Immunomodulation therapy of diabetes by oral administration of a surfactin lipopeptide in NOD mice

The Physicochemical and Functional Properties of Biosurfactants: A Review

Surfactants, also known as surface-active agents, have emerged as an important class of compounds with a wide range of applications. However, the use of chemical-derived surfactants must be restricted due to their potential adverse impact on the ecosystem and the health of human and other living organisms. In the past few years, there has been a growing inclination towards natural-derived alternatives, particularly microbial surfactants, as substitutes for synthetic or chemical-based counterparts. Microbial biosurfactants are abundantly found in bacterial species, predominantly Bacillus spp. and Pseudomonas spp. The chemical structures of biosurfactants involve the complexation of lipids with carbohydrates (glycolipoproteins and glycolipids), peptides (lipopeptides), and phosphates (phospholipids). Lipopeptides, in particular, have been the subject of extensive research due to their versatile properties, including emulsifying, antimicrobial, anticancer, and anti-inflammatory properties. This review provides an update on research progress in the classification of surfactants. Furthermore, it explores various bacterial biosurfactants and their functionalities, along with their advantages over synthetic surfactants. Finally, the potential applications of these biosurfactants in many industries and insights into future research directions are discussed.

The Secondary Metabolites of Bacillus subtilis Strain Z15 Induce Apoptosis in Hepatocellular Carcinoma Cells

The lipopeptides produced by Bacillus subtilis have anti-cancer potential. We had previously identified a secondary metabolite of B. subtilis strain Z15 (BS-Z15), which has an operon that regulates lipopeptide synthesis, and also demonstrated that the fermentation products of this strain exerted antioxidant and pro-immune effects. The purpose of this study was to investigate in vitro and in vivo the anticancer effects of BS-Z15 secondary metabolites (BS-Z15 SMs) on hepatocellular carcinoma (HCC) cells. BS-Z15 SMs significantly inhibited H22 cell-derived murine xenograft tumor growth without any systemic toxicity. In addition, BS-Z15 SMs decreased the viability of H22 cells and BEL-7404 cells in vitro with respective IC50 values of 33.83 and 27.26 µg/mL. Consistent with this, BS-Z15 SMs induced apoptosis and G0/G1 phase arrest in the BEL-7404 cells, and the mitochondrial membrane potential was also significantly reduced in a dose-dependent manner. Mechanistically, BS-Z15 SMs upregulated the pro-apoptotic p53, Bax, cytochrome C, and cleaved-caspase-3/9 proteins and downregulated the anti-apoptotic Bcl-2. These findings suggest that the induction of apoptosis in HCC cells by BS-Z15 SMs may be related to the mitochondrial pathway. Thus, the secondary metabolites of B. subtilis strain Z15 are promising to become new anti-cancer drugs for the clinical treatment of liver cancer.

Safety assessment of surfactin-producing Bacillus strains and their lipopeptides extracts in vitro and in vivo

Beneficial Bacillus strains can be administered to livestock as probiotics to improve animal health. Cyclic lipopeptides produced by Bacillus such as surfactins may be responsible for some of the beneficial effects due to their anti-inflammatory and immunomodulatory activity. The aim of the present study was to isolate and evaluate the biocompatibility of native Bacillus spp. strains and their surfactin-like lipopeptides in vitro and in vivo to determine their potential to be used on animals. Biocompatibility of endospore suspensions (10⁸  UFC/mL), and different dilutions (1:10; 1:50; 1:100; 1:500, and 1:1000) of Bacillus lipopeptide extracts containing surfactin was tested on Caco-2 cells by microculture tetrazolium-based colorimetric assay. Genotoxicity was tested on BALB/c mice (n = 6) administered 0.2 mL of endospore suspensions by the bone marrow erythrocyte micronuclei assay. All the isolates tested produced between 26.96 and 239.97 µg mL^{- 1} of surfactin. The lipopeptide extract (LPE) from isolate MFF1.11 demonstrated significant cytotoxicity in vitro. In contrast, LPE from MFF 2.2; MFF 2.7, TL1.11, TL 2.5, and TC12 had no cytotoxic effect (V% > 70%) on Caco-2 cells, not affecting cell viability signifficantly in most treatments. Similarly, none of the endospore suspensions affected cell viability (V% > 80%). Likewise, endospores did not cause genotoxicity on BALB/c mice. This study was elementary as a first step for a new line of research, since it allowed us to choose the safest isolates to keep working on the search of new potentially probiotic strains destined to production animals to improve their performance and health.

T cells and their products in diabetic kidney disease

Diabetic kidney disease (DKD) is the most common cause of end-stage renal disease and has gradually become a public health problem worldwide. DKD is increasingly recognized as a comprehensive inflammatory disease that is largely regulated by T cells. Given the pivotal role of T cells and T cells-producing cytokines in DKD, we summarized recent advances concerning T cells in the progression of type 2 diabetic nephropathy and provided a novel perspective of immune-related factors in diabetes. Specific emphasis is placed on the classification of T cells, process of T cell recruitment, function of T cells in the development of diabetic kidney damage, and potential treatments and therapeutic strategies involving T cells.

Surfactin Mitigates a High-Fat Diet and Streptozotocin-Induced Type 2 Diabetes through Improving Pancreatic Dysfunction and Inhibiting Inflammatory Response

Surfactin from Bacillus amyloliquefaciens fmb50 was utilized to treat mice with type 2 diabetes (T2DM) induced by a high-fat diet/streptozotocin (HFD/STZ). Our group’s earlier research indicated that surfactin could lower blood glucose and mitigate liver dysfunction to further improve HFD/STZ-induced T2DM through modulating intestinal microbiota. Thus, we further investigated the effects of surfactin on the pancreas and colon in mice with T2DM to elucidate the detailed mechanism. In the present study, mice with HFD/STZ-induced T2DM had their pancreatic and colon inflammation, oxidative stress, and endoplasmic reticulum stress (ERS) reduced when given oral surfactin at a dose of 80 mg/kg body weight. According to further research, surfactin also improved glucose metabolism by activating the phosphatidylinositol kinase (PI3K)/protein kinase B (Akt) signaling pathway, further protecting islets β-cell, promoting insulin secretion, inhibiting glucagon release and mitigating pancreas dysfunction. Additionally, after surfactin treatment, the colon levels of the tight junction proteins Occludin and Claudin-1 of T2DM mice were considerably increased by 130.64% and by 36.40%, respectively. These findings revealed that surfactin not only ameliorated HFD/STZ-induced pancreas inflammation and dysfunction and preserved intestinal barrier dysfunction and gut microbiota homeostasis but also enhanced insulin sensitivity and glucose homeostasis in T2DM mice. Finally, in the further experiment, we were able to demonstrate that early surfactin intervention might delay the development of T2DM caused by HFD/STZ, according to critical biochemical parameters in serum.

A mini-review: mechanism of antimicrobial action and application of surfactin

Surfactin, an antibacterial lipopeptide produced by different strains of Bacillus subtilis, is a powerful biosurfactant. It also has multiple biological activities including antiviral, anti-mycoplasma and antiprotozoal activities, in addition to the broad-spectrum antimicrobial activities against Gram-positive bacteria, Gram-negative bacteria and fungi. Surfactin may be one of the promising alternatives to antibiotics. Surfactin's chemical structure and physicochemical properties are briefly discussed in this mini-review. Surfactin's antibacterial mechanism is mainly outlined as follows: (1) attacking pathogenic bacteria's cell membrane, causing cell membrane disintegration or osmotic pressure imbalance; (2) inhibiting pathogenic bacteria's protein synthesis, preventing cell reproduction; (3) inhibiting pathogenic bacteria's enzyme activity, affecting normal cell metabolism. This provides basis for the further research and application of surfactin. Finally, the application of surfactin in food and its prospect are summarized in brief.

Ameliorated effects of a lipopeptide surfactin on insulin resistance in vitro and in vivo

Surfactin, produced by Bacillus amyloliquefaciens fmb50, was used to treat insulin‐resistant (IR) hepatocyte. It was found that surfactin increased glucose consumption in insulin‐resistant HepG2 (IR‐HepG2) cells and ameliorated IR by increasing glucose transporter 4 (GLUT4) protein expression and AMP‐activated protein kinase (AMPK) mRNA expression, promoting GLUT4 translocation and activating phosphatidylinositol 3‐kinase (PI3K)/protein kinase B (Akt) in IR‐HepG2 cells. Meanwhile, surfactin downregulated protein expression of phosphoenolpyruvate carboxy kinase (PEPCK) and glucose‐6‐phosphatase (G6Pase), further inhibiting hepatic gluconeogenesis. In addition, surfactin played important roles in eliminating reactive oxygen species (ROS), improving mitochondrial dysfunction, and inhibiting proinflammatory mediators. We observed that surfactin promoted glucose consumption, meanwhile increased translocation and protein expression of GLUT4 in Caco‐2 cells. These results confirmed the conclusion in hepatic cells. Furthermore, surfactin supplement decreased body weight, food intake, and fasting blood glucose of type 2 diabetes mellitus (T2DM) mice induced by streptozotocin (STZ)/high‐fat diet (HFD). Our data indicated that surfactin ameliorated insulin resistance and lowered blood glucose in intro and in vivo.

Application of surfactants in papermaking industry and future development trend of green surfactants

In this work, the application of chemical surfactants, including cooking aids, detergents, surface sizing agents, and deinking agents as core components, is introduced in the wet end of pulping and papermaking. This method for the combined application of enzymes and surfactants has expanded, promoting technological updates and improving the effect of surfactants in practical applications. Finally, the potential substitution of green surfactants for chemical surfactants is discussed. The source, classification, and natural functions of green surfactants are introduced, including plant extracts, biobased surfactants, fermentation products, and woody biomass. These green surfactants have advantages over their chemically synthesized counterparts, such as their low toxicity and biodegradability. This article reviews the latest developments in the application of surfactants in different paper industry processes and extends the methods of use. Additionally, the application potential of green surfactants in the field of papermaking is discussed. KEY POINTS: • Surfactants as important chemical additives in papermaking process are reviewed. • Deinking technologies by combined of surfactants and enzymes are reviewed. • Applications of green surfactant in papermaking industry are prospected.

Characterization of Iturin V, a Novel Antimicrobial Lipopeptide from a Potential Probiotic Strain Lactobacillus sp. M31

Members of lactic acid bacteria group are known to produce various antimicrobial substances. Cyclic lipopeptides are one such potent class of amphipathic natural biosurfactants that exhibit bactericidal and immunomodulatory properties. In this study, we aimed to investigate antimicrobial and immunomodulatory activities of a lipopeptide secreted by a LAB isolate strain M31 identified as a member of the genus Lactobacillus. The lipopeptide that was purified using a combination of chromatographic techniques and matrix-assisted laser desorption/ionization-time of flight of pure lipopeptide displayed a molecular weight of 1002 Da. MS/MS analysis confirmed the presence of 7 amino acids (Asp-Tyr-Asp-Val-Pro-Asp-Ser) and a C13 beta-hydroxy fatty acid. The amino acid composition assigned lipopeptide to iturin class. However, the replacement of Gln with Val revealed it to represent a novel iturin named as iturin V. Iturin V showed antibacterial activity and did not cause hemolysis or cytotoxicity upto 125 µg/mL. It induced secretion of pro-inflammatory cytokines TNF-alpha and IL-12 in murine dendritic cells. Probiotic features of strain M31 coupled with notable activity of iturin V against species of the genera Pseudomonas and Vibrio suggest that strain M31 has potential application for pathogen intervention treatments in processing of aquatic food products.

Study on the interaction between surfactin and alkaline protease in aqueous solution

The interaction between surfactin and alkaline protease in aqueous solution has been studied. Ultraviolet visible absorption spectra (UV-vis) show that surfactin causes the extension of peptide chain of the alkaline protease resulting in the weakening of hydrophobic interaction between the hydrophobic groups. Fluorescence spectra indicate that the interaction of surfactin with the tryptophan and tyrosine residues led to a change of conformation of the alkaline protease. Fourier transform infrared spectroscopy (FTIR) proves complex weak interactions between surfactin and alkaline protease, especially hydrogen bonds. Enzyme activity measurements demonstrate that low concentration of surfactin can increase the enzyme activity of alkaline protease, while high concentrations inhibit it. The particle size and Zeta potential measurements confirm that the system particle size and Zeta potential are dependent on the concentration of surfactin, in addition, there is the electrostatic interaction between surfactin and alkaline protease. Surface tension measurements indicate that the binds of surfactin and alkaline protease molecules are spontaneous. Based on experimental results, the composite model of surfactin and alkaline protease in aqueous solution is proposed.

Effects of dietary Bacillus amyloliquefaciens supplementation on growth performance, intestinal morphology, inflammatory response, and microbiota of intra-uterine growth retarded weanling piglets

BACKGROUND

The focus of recent research has been directed toward the probiotic potential of Bacillus amyloliquefaciens (BA) on the gut health of animals. However, little is known about BA's effects on piglets with intra-uterine growth retardation (IUGR). Therefore, this study investigated the effects of BA supplementation on the growth performance, intestinal morphology, inflammatory response, and microbiota of IUGR piglets.

METHODS

Eighteen litters of newborn piglets were selected at birth, with one normal birth weight (NBW) and two IUGR piglets in each litter (i.e., 18 NBW and 36 IUGR piglets in total). At weaning, the NBW piglet and one of the IUGR piglets were assigned to groups fed a control diet (i.e., the NBW-CON and IUGR-CON groups). The other IUGR piglet was assigned to a group fed the control diet supplemented with 2.0 g BA per kg of diet (i.e., IUGR-BA group). The piglets were thus distributed across three groups for a four-week period.

RESULTS

IUGR reduced the growth performance of the IUGR-CON piglets compared with the NBW-CON piglets. It was also associated with decreased villus sizes, increased apoptosis rates, reduced goblet cell numbers, and an imbalance between pro- and anti-inflammatory cytokines in the small intestine. Supplementation with BA improved the average daily weight gain and the feed efficiency of the IUGR-BA group compared with the IUGR-CON group (P < 0.05). The IUGR-BA group exhibited increases in the ratio of jejunal villus height to crypt depth, in ileal villus height, and in ileal goblet cell density. They also exhibited decreases in the numbers of jejunal and ileal apoptotic cells and ileal proliferative cells (P < 0.05). Supplementation with BA increased interleukin 10 content, but it decreased tumor necrosis factor alpha level in the small intestines of the IUGR-BA piglets (P < 0.05). Furthermore, compared with the IUGR-CON piglets, the IUGR-BA piglets had less Escherichia coli in their jejunal digesta, but more Lactobacillus and Bifidobacterium in their ileal digesta (P < 0.05).

CONCLUSIONS

Dietary supplementation with BA improves morphology, decreases inflammatory response, and regulates microbiota in the small intestines of IUGR piglets, which may contribute to improved growth performance during early life.

Biological activity of lipopeptides from Bacillus

The lipopeptides of Bacillus are small metabolites that contain a cyclic structure formed by 7-10 amino acids (including 2-4 D-amino acids) and a beta-hydroxy fatty acid with 13-19 C atoms. These lipopeptides exhibit a variety of biological activities, including interactions with biofilms, and anti-fungal, anti-inflammatory, anti-tumor, anti-virus, and anti-platelet properties. The multiple activities of lipopeptides have stimulated significant interest in the exploitation of these lipopeptides for use as antibiotics, feed additives, anti-tumor agents, urgent thrombolytic therapeutic agents, and drug delivery systems. Understanding the natural function of these structurally diverse lipopeptides in Bacillus provides insight into microbial regulatory programs and is required for efficient development of more effective products. Currently, there is still insufficient knowledge of the direct target of these lipopeptides, and continued efforts are needed to enhance their biosynthesis efficiency for industrial applications.

Orally Absorbed Cyclic Peptides

Peptides and proteins are not orally bioavailable in mammals, although a few peptides are intestinally absorbed in small amounts. Polypeptides are generally too large and polar to passively diffuse through lipid membranes, while most known active transport mechanisms facilitate cell uptake of only very small peptides. Systematic evaluations of peptides with molecular weights above 500 Da are needed to identify parameters that influence oral bioavailability. Here we describe 125 cyclic peptides containing four to thirty-seven amino acids that are orally absorbed by mammals. Cyclization minimizes degradation in the gut, blood, and tissues by removing cleavable N- and C-termini and by shielding components from metabolic enzymes. Cyclization also folds peptides into bioactive conformations that determine exposure of polar atoms to solvation by water and lipids and therefore can influence oral bioavailability. Key chemical properties thought to influence oral absorption and bioavailability are analyzed, including molecular weight, octanol-water partitioning, hydrogen bond donors/acceptors, rotatable bonds, and polar surface area. The cyclic peptides violated to different degrees all of the limits traditionally considered to be important for oral bioavailability of drug-like small molecules, although fewer hydrogen bond donors and reduced flexibility generally favored oral absorption.

Evaluation of Bacillus subtilis SPB1 biosurfactant effects on hyperglycemia, angiotensin I-converting enzyme (ACE) activity and kidney function in rats fed on high-fat-high-fructose diet

This study investigated the protective and the curative effects of Bacillus subtilis SPB1 crude lipopeptide biosurfactant in alleviating induced obesity complications in rats fed on high-fat-high-fructose diet (HFFD). Male Wistar rats were divided into five groups with the following treatment schedule: normal diet-fed rats (CD), HFFD-fed rats, HFFD-fed rats supplemented with SPB1 biosurfactant from the first day of the experiment (HFFD + Bios1), rats fed on HFFD receiving standard drug (HFFD + Torva), or SPB1 biosurfactant (HFFD + Bios2) during the last 4 weeks of the study. HFFD induced hyperglycemia, manifested by a significant (p < 0.001) increase (20%) in the levels of glucose and α-amylase activity in the plasma, when compared with CD. The administration of SPB1 biosurfactant to rats fed on HFFD reverted back normal blood glucose and α-amylase activity levels. Also, the findings clearly showed that acute oral administration of SPB1 biosurfactant reduced significantly (34%) the peak of blood glucose concentration 60 min after glucose administration, as compared with untreated rats fed on HFFD. Furthermore, renal dysfunction indices such as creatinine and urea as well as the level of angiotensin I-converting enzyme (ACE) exhibited remarkable increases in serum of rats fed on HFFD by 28.35%, 46%, and 92%,. Interestingly, SPB1 lipopeptides treatments decreased the creatinine and urea levels significantly (p < 0.001) near normal values, as compared with that of the HFFD group, and also showed an improvement of the kidney cortex architecture. Moreover, SPB1 biosurfactant displayed a potent inhibition of ACE activity in vitro (CI₅₀ value=1.37 mg/mL) as well as in vivo in obese rats by 42% and 27.25% with HFFD + Bios1 and HFFD + Bios2 treatments, respectively, and comparatively with the HFFD group. Besides, SPB1 lipopeptides treatments improved some of serum electrolytes such as Na⁺, K⁺, Ca²⁺, and Mg²⁺. The results showed that SPB1 lipopeptide biosurfactant presented useful hypoglycemic and antihypertensive properties, and was able to alleviate renal lipid deposition in rats fed on a hypercaloric diet.

Bacillus-produced surfactin attenuates chronic inflammation in atherosclerotic lesions of ApoE(-/-) mice

Bacillus-produced surfactin can inhibit acute inflammation in vitro and in vivo. However, there is no report whether surfactin could inhibit chronic inflammation in the atherosclerotic lesions. Apoliprotein E deficient (ApoE(-/-)) mice (fed on atherogenic diet) were intragastrically administered with surfactin for 9 doses, then the athero-protective effect of surfactin was determined in vivo. The results showed surfactin could induce anti-inflammatory factors such as IgA, transforming growth factor (TGF)-β and interleukin (IL)-10 in the intestine. Further investigation discovered that surfactin also systemically induced CD4(+)CD25(+)FoxP3(+) Tregs in spleen, which could inhibit T cells to produce pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α and interferon (IFN)-γ. The IgG subclass pattern with high titer of IgG1 (Th2-type) but low titer of IgG2a (Th1-type) was also found in the surfactin-treated mice. As a result, the attenuation of chronic inflammation was observed in the surfactin-treated groups accompanying with less TNF-α but more IL-10 in the atherosclerotic lesions. Moreover, surfactin could reduce serum total cholesterol and cholesterol in low-density lipoprotein, and increase serum cholesterol in high-density lipoprotein in mice. Collectively, surfactin could significantly attenuate atherosclerotic lesions on the aorta by restoration of the delicate balance of Th1/Th2 response in mice.

Canonical Wnt signaling pathway contributes to the proliferation and survival in porcine pancreatic stem cells (PSCs)

Pancreatic stem cells (PSCs) transplantation is a potential therapeutic approach to type 1 diabetes mellitus (D1M). However, before clinical use, there are some major hurdles to be faced that need to be comprehensively considered and given some potential solutions in vitro. Human PSCs are difficult to obtain and have a short replicative senescence. As an alternative, we instead established porcine PSCs; as insulin is highly conserved and physiological glucose levels are similar between human and porcine. In order to solve the problems during transplantation therapy, such as the need for an enormous amount of PSCs and good cell survival in overactive autoimmunity induced by reactive oxygen cpecies (ROS) in D1M patients, we utilized Wnt3a overexpression to activate the canonical Wnt signaling pathway in PSCs. We found that the expression of proliferation genes, such as c-Myc, was up-regulated as the downstream of β-catenin, which promoted the PSCs proliferation and made cell numbers to meet the transplantation needs. We also showed that activation of the Wnt pathway made cells more readily tolerate ROS-caused mitochondria injury and cell apoptosis, thus making cells survive in autoimmune patients. The present study provides a theoretical basis for cell transplantation therapy of diabetes.

Therapeutic cyclic lipopeptides mining from microbes: latest strides and hurdles

Infectious diseases impose serious public health burdens and often have devastating consequences. The cyclic lipopeptides elaborated by bacteria Bacillus, Paenibacillus, Pseudomonas, Streptomyces, Serratia, Propionibacterium and fungus Fusarium are very crucial in restraining the pathogens. Composed of a peptide and a fatty acyl moiety these amphiphilic metabolites exhibit broad spectrum antimicrobial effects. Among the plethora of cyclic lipopeptides, only selective few have emerged as robust antibiotics. For their functional vigor, polymyxin, daptomycin, surfactin, iturin, fengysin, paenibacterin and pseudofactin have been integrated in mainstream healthcare. Daptomycin has been a significant part of antimicrobial arsenal since the past decade. As the magnitude of drug resistance rises in unprecedented manner, the urgency of prospecting novel cyclic lipopeptides is being perceived. Intense research has revealed the implication of these bioactive compounds stretching beyond antibacterial and antifungal. Anticancer, immunomodulatory, prosthetic parts disinfection and vaccine adjuvancy are some of the validated prospects. This review discusses the emerging applications, mechanisms governing the biological actions, role of genomics in refining structure and function, semi-synthetic analog discovery, novel strain isolation, setbacks etc. Though its beyond the scope of the current topic, for holistic purpose, the role of lipopeptides in bioremediation and crop biotechnology has been briefly outlined. This updated critique is expected to galvanize innovations and diversify therapeutic recruitment of microbial lipopeptides.

Bacillus amyloliquefaciens supplementation alleviates immunological stress in lipopolysaccharide-challenged broilers at early age

This study was conducted to investigate the effect of Bacillus amyloliquefaciens ( BA: ) on the immune function of broilers challenged with lipopolysaccharide ( LPS: ). 192 one-day-old male Arbor Acre broiler chickens were randomly distributed into four treatments: 1) broilers fed a basal diet; 2) broilers fed a basal diet supplemented with BA; 3) LPS-challenged broilers fed a basal diet; and 4) LPS-challenged broilers fed a basal diet supplemented with BA. Each treatment consisted of six replicates with eight broilers per replicate. Broilers were intraperitoneally injected with either 500 μg LPS per kg body weight or sterile saline at 16, 18 and 20 d of age. LPS decreased the average daily gain ( ADG: , P = 0.001) and average daily feed intake (P = 0.001). The decreased ADG (P = 0.009) and increased feed conversion ratio (P = 0.047) in LPS-challenged broilers were alleviated by BA. LPS increased the relative spleen weight (P = 0.001). Relative spleen (P = 0.014) and bursa (P = 0.024) weights in the LPS-challenged broilers were reduced by BA. LPS increased white blood cell ( WBC: ) numbers (P = 0.001). However, the WBC numbers (P = 0.042) and the ratio of lymphocytes to WBC (P = 0.020) in LPS-challenged broilers were decreased with BA treatment. LPS decreased plasma lysozyme activity (P = 0.001), but increased concentrations of plasma corticosterone (P = 0.012) and IL-2 (P = 0.020). In contrast, BA increased lysozyme activity in plasma (P = 0.040). LPS increased mRNA abundances of splenic toll-like receptor 4 (P = 0.046), interferon γ (P = 0.008), IL-1β (P = 0.045) and IL-6, (P = 0.006). IL-2 (P = 0.014) and IL-6 (P = 0.074) mRNA abundances in LPS-challenged broilers were reduced by BA, although BA had an opposite effect for IL-10 mRNA expression in those broilers (P = 0.004). In conclusion, BA supplementation could partially alleviate the compromised growth performance and immune status of broilers under immune stress induced by LPS challenge at early age.