancer is well-established and supported by genetic, pharmacological and epidemiological data. The inflammatory bowel diseases (IBDs), including Crohn's disease and ulcerative colitis, have been described as important promoters for colorectal cancer development. Risk factors include environmental and food-borne mutagens, dysbalance of intestinal microbiome composition and chronic intestinal inflammation, with loss of intestinal epithelial barrier and enhanced cell proliferation rate. Therapies aimed at shutting down mucosal inflammatory response represent the foundation for IBDs treatment. However, when applied for long periods, they can alter the immune system and promote microbiome dysbiosis and carcinogenesis. Therefore, it is imperative to find new safe substances acting as both potent anti-inflammatory and anti-pathogen agents. Lactoferrin (Lf), an iron-binding glycoprotein essential in innate immunity, is generally recognized as safe and used as food supplement due to its multifunctionality. Lf possesses a wide range of immunomodulatory and anti-inflammatory properties against different aseptic and septic inflammatory pathologies, including IBDs. Moreover, Lf exerts anti-adhesive, anti-invasive and anti-survival activities against several microbial pathogens that colonize intestinal mucosa of IBDs patients. This review focuses on those activities of Lf potentially useful for the prevention/treatment of intestinal inflammatory pathologies associated with colorectal cancer development.

Lactoferrin Induces Tolerogenic Bone Marrow-Derived Dendritic Cells

Dendritic cells (DCs) are professional antigen-presenting cells (APCs) that initiate both T-cell responses and tolerance. Tolerogenic DCs (tDCs) are regulatory DCs that suppress immune responses through the induction of T-cell anergy and Tregs. Because lactoferrin (LF) was demonstrated to induce functional Tregs and has a protective effect against inflammatory bowel disease, we explored the tolerogenic effects of LF on mouse bone marrow-derived DCs (BMDCs). The expression of CD80/86 and MHC class II was diminished in LF-treated BMDCs (LF-BMDCs). LF facilitated BMDCs to suppress proliferation and elevate Foxp3⁺ induced Treg (iTreg) differentiation in ovalbumin-specific CD4⁺ T-cell culture. Foxp3 expression was further increased by blockade of the B7 molecule using CTLA4-Ig but was diminished by additional CD28 stimulation using anti-CD28 Ab. On the other hand, the levels of arginase-1 and indoleamine 2,3-dioxygenase-1 (known as key T-cell suppressive molecules) were increased in LF-BMDCs. Consistently, the suppressive activity of LF-BMDCs was partially restored by inhibitors of these molecules. Collectively, these results suggest that LF effectively causes DCs to be tolerogenic by both the suppression of T-cell proliferation and enhancement of iTreg differentiation. This tolerogenic effect of LF is due to the reduction of costimulatory molecules and enhancement of suppressive molecules.

The potential of lactoferrin, ovotransferrin and lysozyme as antiviral and immune-modulating agents in COVID-19

Coronavirus disease 2019 (COVID-19), caused by SARS coronavirus 2 (SARS-CoV-2), is spreading rapidly with no established effective treatments. While most cases are mild, others experience uncontrolled inflammatory responses with oxidative stress, dysregulation of iron and coagulation as features. Lactoferrin, ovotransferrin and lysozyme are abundant, safe antimicrobials that have wide antiviral as well as immunomodulatory properties. In particular, lactoferrin restores iron homeostasis and inhibits replication of SARS-CoV, which is closely related to SARS-CoV-2. Ovotransferrin has antiviral peptides and activities that are shared with lactoferrin. Both lactoferrin and lysozyme are ‘immune sensing’ as they may stimulate immune responses or resolve inflammation. Mechanisms by which these antimicrobials may treat or prevent COVID-19, as well as sources and forms of these, are reviewed.

Lactoferrin from Bovine Milk: A Protective Companion for Life

Lactoferrin (Lf), an iron-binding multifunctional glycoprotein belonging to the transferrin family, is present in most biological secretions and reaches particularly high concentrations in colostrum and breast milk. A key function of lactoferrin is non-immune defence and it is considered to be a mediator linking innate and adaptive immune responses. Lf from bovine milk (bLf), the main Lf used in human medicine because of its easy availability, has been designated by the United States Food and Drug Administration as a food additive that is generally recognized as safe (GRAS). Among the numerous protective activities exercised by this nutraceutical protein, the most important ones demonstrated after its oral administration are: Antianemic, anti-inflammatory, antimicrobial, immunomodulatory, antioxidant and anticancer activities. All these activities underline the significance in host defence of bLf, which represents an ideal nutraceutical product both for its economic production and for its tolerance after ingestion. The purpose of this review is to summarize the most important beneficial activities demonstrated following the oral administration of bLf, trying to identify potential perspectives on its prophylactic and therapeutic applications in the future.

The Effects of Recombinant Human Lactoferrin on Immune Activation and the Intestinal Microbiome Among Persons Living with Human Immunodeficiency Virus and Receiving Antiretroviral Therapy

Lactoferrin modulates mucosal immunity and targets mechanisms contributing to inflammation during human immunodeficiency virus disease. A randomized placebo-controlled crossover clinical trial of recombinant human (rh) lactoferrin was conducted among 54 human immunodeficiency virus-infected participants with viral suppression. Outcomes were tolerability, inflammatory, and immunologic measures, and the intestinal microbiome. The median age was 51 years, and the median CD4+ cell count was 651/µL. Adherence and adverse events did not differ between rh-lactoferrin and placebo. There was no significant effect on plasma interleukin-6 or D-dimer levels, nor on monocyte/T-cell activation, mucosal integrity, or intestinal microbiota diversity. Oral administration of rh-lactoferrin was safe but did not reduce inflammation and immune activation. Clinical Trials Registration: NCT01830595.

A Review of the Immunomodulating Components of Maternal Breast Milk and Protection Against Necrotizing Enterocolitis

Breast milk contains immunomodulating components that are beneficial to newborns during maturation of their immune system. Human breast milk composition is influenced by an infant's gestational and chronological age, lactation stage, and the mother and infant's health status. Major immunologic components in human milk, such as secretory immunoglobulin A (IgA) and growth factors, have a known role in regulating gut barrier integrity and microbial colonization, which therefore protect against the development of a life-threatening gastrointestinal illness affecting newborn infants called necrotizing enterocolitis (NEC). Breast milk is a known protective factor in the prevention of NEC when compared with feeding with commercial formula. Breast milk supplements infants with human milk oligosaccharides, leukocytes, cytokines, nitric oxide, and growth factors that attenuate inflammatory responses and provide immunological defenses to reduce the incidence of NEC. This article aims to review the variety of immunomodulating components in breast milk that protect the infant from the development of NEC.

Modulation activity of heat-treated and untreated lactoferrin on the TLR-4 pathway in anoxia cell model and cerebral ischemia reperfusion mouse model

This study aimed to investigate the modulation activity of heated and nonheated lactoferrins in an inflammatory pathway in anoxia and reoxygenation cell and cerebral ischemic reperfusion mouse models. Rat pheochromocytoma 12 (PC-12) cells were subjected to oxygen and glucose deprivation in vitro to construct an anoxia and reoxygenation cell model, and Institute for Cancer Research (ICR) mice were given carotid artery "ligation-relaxation" in vivo to construct a cerebral ischemic reperfusion mouse model. The protein levels of toll-like receptor 4 (TLR-4) and downstream inflammatory proteins including nuclear factor-κB (NF-κB), tumor necrosis factor-α (TNF-α), and IL-1β were detected. Meanwhile, metabonomic detection of overall metabolites of PC-12 cells was performed to screen out the specific changed metabolite affected by lactoferrin at the condition of anoxia and reoxygenation. The results showed that lactoferrin could inhibit the TLR-4-related pathway triggered by anoxia and reoxygenation and ischemic reperfusion. A total of 41 significantly changed metabolites were identified by metabonomic analysis, and glutathione was seen as a metabolite of interest in suppressing TLR-4-related pathway in anoxia and reoxygenation cell models. However, heated lactoferrin lost the ability of attenuating the TLR-4-related pathway. The loss of modulation activity of heated lactoferrin might be due to its protein aggregation, which was evidenced by larger average particle diameter than the unheated lactoferrin. This study is the first to investigate the effect of heat treatment on the modulation activity of lactoferrin in the TLR-4-related pathway in anoxia and reoxygenation cell and cerebral ischemic reperfusion mouse models, and indicate that lactoferrin may serve as a dietary intervention for cerebral ischemia.

Protective effects of the combination Bifidobacterium longum plus lactoferrin against NSAID-induced enteropathy

OBJECTIVES

Nonsteroidal anti-inflammatory drugs can exert detrimental effects in the lower digestive tract. The aim of this study was to examine the protective effects of a combination of the probiotic Bifidobacterium longum BB536 (Bifidobacterium) with the prebiotic lactoferrin in a rat model of diclofenac-induced enteropathy.

METHODS

Enteropathy was induced in 40-wk-old male rats by intragastric diclofenac (4 mg/kg twice daily for 14 d). Lactoferrin (100 mg/kg twice daily), Bifidobacterium (2.5 × 10⁶ CFU/rat twice daily) or their combination were administered 1 h before diclofenac. At the end of treatments, the ileum was processed for the evaluation of histologic damage, myeloperoxidase (MPO) and malondialdehyde (MDA) levels, as well as the expression of Toll-like receptors 2 and 4 (TLR-2/-4) and the activation of downstream signaling molecules (MyD88 and nuclear factor [NF]-κB p65). Blood hemoglobin and fecal calprotectin were also assessed.

RESULTS

Diclofenac induced intestinal damage, along with increments of MPO and MDA, overexpression of TLR-2, TLR-4, MyD88, and NF-κB p65, increased fecal calprotectin and decreased blood hemoglobin levels. Lactoferrin or Bifidobacterium alone prevented diclofenac-induced enteric damage, and the changes in blood hemoglobin, MPO, MDA, fecal calprotectin, and NF-κB p65. Bifidobacterium, but not lactoferrin, decreased TLR-4 expression, although none of them affected MyD88 overexpression. TLR-2 expression was slightly enhanced by all treatments. The combined administration of lactoferrin and Bifidobacterium reduced further the intestinal damage, and restored MPO and blood hemoglobin levels.

CONCLUSIONS

Diclofenac induced ileal mucosal lesions by activation of inflammatory and pro-oxidant mechanisms. These detrimental actions were prevented by the combination of lactoferrin with Bifidobacterium likely through the modulation of TLR-2/-4/NF-κB proinflammatory pathways.

Lactoferrin in Aseptic and Septic Inflammation

Lactoferrin (Lf), a cationic glycoprotein able to chelate two ferric irons per molecule, is synthesized by exocrine glands and neutrophils. Since the first anti-microbial function attributed to Lf, several activities have been discovered, including the relevant anti-inflammatory one, especially associated to the down-regulation of pro-inflammatory cytokines, as IL-6. As high levels of IL-6 are involved in iron homeostasis disorders, Lf is emerging as a potent regulator of iron and inflammatory homeostasis. Here, the role of Lf against aseptic and septic inflammation has been reviewed. In particular, in the context of aseptic inflammation, as anemia of inflammation, preterm delivery, Alzheimer’s disease and type 2 diabetes, Lf administration reduces local and/or systemic inflammation. Moreover, Lf oral administration, by decreasing serum IL-6, reverts iron homeostasis disorders. Regarding septic inflammation occurring in Chlamydia trachomatis infection, cystic fibrosis and inflammatory bowel disease, Lf, besides the anti-inflammatory activity, exerts a significant activity against bacterial adhesion, invasion and colonization. Lastly, a critical analysis of literature in vitro data reporting contradictory results on the Lf role in inflammatory processes, ranging from pro- to anti-inflammatory activity, highlighted that they depend on cell models, cell metabolic status, stimulatory or infecting agents as well as on Lf iron saturation degree, integrity and purity.

Whey protein concentrate limits venous thrombosis in rats

To study the influence of whey protein concentrate (WPC-80) on the development of thrombosis, rats were supplemented with 2 doses of WPC-80 (0.3 or 0.5 g/kg) for 7, 14, or 21 days. Then, a 1-h venous thrombosis model was performed in half of the animals. Coagulation parameters, platelet count, and thrombus weight were assessed. Thrombus weight was decreased in rats obtaining WPC-80 and that was significant only for 14- and 21-day supplementation. There were slight differences between groups in coagulation parameters and platelet count but without evident direction. Further research is needed to clarify the observed effects.

Orchestration of Adaptive T Cell Responses by Neutrophil Granule Contents

Neutrophils are the most abundant leukocytes in peripheral blood and respond rapidly to danger, infiltrating tissues within minutes of infectious or sterile injury. Neutrophils were long thought of as simple killers, but now we recognise them as responsive cells able to adapt to inflammation and orchestrate subsequent events with some sophistication. Here, we discuss how these rapid responders release mediators which influence later adaptive T cell immunity through influences on DC priming and directly on the T cells themselves. We consider how the release of granule contents by neutrophils—through NETosis or degranulation—is one way in which the innate immune system directs the phenotype of the adaptive immune response.

Damage-associated molecular patterns in inflammatory bowel disease: From biomarkers to therapeutic targets

The chronic inflammatory process underlying inflammatory bowel disease (IBD), comprising Crohn’s disease and ulcerative colitis, derives from the interplay of several components in a genetically susceptible host. These components include environmental elements and gut microbiota a dysbiosis. For decades, immune abnormalities have been investigated as critically important in IBD pathogenesis, and attempts to develop effective therapies have predominantly targeted the immune system. Nevertheless, immune events represent only one of the constituents contributing to IBD pathogenesis within the context of the complex cellular and molecular network underlying chronic intestinal inflammation. These factors need to be appreciated within the milieu of non-immune components. Damage-associated molecular patterns (DAMPs), which are essentially endogenous stress proteins expressed or released as a result of cell or tissue damage, have been shown to act as direct pro-inflammatory mediators. Excessive or persistent signalling mediated by such molecules can underlie several chronic inflammatory disorders, including IBD. The release of endogenous DAMPs amplifies the inflammatory response driven by immune and non-immune cells and promotes epigenetic reprogramming in IBD. The effects determine pathologic changes, which may sustain chronic intestinal inflammation and also underlie specific disease phenotypes. In addition to highlighting the potential use of DAMPs such as calprotectin as biomarkers, research on DAMPs may reveal novel mechanistic associations in IBD pathogenesis and is expected to uncover putative therapeutic targets.

How are the expression patterns of gut antimicrobial peptides modulated by human gastrointestinal diseases? A bridge between infectious, inflammatory, and malignant diseases

The human gut barrier is the tissue exposed to the highest load of microorganisms, harbouring 100 trillion bacteria. In addition, the gut's renewal rate outruns that of any other human tissue. Antimicrobial peptides (AMPs) are highly optimized defense molecules in the intestinal barrier optimized to maintain gastrointestinal homeostasis. Alterations in AMPs activity can lead to or result from human gastrointestinal diseases. In this review, unique, conserved, or otherwise regular alterations in the expression patterns of human AMPs across gastrointestinal inflammatory and infectious diseases were analyzed for pattern elucidation. Human gastrointestinal diseases are associated with alterations in gut AMPs' expression patterns in a peptide-specific, disease-specific, and pathogen-specific way, modulating human gastrointestinal functioning. Across diseases, there is a (i) marked reduction in otherwise constitutively expressed AMPs, leading to increased disease susceptibility, and a (ii) significant increase in the expression of inducible AMPs, leading to tissue damage and disease severity. Infections and inflammatory conditions are associated with altered gene expression in the gut, whose patterns may favour cellular metaplasia, mucosal dysfunction, and disease states. Altered expression of AMPs can thus thrive disease severity and evolution since its early stages. Nevertheless, the modulation of AMP expression patterns unveils promising therapeutic targets.

Lactoferrin in a Context of Inflammation-Induced Pathology

Much progress has been achieved to elucidate the function of lactoferrin (LTF), an iron-binding glycoprotein, in the milieu of immune functionality. This review represents a unique examination of LTF toward its importance in physiologic homeostasis as related to development of disease-associated pathology. The immunomodulatory nature of this protein derives from its unique ability to "sense" the immune activation status of an organism and act accordingly. Underlying mechanisms are proposed whereby LTF controls disease states, thereby pinpointing regions of entry for LTF in maintenance of various physiological pathways to limit the magnitude of tissue damage. LTF is examined as a first line mediator in immune defense and response to pathogenic and non-pathogenic injury, as well as a molecule critical for control of oxidative cell function. Mechanisms of interaction of LTF with its receptors are examined, with a focus on protective effects via regulation of enzyme activities and reactive oxygen species production, immune deviation, and prevention of cell apoptosis. Indeed, LTF serves as a critical control point in physiologic homeostasis, functioning as a sensor of immunological performance related to pathology. Specific mediation of tissue pathophysiology is described for maintenance of intestinal integrity during endotoxemia, elicited airway inflammation due to allergens, and pulmonary damage during tuberculosis. Finally, the role of LTF to alter differentiation of adaptive immune function is examined, with specific recognition of its utility as a vaccine adjuvant to control subsequent lymphocytic reactivity. Overall, it is clear that while the ability of LTF to both sequester iron and to direct reactive oxygen intermediates is a major factor in lessening damage due to excessive inflammatory responses, further effects are apparent through direct control over development of higher order immune functions that regulate pathology due to insult and injury. This culminates in attenuation of pathological damage during inflammatory injury.

Aloperine Protects Mice against DSS-Induced Colitis by PP2A-Mediated PI3K/Akt/mTOR Signaling Suppression

Colitis is a major form of inflammatory bowel disease which involved mucosal immune dysfunction. Aloperine is an alkaloid isolated from the shrub Sophora alopecuroides L. and has been recognized as an effective treatment for inflammatory and allergic diseases. The present study aimed to examine the molecular mechanisms underlying aloperine-mediated colitis protection. We found that aloperine treatment improved colitis induced by dextran sodium sulfate (DSS) based on body weight, disease activity index, colonic length, and spleen index. Aloperine also effectively attenuated DSS-induced intestinal inflammation based on the pathological score and myeloperoxidase expression and activity in colon tissues. In addition, aloperine regulated T-cell proportions and promoted Foxp3 expression in the spleens and mesenteric lymph nodes of DSS-induced colitis mice and in the spleens of the Foxp3^GFP mice. Aloperine inhibited Jurkat and mouse naïve T-cell apoptosis. Furthermore, aloperine inhibited PI3K/Akt/mTOR signaling and upregulated PP2A expression in the DSS-induced colitis mice and in Jurkat cells, but LB-100 (PP2A inhibitor) resulted in an elevated Akt activity in Jurkat cells, activated T-cells, and human splenic mononuclear cells. Aloperine inhibited T-cell and lymphocyte proliferation, but LB-100 reverse these effects. In conclusion, aloperine regulates inflammatory responses in colitis by inhibiting the PI3K/Akt/mTOR signaling in a PP2A-dependent manner.

VEN-120, a Recombinant Human Lactoferrin, Promotes a Regulatory T Cell [Treg] Phenotype and Drives Resolution of Inflammation in Distinct Murine Models of Inflammatory Bowel Disease

BACKGROUND AND AIMS

Inflammatory bowel disease [IBD] is characterised by a disruption of immune homeostasis, which is tightly regulated to protect against harmful pathogens yet not react to commensal antigens. Animal studies indicate that regulatory T cells [Treg] modulate the immune response to prevent IBD development. Lactoferrin [LF] is an endogenous anti-inflammatory pleiotropic protein secreted at high concentrations in colostrum and at mucosal sites. However, the effect of LF on specific T lymphocyte populations has not been studied. Here, we identify a novel mechanism by which a recombinant human LF, VEN-120, regulates T cell populations in health and disease.

METHODS

Two murine models of intestinal inflammation, the dextran sodium sulphate colitis model and the TNFΔARE/+ model of ileitis, were used to study the anti-inflammatory and T cell modulating ability of VEN-120. Flow cytometry was used to evaluate T cell populations within the lamina propria and mesenteric lymph nodes, and to evaluate the effect of VEN-120 on CD4+ T cells in vitro.

RESULTS

VEN-120 reduced inflammation in both models of IBD, accompanied by increased Tregs in the intestinal lamina propria. Treatment of CD4+ T cells in vitro resulted in an upregulation of Treg genes and skewing towards a Treg population. This in vitro T cell skewing translated to an increase of Treg homing to the intestinal lamina propria and associated lymph tissue in healthy mice.

CONCLUSIONS

These data provide a novel immunological mechanism by which VEN-120 modulates T cells to restrict inflammatory T cell-driven disease.

Bovine lactoferrin regulates cell survival, apoptosis and inflammation in intestinal epithelial cells and preterm pig intestine

Bovine lactoferrin (bLF) may modulate neonatal intestinal inflammation. Previous studies in intestinal epithelial cells (IECs) indicated that moderate bLF doses enhance proliferation whereas high doses trigger inflammation. To further elucidate cellular mechanisms, we profiled the porcine IEC proteome after stimulation with bLF at 0, 0.1, 1 and 10g/L by LC-MS-based proteomics. Key pathways were analyzed in the intestine of formula-fed preterm pigs with and without supplementation of 10g/L bLF. Levels of 123 IEC proteins were altered by bLF. Low bLF doses (0.1-1g/L) up-regulated 11 proteins associated with glycolysis, energy metabolism and protein synthesis, indicating support of cell survival. In contrast, a high bLF dose (10g/L) up-regulated three apoptosis-inducing proteins, down-regulated five anti-apoptotic and proliferation-inducing proteins and 15 proteins related to energy and amino acid metabolism, and altered three proteins enhancing the hypoxia inducible factor-1 (HIF-1) pathway. In the preterm pig intestine, bLF at 10g/L decreased villus height/crypt depth ratio and up-regulated the Bax/Bcl-2 ratio and HIF-1α, indicating elevated intestinal apoptosis and inflammation. In conclusion, bLF dose-dependently affects IECs via metabolic, apoptotic and inflammatory pathways. It is important to select an appropriate dose when feeding neonates with bLF to avoid detrimental effects exerted by excessive doses.

BIOLOGICAL SIGNIFICANCE

The present work elucidates dose-dependent effects of bLF on the proteomic changes of IECs in vitro supplemented with data from a preterm pig study confirming detrimental effects of enteral feeding with the highest dose of bLF (10g/L). The study contributes to further understanding on mechanisms that bLF, as an important milk protein, can regulate the homeostasis of the immature intestine. Results from this study urge neonatologists to carefully consider the dose of bLF to supplement into infant formula used for preterm neonates.

Lactoferrin and the newborn: current perspectives

Neonatal sepsis and necrotizing enterocolitis (NEC) are associated with significant mortality and morbidity. Inflammation secondary to sepsis and NEC increases morbidity, especially those related to the lung, brain and eye. Therapeutic strategies that target inflammation and decrease the emergence of antibiotic resistance are urgently needed. Lactoferrin (Lf) is a multifunctional protein that modulates inflammation, cell growth and differentiation and has broad antimicrobial activity. Studies evaluating the efficacy and safety of Lf in the prevention of neonatal sepsis and NEC are currently in progress, and one completed study shows significant promise. In this article, the functions of this multifunctional molecule and current clinical evidence for its use in the newborn are reviewed. Lf prophylaxis and therapy may have a significant impact in improving clinical outcomes of vulnerable preterm neonates.

Antimicrobial proteins in intestine and inflammatory bowel diseases

Mucosal surface of the intestinal tract is continuously exposed to a large number of microorganisms. To manage the substantial microbial exposure, epithelial surfaces produce a diverse arsenal of antimicrobial proteins (AMPs) that directly kill or inhibit the growth of microorganisms. Thus, AMPs are important components of innate immunity in the gut mucosa. They are frequently expressed in response to colonic inflammation and infection. Expression of many AMPs, including human β-defensin 2-4 and cathelicidin, is induced in response to invasion of pathogens or enteric microbiota into the mucosal barrier. In contrast, some AMPs, including human α-defensin 5-6 and human β-defensin 1, are constitutively expressed without microbial contact or invasion. In addition, specific AMPs are reported to be associated with inflammatory bowel disease (IBD) due to altered expression of AMPs or development of autoantibodies against AMPs. The advanced knowledge for AMPs expression in IBD can lead to its potential use as biomarkers for disease activity. Although the administration of exogenous AMPs as therapeutic strategies against IBD is still at an early stage of development, augmented induction of endogenous AMPs may be another interesting future research direction for the protective and therapeutic purposes. This review discusses new advances in our understanding of how intestinal AMPs protect against pathogens and contribute to pathophysiology of IBD.

Protective effects of human lactoferrin during Aggregatibacter actinomycetemcomitans-induced bacteremia in lactoferrin-deficient mice

Aggregatibacter actinomycetemcomitans, a periodontopathogen, has been associated with several systemic diseases. Herein, we report the protective effect of human lactoferrin (hLF) during A. actinomycetemcomitans bacteremia in lactoferrin knockout (LFKO(-/-)) mice. The prophylactic, concurrent, and therapeutic intravenous (i.v.) administrations of hLF significantly cleared the bacteria from blood and organs. Nevertheless, all modes of hLF administration significantly decreased the concentrations of serum proinflammatory cytokines, such as interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), IL-6, IL-10, and IL-12p70. Additionally, hLF administration significantly decreased hepatic and splenic proinflammatory cytokine expression levels compared to those in the non-hLF-treated group. Furthermore, administration of hLF decreased the serum C-reactive protein level, inducible nitric oxide synthase (iNOS) and myeloperoxidase (MPO) gene expression levels in liver and spleen. hLF treatment has also resulted in a 6-fold decrease in spleen weight with the migration of typical inflammatory cells in infected mice as a result of decreased inflammatory response. These results reveal that hLF protects against A. actinomycetemcomitans bacteremia, as indicated by rapid bacterial clearance and decreased host proinflammatory mediators.

Effects of bovine lactoferrin on the immature porcine intestine

Bioactive milk proteins may be important in protecting preterm infants from developing inflammation and necrotising enterocolitis (NEC). A preterm pig model was used to investigate the protective effects of enteral bovine lactoferrin (bLF) against NEC development and inflammation. Caesarean-delivered preterm pigs were fed parenteral and minimal enteral nutrition for the first 2 d followed by 2 d of total enteral nutrition before euthanasia. Pigs were stratified into two groups and fed with either a control formula (CON, n 15) or a 10 g/l of bLF-enriched formula (LF, n 13). NEC incidence, gut functions and inflammatory cytokines were analysed. NEC incidence and nutrient absorption were similar between the two groups. In pigs that developed NEC, disease outcome was more severe in the colon accompanied by increased intestinal permeability in LF pigs. In contrary, the LF pigs had a lowered IL-1β level in the proximal small intestine. Dose-dependent effects of bLF on cell proliferation, intracellular signalling and cytokine secretion were tested in porcine intestinal epithelial cells (PsIc1) in vitro. Low doses (0·1-1 g/l) increased cell proliferation via extracellular signal-regulated kinase (ERK), limited IL-8 secretion and prevented NF-κB and hypoxia-inducible factor-1α (HIF-1α) activation, suggesting anti-inflammatory effects. In contrast, at a higher dose (10 g/l), bLF exerted adverse effects by reducing cell proliferation, stimulating IL-8 release, inhibiting ERK activation and up-regulating NF-κB and HIF-1α activation. Overall, at a dose of 10 g/l, bLF exacerbated disease severity in pigs that developed NEC, while the in vitro studies indicated the positive effects of bLF at low doses (0·1-1 g/l). Supplementation of infant formulas with bLF should therefore be optimised carefully.

Antimicrobial peptides and colitis

Antimicrobial peptides (AMPs) are important components of innate immunity. They are often expressed in response to colonic inflammation and infection. Over the last several years, the roles of several antimicrobial peptides have been explored. Gene expression of many AMPs (beta defensin HBD2-4 and cathelicidin) is induced in response to invasion of gut microbes into the mucosal barrier. Some AMPs are expressed in a constitutive manner (alpha defensin HD 5-6 and beta defensin HBD1), while others (defensin and bactericidal/ permeability increasing protein BPI) are particularly associated with Inflammatory Bowel Disease (IBD) due to altered defensin expression or development of autoantibodies against Bactericidal/permeability increasing protein (BPI). Various AMPs have different spectrum and strength of antimicrobial effects. Some may play important roles in modulating the colitis (cathelicidin) while others (lactoferrin, hepcidin) may represent biomarkers of disease activity. The use of AMPs for therapeutic purposes is still at an early stage of development. A few natural AMPs were shown to be able to modulate colitis when delivered intravenously or intracolonically (cathelicidin, elafin and SLPI) in mouse colitis models. New AMPs (synthetic or artificial non-human peptides) are being developed and may represent new therapeutic approaches against colitis. This review discusses the latest research developments in the AMP field with emphasis in innate immunity and pathophysiology of colitis.

Alteration of DSS-mediated immune cell redistribution in murine colitis by oral colostral immunoglobulin

Background

Oral bovine colostrum prophylaxis accelerates the recovery of dextran sulfate sodium (DSS)-induced colitis. In the present study the beneficial effects on acute intestinal inflammation of two major colostral components, secretory immunoglobulin A and lactoferrin, were investigated. Outbred NMRI mice received whole bovine colostrum (BC, 20 mg/kg body weight), colostral bovine lactoferrin (bLf, 150 mg/kg), or secretory immunoglobulin A (sIgA, 1–2 mg/kg body weight) daily by oral gavage, either two weeks before induction of colitis (prophylaxis) or after disease establishment (therapy). Bovine serum albumin (BSA, 150 mg/kg body weight) and immunoglobulin G (IgG, 1 and 2 mg/kg body weight) served as protein controls. Colitis was induced by providing 5% DSS solution ad libitum for seven days.

Results

Compared to BSA, BC therapy improved occult blood, stool consistency, and clinical recovery from colitis but did not prevent initial weight loss. In contrast, administration of bLf did not influence the course of colitis in either the prophylactic or the therapeutic setting. Therapeutic application of sIgA promoted weight gain in the recovery phase of colitis but failed to improve other clinical parameters. Prophylactically-fed sIgA influenced immune cell redistribution, normalized peripheral blood CD11c⁺CD83⁺ mature dendritic cells, modulated colonic immune cell infiltration, and altered the numbers of both DSS-induced regulatory γδ TCR⁺ T cells and CD11b⁺Gr-1⁺ myeloid suppressor cells in the lymph nodes and spleens of mice.

Conclusions

These data demonstrated the potential of colostrum in disease recovery and epithelial homeostasis following intestinal injury. Colostral sIgA failed to improve acute disease activity but promoted weight gain and modulated immune cell responses that are involved in the genesis of colitis.

Oral administration of lactoferrin attenuates intestinal ischemia-reperfusion injury in rats

BACKGROUND

Intestinal ischemia-reperfusion (I/R) is a common and serious clinical condition. Lactoferrin (Lf) has displayed antioxidative and anti-inflammatory activities in protecting the intestinal mucosa. The objective of this study was to investigate whether oral administration of Lf could attenuate I/R-induced intestinal injury.

METHODS

The experimental design consisted of three groups of Wistar rats (24 per group): sham operation, control (I/R, saline), Lf (I/R, Lf). Intestinal I/R was produced by occlusion of the superior mesenteric artery for 45 min. Eight rats from each group were randomly sacrificed 3, 12 or 36 h after reperfusion, and blood and intestinal samples were collected.

RESULTS

Intestinal I/R resulted in gut damage evidenced by morphological alteration, reduction of γ-glutamyl transpeptidase (γ-GGT) activity and increased cell apoptosis. Daily administration of Lf (200 mg/kg) for 14 days before surgery significantly attenuated gut damage by reducing the histologic score and apoptosis index, and restoring intestinal γ-GGT activity. Lf reduced intestinal malondialdehyde and myeloperoxidase, restored glutathione and decreased serum levels of tumor necrosis factor-α, interleukin (IL)-1β and IL-6 compared with saline control in I/R rats. In addition, oral administration of Lf did not produce any significant effects in healthy rats; Lf at doses of 50 or 100 mg/kg also attenuated I/R-induced gut damage, but administration of Lf for 7 days did not exert a significant protective effect against I/R-induced gut damage.

CONCLUSIONS

These results indicate that Lf may serve as a potent supplement in protecting the gut from intestinal I/R-induced injury by its antioxidative, anti-inflammatory and antiapoptotic activities.

Resting of Cryopreserved PBMC Does Not Generally Benefit the Performance of Antigen-Specific T Cell ELISPOT Assays

T cell monitoring is increasingly performed using cryopreserved PBMC. It has been suggested that resting of PBMC after thawing, that is, culturing them overnight in test medium, produces higher antigen-induced spot counts in ELISPOT assays. To evaluate the importance of overnight resting, we systematically tested cryopreserved PBMC from 25 healthy donors. CEF peptides (comprising CMV, EBV and flu antigens) were used to stimulate CD8 cells and mumps antigen to stimulate CD4 cells. The data show that resting significantly increased antigen-elicited T cell responses only for CEF high responder PBMC. The maximal gain observed was doubling of spot counts. For CEF low responders, and for mumps responders of either low- or high reactivity levels, resting had no statistically significant effect on the observed spot counts. Therefore, resting is not a generally applicable approach to improve ELISPOT assay performance, but can be recommended only for clinical subject cohorts and antigens for which it has a proven benefit. Because resting invariably leads to losing about half of the PBMC available for testing, and because doubling the PBMC numbers plated into the assay reliably doubles the antigen-induced spot counts, we suggest the latter approach as a simple and reliable alternative to resting for enhancing the performance of ELISPOT assays. Our data imply that resting is not required if PBMC were cryopreserved and thawed under conditions that minimize apoptosis of the cells. Therefore, this study should draw attention to the need to optimize freezing and thawing conditions for successful T cell work.

Regulation of the inflammatory response: enhancing neutrophil infiltration under chronic inflammatory conditions

Neutrophil (polymorphonuclear leukocytes [PMN]) infiltration plays a central role in inflammation and is also a major cause of tissue damage. Thus, PMN infiltration must be tightly controlled. Using zymosan-induced peritonitis as an in vivo PMN infiltration model, we show in this study that PMN response and infiltration were significantly enhanced in mice experiencing various types of systemic inflammation, including colitis and diabetes. Adoptive transfer of leukocytes from mice with inflammation into healthy recipients or from healthy into inflammatory recipients followed by inducing peritonitis demonstrated that both circulating PMN and tissue macrophages were altered under inflammatory conditions and that they collectively contributed to enhanced PMN infiltration. Detailed analyses of dextran sulfate sodium-elicited colitis revealed that enhancement of PMN infiltration and macrophage function occurred only at the postacute/chronic phase of inflammation and was associated with markedly increased IL-17A in serum. In vitro and ex vivo treatment of isolated PMN and macrophages confirmed that IL-17A directly modulates these cells and significantly enhances their inflammatory responses. Neutralization of IL-17A eliminated the enhancement of PMN infiltration and IL-6 production and also prevented severe tissue damage in dextran sulfate sodium-treated mice. Thus, IL-17A produced at the chronic stage of colitis serves as an essential feedback signal that enhances PMN infiltration and promotes inflammation.