Immunomodulatory agents as potential therapeutic or preventive strategies for COVID-19.

Currently, the COVID-19 pandemic, caused by the novel SARS-CoV-2 coronavirus, represents the greatest global health threat. Most people infected by the virus present mild to moderate respiratory symptoms and recover with supportive treatments. However, certain susceptible hosts develop an acute respiratory distress syndrome (ARDS), associated with an inflammatory "cytokine storm", leading to lung damage. Despite the current availability of different COVID-19 vaccines, the new emerging SARS-CoV-2 genetic variants represent a major concern worldwide, due to their increased transmissibility and rapid spread. Indeed, it seems that some mutations or combinations of mutations might confer selective advantages to the virus, such as the ability to evade the host immune responses elicited by COVID-19 vaccines. Several therapeutic approaches have been investigated but, to date, a unique and fully effective therapeutic protocol has not yet been achieved. In addition, steroid-based therapies, aimed to reduce inflammation in patients with severe COVID-19 disease, may increase the risk of opportunistic infections, increasing the hospitalization time and mortality rate of these patients. Hence, there is an unmet need to develop more effective therapeutic options. Here, we discuss the potential use of natural immunomodulators such as Thymosin α1 (Tα1), all-trans retinoic acid (ATRA), and lactoferrin (LF), as adjunctive or preventive treatment of severe COVID-19 disease. These agents are considered to be multifunctional molecules because of their ability to enhance antiviral host immunity and restore the immune balance, depending on the host immune status. Furthermore, they are able to exert a broad-spectrum antimicrobial activity by means of direct interactions with cellular or molecular targets of pathogens or indirectly by increasing the host immune response. Thus, due to the aforementioned properties, these agents might have a great potential in a clinical setting, not only to counteract SARS-CoV-2 infection, but also to prevent opportunistic infections in critically ill COVID-19 patients.

Lactoferrin as an Adjuvant for the Generation of Delayed Type Hypersensitivity to Orally Administered Antigen.

OBJECTIVE: The aim of this investigation was to evaluate the property of bovine lactoferrin (LF) in the generation of delayed type hypersensitivity (DTH) as an oral adjuvant during immunization with ovalbumin (OVA) and BCG. METHODS: LF admixed with OVA or BCG was used for immunization of CBA or C57BL/6 mice when given via oral or subcutaneous routes. Elicited DTH response was measured post immunization. Inhibition studies using mannose or galactose were accomplished by gavage prior to oral administration of antigens. LF was also examined for effects on BCG uptake by bone marrow derived macrophages (BMM). RESULTS: LF at doses of 1.0 mg and 10.0 mg, admixed with OVA (10.0 mg), significantly enhanced the antigen-specific DTH reaction. The stimulatory effects of LF were inhibited by the oral pretreatment of mice with 50.0 mg of mannose but not galactose. LF also enhanced the DTH reaction to orally administered BCG. LF enhanced uptake of BCG by BMM in a dose-dependent manner. CONCLUSION: LF was able to augment development of DTH when orally administered with OVA or BCG antigens. Inhibition studies suggest the involvement of the receptor with an affinity to mannose in mediation of the adjuvant effect. LF augmentation of the DTH response was partially effective when given in advance of oral delivery of the antigen; this effect could also be saturated by mannose. BCG studies provide preliminary evidence for LF in the potential augmentation of oral vaccination to prevent mycobacterial infection. In vitro experiments provide evidence that LF plays a role in modulation of antigen presenting cell activation.

Lactoferrin Retargets Human Adenoviruses to TLR4 to Induce an Abortive NLRP3-Associated Pyroptotic Response in Human Phagocytes.

Despite decades of clinical and preclinical investigations, we still poorly grasp our innate immune response to human adenoviruses (HAdVs) and their vectors. In this study, we explored the impact of lactoferrin on three HAdV types that are being used as vectors for vaccines. Lactoferrin is a secreted globular glycoprotein that influences direct and indirect innate immune response against a range of pathogens following a breach in tissue homeostasis. The mechanism by which lactoferrin complexes increases HAdV uptake and induce maturation of human phagocytes is unknown. We show that lactoferrin redirects HAdV types from species B, C, and D to Toll-like receptor 4 (TLR4) cell surface complexes. TLR4-mediated internalization of the HAdV-lactoferrin complex induced an NLRP3-associated response that consisted of cytokine release and transient disruption of plasma membrane integrity, without causing cell death. These data impact our understanding of HAdV immunogenicity and may provide ways to increase the efficacy of HAdV-based vectors/vaccines.

Bovine γ-globulin, lactoferrin, and lactoperoxidase are relevant bovine milk allergens in patients with α-Gal syndrome.

BACKGROUND: Mammalian meat is the most common trigger of the allergic reactions in patients with α-Gal syndrome (AGS). Milk and dairy, although less often, also cause a significant number of allergic manifestations. The aim of this study was to identify α-Gal-containing bovine milk proteins with allergenic properties among AGS patients. METHODS: Thirty-eight AGS patients with IgE to milk were included in the study. Milk proteins were analyzed for the presence of α-Gal and for binding by patients' IgE using immunoblot, ImmunoCAP, and inhibition ELISA. Allergenicity of milk and milk proteins was assessed by basophil activation test. RESULTS: More than half of the AGS patients reported allergic reactions to milk or dairy products. Bovine γ-globulin (BGG), lactoferrin (LF), and lactoperoxidase (LPO) were identified as α-Gal carrying proteins which were recognized by AGS patients' IgE. Whey mirrored the anti-α-Gal and IgE reactivity of BGG, LF, and LPO. Eighty-nine percent of the patients displayed IgE to BGG, 91% to LF, and 57% to LPO. Inhibition of α-Gal-specific IgE binding was achieved by BGG, LF, LPO, and whey. These proteins also activated AGS patients' basophils. Interestingly, at lower concentrations, LF was the most potent inhibitor of IgE binding, and the most potent activator of basophils. CONCLUSION: BGG, LF, and LPO were all found to be relevant milk α-Gal-containing glycoproteins that bound AGS patients' IgE antibodies and activated their basophils. These proteins are probably involved in the allergic reactions to milk in AGS patients. LPO was for the first time shown to be an allergen.

The potential for Lactoferrin to reduce SARS-CoV-2 induced cytokine storm.

The COVID-19 pandemic is a serious global health threat caused by severe acute respiratory syndrome of coronavirus 2 (SARS-CoV-2). Symptoms of COVID-19 are highly variable with common hyperactivity of immune responses known as a "cytokine storm". In fact, this massive release of inflammatory cytokines into in the pulmonary alveolar structure is a main cause of mortality during COVID-19 infection. Current management of COVID-19 is supportive and there is no common clinical protocol applied to suppress this pathological state. Lactoferrin (LF), an iron binding protein, is a first line defense protein that is present in neutrophils and excretory fluids of all mammals, and is well recognized for its role in maturation and regulation of immune system function. Also, due to its ability to sequester free iron, LF is known to protect against insult-induced oxidative stress and subsequent "cytokine storm" that results in dramatic necrosis within the affected tissue. Review of the literature strongly suggests utility of LF to silence the "cytokine storm", giving credence to both prophylactic and therapeutic approaches towards combating COVID-19 infection.

Antibacterial and Anti-biofilm Activity of the Human Breast Milk Glycoprotein Lactoferrin against Group B Streptococcus.

Group B Streptococcus (GBS) is an encapsulated Gram-positive human pathogen that causes invasive infections in pregnant hosts and neonates, as well as immunocompromised individuals. Colonization of the human host requires the ability to adhere to mucosal surfaces and circumnavigate the nutritional challenges and antimicrobial defenses associated with the innate immune response. Biofilm formation is a critical process to facilitate GBS survival and establishment of a replicative niche in the vertebrate host. Previous work has shown that the host responds to GBS infection by producing the innate antimicrobial glycoprotein lactoferrin, which has been implicated in repressing bacterial growth and biofilm formation. Additionally, lactoferrin is highly abundant in human breast milk and could serve a protective role against invasive microbial pathogens. This study demonstrates that human breast milk lactoferrin has antimicrobial and anti-biofilm activity against GBS and inhibits its adherence to human gestational membranes. Together, these results indicate that human milk lactoferrin could be used as a prebiotic chemotherapeutic strategy to limit the impact of bacterial adherence and biofilm formation on GBS-associated disease outcomes.

Growth differentiation factor-15 and lactoferrin immuno-expression in breast cancer: relationship with body iron-status and survival outcome.

We aimed to evaluate the expression of growth differentiation factor-15 (GDF-15) and lactoferrin (Lf) in tumor and their relationship with the body iron-status and overall survival (OS) outcome of patients with breast cancer. A retrospective cohort study of female patients with primary breast cancer was performed. Clinical tumor samples from the Second Affiliated Hospital of Soochow University between December 2008 and June 2014 were collected. The immuno-expression of GDF-15 and Lf was stratified into positive or negative expression. Kaplan-Meier method and Cox proportional hazards regression model were used for data analysis. 74 breast cancer patients with a mean age of 52 years were included into our study. 14 (18.9%) patients were died by the end of August 1, 2019. The serum iron level of patients with GDF-15 (+)/Lf(-) expression was higher than that of patients with other expression patterns (18.2 ± 5.4 vs. 15.5 ± 5.0 µmol/L, P = 0.038), but was not associated with OS. In univariate Cox analyses, GDF-15(+) and GDF-15(+)/Lf(-) were significantly correlated with high mortality risk (HR = 3.75, 95%CI 1.05-13.48, P = 0.025; HR = 5.00, 95%CI 1.56-16.04, P = 0.004, respectively). After adjusted for age, menopause status and primary tumor grade, the association between GDF-15 and OS disappeared. However, the association between GDF-15/Lf and OS still existed in GDF-15(+)/Lf(-) (HR = 4.50, 95%CI 1.31-15.51, P = 0.017). The combined immuno-expression pattern of GDF-15 and Lf was significant associated with high serum iron level. GDF-15/Lf could be a powerful biomarker to predict survival outcome of patients with breast cancer but still needed to be confirmed by future studies.

Comparative effect of bovine buttermilk, whey, and lactoferrin on the innate immunity receptors and oxidative status of intestinal epithelial cells.

Milk contains bioactive molecules with important functions as defensive proteins; among them are the whey protein lactoferrin and proteins of the milk fat globule membrane (MFGM) present in buttermilk. The aim of this study has been to investigate the effects of lactoferrin, whey, and buttermilk as modulators of intestinal innate immunity and oxidative stress on intestinal epithelial cells, to evaluate its potential use for the development of functional foods. The mRNA expression levels of innate immune system Toll-like receptors (TLR2, TLR4, and TLR9), lipid peroxidation (malondialdehyde + 4-hydroxyalkenals) and protein expression levels of carbonyl were analyzed in enterocyte-like Caco-2/TC7 cells treated for 24 h with different concentrations of lactoferrin, whey, or buttermilk. None of the substances analyzed caused oxidative damage; however, whey significantly decreased the levels of lipid peroxidation. Furthermore, both lactoferrin and whey reduced the oxidative stress induced by lipopolysaccharide. With respect to TLR receptors, lactoferrin, whey, and buttermilk specifically altered the expression of TLR2, TLR4, and TLR9 receptors, with a strong decrease in the expression levels of TLR4. These results suggest that lactoferrin, whey, and buttermilk are potentially interesting ingredients for functional foods because they seem to modulate oxidative stress and the inflammatory response induced by the activation of TLRs.

Sensitive immunoassays based on specific monoclonal IgG for determination of bovine lactoferrin in cow milk samples.

Lactoferrin (LF), a bioactive multifunctional protein of the transferrin family, is found mainly in the secretions of all mammals, especially in milk. In the present study, a hybridoma cell (LF8) secreting IgG against bovine LF was screened, and the purified LF8 mAb showed high specificity and affinity to bovine LF. The linear range of ic-ELISA to detect LF was 9.76 ~ 625 ng/mL, with a limit of detection (LOD) of 0.01 ng/mL. The average recovery of intra- and inter-assay were (104.45 ± 4.12)% and (107.13 ± 4.72)%, respectively. The LOD of colloidal gold- and AuNFs-based strip by naked eye were 9.7 and 2.4 ng/mL, respectively, and the detection time was less than 10 min without any samples pretreatment and expensive equipment. The developed ELISA and lateral flow immunosensors based on specific IgG could be used directly for rapid detection of the bovine LF content in cow milk samples.

An immune-based biomarker signature is associated with mortality in COVID-19 patients.

Immune and inflammatory responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contribute to disease severity of coronavirus disease 2019 (COVID-19). However, the utility of specific immune-based biomarkers to predict clinical outcome remains elusive. Here, we analyzed levels of 66 soluble biomarkers in 175 Italian patients with COVID-19 ranging from mild/moderate to critical severity and assessed type I IFN-, type II IFN-, and NF-κB-dependent whole-blood transcriptional signatures. A broad inflammatory signature was observed, implicating activation of various immune and nonhematopoietic cell subsets. Discordance between IFN-α2a protein and IFNA2 transcript levels in blood suggests that type I IFNs during COVID-19 may be primarily produced by tissue-resident cells. Multivariable analysis of patients' first samples revealed 12 biomarkers (CCL2, IL-15, soluble ST2 [sST2], NGAL, sTNFRSF1A, ferritin, IL-6, S100A9, MMP-9, IL-2, sVEGFR1, IL-10) that when increased were independently associated with mortality. Multivariate analyses of longitudinal biomarker trajectories identified 8 of the aforementioned biomarkers (IL-15, IL-2, NGAL, CCL2, MMP-9, sTNFRSF1A, sST2, IL-10) and 2 additional biomarkers (lactoferrin, CXCL9) that were substantially associated with mortality when increased, while IL-1α was associated with mortality when decreased. Among these, sST2, sTNFRSF1A, IL-10, and IL-15 were consistently higher throughout the hospitalization in patients who died versus those who recovered, suggesting that these biomarkers may provide an early warning of eventual disease outcome.

Lactoferrin, a versatile natural antimicrobial glycoprotein that modulates the host's innate immunity.

Lactoferrin is a multifunctional protein found in the secretions of mammals. The antimicrobial activity of lactoferrin was the first to be discovered and was assumed to be solely dependent on its iron-chelating ability. However, lactoferrin has been reported to display proteolytic activity towards bacterial virulence factors and to modulate the host defence by stimulating the immune system and balancing pathogen-induced inflammation. Here, we review the current understandings of the antimicrobial effect, interaction with host cells, and innate immune modulation of lactoferrin, and put forward this moonlighting protein as a possible alternative for antibiotics.

A prospective on multiple biological activities of lactoferrin contributing to piglet welfare.

Piglets, especially weaning piglets, show a lower level of immunity and higher morbidity and mortality, owing to their rapid growth, physiological immaturity, and gradual reduction of maternal antibodies, which seriously affects their growth and thus, value. It is important that piglets adapt to nutrient digestion and absorption and develop sound intestinal function and colonization with gut microbiota as soon as possible during their early life stage. Lactoferrin is a natural glycoprotein polypeptide that is part of the transferrin family. It is widely found in mucosal secretions such as saliva and tears, and most highly in milk and colostrum. As a multifunctional bioactive protein and a recommended food additive, lactoferrin is a potential alternative therapy to antibiotics and health promoting additive for piglet nutrition and development. It is expected that lactoferrin, as a natural food additive, could play an important role in maintaining pig health and development. This review examines the following known beneficial effects of lactoferrin: improves the digestion and capacity for absorption in the intestinal tract; promotes the absorption of iron and reduces the incidence of iron deficiency anemia; regulates intestinal function and helps to balance the microbial biota; and enhances the resistance to disease of the piglets via modulating and enhancing the immune system.

Denaturation of selected bioactive whey proteins during pasteurization and their ability to modulate milk immunogenicity.

This research communication relates to the hypothesis that the consumption of raw or unprocessed cow's milk contributes to lowered prevalence of allergies. Thermal pasteurization of bovine milk can result in denaturation of minor whey proteins and loss of their bioactivity. Denaturation of bovine serum albumin (BSA), immunoglobulin G (IgG) and lactoferrin (LF) in skim milk was studied under different temperature (72, 75 or 78°C) and time (0-300 s) combinations. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) results revealed that denaturation of all 3 proteins occurred at 72°C and progressed with increase in temperature and holding time. About 59% of LF and 12% of IgG denatured under high-temperature short-time (72°C/ 15 s) pasteurization, while BSA was least impacted. To assess modulation of milk immunogenicity, secretion of selected T helper (Th)-type cytokines by human peripheral blood mononuclear cells (PBMCs) was studied in vitro in response to different concentrations of BSA (0.4-1.0 mg/ml) and IgG (0.8-1.6 mg/ml) in unheated skim milk. Addition of IgG at 1.6 mg/ml induced a prominent Th1-skewed cytokine profile that may not trigger a Th2-skewed allergic reaction. BSA did not appear to modulate milk immunogenicity to any significant extent.

Lactoferrin-containing immunocomplex mediates antitumor effects by resetting tumor-associated macrophages to M1 phenotype.

BACKGROUND: Tumor-associated macrophages (TAMs) resemble M2-polarized cells with potent immunosuppressive activity and play a pivotal role in tumor growth and progression. Converting TAMs to proinflammatory M1-like phenotype is thus an attractive strategy for antitumor immunotherapy. METHODS: A mouse IgG1 (kappa) monoclonal Ab, M-860, specific to human lactoferrin (LTF) was generated by using the traditional hybridoma cell fusion technology. TAMs were generated by culturing human and mouse CD14+ monocytes in tumor-conditioned media containing a cytokine cocktail containing recombinant interleukin-4 (IL-4), interleukin-10 (IL-10) and macrophage colony stimulating factor (M-CSF). TAMs after treatment with immunocomplex (IC) between human LTF and M860 (LTF-IC) were phenotypically and functionally characterized by flow cytometry (FACS), ELISA, Q-PCR and killing assays. The antitumor effects of LTF-IC were further analyzed using in vivo experiments employing tumor-bearing human FcγRIIa-transgenic mouse models. RESULTS: Through coligation of membrane-bound CD14 and FcγRIIa, LTF-IC rendered TAMs not only M2 to M1 conversion, evidenced by increased tumor necrosis factor α production, down-regulated M2-specific markers (CD206, arginase-1 and vascular endothelial growth factor) and upregulated M1-specific markers (CD86 and HLA-DR) expression, but also potent tumoricidal activity in vitro. LTF-IC administration conferred antitumor protective efficacy and prolonged animal survival in FcγRIIa-transgenic mice, accompanied by accumulation of M1-like macrophages as well as significantly reduced infiltration of immunosuppressive myeloid-derived suppressor cells and regulatory T cells in solid tumor tissues. CONCLUSIONS: LTF-IC is a promising cancer therapeutic agent capable of converting TAMs into tumoricidal M1-like cells.

Serum Levels of Autoantibodies Against Extracellular Antigens and Neutrophil Granule Proteins Increase in Patients with COPD Compared to Non-COPD Smokers.

Background: Chronic obstructive pulmonary disease (COPD) is a highly prevalent disease leading to irreversible airflow limitation and is characterized by chronic pulmonary inflammation, obstructive bronchiolitis and emphysema. Etiologically, COPD is mediated by toxic gases and particles, eg, cigarette smoke, while the pathogenesis of the disease is largely unknown. Several lines of evidence indicate a link between COPD and autoimmunity but comprehensive studies are lacking. Methods: By using a protein microarray assaying more than 19,000 human proteins we determined in this study the autoantibody profiles of COPD and non-COPD smokers. The discovery cohort included 5 COPD patients under acute exacerbation (AECOPD) and 5 age- and gender-matched non-COPD smokers. One putative candidate autoantibody, anti-lactoferrin IgG, was further investigated by using immunoblotting with a large validation cohort containing 124 healthy controls, 92 patients with AECOPD and 52 patients with stable COPD. Results: We show that i) autoantigens targeted by autoantibodies with higher titers in COPD patients were enriched in extracellular regions, while those with lower titers in COPD patients were enriched in intracellular compartments. ii) levels of IgG autoantibodies against many neutrophil granule proteins were significantly higher in COPD patients than in non-COPD smokers. Furthermore, increased levels of anti-lactoferrin antibodies in COPD patients were confirmed in a cohort with a large number of samples. Conclusion: The comprehensive autoantibody profiles from COPD patients established in this study demonstrated for the first time a shift in the cellular localization of antigens targeted by autoantibodies in COPD.

Lactoferrin in Human Milk of Prolonged Lactation.

Among the immunologically important bioactive factors present in human milk, lactoferrin (Lf) has emerged as a key player with wide-ranging features that directly and indirectly protect the neonate against infection caused by a variety of pathogens. The concentration of Lf in human milk is lactation-stage related; colostrum contains more than 5 g/L, which then significantly decreases to 2-3 g/L in mature milk. The milk of mothers who are breastfeeding for more than one year is of a standard value, containing macronutrients in a composition similar to that of human milk at later stages. The aim of this study was to evaluate lactoferrin concentration in prolonged lactation from the first to the 48th month postpartum. Lactating women (n = 120) up to 48 months postpartum were recruited to the study. The mean value of lactoferrin concentration was the lowest in the group of 1-12 months of lactation (3.39 ± 1.43 g/L), significantly increasing in the 13-18 months group (5.55 ± 4.00 g/L; p < 0.006), and remaining at a comparable level in the groups of 19-24 month and over 24 months (5.02 ± 2.97 and 4.90 ± 3.18 g/L, respectively). The concentration of lactoferrin in mother's milk also showed a positive correlation with protein concentration over lactation from the first to the 48th month (r = 0.3374; p = 0.0002). Our results demonstrate the high immunology potential of human milk during prolonged lactation and that Lf concentration is close to the Lf concentration in colostrum. Evidence of stable or rising immunoprotein levels during prolonged lactation provides an argument for foregoing weaning; however, breastfeeding must be combined with solid foods meet the new requirements of a rapidly growing six-month or older baby.

Lactoferrin-induced myeloid-derived suppressor cell therapy attenuates pathologic inflammatory conditions in newborn mice.

Inflammation plays a critical role in the development of severe neonatal morbidities. Myeloid-derived suppressor cells (MDSCs) were recently implicated in the regulation of immune responses in newborns. Here, we report that the presence of MDSCs and their functional activity in infants are closely associated with the maturity of newborns and the presence of lactoferrin (LF) in serum. Low amounts of MDSCs at birth predicted the development of severe pathology in preterm infants - necrotizing enterocolitis (NEC). In vitro treatment of newborn neutrophils and monocytes with LF converted these cells to MDSCs via the LRP2 receptor and activation of the NF-κB transcription factor. Decrease in the expression of LRP2 was responsible for the loss of sensitivity of adult myeloid cells to LF. LF-induced MDSCs (LF-MDSCs) were effective in the treatment of newborn mice with NEC, acting by blocking inflammation, resulting in increased survival. LF-MDSCs were more effective than treatment with LF protein alone. In addition to affecting NEC, LF-MDSCs demonstrated potent ability to control ovalbumin-induced (OVA-induced) lung inflammation, dextran sulfate sodium-induced (DSS-induced) colitis, and concanavalin A-induced (ConA-induced) hepatitis. These results suggest that cell therapy with LF-MDSCs may provide potent therapeutic benefits in infants with various pathological conditions associated with dysregulated inflammation.

Antimicrobial peptides, disease severity and exacerbations in bronchiectasis.

RATIONALE: Recently a frequent exacerbator phenotype has been described in bronchiectasis, but the underlying biological mechanisms are unknown. Antimicrobial peptides (AMPs) are important in host defence against microbes but can be proinflammatory in chronic lung disease. OBJECTIVES: To determine pulmonary and systemic levels of AMP and their relationship with disease severity and future risk of exacerbations in bronchiectasis. METHODS: A total of 135 adults with bronchiectasis were prospectively enrolled at three European centres. Levels of cathelicidin LL-37, lactoferrin, lysozyme and secretory leucocyte protease inhibitor (SLPI) in serum and sputum were determined at baseline by ELISA. Patients were followed up for 12 months. We examined the ability of sputum AMP to predict future exacerbation risk. MEASUREMENTS AND MAIN RESULTS: AMP levels were higher in sputum than in serum, suggesting local AMP release. Patients with more severe disease at baseline had dysregulation of airway AMP. Higher LL-37 and lower SLPI levels were associated with Bronchiectasis Severity Index, lower FEV1 (forced expiratory volume in 1 s) and Pseudomonas aeruginosa infection. Low SLPI levels were also associated with the exacerbation frequency at baseline. During follow-up, higher LL-37 and lower SLPI levels were associated with a shorter time to the next exacerbation, whereas LL-37 alone predicted exacerbation frequency over the next 12 months. CONCLUSIONS: Patients with bronchiectasis showed dysregulated sputum AMP levels, characterised by elevated LL-37 and reduced SLPI levels in the frequent exacerbator phenotype. Elevated LL-37 and reduced SLPI levels are associated with Pseudomonas aeruginosa infection and can predict future risk of exacerbations in bronchiectasis.

The pathogenesis of post-primary tuberculosis. A game changer for vaccine development.

A vaccine that prevents transmission of infection is urgently needed in the fight against tuberculosis (TB). Results of clinical trials have been disappointing. Major problems include lack of biomarkers and understanding of the mechanisms of disease and protection. A more fundamental problem is that the scientific community seldom recognizes that primary and post-primary TB are distinct disease entities. Nearly all vaccine candidates have been designed and tested in models of primary TB, while transmission of infection is mediated by post-primary TB. Post-primary TB is seldom studied because no animal develop complete symptoms of the disease as it exists in humans. Nevertheless, mice, guinea pigs and rabbits all develop infections that at certain points appear to be models of human post-primary TB. Slowly progressive pulmonary TB in immunocompetent mice is an example. It is characterized by an alveolitis with infected foamy macrophages that have multiple characteristics of the human disease. We demonstrated that inclusion of an immune modulating agent, lactoferrin, with a BCG vaccine in this model induced a sustained reduction in lung pathology, but not numbers of organisms in tissue. Since the animals die of expanding pathology, this demonstrates the feasibility of using selected animal models for studies of vaccines against post-primary TB.

Effect of the Zn Supplementation on Immuno-Modulatory Activities of Bovine Lactoferrin in the Murine Splenocytes and RAW264.7 Macrophages.

Lactoferrin (LF) has important bio-functions including immuno-modulation, while essential trace metals may interact with LF and thereby induce property especially bio-activity changes. Bovine LF was thus supplemented with Zn2+ at 0.16, 0.32, and 0.64 mg/g LF to yield 10%, 20%, and 40% Zn-saturation, respectively. Afterwards, bovine LF and the Zn-supplemented LF products at 10-40-µg/mL doses were compared for their immuno-modulatory activities in two immune cells (murine splenocytes and RAW264.7 macrophages), using the stimulation index of the splenocytes, T lymphocyte subpopulations, macrophage phagocytosis, and cytokine production as evaluation reflectors. The results showed that bovine LF and the Zn-supplemented LF products had suppressive effect on the splenocytes and concanavalin A (ConA)- and lipopolysaccharide-stimulated splenocytes, but lower Zn-saturation and lower dose could alleviate and even counteract this suppressive effect (P < 0.05). More importantly, the Zn-supplemented LF product with lower Zn-saturation at lower dose exerted slightly higher macrophage stimulation, increased CD4+/CD8+ ratio of T lymphocyte subpopulations, and were capable of enhancing the interleukin-2 (IL-2), IL-4, and interferon-γ production in the splenocytes or the IL-1ß, IL-6, and tumor necrosis factor-α production in the macrophages significantly (P < 0.05). Contrary to its counterpart at lower dose, the Zn-supplemented LF product with higher Zn-saturation at higher dose mostly showed opposite effects in the two cell models. It is concluded that Zn supplementation has an impact on the immuno-modulation of bovine LF, while Zn-saturation is a key factor to modulate these assessed immune activities.