Human Innate Response Research Articles

A Corylus avellana L. extract enhances human macrophage bactericidal response against Staphylococcus aureus by increasing the expression of anti-inflammatory and iron metabolism genes

Corylus avellana L. is known for its healthy properties, and yet previous studies have not dealt with its effects on human innate response. The aim of this study is to assess if C. avellana has an immune adjuvant effect. Human macrophages were pre-treated with hazelnut liquid extract, found to be rich in phenylpropanoids, and subsequently infected with Staphylococcus aureus. Based on the intracellular bacteria CFU reduction and on the treatment doses used, the donors were divided into High-Dose and Low-Dose-Responders. Expression profile for inflammatory and Iron metabolism genes, both for Peripheral Blood Mononuclear Cells and Macrophages, highlighted that Low-Dose-Responders came from a more pronounced pro-inflammatory milieu as compared with High-Dose-Responders. Blood test results revealed that Low-Dose-Responders had higher LDL C and Triglycerides and lower HDL C. Overall, our results suggest that the effect of the extract on Macrophage immune response is influenced by the intracellular inflammatory status of the donor.

Human innate responses and adjuvant activity of TLR ligands in vivo in mice reconstituted with a human immune system.

TLR ligands (TLR-Ls) represent a class of novel vaccine adjuvants. However, their immunologic effects in humans remain poorly defined in vivo. Using a humanized mouse model with a functional human immune system, we investigated how different TLR-Ls stimulated human innate immune response in vivo and their applications as vaccine adjuvants for enhancing human cellular immune response. We found that splenocytes from humanized mice showed identical responses to various TLR-Ls as human PBMCs in vitro. To our surprise, various TLR-Ls stimulated human cytokines and chemokines differently in vivo compared to that in vitro. For example, CpG-A was most efficient to induce IFN-α production in vitro. In contrast, CpG-B, R848 and Poly I:C stimulated much more IFN-α than CpG-A in vivo. Importantly, the human innate immune response to specific TLR-Ls in humanized mice was different from that reported in C57BL/6 mice, but similar to that reported in nonhuman primates. Furthermore, we found that different TLR-Ls distinctively activated and mobilized human plasmacytoid dendritic cells (pDCs), myeloid DCs (mDCs) and monocytes in different organs. Finally, we showed that, as adjuvants, CpG-B, R848 and Poly I:C can all enhance antigen specific CD4+ T cell response, while only R848 and Poly I:C induced CD8+ cytotoxic T cells response to a CD40-targeting HIV vaccine in humanized mice, correlated with their ability to activate human mDCs but not pDCs. We conclude that humanized mice serve as a highly relevant model to evaluate and rank the human immunologic effects of novel adjuvants in vivo prior to testing in humans.

Human innate responses and adjuvant activity of TLR ligands in vivo in mice reconstituted with a human immune system

Human innate responses and adjuvant activity of TLR ligands in vivo in mice reconstituted with a human immune system

Immunity to gastrointestinal microparasites of fish

Fish intestinal parasites cause direct mortalities and also morbidity, poor growth, higher susceptibility to opportunistic pathogens and lower resistance to stress. This review is focused on microscopic parasites (Protozoa and Metazoa) that invade the gastrointestinal tract of fish. Intracellular parasites (mainly Microsporidia and Apicomplexa) evoke almost no host immune reaction while they are concealed in the cytoplasmic and nuclear compartments, and can even use fish cells (macrophages) as Trojan horses to spread in the host. Inflammatory reaction only appears when the parasite bursts infected cells. Immunity against extracellular parasites is depicted for the myxozoans Ceratonova shasta and Enteromyxum spp. The cellular and humoral innate responses and the production of antibodies are crucial for resolving some of these myxozoonoses, but an excessive inflammatory reaction (concerted by cytokines) can become a fatal pathophysiological consequence. The local immune response plays a key role, with numerous genes more strongly regulated in the intestine than at lymphohaematopoietic organs.

Dietary administration of the extract of Rhodobacter sphaeroides WL-APD911 enhances the growth performance and innate immune responses of seawater red tilapia (Oreochromis mossambicus × Oreochromis niloticus)

A commercial carotenoid product from the extract of probiotic Rhodobacter sphaeroides mutant strain WL-APD911 (Lycogen™) contains neurosporene, ξ-carotene, spheroidenone and methoxyneurosporene rather than lycopene. In the present study, Lycogen™ was used to improve the growth performance of seawater red tilapia (Oreochromis mossambicus×Oreochromis niloticus) for 7weeks. The results showed that dietary supplementation with 1.0% Lycogen™ in seawater tilapia did not cause changes in body length but significantly increased muscle weight, weight gain, the specific growth rate (SGR) and the feed conversion ratio (FCR). Because there were no intergroup differences in the proximate composition of the fish muscle, the increased body weight of Lycogen™-supplemented tilapia might have resulted from muscle growth instead of changes in muscle composition. An analysis of the expression levels of growth-associated genes, i.e., growth hormone receptor 1 (GHR1) and insulin growth factor-1 (IGF-1), showed that an alternative splicing form of GHR1 accumulated to a significant extent in the muscle of tilapia fed with a Lycogen™-supplemented diet. In addition, innate humoral responses, reflected by lysozyme activity and alternative complement activity (ACH50), also significantly increased in the sera of Lycogen™-treated tilapia. The present study suggests a potential application of the biomaterial Lycogen™ in the aquaculture field: to enhance tilapia growth performance via immune regulation.

Distinct pathogenesis and host responses during infection of C. elegans by P. aeruginosa and S. aureus.

The genetically tractable model host Caenorhabditis elegans provides a valuable tool to dissect host-microbe interactions in vivo. Pseudomonas aeruginosa and Staphylococcus aureus utilize virulence factors involved in human disease to infect and kill C. elegans. Despite much progress, virtually nothing is known regarding the cytopathology of infection and the proximate causes of nematode death. Using light and electron microscopy, we found that P. aeruginosa infection entails intestinal distention, accumulation of an unidentified extracellular matrix and P. aeruginosa-synthesized outer membrane vesicles in the gut lumen and on the apical surface of intestinal cells, the appearance of abnormal autophagosomes inside intestinal cells, and P. aeruginosa intracellular invasion of C. elegans. Importantly, heat-killed P. aeruginosa fails to elicit a significant host response, suggesting that the C. elegans response to P. aeruginosa is activated either by heat-labile signals or pathogen-induced damage. In contrast, S. aureus infection causes enterocyte effacement, intestinal epithelium destruction, and complete degradation of internal organs. S. aureus activates a strong transcriptional response in C. elegans intestinal epithelial cells, which aids host survival during infection and shares elements with human innate responses. The C. elegans genes induced in response to S. aureus are mostly distinct from those induced by P. aeruginosa. In contrast to P. aeruginosa, heat-killed S. aureus activates a similar response as live S. aureus, which appears to be independent of the single C. elegans Toll-Like Receptor (TLR) protein. These data suggest that the host response to S. aureus is possibly mediated by pathogen-associated molecular patterns (PAMPs). Because our data suggest that neither the P. aeruginosa nor the S. aureus–triggered response requires canonical TLR signaling, they imply the existence of unidentified mechanisms for pathogen detection in C. elegans, with potentially conserved roles also in mammals.

Classical swine fever virus induces activation of plasmacytoid and conventional dendritic cells in tonsil, blood, and spleen of infected pigs

Classical swine fever virus (CSFV) compromises the host immune system, causing indirect leucopoenia and disruption of in vitro T cell stimulation capacity. In order to explore the potential role of dendritic cells (DC) in such phenomena, the activation of conventional DC (cDC) and plasmacytoid DC (pDC) in blood and secondary lymphoid organs of infected pigs was investigated in the early time course post-inoculation (pi), together with viral components dissemination and cytokine production in serum. Whereas CD11R1+CD172a+ cDC frequencies were markedly reduced in blood and spleen, analysis of CD4+CD172a+ pDC numbers revealed a rapid turn-over of this DC subset in tissues pi. Both subsets matured and were activated after infection, as demonstrated by down-regulation of CD1a, up-regulation of the co-stimulation molecule CD80/86 and expression of cytokines. cDC essentially expressed tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-10, whereas pDC produced alpha interferon (IFN-alpha) and IL-12. IFN-alpha and TNF-alpha productions revealed an enhancement of innate anti-viral immune responses. Detection of antigen activated B lymphocytes in tonsil T-cell areas at 72 h pi, subsequently to the transient translocation of the viral E2 protein within germinal centres at 48 h pi, indicates the initiation of humoral response. This response was also evidenced by an important IL-10 production in serum one week pi. IL-12 expression in organs, as well as transient detection of IL-18 and IFN-gamma in serum, reflected the initiation of cellular immune responses. However, the uncommonly high levels of TNF-alpha and IFN-alpha produced by DC and measured in serum early post-infection, together with IL-10 expression in spleen, could play a role in the disruption of immune system cells, either inducing apoptosis or impairing DC functionalities themselves.

CD34+ Hematopoietic Progenitors From Human Cord Blood Differentiate Along Two Independent Dendritic Cell Pathways in Response to Granulocyte-Macrophage Colony-Stimulating Factor Plus Tumor Necrosis Factor α: II. Functional Analysis

In response to granulocyte-macrophage colony-stimulating factor plus tumor necrosis factor α, cord blood CD34+ hematopoietic progenitor cells differentiate along two unrelated dendritic cell (DC) pathways: (1) the Langerhans cells (LCs), which are characterized by the expression of CD1a, Birbeck granules, the Lag antigen, and E cadherin; and (2) CD14+ cell-derived DCs, characterized by the expression of CD1a, CD9, CD68, CD2, and factor XIIIa (Caux et al, J Exp Med 184:695, 1996). The present study investigates the functions of each population. Although the two populations are equally potent in stimulating naive CD45RA cord blood T cells through apparently identical mechanisms, each also displays specific activities. In particular CD14-derived DCs show a potent and long-lasting (from day 8 to day 13) antigen uptake activity (fluorescein isothiocyanate dextran or peroxidase) that is about 10-fold higher than that of CD1a+ cells, which is restricted to the immature stage (day 6). The antigen capture is exclusively mediated by receptors for mannose polymers. The high efficiency of antigen capture of CD14-derived cells is coregulated with the expression of nonspecific esterase activity, a tracer of lysosomial compartment. In contrast, the CD1a+ population never expresses nonspecific esterase activity. The most striking difference is the unique capacity of CD14-derived DCs to induce naive B cells to differentiate into IgM-secreting cells, in response to CD40 triggering and interleukin-2. Thus, although the two populations can allow T-cell priming, initiation of humoral responses might be preferentially regulated by the CD14-derived DCs. Altogether, those results show that different pathways of DC development might exist in vivo: (1) the LC type, which might be mainly involved in cellular immune responses, and (2) the CD14-derived DC related to dermal DCs or circulating blood DCs, which could be involved in humoral immune responses.

CD34+ Hematopoietic Progenitors From Human Cord Blood Differentiate Along Two Independent Dendritic Cell Pathways in Response to Granulocyte-Macrophage Colony-Stimulating Factor Plus Tumor Necrosis Factor α: II. Functional Analysis

AbstractIn response to granulocyte-macrophage colony-stimulating factor plus tumor necrosis factor α, cord blood CD34+ hematopoietic progenitor cells differentiate along two unrelated dendritic cell (DC) pathways: (1) the Langerhans cells (LCs), which are characterized by the expression of CD1a, Birbeck granules, the Lag antigen, and E cadherin; and (2) CD14+ cell-derived DCs, characterized by the expression of CD1a, CD9, CD68, CD2, and factor XIIIa (Caux et al, J Exp Med 184:695, 1996). The present study investigates the functions of each population. Although the two populations are equally potent in stimulating naive CD45RA cord blood T cells through apparently identical mechanisms, each also displays specific activities. In particular CD14-derived DCs show a potent and long-lasting (from day 8 to day 13) antigen uptake activity (fluorescein isothiocyanate dextran or peroxidase) that is about 10-fold higher than that of CD1a+ cells, which is restricted to the immature stage (day 6). The antigen capture is exclusively mediated by receptors for mannose polymers. The high efficiency of antigen capture of CD14-derived cells is coregulated with the expression of nonspecific esterase activity, a tracer of lysosomial compartment. In contrast, the CD1a+ population never expresses nonspecific esterase activity. The most striking difference is the unique capacity of CD14-derived DCs to induce naive B cells to differentiate into IgM-secreting cells, in response to CD40 triggering and interleukin-2. Thus, although the two populations can allow T-cell priming, initiation of humoral responses might be preferentially regulated by the CD14-derived DCs. Altogether, those results show that different pathways of DC development might exist in vivo: (1) the LC type, which might be mainly involved in cellular immune responses, and (2) the CD14-derived DC related to dermal DCs or circulating blood DCs, which could be involved in humoral immune responses.

Humoral immune responses in L-selectin-deficient mice.

L-selectin regulates lymphocyte migration by mediating lymphocyte attachment to high endothelial venules of peripheral lymph nodes (PLN). L-selectin-deficient mice display a 70 to 90% reduction in the number of lymphocytes within PLNs and a 30 to 55% increase in spleen cellularity. The altered distribution of lymphocyte subpopulations in L-selectin-deficient mice resulted in significantly elevated serum IgM and IgG1 levels and augmented humoral immune responses to T cell-independent and T cell-dependent Ags following i.p. immunization. By contrast, s.c. immunization of L-selectin-deficient mice with a T cell-dependent Ag resulted in serum IgM responses that were 40% lower when compared with wild-type littermates on day 7, while primary IgG responses were essentially absent. Most serum Ig responses were normal by day 14 and secondary responses were higher in L-selectin-deficient mice. Although lymphocytes from L-selectin-deficient mice were unable to enter Ag-stimulated lymph nodes through high endothelial venules, the cellularity of draining lymph nodes increased significantly following immunization. Germinal centers developed rapidly following immunization, although PLNs of L-selectin-deficient mice contained few follicles. Germinal centers within PLNs and the spleen were also consistently much larger and more well defined in L-selectin-deficient mice when compared with wild-type littermates. These results confirm that lymphocyte migration plays an important role in the initiation of humoral responses and demonstrate complementary and overlapping roles for the spleen and other peripheral lymphoid tissues in the generation of immune responses.