Effect of the synthetic Toll-like receptor ligands LPS, Pam3CSK4, HKLM and FSL-1 in the function of bovine polymorphonuclear neutrophils

Cytotoxic Oxidative Stress Effects of Neutrophil Extracellular Traps' Components on Cattle Spermatozoa

Bovine spermatozoa are highly susceptible to oxidative stress (OS), and it is known to affect their cellular functions. The main leukocyte producers of reactive oxygen species (ROS) in mammalian semen are polymorphonuclear neutrophils (PMN). PMN activation can result in the formation of neutrophil extracellular traps (NETs), which have been shown to affect the motility and function of spermatozoa. However, OS effects on bull spermatozoa derived from individual NETs components have not been investigated. The hypothesis of this study was that specific NETs components might generate OS on bull spermatozoa. Bovine sperm cells were incubated with five NETs-associated molecules, including 30 μg/mL histone 2A (H2A), neutrophil elastase (NE), 1 μg/mL myeloperoxidase (MPO), cathepsin G (Cat-G), and cathelicidin LL37 (LL-37), for a time course ranging from 15 to 240 min. Fluorescence microscopy was used to evaluate the coincubation of bovine PMN and sperm cells. Within 15 min, H2A, NE, and LL-37 caused membrane disruption, while MPO and Cat-G caused OS on bull spermatozoa after 1 h of coincubation. NET formation was observed within 15 min of coincubation in co-cultures of bovine PMN/sperm cells. This study is the first to report on the role of cytotoxic OS effects caused by NETs-derived components in bovine sperm in vitro.

Divergent Immune Responses to Minor Bovine Mastitis-Causing Pathogens

Traditionally, non-aureus staphylococci and mammaliicocci (NASM) were not considered significant players in bovine mastitis. This study investigated the involvement of NASM (Staphylococcus hominis and Staphylococcus chromogenes) and lactic acid bacteria (LAB) strains (Weissella paramesenteroides) through bovine neutrophil responses. Bovine neutrophils displayed minimal apoptosis upon NASM and LAB challenge. Neutrophils expressed high TLR2 after challenge, but TLR6 expression varied and remained low in NASM pathogen recognition. Bovine neutrophils effectively engulfed and killed LAB, but their activity was significantly impaired against NASM. This was evident in S. chromogenes, where reduced TLR6 recognition and a weakened phagocytic response likely contributed to a lower bactericidal effect. Regardless of the bacteria encountered, intracellular ROS production remained high. S. chromogenes-challenged neutrophils displayed upregulation in genes for pathogen recognition (TLRs), ROS production, and both pro- and anti-apoptotic pathways. This response mirrored that of Weissella. except for CASP9 and BCL2, suggesting these bacteria have divergent roles in triggering cell death. Our findings suggest that S. chromogenes manipulates bovine neutrophil defenses through coordinated changes in functional responses and gene expression, while LAB strains have a weaker influence on apoptosis.

Homology Modeling, Molecular Dynamics Simulation, and Prediction of Bovine TLR2 Heterodimerization

Toll-like receptor 2 (TLR2) is a major membrane-bound receptor with ligand and species specificity that activates the host immune response. Heterodimerization of TLR2 with TLR1 (TLR2/1) or TLR6 (TLR2/6), triggered by ligand binding, is essential to initiating the signaling pathway. Bovine TLR2 (bTLR2) heterodimerization has not been defined yet compared with human and mouse TLR2s (hTLR2 and mTLR2). The aim of the present study was to model bovine TLRs (TLRs 1, 2 and 6) and create the heterodimeric forms of the bovine TLR2 using molecular dynamics (MD) simulations. We compared the intermolecular interactions in bTLR2/1-PAM3 and bTLR2/6-PAM2 with the hTLR2 and mTLR2 complexes through docking simulations and subsequent MD analyses. The present computational findings showed that bTLR2 dimerization could have a biological function and activate the immune response, similar to hTLR2 and mTLR2. Agonists and antagonists that are designed for hTLR2 and mTLR2 can target bTLR2. However, the experimental approaches to comparing the functional immune response of TLR2 across species were missing in the present study. This computational study provides a structural analysis of the bTLR2 interaction with bTLR1 and bTLR6 in the presence of an agonist/antagonist and reveals the three-dimensional structure of bTLR2 dimerization. The present findings could guide future experimental studies targeting bTLR2 with different ligands and lipopeptides.

Effect of different sperm populations on neutrophils extracellular traps (NETs) formation in cattle

In cattle, clinical and subclinical inflammation in the bovine female reproductive tract (FRT) significantly reduces fertility. PMN participate in this FRT-associated inflammation by eliminating pathogens by eliciting various defense mechanisms, with the release of neutrophil extracellular traps NETs) being the latest process discovered. Consistently, human-, bovine- and porcine-derived spermatozoa induce release of NETs in exposed PMN of the same species origin, and thereby decreasing sperm motility through NETs-mediated entrapment. The release of NETs in the presence of different sperm sub-populations is evaluated in this work. Cryopreserved bovine sperm were selected and different sperm populations were used: viable sperm, sperm with oxidative stress, capacitated sperm, and sperm with loss of viability. Isolated PMN of dairy cows were co-incubated with these sperm populations for 4 h. Neutrophil elastase (NE) and DNA were detected by fluorescence microscopy analysis. It was noted that exposed bovine PMN released NETs in the presence of sperm. Moreover, sperm-triggered NETosis resulted different phenotypes of NETs, i. e. spread NETs (sprNETs), diffused NETs (diffNETs) and aggregated NETs (aggNETs). Viable/motile spermatozoa induced a higher proportion of NETotic cells at 15, 60 and 120 min in comparison to controls. In conclusion, all bovine sperm populations in co-culture with PMN generated NETs extrusion while viable sperm activated NETotic cells to a greater extent. With this being an early event in the activation of bovine PMN.

Impact of Selected Bacterial and Viral Toll-like Receptor Agonists on the Phenotype and Function of Camel Blood Neutrophils

Innate recognition of pathogens depends on the interaction between microbial structures known as pathogen-associated molecular patterns (PAMPs) and pattern recognition receptors (PRRs) in host cells. Toll-like receptors (TLR) are among the most important PRRs being expressed on and in a wide range of immune cell types. Studies on the interaction mechanisms between different pathogen species and the immune system of the dromedary camel are still scarce. The present study aimed to investigate the immunomodulatory effect of synthetic bacterial and viral TLR ligands on some phenotypic properties and selected functions of neutrophils purified from dromedary camel blood. Neutrophils were separated from camel blood (n = five animals) and were stimulated in vitro with the TLR ligands LPS, Pam3CSK4, R848 (Resiquimod), and Poly IC or were left without stimulation. Stimulation with the protein kinase C activator phorbol 12-myristate 13-acetate (PMA) was used as a positive control stimulation. Shape change, phagocytosis activity, ROS production, the expression of cell surface markers, and cell vitality were compared between stimulated and non-stimulated cells. With exception of the TLR3 agonist Poly IC, all TLR ligands used showed the potential to stimulate camel neutrophils resulting in increased cell size and the upregulation of CD18 and CD14 on their surface. Similarly, the phagocytosis activity of camel neutrophils was significantly improved after priming with all TLR ligands, except Poly IC, which, in contrast, resulted in a reduced percentage of phagocytosis-positive cells. In contrast to stimulation with PMA, which induced a significant ROS production in camel neutrophils, none of the TLR ligands used stimulated ROS generation in neutrophils. Only stimulation with Pam3CSK4 increased the expression of MHCII molecules on camel neutrophils, resulting in an expanded MHCII^high fraction within camel neutrophils. Our study indicates selective immunomodulating effects of TLR agonists on purified camel neutrophils without affecting their vitality.

Immunomodulatory Effects of Bacterial Toll-like Receptor Ligands on the Phenotype and Function of Milk Immune Cells in Dromedary Camel

(1) Toll-like receptors (TLR) are a family of pattern recognition receptors that sense distinct molecular patterns of microbial origin. Although the immune cell composition of camel milk has been recently described, host-pathogen interaction studies in the camel mammary gland are still scarce. The present study aimed to use a whole milk stimulation assay for investigating the modulatory effect of selected Toll-like receptor (TLR) ligands on the phenotype and function of milk immune cells. (2) Methods-camel milk samples (n = 7) were stimulated in vitro with the TLR4 ligand LPS or the TLR2/1 ligand Pam3CSK4, and separated milk cells were evaluated for stimulation-induced shape change, the expression of cell surface markers, phagocytosis, apoptosis, ROS production, and NETosis. Stimulation with PMA was used as a control stimulation. (3) Results-all stimulants induced shape change in milk cells, change in the expression of several cell markers, and increased cell apoptosis and NETosis. In addition, stimulation with Pam3CSK4 and PMA was associated with enhanced ROS production, while only PMA stimulation resulted in enhanced bacterial phagocytosis by milk immune cells. (4) Conclusions-our data indicates selective modulating effects of the TLR ligands LPS and Pam3CSK4 on camel milk phagocytes. These results may have implications for the use of synthetic TLR agonists as immunomodulatory adjuvants of the immune response to intra-mammary vaccines against mastitis pathogens.

Dynamics of cell cycle proteins involved in Toxoplasma gondii-induced bovine NET formation

Neutrophil extracellular traps (NET) formation is one important host innate defense mechanism elicited by polymorphonuclear neutrophils (PMN). NETs are composed by chromatin and proteins with microbicidal and signaling activity. So far, there is one report on Toxoplasma gondii-triggered NETs in cattle, however, exact mechanisms, including signalling pathways and dynamics governing this reaction remain largely unknown. Recently, involvement of cell cycle proteins was demonstrated for phorbol myristate acetate (PMA)-triggered human PMN-derived NETs. Here, we studied the involvement of cell cycle proteins in T. gondii-induced NETs in exposed bovine PMN. Through confocal and transmission electron microscopy we discovered that Ki-67 and lamin B1 signals are upregulated and relocated during T. gondii-induced NETosis. Nuclear membrane disruption was also observed as a hallmark of NET formation in bovine PMN confronted with viable T. gondii tachyzoites, mimicking some steps of mitosis. However, we did not observe centrosome duplication as previously described for human PMN-derived NET formation stimulated with PMA.

Toll-like Receptor 2 is Involved in Calcium Influx and Acrosome Reaction to Facilitate Sperm Penetration to Oocytes During in vitro Fertilization in Cattle

Cumulus cells of ovulated cumulus-oocyte complexes (COCs) express Toll-like receptor 2 (TLR2), pathogen recognition receptors, to recognize and react to sperm signals during fertilization. Sperm also express TLR2, but its contribution to the sperm-oocytes crosstalk is still unclear. Here, we adapted the in vitro fertilization (IVF) model to characterize the potential relevance of sperm TLR2 in sperm-oocytes interactions during fertilization in bovine. The IVF results showed that the ligation of sperm TLR2 with its specific antagonist/agonist resulted in down/up-regulation of the cleavage and blastocyst rates either in COCs or cumulus-free oocytes, but not in zona pellucida (ZP)-free oocytes. The computer-assisted sperm analysis (CASA) system revealed that sperm motility parameters were not affected in TLR2 antagonist/agonist-treated sperm. However, fluorescence imaging of sperm-ZP interactions revealed that the blockage or activation of the TLR2 system in sperm reduced or enhanced both binding and penetration abilities of sperm to ZP compared to control, respectively. Flow cytometrical analysis of acrosome reaction (AR) demonstrated that the TLR2 system adjusted the occurrence of AR in ZP-attached sperm, suggesting that sperm TLR2 plays physiological impacts on the sperm-oocyte crosstalk via regulating ZP-triggered AR in sperm. Given that calcium (Ca²⁺) influx is a pre-requisite step for the induction of AR, we investigated the impact of the TLR2 system on the ionophore A23187-induced Ca²⁺ influx into sperm. Notably, the exposure of sperm to TLR2 antagonist/agonist reduced/increased the intracellular Ca²⁺ level in sperm. Together, these findings shed new light that the TLR2 system is involved in sperm AR induction which enables sperm to penetrate and fertilize oocytes during the fertilization, at least in vitro, in cows. This suggests that sperm possibly developed a quite flexible sensing mechanism simultaneously against pathogens as well as COCs toward fertilization with the same TLR2 of the innate immune system.

Oral vaccination stimulates neutrophil functionality and exerts protection in a Mycobacterium avium subsp. paratuberculosis infection model

Mycobacterium avium subsp. paratuberculosis (Map) causes paratuberculosis (PTB), a granulomatous enteritis in ruminants that exerts high economic impact on the dairy industry worldwide. Current vaccines have shown to be cost-effective against Map and in some cases confer beneficial non-specific effects against other pathogens suggesting the existence of trained immunity. Although Map infection is mainly transmitted by the fecal-oral route, oral vaccination has not been deeply studied. Therefore, the aim of this study was to compare the oral route with a set of mycobacterial and non-mycobacterial vaccines with a subcutaneously administered commercially available vaccine. Training effects on polymorphonuclear neutrophils (PMNs) and homologous and heterologous in vivo protection against Map were investigated in the rabbit infection model. Oral vaccination with inactivated or live vaccines was able to activate mucosal immunity as seen by elevation of serum IgA and the expression of IL4 in peripheral blood mononuclear cells (PBMCs). In addition, peripheral PMN phagocytosis against Map was enhanced by vaccination and extracellular trap release against Map and non-related pathogens was modified by both, vaccination and Map-challenge, indicating trained immunity. Finally, PBMCs from vaccinated animals stimulated in vitro with Map antigens showed a rapid innate activation cytokine profile. In conclusion, our data show that oral vaccination against PTB can stimulate neutrophil activity and both innate and adaptive immune responses that correlate with protection.

Regulatory role of the TLR4/JNK signaling pathway in sepsis‑induced myocardial dysfunction

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection, and is a leading cause of mortality worldwide. Myocardial dysfunction is associated with poor prognosis in patients with sepsis and contributes to a high risk of mortality. However, the pathophysiological mechanisms underlying sepsis-induced myocardial dysfunction are not completely understood. The aim of the present study was to investigate the role of toll-like receptor 4 (TLR4)/c-Jun N-terminal kinase (JNK) signaling in pro-inflammatory cytokine expression and cardiac dysfunction during lipopolysaccharide (LPS)-induced sepsis in mice. C57BL/6 mice were pretreated with TAK-242 or saline for 1 h and then subjected to LPS (12 mg/kg, intraperitoneal) treatment. Cardiac function was assessed using an echocardiogram. The morphological changes of the myocardium were examined by hematoxylin and eosin staining and transmission electron microscopy. The serum protein levels of cardiac troponin I (cTnI) and tumor necrosis factor-α (TNF-α) were determined by an enzyme-linked immunosorbent assay (ELISA). The TLR4 and JNK mRNA levels were analyzed via reverse transcription-quantitative PCR. TLR4, JNK and phosphorylated-JNK protein levels were measured by western blotting. In response to LPS, the activation of TLR4 and JNK in the myocardium was upregulated. There were significant increases in the serum levels of TNF-α and cTnI, as well as histopathological changes in the myocardium and suppressed cardiac function, following LPS stimulation. Inhibition of TLR4 activation using TAK-242 led to a decrease in the activation of JNK and reduced the protein expression of TNF-α in plasma, and alleviated histological myocardial injury and improved cardiac function during sepsis in mice. The present data suggested that the TLR4/JNK signaling pathway played a critical role in regulating the production of pro-inflammatory cytokines and myocardial dysfunction induced by LPS.

The Role of TLR2 and TLR4 in Recognition and Uptake of the Apicomplexan Parasite Eimeria bovis and Their Effects on NET Formation

BACKGROUND

Bovine polymorphonuclear neutrophils (PMN) constitutively express the Toll-like receptors (TLRs) TLR2 and TLR4 and have been shown to generate Neutrophil extracellular traps (NETs) upon exposure to Eimeria bovis. The present work investigated the role of TLR2 and TLR4 in the recognition and uptake of E. bovis sporozoites, IL-8 production and neutrophil extracellular trap (NET) formation.

METHODS

TLR expression was performed by flow cytometric analysis on PMN exposed to live carboxyfluorescein succinimidyl ester (CFSE)-stained sporozoites. Supernatants of PMN exposed to different E. bovis sporozoite preparations and antigens in the absence or presence of TLR antibodies were assessed for IL-8 secretion. Cells were exposed to sporozoite preparations and assessed for the activation of transcription factor NF-κB using a luciferase reporter assay. Immunofluorescence analysis was done to investigate TLR2 and TLR4 surface expression and NET formation on bovine PMN exposed to vital sporozoites.

RESULTS

we observed significantly increased TLR2 and TLR4 expression with a mean increase in expression that was greater for TLR2 than TLR4. This upregulation neither inhibited nor promoted sporozoite phagocytosis by bovine PMN. Live sporozoites together with anti-TLR2 mAb resulted in a significant enhancement of IL-8 production. NF-κB activation was more strongly induced in TLR2-HEK cells than in TLR4/MD2-HEK cells exposed to heat-killed sporozoites and antigens. Immunofluorescence analysis showed TLR-positive signals on the surface of PMN and concomitant NET formation.

CONCLUSIONS

This is the first report on E. bovis-induced concomitant TLR2 and TLR4 expression during bovine PMN-derived NETosis.

Enterobactin Deficiency in a Coliform Mastitis Isolate Decreases Its Fitness in a Murine Model: A Preliminary Host-Pathogen Interaction Study

Iron is an essential nutrient for bacterial growth. Therefore, bacteria have evolved chelation mechanisms to acquire iron for their survival. Enterobactin, a chelator with high affinity for ferric iron, is secreted by Escherichia coli and contributes to its improved bacterial fitness. In this preliminary study, we evaluated enterobactin deficiency both in vitro and in vivo in the context of E. coli mastitis. Firstly, we showed that expression of lipocalin 2, a protein produced by the host that is able to both bind and deplete enterobactin, is increased upon E. coli infection in the cow's mastitic mammary gland. Secondly, we demonstrated in vitro that enterobactin deficiency does not alter interleukin (IL)-8 expression in bovine mammary epithelial cells and its associated neutrophil recruitment. However, a significantly increased reactive oxygen species production of these neutrophils was observed. Thirdly, we showed there was no significant difference in bacterial in vitro growth between the enterobactin-deficient mutant and its wild-type counterpart. However, when further explored in a murine model for bovine mastitis, the enterobactin-deficient mutant vs. the wild-type strain revealed a significant reduction of the bacterial load and, consequently, a decrease in pro-inflammatory cytokines (IL-1α,-1β,-4,-6, and-8). A reduced neutrophilic influx was also observed immunohistochemically. These findings therefore identify interference of the enterobactin iron-scavenging mechanism as a potential measure to decrease the fitness of E. coli in the mastitic mammary gland.

Interaction between stress hormones and phagocytic cells and its effect on the health status of dairy cows: A review

Dairy cows are exposed to various stressors during their production cycle that makes them more susceptible to various diseases. Phagocytes (neutrophils and macrophages) are important soldiers of the innate immune system. Neutrophils are the first responders to an inflammatory response and stress and kill pathogens by generating reactive oxygen species and by the release of various antimicrobial peptides, enzymes, neutrophil extracellular trap formation, etc. Macrophages, the other phagocytes, are also the cleanup crew for the innate immune system that removes debris, pathogens, and dead neutrophils later on after an inflammatory response. The neuroendocrine system along with phagocytes exhibits an immunomodulatory potential during stressful conditions. Neuroendocrine system directly affects the activity of phagocytes by communicating bidirectionally through shared receptors and messenger molecules such as hormones, neurotransmitters, or cytokines. Different immune cells may show variable responses to each hormone. Short time exposure to stress can be beneficial, but repeated or extended exposure to stress may be detrimental to the overall health and well-being of an animal. Although some stresses associated with farming practices in dairy cows are unavoidable, better understanding of the interactions occurring between various stress hormones and phagocytic cells can help to reduce stress, improve productivity and animal welfare. This review highlights the role played by various stress hormones in modulating phagocytic cell performance of dairy cattle under inflammatory conditions.

Neutrophil β-defensin gene expression of postpartum dairy cows is altered by prepartum dietary cation-anion difference

The objective of this study was to evaluate expression of a cluster of genes encoding β-defensin antimicrobial peptides in neutrophils of postpartum cows in relation to prepartum dietary cation-anion difference (DCAD), vitamin D, and postpartum disease. Pregnant dry Holstein cows (28 nulliparous and 51 parous) at 255 d gestation were blocked by parity and randomly assigned to 4 prepartum diets of positive (+130 mEq/kg) or negative (-130 mEq/kg) DCAD and either 3 mg vitamin D₃ or 3 mg of 25-hydroxyvitamin D₃ per 11 kg of dry matter/d. Treatment diets were fed from 255 d of gestation until calving. Peripheral blood neutrophils of 35 parous cows were collected at 0 and 3 d after calving and stimulated with 0 or 100 ng/mL of lipopolysaccharide (LPS). Furthermore, serum Ca and incidences of postpartum diseases were recorded for all cows. The mRNA transcripts of β-defensin genes were quantified by real-time PCR, and data were analyzed with a general linear mixed model to test for fixed effects and interactions of day, level of DCAD, source of vitamin D, and incidence of disease. Effects of DCAD and vitamin D on neutrophil oxidative burst and phagocytosis were previously reported but were analyzed for effects of disease in the present study. Transcripts for DEFB1, DEFB3, DEFB4, DEFB5, DEFB7, DEFB10, and lingual antimicrobial peptide (LAP) in neutrophils were upregulated by LPS at 0 d but not at 3 d. Transcripts for DEFB4 and DEFB7 in LPS-stimulated neutrophils were greater in cows fed negative DCAD diets compared with positive DCAD. Source of vitamin D (vitamin D₃ vs. 25-hydroxyvitamin D₃) did not affect expression of β-defensins in neutrophils. Cows with postpartum subclinical hypocalcemia (serum Ca <2.0 mM) had decreased DEFB3, DEFB4, DEFB6, DEFB7, DEFB10, and LAP expression in LPS-stimulated neutrophils compared with cows that did not experience subclinical hypocalcemia. Likewise, DEFB4, DEFB6, DEFB7, DEFB10, and LAP in LPS-stimulated neutrophils at 3 d postpartum were positively associated with serum Ca at 0 d postpartum. Transcripts for DEFB7, DEFB10 and LAP also were less abundant in neutrophils from cows with metritis compared with healthy cows. In conclusion, feeding a prepartum negative DCAD to improve postpartum serum Ca resulted in greater neutrophil β-defensin expression, and greater neutrophil β-defensin expression was positively associated with postpartum health.

Short communication: Pegbovigrastim treatment in vivo does not affect granulocyte ability to migrate to endometrial cells and kill bacteria in vitro in healthy cows

In periparturient dairy cows, immune suppression, resulting in decreased neutrophil numbers and function, leads to increased susceptibility to postpartum conditions such as mastitis, retained placenta, and metritis. Administration of polyethylene glycol-conjugated bovine granulocyte colony stimulating factor (pegbovigrastim, Imrestor; Elanco Animal Health, Greenfield, IN) 7 d before and within 24 h of calving, effectively improves granulocyte production and function in vivo as well as in milk. A recently developed coculture assay was adapted for use with endometrial epithelial cells to assess the effects of pegbovigrastim application on directed granulocyte migration and bactericidal activity in vitro on a per-cell basis in endometrial cell cultures. Granulocytes from treated and untreated periparturient cows (6 and 5 per group, respectively) were evaluated for their ability to migrate to and kill bacteria after treatment, in context of the infected endometrium. We hypothesized that in addition to increasing the absolute concentration of circulating neutrophil granulocytes, pegbovigrastim treatment in vivo alters the ability of granulocytes to migrate to endometrial cells in vitro. The results clearly show a marked increase in the total concentration of granulocytes and monocytes between the 2 treatment groups as early as 2 d after the first injection, and this increased between the samples taken 2 d after calving. No migratory or killing differences were identified between granulocytes of both groups, suggesting that pegbovigrastim-induced granulocytes were as effective as non-induced cells. This may also be due to the absence of negative energy balance in the study animals and leads us to conclude that the positive effects seen in vivo are most likely based on the larger number of granulocytes present rather than a direct effect of pegbovigrastim treatment on the functionality of cells for the parameters tested in this study.

Functional expression of the free fatty acids receptor-1 and -4 (FFA1/GPR40 and FFA4/GPR120) in bovine endometrial cells

Endometrial epithelial cells play a key defensive role as part of the innate immune response of cow uterus. An association between risk of acquiring infectious diseases and increased levels of free fatty acids postpartum has been suggested, and the use of omega-3 fatty acids such as docosahexaenoic acid (DHA) has been proposed as a beneficial strategy to improve immunity and fertility. The goal of our study was to demonstrate the presence of free fatty acid (FFA)-1 and 4 receptors in endometrial cells and to investigate their role on DHA interference in lipopolysaccharide (LPS)-induced inflammatory endometrial activation. We demonstrated that the bovine endometrial (BEND) cells line and bovine endometrium express both FFA1 and FFA4 receptors. FFA1 and FFA4 receptors were localized in the epithelium lining the endometrial cavity and in endometrial glands whereas in BEND cells a characteristic cell membrane localization of both receptors was observed. DHA, a FFA4 natural agonist, increased intracellular calcium mobilization in BEND cells, but the FFA1 agonists oleic and linoleic acids did not increase this response. DHA-induced intracellular calcium mobilization was inhibited by the FFA4 and FFA1 antagonists AH7614 and GW1100, respectively. DHA significantly reduced LPS-induced prostaglandin E2 (PGE2) production, but none of the antagonists reduced the effect produced by DHA. On the contrary, linoleic acid increased LPS-induced PGE2 production. In conclusion, endometrial cells express FFA4 and FFA1 receptors, and DHA induces intracellular calcium release via FFA4 and FFA1 receptors. DHA reduces PGE2, but this response was not mediated by FFA4 or FFA1 receptors.

Bovine neutrophils in health and disease

Bovine neutrophils have similarities to those of other species with respect to mechanisms of their activation and migration into tissue, modulation of immune responses and the balance between microbial killing and host tissue damage. However, bovine neutrophils have biochemical and functional differences from those of other species, which may yield insights about the comparative biology of neutrophils. Neutrophils play protective and harmful roles in the infectious diseases of cattle that occur at times of transition: respiratory disease in beef calves recently arrived to feedlots and mastitis and other diseases of postparturient dairy cows. An important research focus is the mechanisms by which risk factors for these diseases affect neutrophil function and thereby lead to disease and the prospect of genetic or pharmacologic improvement of disease resistance. Further, in keeping with the One Health paradigm, cattle can be considered a model for studying the role of neutrophils in naturally occurring diseases caused by host-adapted pathogens and are thus an intermediary between studies of mouse models and investigations of human disease. Finally, the study of bovine neutrophils is important for agriculture, to understand the pathogenesis of these production-limiting diseases and to develop novel methods of disease prevention that improve animal health and reduce the reliance on antimicrobial use.

HIV-1-derived single-stranded RNA acts as activator of human neutrophils

Neutrophils are key effector cells of the innate immune system and are involved in the host defense against invading pathogens such as viruses. Recently, it was reported that HIV-1-neutrophil interaction triggers neutrophil activation and promotes expression of Toll-like receptors (TLRs). Here, we assessed the role of single-stranded RNA40 (ssRNA40) derived from HIV-1 in neutrophil activation. We observed functional activation of neutrophils in response to HIV-1-derived ssRNA40 based on the expression of TLR7/8, RIG-I, and MDA5, induction of cytokines (IL-6 and TNF-α), and the production of reactive oxygen species (ROS). Additionally, ssRNA40 promoted the expression of CD62L and TNF-α and the production of ROS in the presence of the TLR2 agonist Pam2CSK4. ssRNA40 together with R848 (a TLR7/8 agonist) increased CD11b expression but decreased CD62L expression. Furthermore, decreased IL-6 expression was observed in the presence of the TLR4 agonist LPS. Finally, we found that ssRNA40 promotes RIG-I and MDA5 expression in the presence of the TLR2, TLR4 and TLR7/8 agonists. This study demonstrates a functional response of TLRs in neutrophils challenged with ssRNA40, suggesting that TLRs could be involved in the innate immune response observed during HIV infection, which might be mediated by its genome.