Inflammatory and regulatory CCL and CXCL chemokine and cytokine cellular responses in patients with patent Mansonella perstans filariasis.

Mansonella perstans (Mp) filariasis is present in large populations in sub-Saharan Africa, and to what extent patent Mp infection modulates the expression of immunity in patients, notably their cellular cytokine and chemokine response profile, remains not well known. We studied the spontaneous and inducible cellular production of chemokines (C-X-C motif) ligand 9 (CXCL9) [monokine induced by interferon (IFN)-γ (MIG)], CXCL-10 [inducible protein (IP)-10], chemokine (C-C motif) ligand 24 (CCL24) (eotaxin-2), CCL22 [macrophage-derived chemokine (MDC)], CCL13 [monocyte chemotactic protein-4 (MCP-4)], CCL18 [pulmonary and activation-regulated chemokine (PARC)], CCL17 [thymus- and activation-regulated chemokine (TARC)] and interleukin (IL)-27 in mansonelliasis patients (Mp-PAT) and mansonelliasis-free controls (CTRL). Freshly isolated peripheral mononuclear blood cells (PBMC) were stimulated with helminth, protozoan and bacterial antigens and mitogen [phytohaemagglutinin (PHA)]. PBMC from Mp-PAT produced spontaneously (without antigen stimulation) significantly higher levels of eotaxin-2, IL-27, IL-8, MCP-4 and MDC than cells from CTRL, while IFN-γ-IP-10 was lower in Mp-PAT. Helminth antigens activated IL-27 and MCP-4 only in CTRL, while Ascaris antigen, Onchocerca antigen, Schistosoma antigen, Entamoeba antigen, Streptococcus antigen, Mycobacteria antigen and PHA stimulated MIG release in CTRL and Mp-PAT. Notably, Entamoeba antigen and PHA strongly depressed (P < 0·0001) eotaxin-2 (CCL24) production in both study groups. Multiple regression analyses disclosed in Mp-PAT and CTRL dissimilar cellular chemokine and cytokine production levels being higher in Mp-PAT for CCL24, IL-27, IL-8, MCP-4, MDC and PARC (for all P < 0·0001), at baseline (P < 0·0001), in response to Entamoeba histolytica strain HM1 antigen (EhAg) (P < 0·0001), Onchocerca volvulus adult worm-derived antigen (OvAg) (P = 0·005), PHA (P < 0·0001) and purified protein derivative (PPD) (P < 0·0001) stimulation. In Mp-PAT with hookworm co-infection, the cellular chemokine production of CXCL10 (IP-10) was diminished. In summary, the chemokine and cytokine responses in Mp-PAT were in general not depressed, PBMC from Mp-PAT produced spontaneously and selectively inducible inflammatory and regulatory chemokines and cytokines at higher levels than CTRL and such diverse and distinctive reactivity supports that patent M. perstans infection will not polarize innate and adaptive cellular immune responsiveness in patients.

Chemokine levels and parasite- and allergen-specific antibody responses in children and adults with severe or uncomplicated Plasmodium falciparum malaria.

Chemokine and antibody response profiles were investigated in children and adults with severe or uncomplicated Plasmodium falciparum malaria; the aim was to reveal which profiles are associated with severe disease, as often seen in nonimmune children, or with mild and uncomplicated disease, as seen in semi-immune adults. Blood samples were obtained from children under 5 years of age as well as adults with falciparum malaria. Classification of malaria was performed according to parasite densities and hemoglobin concentrations. Plasma levels of chemokines (IL-8, IP-10, MCP-4, TARC, PARC, MIP-1δ, eotaxins) were quantified, and antibody responses (IgE, IgG1, and IgG4) to P. falciparum, Entamoeba histolytica-specific antigen, and mite allergen extracts were determined. In children with severe malaria proinflammatory, IL-8, IP10, MIP-1δ, and LARC were at highly elevated levels, suggesting an association with severe disease. In contrast, the Th2-type chemokines TARC, PARC, and eotaxin-2 attained in children the same levels as in adults suggesting the evolution of immune regulatory components. In children with severe malaria, an elevated IgG1 and IgE reactivity to mite allergens and intestinal protozoan parasites was observed. In conclusion, exacerbated proinflammatory chemokines together with IgE responses to mite allergens or E. histolytica-specific antigen extract were observed in children with severe falciparum malaria.

[Tropical endemic limbo-conjunctivitis (TELC) and allergic management: a preliminary study in Togolese children]. / Limbo-conjonctivite endémique des tropiques (LCET) et prise en charge allergologique : étude préliminaire chez l'enfant togolais.

PURPOSE: To study the impact of certain allergens on the manifestations of tropical endemic limbo-conjunctivitis (TELC) in Togolese children. METHODS: This is a 3-year prospective study of 36 Togolese children with acute recurrences of TELC after 1 to 5 months of remission. Skin prick tests were conducted with five perennial respiratory allergens (dust mites, paper mites, roaches, dog and cat, grass pollen) and three food allergens (egg, peanut, shrimp). The reactions were compared to a negative control (saline solution) and a positive control (histamine or codeine sulfate). Length of remissions between acute exacerbations before and after allergy testing were noted. RESULTS: Thirty-five children were polysensitive. Individual allergens were: dust mites (83.3%), followed by cockroach (72.2%), shrimp (61.1%), peanuts (55.6%), eggs (44.4%), the cat and/or dog dander (38.9%), and grass pollen (22.2%). The rate of remission prior to allergy testing was 77.8% within 2 months after treatment of an exacerbation; with allergy management, 55.5% of patients experienced remission beyond 1 year. DISCUSSION: The literature reports that TELC is caused by multiple antigens. The clear predominance of respiratory and food allergens may lead to a new pathway for managing TELC in Togolese children. CONCLUSION: Allergy testing is of great importance for patients with frequent acute exacerbations of TELC.

Proinflammatory and regulatory cytokines and chemokines in infants with uncomplicated and severe Plasmodium falciparum malaria.

Cytokine and chemokine levels were studied in infants (<5 years) with uncomplicated (MM) and severe malaria tropica (SM), and in Plasmodium falciparum infection-free controls (NEG). Cytokine plasma levels of interleukin (IL)-10, IL-13, IL-31 and IL-33 were strongly elevated in MM and SM compared to NEG (P<0·0001). Inversely, plasma concentrations of IL-27 were highest in NEG infants, lower in MM cases and lowest in those with SM (P<0·0001, NEG compared to MM and SM). The levels of the chemokines macrophage inflammatory protein (MIP3)-α/C-C ligand 20 (CCL20), monokine induced by gamma interferon (MIG)/CXCL9 and CXCL16 were enhanced in those with MM and SM (P<0·0001 compared to NEG), and MIP3-α/CCL20 and MIG/CXCL9 were correlated positively with parasite density, while that of IL-27 were correlated negatively. The levels of 6Ckine/CCL21 were similar in NEG, MM and SM. At 48-60 h post-anti-malaria treatment, the plasma concentrations of IL-10, IL-13, MIG/CXCL9, CXCL16 and MIP3-α/CCL20 were clearly diminished compared to before treatment, while IL-17F, IL-27, IL-31 and IL-33 remained unchanged. In summary, elevated levels of proinflammatory and regulatory cytokines and chemokines were generated in infants during and after acute malaria tropica. The proinflammatory type cytokines IL-31 and IL-33 were enhanced strongly while regulatory IL-27 was diminished in those with severe malaria. Similarly, MIP3-α/CCL20 and CXCL16, which may promote leucocyte migration into brain parenchyma, displayed increased levels, while CCL21, which mediates immune surveillance in central nervous system tissues, remained unchanged. The observed cytokine and chemokine production profiles and their dynamics may prove useful in evaluating either the progression or the regression of malarial disease.

Onchocerca volvulus-specific antibody and cytokine responses in onchocerciasis patients after 16 years of repeated ivermectin therapy.

The recommended control option against onchocerciasis is repeated ivermectin treatment, which will need to be implemented for decades, and it remains unknown how repeated ivermectin therapy might affect immunity against Onchocerca volvulus in the long term. O. volvulus-specific antibody reactivity and cellular cytokine production were investigated in onchocerciasis patients receiving ivermectin (150 microg/kg) annually for 16 years. In treated patients, the T helper type 2 (Th2) cytokine interleukin (IL)-5 and T regulatory IL-10 in response to O. volvulus antigen (OvAg) and bacteria-derived Streptolysin O (SL-O) diminished to levels found in infection-free endemic controls; also, cellular release of Th1-type interferon (IFN)-gamma at 16 years post initial ivermectin treatment (p.i.t.) approached control levels. In ivermectin-treated onchocerciasis patients, IL-5 production in responses to the mitogen phytohaemagglutinin (PHA) decreased, but IL-10 in response PHA increased, and neither attained the cytokine production levels of endemic controls. At 16 years p.i.t., O. volvulus-specific IgG1 and IgG4 subclass reactivity still persisted at higher levels in onchocerciasis patients than in O. volvulus exposed but microfilariae-free endemic controls. In addition, cytokine responses remained depressed in onchocerciasis patients infected concurrently with Mansonella perstans and Necator americanus or Entamoeba histolytica/dispar. Thus, long-term ivermectin therapy of onchocerciasis may not suffice to re-establish fully a balanced Th1 and Th2 immune responsiveness in O. volvulus microfilariae-negative individuals. Such deficient reconstitution of immune competence may be due to an as yet continuing and uncontrolled reinfection with O. volvulus, but parasite co-infections can also bias and may prevent the development of such immunity.

Echinococcus multilocularis metacestodes modulate cellular cytokine and chemokine release by peripheral blood mononuclear cells in alveolar echinococcosis patients.

Infection with the cestode Echinococcus multilocularis causes human alveolar echinococcosis (AE), a life-threatening disease affecting primarily the liver. Despite the severity of AE, clinical symptoms often develop only many years after infection, which suggests that E. multilocularis has developed mechanisms which depress anti-parasite immune response, thus favouring immune evasion. In this study we examined the production of cytokines, chemokines and the expression of CD molecules on peripheral blood mononuclear cells (PBMC) from AE patients and healthy controls in response to E. multilocularis metacestode culture supernatant, viable E. multilocularis vesicles and E. multilocularis vesicle fluid antigen in vitro. After 48 h of co-culture, E. multilocularis metacestode culture supernatant and E. multilocularis vesicles depressed the release of the proinflammatory cytokine interleukin (IL)-12 by PBMC. This effect was dose-dependent and a suppression of tumour necrosis factor (TNF)-alpha and IL-12 was observed even when PBMC were activated with lipopolysaccharide (LPS). Comparing proinflammatory cytokine release by AE patients and controls showed that the release of IL-12 and TNF-alpha was reduced in AE patients, which was accompanied by an increased number of CD4+ CD25+ cells and a reduced release of the Th2 type chemokine CCL17 (thymus and activation regulated chemokine, TARC), suggesting an anti-inflammatory response to E. multilocularis metacestode in AE patients. Instead the production of interferon (IFN)-gamma and the expression of CD28 on CD4+ T cells were increased in PBMC from AE patients when compared to controls. This was accompanied by a higher release of the Th2-type chemokine CCL22 (macrophage derived chemokine, MDC) supporting that E. multilocularis also generates proinflammatory immune responses. These results indicate that E. multilocularis antigens modulated both regulatory and inflammatory Th1 and Th2 cytokines and chemokines. Such a mixed profile might be required for limiting parasite growth but also for reducing periparasitic tissue and organ damage in the host.

Chemokines in onchocerciasis patients after a single dose of ivermectin.

Ivermectin treatment will effectively diminish microfilariae (Mf) of Onchocerca volvulus in the skin of patients, but therapy is associated with adverse host inflammatory responses. To investigate the association of proinflammatory chemokines with the intensity of infection and clinical adverse reactions, chemokine serum levels were measured in patients following ivermectin treatment (100 microg/kg, 150 microg/kg or 200 microg/kg) or placebo. The density of O. volvulus Mf per mg skin decreased by 85%, 97%, 97% and 90% at day 3, at month 3, month 6 and at 1 year post-ivermectin. The cutaneous T cell-attracting chemokine (CTACK/CCL27) was found highly elevated in onchocerciasis patients compared to infection-free European controls (P = 0.0004) and it did not change following ivermectin or placebo to 1 year post-therapy. The chemokine RANTES/CCL5 (regulated on activated and normally T cell-expressed) was similarly high in onchocerciasis patients and infection-free European controls; the RANTES/CCL5 levels did not change following treatment until 6 months post-therapy but were slightly elevated at 1 year post-therapy (P < 0.02). In contrast, the Th2-type chemoattractants, thymus and activation regulated chemokine (TARC/CCL17) and macrophage-derived chemokine (MDC/CCL22), were activated at 3 days post-ivermectin (P < 0.0001) to return to pretreatment or lower levels thereafter. The Th1-type chemoattractants, macrophage inflammatory protein (MIP)-1alpha/CCL3 and MIP-1beta/CCL4 were low before ivermectin treatment, but following clearance of microfilariae of O. volvulus their levels increased from 6 months post-therapy onwards (for both at 12 months post-therapy, P < 0.0001). The adverse reaction scores (RS) in treated patients increased significantly on day 3 (P < 0.02) while it remained unchanged in those who received placebo (P = 0.22); RS interacted with the microfilarial density (P = 0.01), but not with the dose of ivermectin or with the serum levels of MIP-1alpha/CCL3, MIP-1beta/CCL4, TARC/CCL17, MDC/CCL22 and CTACK/CCL27. Our observations suggest that following ivermectin, macrophages as well as memory Th2-type lymphocytes and B cells, attracted and activated by MDC/CCL22, TARC/CCL17 and CTACK/CCL27, may contribute to dermal immune responses and O. volvulus Mf killing and clearance. The transient changes of TARC/CCL17 and MDC/CCL22 were not associated with clinical adverse responses, and the later rise of MIP-1alpha/CCL3 and MIP-1beta/CCL4 showed a reactivation of Type 1 immune responses associated with persistent low levels of O. volvulus microfilariae and an expiring O. volvulus infection.

Cellular responses and cytokine production in post-treatment hookworm patients from an endemic area in Brazil.

Human hookworm infections are distributed widely in tropical areas and have a significant impact on host morbidity and human health. In the present study, we investigated the cellular responsiveness and cytokine production in peripheral blood mononuclear cells (PBMC) from Necator americanus-infected schoolchildren who had recently received chemotherapy, and compared them with non-infected endemic controls. Hookworm patients and treated, egg-negative individuals showed a lower cellular reactivity against phytohaemagglutinin (PHA) and hookworm antigen when compared with egg-negative endemic controls. The baseline production of proinflammatory tumour necrosis factor-alpha (TNF-alpha) in PBMC from infected patients and treated, egg-negative individuals was elevated. On the other hand, PHA- or hookworm antigen-induced interleukin (IL)-12 and interferon (IFN)-gamma secretion was higher in endemic controls than in hookworm patients, who either continued egg-positive or were egg-negative after treatment. Also, PBMC from endemic controls secreted more IL-5 and IL-13 than the other patient groups. Opposite to that, the spontaneous as well as the antigen-driven IL-10 secretion was lower in endemic controls when compared with the other groups. In summary, patently hookworm-infected as well as egg-negative treated patients disclosed an elevated spontaneous cellular secretion of proinflammatory TNF-alpha, a prominent secretion of regulatory Th2-type IL-10 and an impaired production of IL-12, IFN-gamma, IL-5 and IL-13.

Impact of parental onchocerciasis and intensity of transmission on development and persistence of Onchocerca volvulus infection in offspring: an 18 year follow-up study.

This study analysed the impact and the extent by which parental Onchocerca volvulus infection, intensity of transmission of O. volvulus infective 3rd-stage larvae (L3) and anthropometric factors may influence the acquisition, development and persistence of O. volvulus infection in offspring. A total of 15290 individuals in 3939 families with 9640 children were surveyed for microfilariae of O. volvulus, and prevalence and level of O. volvulus infection in children aged 0 to 20 years from infected and non-infected parents were followed longitudinally for 18 years. Children from O. volvulus-infected mothers had not only a substantially higher risk to become infected; they also acquired infection earlier in life and developed higher infection levels. Multiple logistic regression analysis showed that maternal O. volvulus infection and children's age are the predominant predictors for patent O. volvulus infection, while the intensity of transmission, measured by the annual transmission potential (ATP) of O. volvulus L3, was less decisive. Longitudinal follow up of children showed that during vector control activities by the Onchocerciasis Control Programme (OCP) and in low-level transmission areas, infection persisted at higher levels in children from O. volvulus-positive mothers. In summary, the dominant risk factor for children to become infected is maternal onchocerciasis, and also age-associated factors will strongly impact on the development of patent O. volvulus infection in offspring.

Pro-inflammatory (IL-1beta, IL-18) cytokines and IL-8 chemokine release by PBMC in response to Echinococcus multilocularis metacestode vesicles.

In humans infected with Echinococcus multilocularis, larval metacestodes will develop, proliferate and progressively infiltrate the surrounding host tissues by exogenous budding of parasitic microvesicles or cell lines which detach from the original tumour and thus become transported through blood or lymph vessels into other organs. Cellular effector mechanisms constitute the most effective means to restrict parasite persistence and proliferation, and here we demonstrate that E. multilocularis vesicle antigens will induce pro-inflammatory, regulatory and chemokine release by PBMC from patients. The pro-inflammatory cytokines IL-1beta and IL-18 were reduced in echinococcosis patients, regulatory IL-10 was similar, but parasite vesicle-induced IL-8 was dominant and clearly elevated in patients. Such selective and opposite dynamics of inflammatory cytokines and chemokine release may prevent overwhelming and pathogenic inflammation, and constitute an appropriate response for attraction of effector cells into the periparasitic tissues with the capacity to limit E. multilocularis metacestode proliferation and dissemination.

Angiostrongylus costaricensis infection in C57BL/6 mice: MHC-II deficiency results in increased larval elimination but unaltered mortality.

During experimental Angiostrongylus costaricensis infections in several inbred mouse strains, genetic factors as well as different cytokine secretion patterns have recently been shown to play a role in the outcome of infection in terms of morbidity and mortality, e.g. BALB/c mice show a high and C57BL/6 mice a low mortality during the acute phase of infection. In this study, C57BL/6 MHC-II knockout mice infected with A. costaricensis did not show increased mortality during the acute phase of infection when compared with wild-type mice. Furthermore, MHC-II knockout mice showed a strongly diminished parasite-specific humoral and cellular immune response, which can be explained by the nearly complete lack of CD4+ T cells in the periphery. This defect in MHC-II genes, the lack of CD4+ T cells, and the resulting cellular and humoral unresponsiveness resulted in a three times higher output of first-stage larvae in feces compared with wild-type animals. The results indicate that during experimental A. costaricensis infection a parasite-specific immune response, directed via MHC-II molecules and CD4+ T cells, is not essential for the survival of C57BL/6 mice during the acute phase of infection, whereas the elimination of first-stage larvae seems to be regulated by a MHC-II- and CD4+ T-cell-dependent mechanism.

Parasite-specific antibody and cellular immune responses in human infected with Necator americanus and Oesophagostomum bifurcum.

In this study parasite-specific antibody, cellular reactivity and Thl-type or Th2-type cytokine responses were investigated in humans concurrently infected with Necator americanus and Oesophagostomum bifurcum. The prospects for O. bifurcum-specific serodiagnosis based on IgG4 and IgE were evaluated. IgG4 showed low specificity for O. bifurcum due to antigen cross-reactivity with N. americanus, while IgE specifically distinguished between hookworm and O. bifurcum, and, in doubly infected patients, levels of O. bifurcum-specific as well as N. americanus-specific IgE were significantly elevated compared to those with N. americanus mono-infections. Cellular immunity was not strictly dominated by a Thl- or Th2- type reactivity. In co-infected patients cellular unresponsiveness to parasite antigens was observed, while cellular production of tumour necrosis factor alpha (TNF-alpha) and gamma-interferon (IFN-gamma) was greater in those doubly infected. Th2-type cytokines (interleukin-5 and interleukin-10) were produced in equal amounts by peripheral blood mononuclear cells from individuals with mono- and coinfections. Such mixed Thl-type and Th2-type immune responsiveness associated with persisting gastrointestinal parasitic nematodes may reflect a state of infection at which parasite-induced inflammatory and enteropathogenic responses co-exist, and furthermore, helminth coinfection will not only suppress parasite-specific cellular responsiveness but may also direct cytokine production towards a "permissive Th1-type cytokine profile" that favours parasite persistence.

Cellular immune responses and cytokine production in BALB/c and C57BL/6 mice during the acute phase of Angiostrongylus costaricensis infection.

In our experimental study we were able to show that the contrasting outcome of Angiostrongylus costaricensis infection in C57BL/6 and BALB/c mice, in respect of morbidity and mortality, can be explained by divergent cellular immune responses and a different cytokine pattern in each strain. In BALB/c mice (i.e. those with high mortality), the initial high proliferation of ConA or LPS stimulated spleen cells dropped to very low levels after 2 weeks post-infection (p.i.), whereas in C57BL/6 mice (i.e. those with low mortality), only a minor reduction in lymphoproliferative responses after mitogenic stimulation was observed. The specific proliferation of spleen cells after stimulation with A. costaricensis adult worm antigen remained low in BALB/c mice throughout the experiment, but showed an augmented proliferation in C57BL/6 mice, especially from 2 weeks p.i. onwards. The mitogen-induced production of Th2-type cytokines (IL-4, IL-5, IL-6, IL-10) in spleen cell cultures remained low in BALB/c mice until 4 weeks p.i., but production of Th1-type cytokines (IL-2, IFN-gamma) was highly elevated at 14 and 28 days p.i. In C57BL/6 mice, an upregulated and balanced production of both Th1- and Th2-type cytokines was measured during the course of infection. In summary, a polarization of the immune response towards cellular hyporesponsiveness and a predominantly Th1 cytokine profile was observed in A. costaricensis infected BALB/c mice, which may contribute to pathogenesis and increased morbidity.

Determinants for resistance and susceptibility to microfilaraemia in Litomosoides sigmodontis filariasis.

Filarial infections of humans are chronic diseases. Despite an ongoing immune response, adult filariae continuously produce their offspring, the microfilariae (Mf), which are able to persist in sufficient numbers to ensure transmission. In this study, host- and parasite-derived factors, which contribute to persistence of Mf, were investigated using the filariasis model of Litomosoides sigmodontis in mice. Different strains of mice were found to differ widely in their capability to eliminate circulating Mf. Studies of congenic mouse strains showed that early and rapid clearance of Mf was mediated by activation pathways relevant to innate immunity, whereas late or delayed clearance of Mf was pre-determined by MHC-related factors. Genetic knock-out of genes for the MHC class-II molecules totally abrogated resistance. Most interestingly, the presence of only I adult female, but not male worms, renders all mice susceptible, irrespective of the genetic background, enabling Mf to circulate for extended periods of time. Such prolonged microfilaraemia was also observed in L. sigmodontis-infected animals challenged with heterologous Mf of Acanthocheilonema viteae. The use of cytokine gene knock-out mice showed that persistence of L. sigmodontis Mf was facilitated by IL-10, but not by IL-4 or IFN-gamma. In conclusion, irrespective of a resistant or susceptible host genetic background, survival of Mf of L. sigmodontis in mice is decisively regulated by the presence of adult female L. sigmodontis which will skew and exploit immune responses to facilitate the survival and persistence of their offspring in the infected host.

The role of nitric oxide in the innate resistance to microfilariae of Litomosoides sigmodontis in mice.

Nitric oxide (NO) has been shown to be an important effector mechanism in the defence against various pathogens, including filariae. The production of NO, as well as H2O2, is induced by the Th1 cytokine IFN-gamma. Therefore, the microfilariae (mf) of filarial nematodes, which are known to elicit the release of IFN-gamma, may be a target of NO release. In this study, we found that mf of the filarial species Litomosoides sigmodontis were resistant to the attack of H2O2, but vulnerable to NO exposure in vitro by a chemical NO donor, as well as activated macrophages. Adult worms were considerably less affected by exposure to NO. In-vivo production of NO following injection of mf, in this and previous studies, suggested a central role in the defence to filariae. However, neither pharmaceutical inhibition of nitric oxide synthesis, nor genetic knockout of the gene for inducible nitric oxide synthase (iNOS), abrogated resistance to circulating mf in mice. Interestingly, however, iNOS-KO mice showed higher interleukin (IL)-2 responses and lower IL-10 production, compared to their wild-type counterparts. In conclusion, despite its effectiveness in vitro and the observed production of NO by ex vivo cells following infection, nitric oxide seems not to be an important factor in elimination of mf of L. sigmodontis in vivo. However, it may have a regulatory role in the immune response.

Prenatal immune priming with helminth infections: parasite-specific cellular reactivity and Th1 and Th2 cytokine responses in neonates.

The present investigation aimed to determine to what extent maternal helminth infection primes parasite-specific cellular responsiveness in neonates. Umbilical cord mononuclear blood cells (UCBC) and peripheral blood mononuclear cells (PBMC) from mothers proliferated in response to mitogenic stimulation with concanavalin A, as well as to bacterial Streptococcus pyogenes-derived (streptolysin O) and helminth-specific antigens of Necator americanus and Onchocerca volvulus. Cellular responses to Echinococcus multilocularis (Em) and Oesophagostomum bifurcum (Oes), helminth parasites not endemic in the study area, were absent (for Em) or very low (for Oes due to antigenic cross-reactivity). Cellular responsiveness to mitogen and antigens was higher in mothers than in their neonates. Several Th1-type (IL-2, IL-12, and IFN-gamma) and Th2-type (IL-5 and IL-10) cytokines were produced by UCBC from neonates and PBMC from mothers. Low levels of IFN-gamma were elicited by UCBC in response to helminth and bacterial antigens, while secretion of IL-2 was pronounced and similarly high in neonates and their mothers. Amounts of IL-5 produced by UCBC in response to bacterial SL-O and mitogenic stimulation (PHA) were low, but equivalent levels of IL-5 were induced by intestinal helminth and filaria-derived antigens in neonates and mothers. A pronounced production of IL-10 and IL-12 by UCBC was observed--spontaneous IL-10 and IL-12 secretion by UCBC was higher in neonates than by PBMC from mothers. Net amounts of IL-10 elicited by helminth antigens were similar, while net IL-12 in response to mitogen, and bacterial and helminth antigens was significantly higher in mothers than their offspring. Our results indicate that human maternal helminth infection does sensitize in utero for parasite-specific cellular responsiveness in offspring, and also activates specific production of several cytokines, and such children do not present a dominant expression of immunity of either Th1 or Th2.

Phosphocholine-containing, zwitterionic glycosphingolipids of adult Onchocerca volvulus as highly conserved antigenic structures of parasitic nematodes.

Human Onchocerca volvulus infection sera were found to recognize zwitterionic glycolipids of O. volvulus and to cross-react with those of other parasitic nematodes (Ascaris suum, Setaria digitata and Litomosoides sigmodontis). By the use of an epitope-specific monoclonal antibody, zwitterionic glycolipids of all these nematode species were observed to contain the antigenic determinant phosphocholine. A hyperimmune serum specific for arthro-series glycolipid structures reacted with the various neutral glycolipids of all these nematodes, which demonstrated that their oligosaccharide moieties belonged to the arthro-series of protostomial glycolipids. These results indicated that arthro-series glycosphingolipids carrying, in part, phosphocholine substituents, represent highly conserved, antigenic glycolipid markers of parasitic nematodes. Three glycolipid components of the O. volvulus zwitterionic fraction were structurally characterized by matrix-assisted laser-desorption/ionization time-of-flight MS, methylation analysis and exoglycosidase treatment. Their chemical structures were elucidated to be phosphocholine-6GlcNAc(beta1-3)Man(beta1-4)Glc(1-1)ceramide, GalNAc(beta1-4)[phosphocholine-6]GlcNAc(beta1-3)Man(beta1-4)Glc(1-1) ceramide and Gal(alpha1-3)GalNAc(beta1-4)[phosphocholine-6]GlcNAc(beta1-3)Man(beta 1-4)Glc(1-1)ceramide for the zwitterionic ceramide tri-, tetra- and penta-hexosides respectively. The ceramide composition was found to be dominated by 2-hydroxylated docosanoic (C(22h:0)), tricosanoic (C(23h:0)) and tetracosanoic (C(24h:0)) acids, and C(17) sphingosine (C(d17:1)) (where (h) is hydroxylated and (d) is dihydroxylated).

Litomosoides sigmodontis: dynamics of the survival of microfilariae in resistant and susceptible strains of mice.

Litomosoides sigmodontis in the BALB/c mouse is the only model of filariasis which allows the observation of the complete development in an immunocompetent mouse. In this study, we injected microfilariae (mf) intravenously, as well as into the pleural cavity, the site of natural release of mf from adult female worms, and followed the kinetics of elimination within the host. In susceptible BALB/c mice, mf circulated at high levels in the blood. In contrast, in C57BL/6 mice, which are refractory to full development, mf were eliminated rapidly from the peripheral blood. However, 6 days after intrapleural injection, viable larvae could be found in the pleural cavity and lung capillaries of both susceptible and resistant strains. The numbers of mf in the pleural cavity and lung capillaries in individual mice were significantly correlated, but not dependent on strain or peripheral microfilaraemia. Thus, although C57BL/6 mice showed enhanced production of nitric oxide by pleural exudate cells and a faster change in the numbers of circulating leukocytes after injection, rapid killing of mf by cell or nitric oxide-mediated mechanisms were not the reason for the different outcome. Furthermore, 3 h after iv injection, only a small percentage of mf could be recovered from the peripheral circulation, indicating the presence of a reservoir for mf containment. In conclusion, injected mf showed disparate dynamics of persistence within susceptible and resistant hosts, which is similar to the disparate outcome of natural infections with L. sigmodontis. This difference became obvious within 1 day after injection. The lung capillary system plays obviously a crucial part in regulation of microfilaremia. Our model also provides a possible means to explain frequent cases of occult infections in human filariasis.

Regulatory effects of Th1-type (IFN-gamma, IL-12) and Th2-type cytokines (IL-10, IL-13) on parasite-specific cellular responsiveness in Onchocerca volvulus-infected humans and exposed endemic controls.

The present study investigated in vitro the regulatory effects of T helper 1 (Th1)-type (interferon-gamma, IFN-gamma; interleukin-12, IL-12) and Th2-type cytokines (IL-10, IL-13) on Onchocerca volvulus-specific cellular reactivity in onchocerciasis patients, and in exposed endemic control individuals presenting no clinical and parasitological signs of disease. In both patients and controls, addition of IL-10 dose-dependently depressed O. volvulus antigen (OvAg)-specific cellular proliferation, and peripheral blood mononuclear cells (PBMC) from patients who were more sensitive to the suppressive effect of IL-10 than those from endemic controls. However, neutralization of IL-10 by specific antibody did not reverse cellular hyporesponsiveness. In contrast to the inhibitory effects of IL-10, exogenous IL-12 and IL-13 augmented PBMC proliferative responses to OvAg both in patients and controls (P<0. 01) and neutralizing of IL-12 or IL-13 significantly decreased OvAg-specific proliferation in both groups. Exogenous IFN-gamma did not activate OvAg-specific proliferative responses in patients, but anti-IFN-gamma antibodies abolished cellular reactivity to OvAg. Antibody to IL-10 increased (P<0.05) OvAg-specific production of IL-5, IL-12 and IFN-gamma, and inversely, anti-IFN-gamma enhanced IL-10 (in patients only) and IL-5 and IL-13 in both patients and controls. Neutralization of IL-12 activated OvAg-specific production of IL-10, IL-2 and IFN-gamma. In conclusion, despite of an overproduction of IL-10, which suppressed cellular reactivity in patients and control individuals, OvAg-specific cellular responses were activated in vitro by exogenous supplementation with IL-12 and IL-13, and cytokine neutralization experiments confirmed that distinct type 1 and type 2 T helper cytokines cross-regulate expression and magnitude of O. volvulus-specific cellular responsiveness in humans.

Cytokine and chemokine secretion by human peripheral blood cells in response to viable Echinococcus multilocularis metacestode vesicles.

In human alveolar echinococcosis, asexually proliferating metacestodes of Echinococcus multilocularis progressively infiltrate host tissues and cause serious pathology to the affected organs. This study employed an in vitro culture of E. multilocularis and examined the production of cytokines and chemokines by peripheral blood cells from echinococcosis patients in response to viable proliferating E. multilocularis metacestode vesicles (Em-vesicles). A significant interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) production was elicited in echinococcosis patients when their cells were cocultured with viable Em-vesicles and autologous immune sera. Furthermore, in echinococcosis patients, substantial amounts of cytokines were detected; and the levels of IL-12 and IL-13 found in patients correlated with the actual state of clinical disease. These observations suggest that viable E. multilocularis vesicles will induce significant cellular production of cytokines and chemokines in patients, and that such immune mediators may activate and enhance antibody-dependent cellular effector mechanism against proliferating metacestodes of E. multilocularis.