Different bacterial cargo in apoptotic cells drive distinct macrophage phenotypes.

The removal of dead cells (efferocytosis) contributes to the resolution of the infection and preservation of the tissue. Depending on the environment milieu, macrophages may show inflammatory (M1) or anti-inflammatory (M2) phenotypes. Inflammatory leukocytes are recruited during infection, followed by the accumulation of infected and non-infected apoptotic cells (AC). Efferocytosis of non-infected AC promotes TGF-ß, IL-10, and PGE2 production and the polarization of anti-inflammatory macrophages. These M2 macrophages acquire an efficient ability to remove apoptotic cells that are involved in tissue repair and resolution of inflammation. On the other hand, the impact of efferocytosis of infected apoptotic cells on macrophage activation profile remains unknown. Here, we are showing that the efferocytosis of gram-positive Streptococcus pneumoniae-AC (Sp-AC) or gram-negative Klebsiella pneumoniae-AC (Kp-AC) promotes distinct gene expression and cytokine signature in macrophages. Whereas the efferocytosis of Kp-AC triggered a predominant M1 phenotype in vitro and in vivo, the efferocytosis of Sp-AC promoted a mixed M1/M2 activation in vitro and in vivo in a model of allergic asthma. Together, these findings suggest that the nature of the pathogen and antigen load into AC may have different impacts on inducing macrophage polarization.

Intestinal host defense outcome is dictated by PGE2 production during efferocytosis of infected cells.

Inflammatory responses are terminated by the clearance of dead cells, a process termed efferocytosis. A consequence of efferocytosis is the synthesis of the antiinflammatory mediators TGF-ß, PGE2, and IL-10; however, the efferocytosis of infected cells favors Th17 responses by eliciting the synthesis of TGF-ß, IL-6, and IL-23. Recently, we showed that the efferocytosis of apoptotic Escherichia coli-infected macrophages by dendritic cells triggers PGE2 production in addition to pro-Th17 cytokine expression. We therefore examined the role of PGE2 during Th17 differentiation and intestinal pathology. The efferocytosis of apoptotic E. coli-infected cells by dendritic cells promoted high levels of PGE2, which impaired IL-1R expression via the EP4-PKA pathway in T cells and consequently inhibited Th17 differentiation. The outcome of murine intestinal Citrobacter rodentium infection was dependent on the EP4 receptor. Infected mice treated with EP4 antagonist showed enhanced intestinal defense against C. rodentium compared with infected mice treated with vehicle control. Those results suggest that EP4 signaling during infectious colitis could be targeted as a way to enhance Th17 immunity and host defense.

COVID-19: The question of genetic diversity and therapeutic intervention approaches.

Coronavirus disease 2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus type 2 (SARS-CoV-2), is the largest pandemic in modern history with very high infection rates and considerable mortality. The disease, which emerged in China's Wuhan province, had its first reported case on December 29, 2019, and spread rapidly worldwide. On March 11, 2020, the World Health Organization (WHO) declared the COVID-19 outbreak a pandemic and global health emergency. Since the outbreak, efforts to develop COVID-19 vaccines, engineer new drugs, and evaluate existing ones for drug repurposing have been intensively undertaken to find ways to control this pandemic. COVID-19 therapeutic strategies aim to impair molecular pathways involved in the virus entrance and replication or interfere in the patients' overreaction and immunopathology. Moreover, nanotechnology could be an approach to boost the activity of new drugs. Several COVID-19 vaccine candidates have received emergency-use or full authorization in one or more countries, and others are being developed and tested. This review assesses the different strategies currently proposed to control COVID-19 and the issues or limitations imposed on some approaches by the human and viral genetic variability.

Decyl Gallate as a Possible Inhibitor of N-Glycosylation Process in Paracoccidioides lutzii.

The available antifungal therapeutic arsenal is limited. The search for alternative drugs with fewer side effects and new targets remains a major challenge. Decyl gallate (G14) is a derivative of gallic acid with a range of biological activities and broad-spectrum antifungal activity. Previously, our group demonstrated the promising anti-Paracoccidioides activity of G14. In this work, to evaluate the antifungal characteristics of G14 for Paracoccidioides lutzii, a chemical-genetic interaction analysis was conducted on a Saccharomyces cerevisiae model. N-glycosylation and/or the unfolded protein response pathway was identified as a high-confidence process for drug target prediction. The overactivation of unfolded protein response (UPR) signaling was confirmed using this model with IRE1/ATF6/PERK genes tagged with green fluorescent protein (GFP). In P. lutzii, this prediction was confirmed by the low activity of glycosylated enzymes [α-(1,3)-glucanase, N-acetyl-ß-d-glucosaminidase (NAGase), and α-(1,4)-amylase], by hyperexpression of genes involved with the UPR and glycosylated enzymes, and by the reduction in the amounts of glycosylated proteins and chitin. All of these components are involved in fungal cell wall integrity and are dependent on the N-glycosylation process. This loss of integrity was confirmed by the reduction in mitochondrial activity, impaired budding, enhancement of wall permeability, and a decrease in viability. These events led to a reduction of the ability of fungi to adhere on human lung epithelial cells (A549) in vitro Therefore, G14 may have an important role in balancing the inflammatory reaction caused by fungal infection, without interfering with the microbicidal activity of nitric oxide. This work provides new information on the activity of G14, a potential anti-Paracoccidioides compound.

Dereplication by HPLC-DAD-ESI-MS/MS and Screening for Biological Activities of Byrsonima Species (Malpighiaceae).

INTRODUCTION: Byrsonima species have been used in the treatment of gastrointestinal and gynecological inflammations, skin infections and snakebites. Based on their biological activities, it is important to study other organisms from this genus and to identify their metabolites. OBJECTIVES: To determine the metabolic fingerprinting of methanol and ethyl acetate extracts of four Byrsonima species (B. intermedia, B. coccolobifolia, B. verbascifolia and B. sericea) by HPLC-DAD-ESI-MS/MS and evaluate their in vitro antioxidant, anti-glycation, anti-inflammatory and cytotoxic activities. MATERIALS AND METHODS: Antioxidant activity was determined by DPPH˙, ABTS˙+ and ROO˙ scavenging assays. Anti-glycation activity was evaluated by the ability to inhibit the formation of advanced glycation endproducts (AGEs). Anti-inflammatory activity was evaluated using a murine macrophage cell line (RAW 264-7) in the presence of lipopolysaccharide (LPS). Tumour necrosis factor alpha (TNF-α) and nitrite (NO2- ) production were measured by ELISA and the Griess reaction, respectively. The compounds present in the extracts were tentatively identified by HPLC-DAD-ESI-MS/MS. RESULTS: The evaluation of the biological activities showed the potential of the extracts. The activities were assigned to the presence of glycoside flavonoids mainly derived from quercetin, quinic acid derivatives, gallic acid derivatives, galloylquinic acids and proanthocyanidins. Two isomers of sinapic acid-O-hexoside were described for the first time in a Byrsonima species. CONCLUSION: This research contributes to the study of the genus, it is the first report of the chemical composition of B. sericea and demonstrates the importance of the dereplication process, allowing the identification of known compounds without time-consuming procedures. Copyright © 2017 John Wiley & Sons, Ltd.

Distinctive role of efferocytosis in dendritic cell maturation and migration in sterile or infectious conditions.

Efferocytosis, or clearance of apoptotic cells (ACs), by dendritic cells (DCs) leads to immune response suppression and tolerance to self-antigens. However, efferocytosis of infected apoptotic cells (IACs) leads to the production of a mixed pro- and anti-inflammatory cytokine milieu. We examined the DC phenotype and ability to migrate after phagocytosis of ACs or IACs and observed higher levels of CD86 and CCR7 expression in DCs, as well as enhanced migration capacity following efferocytosis of IACs. Interestingly, higher levels of interleukin-1ß, interleukin-10 and prostaglandin E2 (PGE2 ) were also produced in this context. Blockage of IAC recognition led to an impaired maturation profile and PGE2 production, which may have contributed to reduced CD86 and CCR7 expression and migration capacity. These data contribute to the understanding of how efferocytosis of sterile or infected cells may regulate the adaptive immune response, although the precise role of PGE2 in this process requires further investigation.

Soluble factors from biofilm of Candida albicans and Staphylococcus aureus promote cell death and inflammatory response.

BACKGROUND: The objective of this study was to better understand the effects of soluble factors from biofilm of single- and mixed-species Candida albicans (C. albicans) and methicillin-sensitive Staphylococcus aureus (MSSA) cultures after 36 h in culture on keratinocytes (NOK-si and HaCaT) and macrophages (J774A.1). Soluble factors from biofilms of C. albicans and MSSA were collected and incubated with keratinocytes and macrophages, which were subsequently evaluated by cell viability assays (MTT). Lactate dehydrogenase (LDH) enzyme release was measured to assess cell membrane damage to keratinocytes. Cells were analysed by brightfield microscopy after 2 and 24 h of exposure to the soluble factors from biofilm. Cell death was detected by labelling apoptotic cells with annexin V and necrotic cells with propidium iodide (PI) and was visualized via fluorescence microscopy. Soluble factors from biofilm were incubated with J774A.1 cells for 24 h; the subsequent production of NO and the cytokines IL-6 and TNF-α was measured by ELISA. RESULTS: The cell viability assays showed that the soluble factors of single-species C. albicans cultures were as toxic as the soluble factors from biofilm of mixed cultures, whereas the soluble factors of MSSA cultures were less toxic than those of C. albicans or mixed cultures. The soluble factors from biofilm of mixed cultures were the most toxic to the NOK-si and HaCaT cells, as confirmed by analyses of PI labelling and cell morphology. Soluble factors from biofilm of single-species MSSA and mixed-species cultures induced the production of IL-6, NO and TNF-α by J744A.1 macrophages. The production of IL-6 and NO induced by the soluble factors from biofilm of mixed cultures was lower than that induced by the soluble factors from biofilm of single-species MSSA cultures, whereas the soluble factors from biofilm of C. albicans cultures induced only low levels of NO. CONCLUSIONS: Soluble factors from 36-h-old biofilm of C. albicans and MSSA cultures promoted cell death and inflammatory responses.

Maternal plasma transforming growth factor-ß1 (TGF-ß1) and newborn size: the Araraquara Cohort Study.

OBJECTIVE: To investigate associations of maternal and cord blood cytokine patterns with newborn size and body composition. METHODS: This cross-sectional study involved 70 pregnant women and their healthy newborns selected from the "Araraquara Cohort Study". Newborn anthropometric measurements were recorded at birth. Body composition was evaluated by air displacement plethysmography. Maternal blood samples were collected from pregnant women between 30 and 36 weeks of gestation, and umbilical cord blood samples were collected immediately after placenta discharge. The concentrations of the cytokines were determined in plasma by ELISA. Multiple linear regression models were used to assess associations between maternal and cord blood cytokine concentrations and newborn anthropometry and body composition measurements. RESULTS: Maternal plasma TGF-ß1 concentration was inversely associated with newborn weight (ß = -43.0; p = 0.012), length (ß = -0.16, p = 0.028), head circumference (ß = -0.13, p = 0.004), ponderal index (ß = -0.32, p = 0.011) and fat-free mass (ß = -0.05, p = 0.005). However, the association persisted just for head circumference (ß = -0.26; p = 0.030) and ponderal index (ß = - 0.28; p = 0.028), after adjusting for pre-gestational BMI, gestational weight gain, gestational age, hours after delivery, newborn sex, smoking and alcohol consumption. CONCLUSIONS: Maternal plasma TGF-ß1 concentration may be involved in the regulation of newborn size, mainly head circumference and ponderal index. Further cohort studies are necessary to investigate the role of TGF-ß1 in different trimesters of pregnancy and its effect during the early stages of fetal development.

11-Oxoaerothionin isolated from the marine sponge Aplysina fistularis shows anti-inflammatory activity in LPS-stimulated macrophages.

Marine sponges of the order Verongida are a rich source of biologically active bromotyrosine-derived secondary metabolites. However, none of these compounds are known to display anti-inflammatory activity. In the present investigation, we report the anti-inflammatory effects of 11-oxoaerothionin isolated from the Verongida sponge Aplysina fistularis. When RAW264.7 cells and primary macrophages were preincubated with 11-oxoaerothionin and stimulated with LPS (lipopolysaccharide), a concentration-dependent inhibition of iNOS(inducible nitric oxide synthase) protein and NO(2)(-) (Nitrite) production were observed. The same effect was observed when proinflammatory cytokines and PGE(2) (Prostaglandin E2) production was evaluated. In summary, we demonstrated that in the presence of LPS, 11-oxoaerothionin suppresses NO(2) and iNOS expression as well as inflammatory cytokines and PGE(2).

RIP2 Contributes to Expanded CD4+ T Cell IFN-γ Production during Efferocytosis of Streptococcus pneumoniae-Infected Apoptotic Cells.

Apoptotic cell clearance by professional and nonprofessional phagocytes in the process of efferocytosis is critical to preserve tissue homeostasis. Uptake of apoptotic cells by dendritic cells generates regulatory T cells and induces immunologic tolerance against self-antigens. In contrast, ingestion of infected apoptotic cells promotes activation of TLR4/MyD88-dependent bone marrow-derived dendritic cells (BMDCs) and triggers Th17 cell differentiation. In this study, we evaluated the impact of Streptococcus pneumoniae-infected apoptotic cell efferocytosis by BMDCs derived from C57BL/6 mice on differentiation and expansion of CD4+ T cell subsets, as well as the role of TLR2/4 and receptor-interacting protein 2 (RIP2) receptors in recognizing intracellular pathogens during efferocytosis. We demonstrated that BMDC-mediated efferocytosis of S. pneumoniae-infected apoptotic cells induced Th1 cell differentiation and expansion. Although TLR2/4 and RIP2 deficiency in BMDCs did not affect Th1 cell differentiation during efferocytosis, the absence of RIP2 decreased IFN-γ production by CD4 T cells during the expansion phase. These findings suggest that RIP2-mediated IL-1ß production during efferocytosis of S. pneumoniae-infected apoptotic cells partially supports a Th1-mediated IFN-γ production microenvironment.

Histoplasma capsulatum cell wall {beta}-glucan induces lipid body formation through CD18, TLR2, and dectin-1 receptors: correlation with leukotriene B4 generation and role in HIV-1 infection.

Histoplasma capsulatum (Hc) is a facultative, intracellular parasite of worldwide significance. Infection with Hc produces a broad spectrum of diseases and may progress to a life-threatening systemic disease, particularly in individuals with HIV infection. Resolution of histoplasmosis is associated with the activation of cell-mediated immunity, and leukotriene B(4) plays an important role in this event. Lipid bodies (LBs) are increasingly being recognized as multifunctional organelles with roles in inflammation and infection. In this study, we investigated LB formation in histoplasmosis and its putative function in innate immunity. LB formation in leukocytes harvested from Hc-infected C57BL/6 mice peaks on day 2 postinfection and correlates with enhanced generation of lipid mediators, including leukotriene B(4) and PGE(2). Pretreatment of leukocytes with platelet-activating factor and BLT1 receptor antagonists showed that both lipid mediators are involved in cell signaling for LB formation. Alveolar leukocytes cultured with live or dead Hc also presented an increase in LB numbers. The yeast alkali-insoluble fraction 1, which contains mainly beta-glucan isolated from the Hc cell wall, induced a dose- and time-dependent increase in LB numbers, indicating that beta-glucan plays a signaling role in LB formation. In agreement with this hypothesis, beta-glucan-elicited LB formation was inhibited in leukocytes from 5-LO(-/-), CD18(low) and TLR2(-/-) mice, as well as in leukocytes pretreated with anti-Dectin-1 Ab. Interestingly, human monocytes from HIV-1-infected patients failed to produce LBs after beta-glucan stimulation. These results demonstrate that Hc induces LB formation, an event correlated with eicosanoid production, and suggest a role for these lipid-enriched organelles in host defense during fungal infection.

Macrophage Polarization and Alveolar Bone Healing Outcome: Despite a Significant M2 Polarizing Effect, VIP and PACAP Treatments Present a Minor Impact in Alveolar Bone Healing in Homeostatic Conditions.

Host inflammatory immune response comprises an essential element of the bone healing process, where M2 polarization allegedly contributes to a favorable healing outcome. In this context, immunoregulatory molecules that modulate host response, including macrophage polarization, are considered potential targets for improving bone healing. This study aims to evaluate the role of the immunoregulatory molecules VIP (Vasoactive intestinal peptide) and PACAP (Pituitary adenylate cyclase activating polypeptide), which was previously described to favor the development of the M2 phenotype, in the process of alveolar bone healing in C57Bl/6 (WT) mice. Experimental groups were submitted to tooth extraction and maintained under control conditions or treated with VIP or PACAP were evaluated by microtomographic (µCT), histomorphometric, immunohistochemical, and molecular analysis at 0, 3, 7, and 14 days to quantify tissue healing and host response indicators at the healing site. Gene expression analysis demonstrates the effectiveness of VIP or PACAP in modulating host response, evidenced by the early dominance of an M2-type response, which was paralleled by a significant increase in M2 (CD206+) in treated groups. However, despite the marked effect of M1/M2 balance in the healing sites, the histomorphometric analysis does not reveal an equivalent/corresponding modulation of the healing process. µCT reveals a slight increase in bone matrix volume and the trabecular thickness number in the PACAP group, while histomorphometric analyzes reveal a slight increase in the VIP group, both at a 14-d time-point; despite the increased expression of osteogenic factors, osteoblastic differentiation, activity, and maturation markers in both VIP and PACAP groups. Interestingly, a lower number of VIP and PACAP immunolabeled cells were observed in the treated groups, suggesting a reduction in endogenous production. In conclusion, while both VIP and PACAP treatments presented a significant immunomodulatory effect with potential for increased healing, no major changes were observed in bone healing outcome, suggesting that the signals required for bone healing under homeostatic conditions are already optimal, and additional signals do not improve an already optimal process. Further studies are required to elucidate the role of macrophage polarization in the bone healing process.

Bacterial cellulose membrane functionalized with hydroxiapatite and anti-bone morphogenetic protein 2: A promising material for bone regeneration.

Bone tissue engineering seeks to adequately restore functions related to physical and biological properties, aiming at a repair process similar to natural bone. The use of compatible biopolymers, such as bacterial cellulose (BC), as well as having interesting mechanical characteristics, presents a slow in vivo degradation rate, and the ability to be chemically modified. To promote better bioactivity towards BC, we synthesized an innovative BC membrane associated to hydroxyapatite (HA) and anti-bone morphogenetic protein antibody (anti-BMP-2) (BC-HA-anti-BMP-2). We present the physical-chemical, biological and toxicological characterization of BC-HA-anti-BMP-2. Presence of BC and HA components in the membranes was confirmed by SEM-EDS and FTIR assays. No toxic potential was found in MC3T3-E1 cells by cytotoxicity assays (XTT Assay and Clonogenic Survival), genotoxicity (Comet Assay) and mutagenicity (Cytokinesis-blocked micronucleus Test). The in vitro release kinetics of anti-BMP-2 antibodies detected gradually reducing antibody levels, reducing approximately 70% in 7 days and 90% in 14 days. BC-HA-anti-BMP-2 increased SPP1, BGLAP, VEGF, ALPL, RUNX2 and TNFRSF11B expression, genes involved in bone repair and also increased mineralization nodules and phosphatase alcalin (ALP) activity levels. In conclusion, we developed BC-HA-anti-BMP-2 as an innovative and promising biomaterial with interesting physical-chemical and biological properties which may be a good alternative to treatment with commercial BMP-2 protein.

Acidic and hepatic derivatives of bioactive clerodane diterpenes casearins J and O.

Clerodane diterpenes from Casearia sylvestris are antiulcerogenic and anti-inflammatory. The finding that they may undergo acid degradation or hepatic metabolization led to an investigation of their degradation products. Purified clerodane diterpenes (casearins J and O) were subjected to in vitro assays to simulate their oral administration. Resulting derivatives were identified using chromatographic and spectrometric techniques. Nitric oxide synthesis by LPS-stimulated macrophages was assayed to verify whether structural modifications alter the anti-inflammatory activity of diterpenes. Nine compounds (1-9) were identified after acid degradation remaining 5.05% of casearin J. Besides the remaining casearin O (13.1%), eight compounds (10-17) were identified. The dialdehydes from each casearin were the major constituents. S9 rat liver treatment of casearins J and O generated two compounds identical to some of those produced by acid degradation, which remained 36.8% and 36.5% intact, respectively. Both casearins and its derivatives were not cytotoxicity at concentrations lower than 0.312 µg/mL (0.555 µM for casearin J and 0.516 µM for casearin O) and did not inhibit the nitric oxide production in this concentration. Thus, the structural modifications conducted did not alter the activity of casearins and the anti-inflammatory pathway of diterpenes probably is not involved on nitric oxide modulation.

Mapping of the structural determinants of artificial and biological membrane damaging activities of a Lys49 phospholipase A2 by scanning alanine mutagenesis.

Scanning alanine mutagenesis has been used to study the structural determinants of several activities of bothropstoxin-I (BthTx-I), a lysine 49 Phospholipases A(2) from the venom of Bothrops jararacussu. A total of 31 mutants were generated in the interfacial recognition site and C-terminal loop regions of the protein. The effects of mutagenesis on the in vivo myotoxic activity, the cytolytic activity against cultured C2C12 myoblasts, the bactericidal activity, and the Ca(2+)-independent membrane damaging activity against liposome membranes were compared. Residues 116-119 and 122-125 in the C-terminal loop region are structural determinants for these activities, indicating that membrane permeabilization by the BthTx-I is an important general property in all the measured effects. The structural determinants of myotoxicity and myoblast membrane permeabilization are highly correlated, demonstrating that cultured C2C12 myoblasts are a good model for the myotoxic effect. However, comparison of the structural determinants for all activities revealed several differences in the structural determinants between the effects against myoblast and bacterial membranes, and further differences when compared to the liposome membrane damaging effect. These membrane dependent effects are interpreted to be the consequence of differences in the activation of the membrane bound form of the protein on biological and artificial membranes.

Inhibition of inflammasome activation by a clinical strain of Klebsiella pneumoniae impairs efferocytosis and leads to bacterial dissemination.

Klebsiella pneumoniae is a Gram-negative bacterium responsible for severe cases of nosocomial pneumonia. During the infectious process, both neutrophils and monocytes migrate to the site of infection, where they carry out their effector functions and can be affected by different patterns of cell death. Our data show that clinical strains of K. pneumoniae have dissimilar mechanisms for surviving within macrophages; these mechanisms include modulation of microbicidal mediators and cell death. The A28006 strain induced high IL-1ß production and pyroptotic cell death in macrophages; by contrast, the A54970 strain induced high IL-10 production and low IL-1ß production by macrophages. Pyroptotic cell death induced by the A28006 strain leads to a significant increase in bacterial sensitivity to hydrogen peroxide, and efferocytosis of the pyroptotic cells results in efficient bacterial clearance both in vitro and in vivo. In addition, the A54970 strain was able to inhibit inflammasome activation and pyroptotic cell death by inducing IL-10 production. Here, for the first time, we present a K. pneumoniae strain able to inhibit inflammasome activation, leading to bacterial survival and dissemination in the host. The understanding of possible escape mechanisms is essential in the search for alternative treatments against multidrug-resistant bacteria.

Maternal plasma transforming growth factor-β1 (TGF-β1) and newborn size: the Araraquara Cohort Study

Abstract Objective To investigate associations of maternal and cord blood cytokine patterns with newborn size and body composition. Methods This cross-sectional study involved 70 pregnant women and their healthy newborns selected from the "Araraquara Cohort Study". Newborn anthropometric measurements were recorded at birth. Body composition was evaluated by air displacement plethysmography. Maternal blood samples were collected from pregnant women between 30 and 36 weeks of gestation, and umbilical cord blood samples were collected immediately after placenta discharge. The concentrations of the cytokines were determined in plasma by ELISA. Multiple linear regression models were used to assess associations between maternal and cord blood cytokine concentrations and newborn anthropometry and body composition measurements. Results Maternal plasma TGF-β1 concentration was inversely associated with newborn weight (β= -43.0; p= 0.012), length (β= -0.16, p= 0.028), head circumference (β= -0.13, p= 0.004), ponderal index (β= -0.32, p= 0.011) and fat-free mass (β= -0.05, p= 0.005). However, the association persisted just for head circumference (β= -0.26; p= 0.030) and ponderal index (β= - 0.28; p= 0.028), after adjusting for pre-gestational BMI, gestational weight gain, gestational age, hours after delivery, newborn sex, smoking and alcohol consumption. Conclusions Maternal plasma TGF-β1 concentration may be involved in the regulation of newborn size, mainly head circumference and ponderal index. Further cohort studies are necessary to investigate the role of TGF-β1 in different trimesters of pregnancy and its effect during the early stages of fetal development.

Hypusine modification of the ribosome-binding protein eIF5A, a target for new anti-inflammatory drugs: understanding the action of the inhibitor GC7 on a murine macrophage cell line.

Inflammation is part of an important mechanism triggered by the innate immune response that rapidly responds to invading microorganisms and tissue injury. One important elicitor of the inflammatory response is the Gram-negative bacteria component lipopolysaccharide (LPS), which induces the activation of innate immune response cells, the release of proinflammatory cytokines, such as interleukin 1 and tumor necrosis factor α(TNF-α), and the cellular generation of nitric oxide (NO) by the inducible nitric oxide synthase (iNOS). Although essential to the immune response, uncontrolled inflammatory responses can lead to pathological conditions, such as sepsis and rheumatoid arthritis. Therefore, identifying cellular targets for new anti-inflammatory treatments is crucial to improving therapeutic control of inflammation-related diseases. More recently, the translation factor eIF5A has been demonstrated to have a proinflammatory role in the release of cytokines and the production of NO. As eIF5A requires and essential and unique modification of a specific residue of lysine, changing it to hypusine, eIF5A is an interesting cellular target for anti-inflammatory treatment. The present study reviews the literature concerning the anti-inflammatory effects of inhibiting eIF5A function. We also present new data showing that the inhibition of eIF5A function by the small molecule GC7 significantly decreases TNF-α release without affecting TNF-α mRNA levels. We discuss the mechanisms by which eIF5A may interfere with TNF-α mRNA translation by binding to and regulating the function of ribosomes during protein synthesis.

The leukotriene B4/BLT1 axis is a key determinant in susceptibility and resistance to histoplasmosis.

The bioactive lipid mediator leukotriene B4 (LTB4) greatly enhances phagocyte antimicrobial functions against a myriad of pathogens. In murine histoplasmosis, inhibition of the LT-generating enzyme 5-lypoxigenase (5-LO) increases the susceptibility of the host to infection. In this study, we investigated whether murine resistance or susceptibility to Histoplasma capsulatum infection is associated with leukotriene production and an enhancement of in vivo and/or in vitro antimicrobial effector function. We show that susceptible C57BL/6 mice exhibit a higher fungal burden in the lung and spleen, increased mortality, lower expression levels of 5-LO and leukotriene B4 receptor 1 (BLT1) and decreased LTB4 production compared to the resistant 129/Sv mice. Moreover, we demonstrate that endogenous and exogenous LTs are required for the optimal phagocytosis of H. capsulatum by macrophages from both murine strains, although C57BL/6 macrophages are more sensitive to the effects of LTB4 than 129/Sv macrophages. Therefore, our results provide novel evidence that LTB4 production and BLT1 signaling are required for a histoplasmosis-resistant phenotype.