Cathelicidin Research Articles

Rosacea: The Blessing of the Celts - An Approach to Pathogenesis Through Translational Research.

Increased expression of cathelicidin antimicrobial peptide (CAMP) is related to the pathogenesis of rosacea. CAMP plays a crucial role in antimicrobial defences, such as the killing of mycobacteria. CAMP gene expression is regulated by vitamin D-dependent (VDR) and vitamin D-independent (C/EBPα) transcription factors. VDR-dependent CAMP expression is sufficient during the summer months in Nordic countries, but insufficient during Nordic winters, due to low ultraviolet (UV) levels. Historically, the Celts may have overcome this geographical disadvantage of deficient CAMP production during the winter through an as-yet undefined acquired mutation that activates the alternative vitamin D-independent CAMP promoter C/EBPα. C/EBPα is the downstream transcription factor of Toll-like receptor (TLR)-mediated innate immune reactions and endoplasmic reticulum (ER) stress responses. At the molecular level, all clinical trigger factors for rosacea can be regarded as ER stressors. A mutation-based upregulation of ER stress responsiveness in rosacea may thus explain patients' reduced threshold for ER stressors. It is notable that ER stress upregulates the potent lipid-mediator sphingosine-1-phosphate (S1P), which explains multiple pathological aberrations observed in rosacea skin. Enhanced ER stress/S1P signalling in rosacea appears to compensate for insufficient VDR-dependent CAMP expression, maintaining adequate CAMP levels during UV-deficient winter to combat life-threatening microbial infections, such as lupus vulgaris. Therefore, rosacea should not be considered as a disadvantage, but as evolution's blessing of the Celts which improved their survival. The concept presented here also explains the mechanism of Finsen's UV treatment of lupus vulgaris by UV- and ER stress-mediated upregulation of CAMP expression. Rosacea could therefore be described as the Celts' "inborn Finsen lamp".

Effects of Probiotics on the Expression of Cathelicidins in Response to Stimulation by Salmonella Minnesota Lipopolysaccharides in the Proventriculus and Cecum of Broiler Chicks.

The aim of this study was to determine whether probiotic-feeding affected the expression of cathelicidins (CATHs), a major family of antimicrobial peptides, in response to lipopolysaccharides (LPS) challenge in the proventriculus and cecum of broiler chicks. One-day-old male Chunky broiler chicks were fed with or without 0.4% probiotics for 7 days (P-group and non-P-group, respectively). Then, they were orally challenged with no LPS (0-LPS), 1 µg LPS (1-LPS), or 100 µg LPS (100-LPS) (n=5 in all groups) in Experiment 1, and with no LPS or 1 µg LPS (n=6 in all groups) in Experiment 2. Five hours after LPS challenge, the proventriculi and ceca were collected to analyze CATHs expression. Expression of CATHs was examined at first by reverse transcription-polymerase chain reaction (RT-PCR) using the 0-LPS chicks of non-P-group. The differences in CATHs expression upon probiotics-feeding and LPS were analyzed by real time-PCR. All four CATHs (CATH1, 2, 3 and 4) were expressed in the proventriculus and cecum of chicks. In the proventriculus, the expression of CATHs after LPS challenge did not show significant differences between non-P and P-groups in Experiment 1 and 2. In the cecum, the interactions of the effects of probiotics and LPS on the expression of CATH2 in Experiment 1 and CATH1 and 2 in Experiment 2 were significant, and their expression in 1-LPS chicks was higher in P-group than in non-P-group. However, CATH3 and 4 did not show any significant differences between non-P- and P-groups challenged with LPS. These results suggest that probiotics-feeding may stimulate the immunodefense system mediated by CATH2 and possibly CATH1 against infection by Gram-negative bacteria in the cecum.

Effects of Virus-associated Molecular Patterns on the Expression of Cathelicidins in the Hen Vagina

The aim of this study was to examine the expression profiles of the cathelicidins (CATHs) in the oviduct and the effects of Toll-like receptor (TLR) ligands of virus-associated molecular patterns on CATHs expression in the vagina of hens. The mRNA expression of cathelicidins (CATH1, -2, -3 and -B1) in the oviductal mucosa was analyzed by RT-PCR. The effects of viral moleculs on the CATHs expression in the vagina was examined by incubating the mucosal tissue with virus molecular patterns, including poly I:C (dsRNA virus, TLR3 ligand), R848 (ssRNA virus, TLR7 ligand) and CpG-ODN (DNA virus, TLR21 ligand), followed by real-time PCR analysis. The expression of CATH1, CATH2 and CATH3 was identified in all oviductal segments, except for CATH2 which was lacked in the magnum. The expression of CATHB1 was not identified at any segments of the oviduct. Poly I:C down-regulated the expression of CATH1, -2 and -3, whereas R848 up-regulated the expression of CATH1 and CATH3 but down-regulated the expression of CATH2. CpG-ODN did not affect the CATHs expression. These results suggest that mucosal tissues of the oviduct express CATHs to provide the defense mechanism against microbes, and the expression of CATH1 and CATH3 is up-regulated against ssRNA viruses, whereas, dsRNA virus may suppress the expression of CATH1, -2 and -3.

Vitamin D3 analog maxacalcitol (OCT) induces hCAP-18/LL-37 production in human oral epithelial cells.

Maxacalcitol (22-oxacalcitriol: OCT) is a synthetic vitamin D3 analog with a limited calcemic effect. In this study, we investigated whether OCT increases the production of LL-37/CAP-18, a human cathelicidin antimicrobial peptide, in human gingival/oral epithelial cells. A human gingival epithelial cell line (Ca9-22) and human oral epithelial cell lines (HSC-2, HSC-3, and HSC-4) exhibited the enhanced expression of LL-37 mRNA upon stimulation with OCT as well as active metabolites of vitamins D3 and D2. Among the human epithelial cell lines, Ca9-22 exhibited the strongest response to these vitamin D-related compounds. OCT induced the higher production of CAP-18 (ng/mL order) until 6 days time-dependently in Ca9-22 cells in culture. The periodontal pathogen Porphyromonas gingivalis was killed by treatment with the LL-37 peptide. These findings suggest that OCT induces the production of hCAP-18/LL-37 in a manner similar to that induced by the active metabolite of vitamin D3.

Cyclic mechanical stretch down-regulates cathelicidin antimicrobial peptide expression and activates a pro-inflammatory response in human bronchial epithelial cells.

Mechanical ventilation (MV) of patients can cause damage to bronchoalveolar epithelium, leading to a sterile inflammatory response, infection and in severe cases sepsis. Limited knowledge is available on the effects of MV on the innate immune defense system in the human lung. In this study, we demonstrate that cyclic stretch of the human bronchial epithelial cell lines VA10 and BCi NS 1.1 leads to down-regulation of cathelicidin antimicrobial peptide (CAMP) gene expression. We show that treatment of VA10 cells with vitamin D3 and/or 4-phenyl butyric acid counteracted cyclic stretch mediated down-regulation of CAMP mRNA and protein expression (LL-37). Further, we observed an increase in pro-inflammatory responses in the VA10 cell line subjected to cyclic stretch. The mRNA expression of the genes encoding pro-inflammatory cytokines IL-8 and IL-1β was increased after cyclic stretching, where as a decrease in gene expression of chemokines IP-10 and RANTES was observed. Cyclic stretch enhanced oxidative stress in the VA10 cells. The mRNA expression of toll-like receptor (TLR) 3, TLR5 and TLR8 was reduced, while the gene expression of TLR2 was increased in VA10 cells after cyclic stretch. In conclusion, our in vitro results indicate that cyclic stretch may differentially modulate innate immunity by down-regulation of antimicrobial peptide expression and increase in pro-inflammatory responses.

Lenalidomide Enhances MOR202 Dependent Macrophage-Mediated Effector Functions Via the Vitamin D Pathway

Multiple myeloma (MM) is considered a chronic and incurable disease due to its highly complex and heterogeneous molecular abnormalities and the support from myeloma microenvironment factors. Macrophages are an abundant component of the stromal cell compartment and are believed to support proliferation, survival, and drug resistance of MM cells. Conversely, macrophages are key immune effector cells for the therapeutic effect of monoclonal antibodies and can directly eliminate tumor cells. However, myeloma-associated macrophages (MAMs) regularly fail to exert direct effector functions. Given their abundance in MM, an attractive therapeutic approach would be to stimulate their tumoricidal activity in order to promote antitumor immunity. Lenalidomide, an immunomodulatory agent that enhances antibody dependent cell mediated cytotoxicity (ADCC), has the potential to synergize with MOR202, an anti-CD38 monoclonal IgG1 antibody currently in phase I/IIa for the treatment of MM. Furthermore, vitamin D plays a key role in regulating effector functions of human macrophages. This is closely linked to the expression of the vitamin D-1-hydroxylase CYP27B1, which catalyzes the conversion of 25-hydroxy-vitamin D (25D) to the bioactive form 1,25-di-hydroxy-vitamin D (1,25D). We have previously shown, that vitamin D promotes tumoricidal activity of macrophages and improves the efficacy of rituximab-dependent cytotoxicity (Bruns et al., Sci. Transl. Med., 2015; Bittenbring et al., JCO, 2014). Therefore, we hypothesized that the combination of MOR202 with lenalidomide and MOR202 with 1,25D would enhance the MOR202- dependent macrophage-mediated effector functions against myeloma cells.Here we report that MAMs exhibit an altered vitamin D metabolism with a reduced expression of the vitamin D receptor (VDR) and CYP27B1, while the expression of CYP24A1, which catabolizes 1,25D, is increased. As a consequence MAMs cannot convert 25D into bioactive 1,25D. Given the importance of the vitamin D pathway for antibody mediated cytotoxicity, we screened several drugs for their ability to restore the vitamin D pathway in human macrophages. We found, by RNA-sequencing, that lenalidomide treatment modulates the phenotype of monocyte-derived macrophages and isolated MAMs, and that lenalidomide significantly increases the expression of the VDR, CYP27B1 and CAMP (cathelicidin antimicrobial peptide) in these macrophages. Furthermore, we demonstrate that isolated MAMs regularly fail to eliminate primary myeloma cells, and that the lack of effector functions can be overcome by treatment with lenalidomide and vitamin D. Moreover, we show that MOR202-dependent elimination of myeloma cells is enhanced by pre-treatment of isolated MAMs with lenalidomide and supplementation of vitamin D.In summary, these data show that the bioactive form of vitamin D (1,25D) is essential for the effector functions of MAMs and that the therapeutic activation of the vitamin D pathway by lenalidomide may restore their tumoricidal effector mechanisms. Furthermore, these findings highlight that stimulating the tumoricidal activity of MAMs, an abundant component of the stromal cell compartment, with lenalidomide and 1,25D is an attractive therapeutic approach in combination with the anti-CD38 monoclonal IgG1 antibody MOR202. DisclosuresBruns:Morphosys: Research Funding; Celgene: Research Funding.

Identification of a novel cathelicidin antimicrobial peptide from ducks and determination of its functional activity and antibacterial mechanism.

The family of antimicrobial peptide, cathelicidins, which plays important roles against infections in animals, has been identified from many species. Here, we identified a novel avian cathelicidin ortholog from ducks and named dCATH. The cDNA sequence of dCATH encodes a predicted 146-amino-acid polypeptide composed of a 17-residue signal peptide, a 109-residue conserved cathelin domain and a 20-residue mature peptide. Phylogenetic analysis demonstrated that dCATH is highly divergent from other avian peptides. The α-helical structure of the peptide exerted strong antimicrobial activity against a broad range of bacteria in vitro, with most minimum inhibitory concentrations in the range of 2 to 4 μM. Moreover, dCATH also showed cytotoxicity, lysing 50% of mammalian erythrocytes in the presence or absence of 10% fetal calf serum at concentrations of 32 μM or 20 μM and killing 50% HaCaT cells at a concentration of 10 μM. The effects on bacterial outer and inner membranes, as examined by scanning electron microscope and transmission electron microscopy, indicate that dCATH kills microbial cells by increasing permeability, causing a loss of membrane integrity.

Effect of Regular Exercise on Inflammation Induced by Drug-resistant Staphylococcus aureus 3089 in ICR mice.

Obesity is often associated with irregular dietary habits and reduced physical activity. Regular exercise induces a metabolic response that includes increased expression of various cytokines, signaling proteins and hormones, and reduced adipocyte size. In this study, mice performed a swimming exercise for 10 min/day, 5 days/week for 3 weeks. We then investigated the effect of this exercise regimen on inflammation induced by infection with drug-resistant Staphylococcus aureus strain 3089 (DRSA). In humans, DRSA causes dermatitis and pneumonitis. Similarly, DRSA induced inflammatory pneumonitis in both no-exercise (No-EX) and swim-trained (SW-EX) ICR mice. Regular exercise increased levels of the pro-inflammatory cytokines TNF-α and IL-1β and nitric oxide in both serum and whole lung tissue in SW-EX, as compared to No-EX control mice. Moreover, levels of the antimicrobial peptide cathelicidin were significantly increased in visceral adipose tissue and whole lung tissue in the SW-EX group, and this was accompanied by a reduction in the size of visceral adipocytes. In addition, levels of the inflammation marker peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) were not increased in the lung tissue of SW-EX mice. These findings suggest that in these model mice, regular exercise strengthens immune system responses, potentially preventing or mitigating infectious disease.

Cathelicidin modulates the function of monocytes/macrophages via the P2X7 receptor in a teleost, Plecoglossus altivelis.

Cathelicidins (CATHs) are a family of endogenous antimicrobial peptides that are capable of both direct bacteria-killing and immunomodulatory effects. P2X7 receptor (P2X7R) is a mediator of CATH in mammalian immune cells. Here, we studied the function and regulation of CATH in head kidney-derived monocytes/macrophages (MO/MФ) from ayu, Plecoglossus altivelis. We investigated the chemotaxis of MO/MФ in response to ayu CATH (PaCATH), and found that PaCATH had a dose-dependent effect on MO/MФ chemotaxis with the optimal concentration of 10.0 μg/ml. The qPCR and Western blot analysis revealed that PaCATH inhibited the expression of ayu P2X7R (PaP2X7R) at both mRNA and protein levels. Knockdown of the PaP2X7R expression in ayu MO/MФ by RNA interference not only significantly inhibited the chemotactic effect of PaCATH on MO/MФ, but also obviously reduced the effect of PaCATH on the phagocytosis, bacteria-killing, respiratory burst, and cytokine expression of ayu MO/MФ. Our study revealed that the immunomodulatory effect of fish CATH is mediated by P2X7R.

Expression of vitamin D receptor and cathelicidin in human corneal epithelium cells during fusarium solani infection.

To observe the expression of vitamin D receptor (VDR) in human specimen and immortalized human corneal epithelium cells (HCEC) when challenged with fusarium solani. Moreover, we decided to discover the pathway of VDR expression. Also, we would like to detect the expression of cathelicidin antimicrobial peptide (CAMP) in the downstream pathway of VDR. Immunohistochemistry was used to examine the VDR expression in HCEC from healthy and fungal keratitis patients. Real time quantitative polymerase chain reaction (qPCR) was performed to observe the messenger ribonucleic acid (mRNA) change of VDR when immortalized HCEC were challenged with fusarium solani for different hours. CAMP was detected at both mRNA and protein levels. We found out that the VDR expression in fusarium solani keratitis patients' specimen was much more than that in healthy people. The mRNA and protein expression of VDR increased when we stimulated HCEC with fusarium solani antigen (P<0.01) and it could be inhibited by toll like receptor 2 (TLR2) monoclonal antibody. The CAMP expression was decreased because of fusarium solani antigen stimulation (P<0.01). The VDR expression can be increased via TLR2/1-VDR pathway while the CAMP expression is decreased by the stimulation of fusarium solani antigen.

Mechanisms of antimicrobial peptide cathelicidin secreted by non-tumorous cells for lung tumor growth

To investigate the effect of antimicrobial peptide cathelicidin secreted by non-tumorous cells in lung tumor growth. CRAMP(-/-) mice and WT mice were used to establish a lung cancer model via tail vein injection of Lewis lung carcinoma cells (LLC1). Lung was weighted and tumor number on the lung surface was counted. Kaplan-Meier (K-M) survival curve was used to analyze survival rate of mice. Expression of cathelicidin, Ki-67 and CD68 in the tumor tissue was measured by immunohistochemical analysis. BALF cells were stained with Diff Quik and percentages of leukocyte types were determined by light microscopy. Cathelicidin was high expression in inflammatory cells of tumor tissue, whereas weak expression in tumor cells. The lung weight and number of tumor in CRAMP-/- mice were (0.25±0.04)g and (9.60± 2.25), respectively, which were significantly lower than those of WT mice (0.65±0.05) g and (23.40± 2.68). The difference was statistically significant (t=6.07, 3.95, all P<0.05). And Kaplan-Meier survival analysis showed median survival time of CRAMP-/- mice was 49(46-51)d, which was longer than 34(28-39) d of WT mice (χ2=12.00, P<0.05). And the positive rate of Ki-67 tumor cells was significant reduced from (35.80±2.96)% in WT mice to (18.80±2.38)% in CRAMP-/- groups (t=4.48, P<0.05). The total cell number as well as the number of lymphocytes, neutrophils, and macrophages in BALFs of CRAMP-/- mice were (4.72±0.86)×10(4), (0.08±0.02)×10(4), (0.05±0.02)×10(4) and (4.60±0.84)×10(4), respectively, while of WT mice were (16.18±1.61)×10(4), (0.32±0.05)×10(4), (0.20±0.05)×10(4) and (15.66±1.57)×10(4). All of them had significant difference (t=6.28, 4.39, 3.00, 6.20, all P<0.05). In addition, the infiltration of macrophages into lung tumors was decreased in CRAMP-/- mice compared to WT mice, from (15.53±2.28)/high power field to (6.77±3.12)/high power field (t=3.41, P<0.05). Non-tumor cells secreted cathelicidin promotes tumor cell proliferation and lung tumor growth. Recruitment of inflammatory cells such as macrophages into the tumor microenvironment may be the main mechanism of action.

Driving Up the Dose: Implications for High-Dose Vitamin D Therapy

Driving Up the Dose: Implications for High-Dose Vitamin D Therapy

Deciphering the microbiology of hidradenitis suppurativa: a step forward towards understanding an enigmatic inflammatory skin disease.

Keywords: anaerobes; hidradenitis suppurativa; inflammatory disease; microbiology; soft tissue and skin infections

Cathelicidin Antimicrobial Peptide: A Novel Regulator of Islet Function, Islet Regeneration, and Selected Gut Bacteria.

Cathelicidin antimicrobial peptide (CAMP) is a naturally occurring secreted peptide that is expressed in several organs with pleiotropic roles in immunomodulation, wound healing, and cell growth. We previously demonstrated that gut Camp expression is upregulated when type 1 diabetes-prone rats are protected from diabetes development. Unexpectedly, we have also identified novel CAMP expression in the pancreatic β-cells of rats, mice, and humans. CAMP was present even in sterile rat embryo islets, germ-free adult rat islets, and neogenic tubular complexes. Camp gene expression was downregulated in young BBdp rat islets before the onset of insulitis compared with control BBc rats. CAMP treatment of dispersed islets resulted in a significant increase in intracellular calcium mobilization, an effect that was both delayed and blunted in the absence of extracellular calcium. Additionally, CAMP treatment promoted insulin and glucagon secretion from isolated rat islets. Thus, CAMP is a promoter of islet paracrine signaling that enhances islet function and glucoregulation. Finally, daily treatment with the CAMP/LL-37 peptide in vivo in BBdp rats resulted in enhanced β-cell neogenesis and upregulation of potentially beneficial gut microbes. In particular, CAMP/LL-37 treatment shifted the abundance of specific bacterial populations, mitigating the gut dysbiosis observed in the BBdp rat. Taken together, these findings indicate a novel functional role for CAMP/LL-37 in islet biology and modification of gut microbiota.

Beta-Lactamase Repressor BlaI Modulates Staphylococcus aureus Cathelicidin Antimicrobial Peptide Resistance and Virulence.

BlaI is a repressor of BlaZ, the beta-lactamase responsible for penicillin resistance in Staphylococcus aureus. Through screening a transposon library in S. aureus Newman for susceptibility to cathelicidin antimicrobial peptide, we discovered BlaI as a novel cathelicidin resistance factor. Additionally, through integrational mutagenesis in S. aureus Newman and MRSA Sanger 252 strains, we confirmed the role of BlaI in resistance to human and murine cathelidicin and showed that it contributes to virulence in human whole blood and murine infection models. We further demonstrated that BlaI could be a target for innate immune-based antimicrobial therapies; by removing BlaI through subinhibitory concentrations of 6-aminopenicillanic acid, we were able to sensitize S. aureus to LL-37 killing.

Acyl carrier protein is a bacterial cytoplasmic target of cationic antimicrobial peptide LL-37.

In addition to membrane disruption, the cathelicidin antimicrobial peptide (AMP) LL-37 translocates through the bacterial inner membrane to target intracellular molecules. The present study aims to identify an alternate mechanism and a cytoplasmic target of LL-37 in Francisella. LL-37 binding proteins from Francisella novicida U112 bacterial lysates were precipitated by using biotinylated LL-37 (B-LL-37) and NeutrAvidin-agarose beads. Bound proteins were identified by LC-MS/MS, validated and characterized by bead pull-down assays and differential scanning fluorimetry (DSF). The cationic AMP (CAMP) LL-37 was able to interact with Francisella cytoplasmic acyl carrier protein (AcpP; FTN1340/FTT1376). Further study confirmed that LL-37 peptide could bind to AcpP and that the sheep cathelicidin SMAP-29 (Sheep Myeloid Antimicrobial Peptide 29) further increased LL-37 binding to AcpP, suggesting a synergistic effect of SMAP-29 on the binding. LL-37 could also bind to both AcpP of Escherichia coli and Bacillus anthracis, implying a mechanism of broad action of LL-37-AcpP binding. Overexpression of the acpP gene in F. novicida led to an increase in LL-37 susceptibility. LL-37 binding to AcpP changed the fatty acid composition profiles. Taken together, we identified a novel cytoplasmic target of LL-37 in Francisella, suggesting a mechanism of action of this peptide beyond membrane permeabilization. Our findings highlight a novel mechanism of antimicrobial activity of this peptide and document a previously unexplored target of α-helical CAMPs.

Recombinant secretory expression, purification and antimicrobial activity of PR39 in Bacillus subtilis using a maltose-inducible vector

As a promising antibiotic candidate, it is necessary to find a safe method to produce the porcine cathelicidin antimicrobial peptide PR39. In this study, the antimicrobial peptide PR39 was successfully expressed with the maltose-inducible vector pGJ148 in the Bacillus subtilis WB800N. After induction with 3% maltose concentration, the fusion protein was successfully secreted onto the culture medium directly. After purification a Ni–NTA resin column, the fusion protein with a concentration of 17mg/l was obtained from fermentation culture. Then, the purified fusion protein was cleaved using enterokinase, and tag-free PR39 was released. Approximately 2mg of the recombinant PR39 with a purity of approximately 92.0% was obtained from a 1-l culture medium after purification with cation exchange column. The evaluation of antimicrobial and haemolytic activity demonstrated that the recombinant PR39 exhibited a high antimicrobial activity against several Gram-negative strains and a low haemolytic activity (256μM) against human red blood cells. The synthetic PR39 produced similar results. This work expanded and provided a safe protocol for the large-scale production of antimicrobial peptides in B. subtilis.

Multiple β-defensin genes are upregulated by the vitamin D pathway in cattle

Experimental models of bacterial and viral infections in cattle have suggested vitamin D has a role in innate immunity of cattle. The intracrine vitamin D pathway of bovine macrophages, however, has only been shown to activate a nitric oxide-mediated defense mechanism, as opposed to cathelicidin and β-defensin antimicrobial peptides in human macrophages. In this study we have investigated the actions of 1,25-dihydroxyvitamin D3 (1,25D) on a cluster of eleven bovine β-defensin genes on the basis of RNAseq data indicating they were targets of 1,25D in cattle. Treatment of bovine monocyte cultures with 1,25D (10nM, 18h) in the absence and presence of LPS stimulation increased the expression of bovine β-defensin 3 (BNBD3), BNBD4, BNBD6, BNBD7, and BNBD10 genes 5 to 10-fold compared to control (P<0.05). Treatment of lipopolysaccharide (LPS)-stimulated monocytes with 0–100ng/mL 25-hydroxyvitamin D3 also increased BNBD3, BNBD4, BNBD7, and BNBD10 in a dose-dependent manner. Treatment of monocytes with the protein translation inhibitor, cycloheximide, however, blocked upregulation of the β-defensins in response to 1,25D suggesting the β-defensins in cattle are not direct targets of the vitamin D receptor. Furthermore, preliminary investigation of vitamin D’s contribution to β-defensin expression in vivo revealed that intramammary 1,25D treatment of lactating cows increased BNBD7 expression in mammary macrophages. In conclusion, our data demonstrate that multiple β-defensin genes are upregulated by 1,25D in cattle, providing further indication that vitamin D contributes to bovine innate immunity.

Vitamin D receptor pathway is required for probiotic protection in colitis.

Low expression of vitamin D receptor (VDR) and dysfunction of vitamin D/VDR signaling are reported in patients with inflammatory bowel disease (IBD); therefore, restoration of VDR function to control inflammation in IBD is desirable. Probiotics have been used in the treatment of IBD. However, the role of probiotics in the modulation of VDR signaling to effectively reduce inflammation is unknown. We identified a novel role of probiotics in activating VDR activity, thus inhibiting inflammation, using cell models and VDR knockout mice. We found that the probiotics Lactobacillus rhamnosus strain GG (LGG) and Lactobacillus plantarum (LP) increased VDR protein expression in both mouse and human intestinal epithelial cells. Using the VDR luciferase reporter vector, we detected increased transcriptional activity of VDR after probiotic treatment. Probiotics increased the expression of the VDR target genes, such as antimicrobial peptide cathelicidin, at the transcriptional level. Furthermore, the role of probiotics in regulating VDR signaling was tested in vivo using a Salmonella-colitis model in VDR knockout mice. Probiotic treatment conferred physiological and histologic protection from Salmonella-induced colitis in VDR(+/+) mice, whereas probiotics had no effects in the VDR(-/-) mice. Probiotic treatment also enhanced numbers of Paneth cells, which secrete AMPs for host defense. These data indicate that the VDR pathway is required for probiotic protection in colitis. Understanding how probiotics enhance VDR signaling and inhibit inflammation will allow probiotics to be used effectively, resulting in innovative approaches to the prevention and treatment of chronic inflammation.

Phenylbutyrate Is Bacteriostatic against Mycobacterium tuberculosis and Regulates the Macrophage Response to Infection, Synergistically with 25-Hydroxy-Vitamin D3.

Adjunctive vitamin D treatment for pulmonary tuberculosis enhances resolution of inflammation but has modest effects on bacterial clearance. Sodium 4-phenylbutyrate (PBA) is in clinical use for a range of conditions and has been shown to synergise with vitamin D metabolites to upregulate cathelicidin antimicrobial peptide (CAMP) expression. We investigated whether clinically attainable plasma concentrations of PBA (0.4-4mM) directly affect Mycobacterium tuberculosis (Mtb) growth and human macrophage and PBMC response to infection. We also tested the ability of PBA to enhance the immunomodulatory actions of the vitamin D metabolite 25(OH)D3 during infection and synergistically inhibit intracellular Mtb growth. PBA inhibited Mtb growth in broth with an MIC99 of 1mM, which was reduced to 0.25mM by lowering pH. During human macrophage infection, PBA treatment restricted Mtb uptake, phagocytic receptor expression and intracellular growth in a dose-dependent manner. PBA independently regulated CCL chemokine secretion and induced expression of the antimicrobial LTF (lactoferrin), the anti-inflammatory PROC (protein C) and multiple genes within the NLRP3 inflammasome pathway. PBA co-treatment with 25(OH)D3 synergistically modulated expression of numerous vitamin D-response genes, including CAMP, CYP24A1, CXCL10 and IL-37. This synergistic effect was dependent on MAPK signalling, while the effect of PBA on LTF, PROC and NLRP3 was MAPK-independent. During PBA and 25(OH)D3 co-treatment of human macrophages, in the absence of exogenous proteinase 3 (PR3) to activate cathelicidin, Mtb growth restriction was dominated by the effect of PBA, while the addition of PR3 enhanced growth restriction by 25(OH)D3 and PBA co-treatment. This suggests that PBA augments vitamin D–mediated cathelicidin-dependent Mtb growth restriction by human macrophages and independently induces antimicrobial and anti-inflammatory action. Therefore through both host-directed and bacterial-directed mechanisms PBA and vitamin D may prove an effective combinatorial adjunct therapy for tuberculosis to both resolve immunopathology and enhance bacterial clearance.