Characterization of the immuno-regulatory response to the tapeworm Hymenolepis diminuta in the non-permissive mouse host

Hymenolepis diminuta is spontaneously expelled from mice; concomitant with worm expulsion was protection against colitis induced by dinitrobenzene sulphonic acid (DNBS). Here we examined the immune response mobilized by Balb/c and C57Bl/6 male mice in response to H. diminuta and assessed the requirement for CD4+ cells (predominantly T cells) in worm expulsion and the anti-colitic effect. Wild-type (CD4+) or CD4 knock-out (CD4-/-) mice received five H. diminuta cysticercoids and segments of jejunum and mesenteric lymph nodes (MLNs), or spleen, were excised 5, 8 and 1l days later for mRNA analysis and cytokine production, respectively. In separate experiments uninfected and infected mice received DNBS by intra-rectal infusion and indices of inflammation were assessed 3 days later (i.e. 11 days p.i.). Infection of Balb/c mice resulted in a time-dependent increase in intestinal mRNA for Foxp3, a marker of natural regulatory T cells, and markers of alternatively activated macrophages (arginase-1, FIZZ1), while concanavalin-A activation of MLN cells revealed a significant increase in T helper 2 (TH2) type cytokines: IL-4, -5, -9, -10, -13. MLN cells showed a reduced ability to induce Foxp3 expression upon stimulation. CD4-/- mice did not display this response to infection, but surprisingly did expel H. diminuta. Moreover, DNBS-induced colitis in CD4-/- mice (wasting, tissue damage, elevated myeloperoxidase) was not reduced by H. diminuta infection, whereas time-matched infected CD4+ C57Bl/6 mice had significantly less DNBS-induced inflammation. In conclusion: (i) in addition to stereotypical TH2 events, H. diminuta-infected Balb/c mice develop a local immuno-regulatory response; and (ii) CD4+ cells are not essential for H. diminuta expulsion from mice but are critical in mediating the anti-colitic effect that accompanies infection in this model.     

Helminth-primed dendritic cells alter the host response to enteric bacterial infection

To examine whether intestinal helminth infection may be a risk factor for enteric bacterial infection, a murine model was established using the intestinal helminth Heligomosomoides polygyrus and a murine pathogen Citrobacter rodentium, which causes infectious colitis. Using this model we recently have shown that coinfection with the Th2-inducing H. polygyrus and C. rodentium promotes bacterial-associated disease and colitis. In this study, we expand our previous observations and examine the hypothesis that dendritic cells (DC) stimulated by helminth infection may play an important role in the regulation of the intestinal immune response to concurrent C. rodentium infection as well as in the modulation of the bacterial pathogenesis. We show that H. polygyrus infection induces DC activation and IL-10 expression, and that adoptive transfer of parasite-primed DC significantly impairs host protection to C. rodentium infection, resulting in an enhanced bacterial infection and in the development of a more severe colonic injury. Furthermore, we demonstrate that adoptive transfer of parasite-primed IL-10-deficient DCs fails to result in the development of a significantly enhanced C. rodentium-mediated colitis. Similarly, when the DC IL-10 response was neutralized by anti-IL-10 mAb treatment in mice that received parasite-primed DC, no deleterious effect of the parasite-primed DC on the host intestinal response to C. rodentium was detected. Thus, our results provide evidence to indicate that the H. polygyrus-dependent modulation of the host response to concurrent C. rodentium infection involves IL-10-producing DCs.     

IL-22 Restrains Tapeworm-Mediated Protection against Experimental Colitis via Regulation of IL-25 Expression

Interleukin (IL)-22, an immune cell-derived cytokine whose receptor expression is restricted to non-immune cells (e.g. epithelial cells), can be anti-inflammatory and pro-inflammatory. Mice infected with the tapeworm Hymenolepis diminuta are protected from dinitrobenzene sulphonic acid (DNBS)-induced colitis. Here we assessed expulsion of H. diminuta, the concomitant immune response and the outcome of DNBS-induced colitis in wild-type (WT) and IL-22 deficient mice (IL-22^-/-) ± infection. Interleukin-22^-/- mice had a mildly impaired ability to expel the worm and this correlated with reduced or delayed induction of TH2 immunity as measured by splenic and mesenteric lymph node production of IL-4, IL-5 and IL-13 and intestinal Muc-2 mRNA and goblet cell hyperplasia; in contrast, IL-25 increased in the small intestine of IL-22^-/- mice 8 and 12 days post-infection compared to WT mice. In vitro experiments revealed that H. diminuta directly evoked epithelial production of IL-25 that was inhibited by recombinant IL-22. Also, IL-10 and markers of regulatory T cells were increased in IL-22^-/- mice that displayed less DNBS (3 mg, ir. 72h)-induced colitis. Wild-type mice infected with H. diminuta were protected from colitis, as were infected IL-22^-/- mice and the latter to a degree that they were almost indistinguishable from control, non-DNBS treated mice. Finally, treatment with anti-IL-25 antibodies exaggerated DNBS-induced colitis in IL-22^-/- mice and blocked the anti-colitic effect of infection with H. diminuta. Thus, IL-22 is identified as an endogenous brake on helminth-elicited TH2 immunity, reducing the efficacy of expulsion of H. diminuta and limiting the effectiveness of the anti-colitic events mobilized following infection with H. diminuta in a non-permissive host.     

Mucosal immunotherapy with CpG oligodeoxynucleotides reverses a murine model of chronic asthma induced by repeated antigen exposure

Murine models of acute atopic asthma may be inadequate to study the effects of recurrent exposure to inhaled allergens, such as the epithelial changes seen in asthmatic patients. We developed a murine model in which chronic airway inflammation is maintained by repeated allergen [ovalbumin (OVA)] inhalation; using this model, we examined the response to mucosal administration of CpG DNA (oligonucleotides) and specific antigen immunotherapy. Mice repeatedly exposed to OVA developed significantly greater airway hyperresponsiveness and goblet cell hyperplasia, but not airway eosinophilia, compared with those exposed only twice. CpG-based immunotherapy significantly reversed both acute and chronic markers of inflammation as well as airway hyperresponsiveness. We further examined the effect of mucosal immunotherapy on the response to a second, unrelated antigen. Mice sensitized to both OVA and schistosome eggs, challenged with inhaled OVA, and then treated with OVA-directed immunotherapy demonstrated significant reduction of airway hyperresponsiveness and a moderate reduction in eosinophilia, after inhalation challenge with schistosome egg antigens. In this model, immunotherapy treatment reduced bronchoalveolar lavage (BAL) levels of Th2 cytokines (IL-4, IL-5, IL-13, and IL-10) without changing BAL IFN-gamma. Antigen recall responses of splenocytes from these mice demonstrated an antigen-specific (OVA) enhanced release of IL-10 from splenocytes of treated mice. These results suggest that CpG DNA may provide the basis for a novel form of immunotherapy of allergic asthma. Both antigen-specific and, to a lesser extent, antigen-nonspecific responses to mucosal administration of CpG DNA are seen.     

Contrasting effects of acute and chronic gastro-intestinal helminth infections on a heterologous immune response in a transgenic adoptive transfer model

We have previously found that co-immunisation with ovalbumin (OVA) and the body fluid of the helminth Ascaris suum inhibited an OVA-specific delayed type hypersensitivity (DTH) response by reducing OVA-specific CD4+ T lymphocyte proliferation via an IL-4 independent mechanism. In the present study, we determined whether parasite infections themselves could induce similar changes to peripheral immunisation by examining the modulation of OVA-specific immune responses during acute and chronic helminth infections. Surprisingly, an acute infection with Trichinella spiralis, but not a chronic infection with Heligmosomoides polygyrus, inhibited the OVA-specific DTH reaction. Correspondingly, the T helper 1 (Th1) OVA-specific response was decreased in mice infected with T. spiralis, but not with H. polygyrus. Inhibition of the Th1 response may be a result of a shift in the Th1/Th2 balance as although both H. polygyrus and T. spiralis infected mice induced a Th2 OVA-specific response, that exhibited by T. spiralis was more potent. Furthermore, although IL-10 secretion upon OVA restimulation was similarly increased by both infections, production of this immunoregulatory cytokine may play a role in the suppression of immune responses observed with T. spiralis infection depending on the context of its release. Interestingly, analysis of the OVA-specific T lymphocyte division by carboxyfluorescein diacetate succinimidyl ester (CFSE) staining revealed that gastro-intestinal infection with the acute helminth T. spiralis, but not with chronic H. polygyrus, inhibited the systemic immune response by significantly inhibiting the antigen-specific T cell proliferation during the primary response, a mechanism similar to that observed when A. suum parasite extracts were directly mixed with the OVA during immunisation in our previous studies.     

Cryopreserved Interleukin-4–Treated Macrophages Attenuate Murine Colitis in an Integrin β7–Dependent Manner

The adoptive transfer of alternatively activated macrophages (AAMs) has proven to attenuate inflammation in multiple mouse models of colitis; however, the effect of cryopreservation on AAMs, the ability of previously frozen AAMs to block dinitrobenzene sulfonic acid (DNBS) (Th1) and oxazolone (Th2) colitis and their migration postinjection remains unknown. Here we have found that while cryopreservation reduced mRNA expression of canonical markers of interleukin (IL)-4–treated macrophages [M(IL-4)], this step did not translate to reduced protein or activity, and the cells retained their capacity to drive the suppression of colitis. The anticolitic effect of M(IL-4) adoptive transfer required neither T or B cell nor peritoneal macrophages in the recipient. After injection into the peritoneal cavity, M(IL-4)s migrated to the spleen, mesenteric lymph nodes and colon of DNBS-treated mice. The chemokines CCL2, CCL4 and CX3CL1 were expressed in the colon during the course of DNBS-induced colitis. The expression of integrin β7 on transferred M(IL-4)s was required for their anticolitic effect, whereas the presence of the chemokine receptors CCR2 and CX3CR1 were dispensable in this model. Collectively, the data show that M(IL-4)s can be cryopreserved M(IL-4)s and subsequently used to suppress colitis in an integrin β7-dependent manner, and we suggest that these proof-of-concept studies may lead to new cellular therapies for human inflammatory bowel disease.     

Inducible cyclooxygenase released prostaglandin mediates immunosuppression in acute phase of experimental Trypanosoma cruzi infection

We investigated the possible role of prostaglandins produced by COX-2 in the immunosuppression observed during Trypanosoma cruzi infection. Con-A-stimulated splenocytes isolated from mice on days 5, 10, and 15 of infection released large amounts of PGE2 and this release was inhibited by the treatment of animals with sodium salicylate or meloxicam. The treatment of the animals with these drugs enhanced the release of IL-2 by splenocytes from T. cruzi-infected animals and significantly reduced the blood parasitemia and delayed the mortality of the infected mice. Furthermore, the release of TNF-alpha, IFN-gamma, IL-4, and IL-10 by Con-A-stimulated splenocytes obtained from infected mice on days 5, 10, and 15 of the infection was significantly inhibited by treatment of the animals with salicylate or meloxicam. In conclusion, the results suggest that the prostaglandins produced mainly by COX-2 mediate the immunosuppression observed in the acute phase of T. cruzi infection.     

Role of M-CSF-dependent macrophages in colitis is driven by the nature of the inflammatory stimulus

Although macrophages are considered a critical factor in determining the severity of acute inflammatory responses in the gut, recent evidence has indicated that macrophages may also play a counterinflammatory role. In this study, we examined the role of a macrophage subset in two models of colitis. Macrophage colony-stimulating factor (M-CSF)-deficient osteopetrotic mice (op/op) and M-CSF-expressing heterozygote (+/?) mice were studied following the induction of colitis by either dinitrobenzene sulfonic acid (DNBS) or dextran sulfate sodium (DSS). DNBS induced a severe colitis in M-CSF-deficient op/op mice compared with +/? mice. This was associated with increased mortality and more severe macroscopic and microscopic injury. Colonic tissue myeloperoxidase (MPO) activity as well as concentrations of TNF-alpha, IL-1beta, and IL-6 were higher and IL-10 lower in op/op mice with DNBS colitis. The severity of inflammation and mortality was attenuated in op/op mice that had received human recombinant M-CSF prior to the induction of colitis. In contrast, op/op mice appeared less vulnerable to colitis induced by DSS. Macroscopic damage, microscopic injury, MPO activity, and tissue concentrations of TNF-alpha, IL-1beta, and IL-6 were all lower in op/op mice compared with +/? mice with DSS colitis, and no changes were seen in IL-10. Macrophage inflammatory protein-1alpha concentrations were increased in op/op but not +/? mice following colitis induced by DNBS but not DSS. These results indicate that M-CSF-dependent macrophages may play either a pro- or counterinflammatory role in acute experimental colitis, depending on the stimulus used to induce colitis.     

Heligmosomoides polygyrus bakeri Induces Tolerogenic Dendritic Cells that Block Colitis and Prevent Antigen-Specific Gut T Cell Responses

Immunological diseases such as inflammatory bowel disease (IBD) are infrequent in less developed countries, possibly because helminths provide protection by modulating host immunity. In IBD murine models, the helminth Heligmosomoides polygyrus bakeri prevents colitis. It was determined whether H. polygyrus bakeri mediated IBD protection by altering dendritic cell (DC) function. We used a Rag IBD model where animals were reconstituted with IL10(-/-) T cells, making them susceptible to IBD and with OVA Ag-responsive OT2 T cells, allowing study of a gut antigenic response. Intestinal DC from H. polygyrus bakeri-infected Rag mice added to lamina propria mononuclear cells (LPMC) isolated from colitic animals blocked OVA IFN-γ/IL-17 responses in vitro through direct contact with the inflammatory LPMC. DC from uninfected Rag mice displayed no regulatory activity. Transfer of DC from H. polygyrus bakeri-infected mice into Rag mice reconstituted with IL10(-/-) T cells protected animals from IBD, and LPMC from these mice lost OVA responsiveness. After DC transfer, OT2 T cells populated the intestines normally. However, the OT2 T cells were rendered Ag nonresponsive through regulatory action of LPMC non-T cells. The process of regulation appeared to be regulatory T cell independent. Thus, H. polygyrus bakeri modulates intestinal DC function, rendering them tolerogenic. This appears to be an important mechanism through which H. polygyrus bakeri suppresses colitis. IFN-γ and IL-17 are colitogenic. The capacity of these DC to block a gut Ag-specific IFN-γ/IL-17 T cell response also is significant.     

Involvement of prostaglandins in the immunosuppression occurring during experimental infection by Paracoccidioides brasiliensis

We investigated whether PGE2 mediates the immunosuppression observed during Paracoccidioides brasilensis infection. Con-A-stimulated splenocytes, isolated from mice on days 15 and 60 of infection, release high amounts of PGE2, this release was inhibited by the treatment of animals with indomethacin, sodium salicylate or meloxicam. The treatment of the animals with salicylate or meloxicam, but not indomethacin, enhanced the release of IL-2 by splenocytes from animals on day 15, but not on day 60 of infection. Furthermore, we demonstrated that the productions of TNF-alpha, IFN-gamma, IL-4, and IL-10 by Con-A-stimulated splenocytes from mice at 15 days of infection were inhibited by treatment with salicylate or meloxicam. Indomethacin inhibited only TNF-alpha and IFN-gamma production. The three treatments caused reduction of granuloma areas in the liver and lungs of infected mice. In conclusion, results suggest that the PGE2 released by COX-2 mediates the immunosuppression early on (day 15), but not during the later phase (60 days) of P. brasiliensis infection by a mechanism dependent upon IL-4 and IL-10.     

Regulation of the immune response to cestode infection by progesterone is due to its metabolism to estradiol

The aim of this work was to investigate the role of progesterone during Taenia crassiceps cysticercosis, and the immunological mechanisms involved in its effects, by relating progesterone treatment to whole parasite counts, to host humoral and cellular immune response, to the presence or absence of nuclear receptors to sex steroids in splenocytes, and to serum sex steroid levels in infected mice of both genders. Progesterone treatment increased parasite loads two-fold in females and three-fold in males compared with control mice. The expression of the Th2 cytokine profile (IL-4, IL-6 and IL-10) was markedly increased in infected mice of both genders, while progesterone treatment returned this expression to basal levels. However, the Th1 cytokine profile (IFN-gamma and TNF-alpha) was not affected by infection, whilst progesterone treatment increased the expression of both cytokines two-fold compared to uninfected, infected and placebo-treated mice. Testosterone serum levels decreased in infected male mice by 95%, and treatment with progesterone did not affect them. In females, no change in testosterone levels was observed. Progesterone levels increased three-fold only in progesterone-treated infected mice of both sexes, while estradiol levels in female and male progesterone-treated infected mice increased two-fold compared to infected control mice. The infection markedly induced the expression of progesterone receptor (PR) isoforms A and B in splenocytes of infected mice of both genders (five-fold). Metabolism of progesterone to estradiol was demonstrated by the use of the anti-estrogen tamoxifen, which reduced parasite loads 100% in infected mice of both sexes treated with progesterone. These results suggest that progesterone, possibly through its metabolism to estradiol, affects establishment, growth and reproduction of the helminth parasite T. crassiceps.     

Role of IL-10 in hepatocyte tight junction alteration in mouse model of experimental colitis

BACKGROUND: A variety of hepatobiliary abnormalities have been described in patients with chronic inflammatory bowel diseases (IBDs). The purpose of this study was to investigate the role of endogenous IL-10 in alteration of hepatocyte TJ paracellular barrier and in the rapid transcytotic vesicular pathway modification associated with intestinal inflammation. MATERIALS AND METHODS: To address this question, we used an experimental model of colitis, induced by dinitrobenzene sulfonic acid (DNBS). When compared to DNBS-treated IL-10 wild-type (IL-10WT) mice, DNBS-treated IL-10 knock-out mice (IL-10KO) mice experienced a higher rate of the extent and severity of the histological signs of colon injury. RESULTS: Colon and liver levels of the pro-inflammatory cytokines tumour necrosis factor, interleukin-1 beta and interleukin-6 were also greatly enhanced in IL-10KO mice in comparison to wild-type mice. Liver histology from IL-10KO and IL-10WT did not show any parenchymal and portal tract inflammation at 4 days after DNBS administration. Serum total bilirubin and Alanine aminotransferase, were significantly increased in DNBS-IL-10KO mice vs. DNBS-IL-10KO mice. Therefore, we found an increase of tight junctional permeability to lanthanum nitrate (molecular weight, 433) in the livers from DNBS-treated IL-10WT mice; lanthanum accumulated throughout the junctional area up to the most apical region bordering the lumen. Absence of a functional IL-10 gene in IL-10KO mice resulted in a significant augmentation of apical diffusion of lanthanum after DNBS-induced colitis. Immunofluorescent labelling of frozen liver sections from DNBS-IL10KO mice, immunolocalization for and claudin-1 and ZO-1 resulted in a significant alteration in the localization of the immunosignals for claudin-1 and ZO-1 after DNBS administration in comparison with DNBS-IL10WT. CONCLUSION: In conclusion, we suggest that the absence of IL-10 may represent an important pathophysiological mechanism of hepatobiliary injuries and cholestasis observed in patients with IBD.     

Helminth protection against autoimmune diabetes in nonobese diabetic mice is independent of a type 2 immune shift and requires TGF-β

Leading hypotheses to explain helminth-mediated protection against autoimmunity postulate that type 2 or regulatory immune responses induced by helminth infections in the host limit pathogenic Th1-driven autoimmune responses. We tested these hypotheses by investigating whether infection with the filarial nematode Litomosoides sigmodontis prevents diabetes onset in IL-4-deficient NOD mice and whether depletion or absence of regulatory T cells, IL-10, or TGF-β alters helminth-mediated protection. In contrast to IL-4-competent NOD mice, IL-4-deficient NOD mice failed to develop a type 2 shift in either cytokine or Ab production during L. sigmodontis infection. Despite the absence of a type 2 immune shift, infection of IL-4-deficient NOD mice with L. sigmodontis prevented diabetes onset in all mice studied. Infections in immunocompetent and IL-4-deficient NOD mice were accompanied by increases in CD4(+)CD25(+)Foxp3(+) regulatory T cell frequencies and numbers, respectively, and helminth infection increased the proliferation of CD4(+)Foxp3(+) cells. However, depletion of CD25(+) cells in NOD mice or Foxp3(+) T cells from splenocytes transferred into NOD.scid mice did not decrease helminth-mediated protection against diabetes onset. Continuous depletion of the anti-inflammatory cytokine TGF-β, but not blockade of IL-10 signaling, prevented the beneficial effect of helminth infection on diabetes. Changes in Th17 responses did not seem to play an important role in helminth-mediated protection against autoimmunity, because helminth infection was not associated with a decreased Th17 immune response. This study demonstrates that L. sigmodontis-mediated protection against diabetes in NOD mice is not dependent on the induction of a type 2 immune shift but does require TGF-β.     

Inflammatory lesion and parasite load are inversely associated in Leishmania amazonensis infected mice genetically selected according to oral tolerance susceptibility

Two strains of mice selected according to extreme phenotypes of susceptibility and resistance to oral tolerance (TS and TR mice, respectively) were infected with 1 x 10(7) Leishmania amazonensis promastigotes and studied comparatively. TS mice developed a minor pathology while permitting parasite growth with the presence of increased IL-4, IL-10 and IFN-gamma, and lower NO and IL-2 levels and delayed-type hypersensitivity (DTH). In contrast, in TR mice, footpad swelling was increased but parasite growth was reduced. They produced lower IL-4, IL-10 and IFN-gamma but increased NO, IL-2 levels, DTH, activated spleen macrophages and periarteriolar lymphoid sheaths. The results suggest that the tolerogenic TS mouse profile, with higher IL-10 production, impaired lesion development but also avoided macrophage leishmanicidal activity, maintaining in this manner a silent parasite load. On the other hand, the TR mouse profile contributed to lesion progression with controlled parasite load. To directly address the influence of oral tolerance on infection, mice were gavaged with OVA, and 7 days afterwards were infected and challenged to bystander suppression with OVA in the same footpad. In TR mice gavaged with 25 mg OVA the inflammatory lesion was largely enhanced, while with 5 mg OVA the lesion was diminished. In TS mice the footpad swelling was always lower. However, the bystander effect did not modify the establishment of infection; and similarly to the control non-bystander mice, parasite clearance was maintained in TR and prevented in TS mice. Therefore, a better comprehension of immunoregulation of innate and adaptive immunity in the early stages of infection is necessary for the development of protocols preventing inflammation and contributing to the elimination of parasites.     

Haemophilus influenzae infection drives IL-17-mediated neutrophilic allergic airways disease

A subset of patients with stable asthma has prominent neutrophilic and reduced eosinophilic inflammation, which is associated with attenuated airways hyper-responsiveness (AHR). Haemophilus influenzae has been isolated from the airways of neutrophilic asthmatics; however, the nature of the association between infection and the development of neutrophilic asthma is not understood. Our aim was to investigate the effects of H. influenzae respiratory infection on the development of hallmark features of asthma in a mouse model of allergic airways disease (AAD). BALB/c mice were intraperitoneally sensitized to ovalbumin (OVA) and intranasally challenged with OVA 12-15 days later to induce AAD. Mice were infected with non-typeable H. influenzae during or 10 days after sensitization, and the effects of infection on the development of key features of AAD were assessed on day 16. T-helper 17 cells were enumerated by fluorescent-activated cell sorting and depleted with anti-IL-17 neutralizing antibody. We show that infection in AAD significantly reduced eosinophilic inflammation, OVA-induced IL-5, IL-13 and IFN-γ responses and AHR; however, infection increased airway neutrophil influx in response to OVA challenge. Augmented neutrophilic inflammation correlated with increased IL-17 responses and IL-17 expressing macrophages and neutrophils (early, innate) and T lymphocytes (late, adaptive) in the lung. Significantly, depletion of IL-17 completely abrogated infection-induced neutrophilic inflammation during AAD. In conclusion, H. influenzae infection synergizes with AAD to induce Th17 immune responses that drive the development of neutrophilic and suppress eosinophilic inflammation during AAD. This results in a phenotype that is similar to neutrophilic asthma. Infection-induced neutrophilic inflammation in AAD is mediated by IL-17 responses.     

Kupffer cells from Schistosoma mansoni-infected mice participate in the prompt type 2 differentiation of hepatic T cells in response to worm antigens

Infection with Schistosoma mansoni, a portal vein-residing helminth, is well known to generate life cycle-dependent, systemic immune responses in the host, type 1 deviation during the prepatent period, and type 2 polarization after oviposition. Here we investigated local immunological changes in the liver after infection. Unlike splenocytes, hepatic lymphocytes from infected mice during the prepatent period already produced a higher amount of IL-4 and a lesser amount of IFN-gamma than those from uninfected mice. Hepatic lymphocytes, particularly conventional T cells, but not NK1.1+ T cells, promptly produced IL-4 in response to worm products, soluble worm Ag preparation (SWAP), whenever presented by Kupffer cells from infected mice. The hepatic lymphocytes that had been stimulated with SWAP presented by infected mice-derived Kupffer cells produced a huge amount of IL-4, IL-13, and IL-5 as well as little IFN-gamma in response to immobilized anti-CD3 mAb. Kupffer cells from uninfected mice produced IL-6 and IL-10, but not IL-12 or IL-18, in response to SWAP stimulation and gained the potential to additionally produce IL-4 and IL-13 after the infection. These results suggested that prompt type 2 deviation in the liver after the infection might be due to the alteration of Kupffer cells that induces SWAP-mediated type 2-development of hepatic T cells.     

Protective effect of ginseng polysaccharides on influenza viral infection

Ginseng polysaccharide has been known to have multiple immunomodulatory effects. In this study, we investigated whether Panax ginseng polysaccharide (GP) would have a preventive effect on influenza infection. Administration of mice with GP prior to infection was found to confer a survival benefit against infection with H1N1 (A/PR/8/34) and H3N2 (A/Philippines/82) influenza viruses. Mice infected with the 2009 H1N1 virus suspended in GP solution showed moderately enhanced survival rates and lower levels of lung viral titers and the inflammatory cytokine (IL-6). Daily treatment of vaccinated mice with GP improved their survival against heterosubtypic lethal challenge. This study demonstrates the first evidence that GP can be used as a remedy against influenza viral infection.     

Immunomodulation by pycnogenol® in retrovirus-infected or ethanol-fed mice

Pycnogenol^® is a commercial mixture of bioflavonoids that exhibits antioxidative activity. The effects of dietary pycnogenol on immune dysfunction in normal mice as well as those fed ethanol or infected with the LP-BM5 murine retrovirus were determined. The ethanol consumption and retrovirus infection cause abnormalities in the function and/or structure of a broad array of cells involved in humoral and cellular immunity. Pycnogenol enhanced in vitro IL-2 production by mitogen-stimulated splenocytes if its production was suppressed in ethanolfed or retrovirus-infected mice. Mitogenesis of splenocytes did not show a significant change in mice treated with pycnogenol. It reduced the elevated levels of interleukin-6 produced in vitro by cells from retrovirus infected mice and IL-10 secreted by spleen cells from mice consuming ethanol. Natural killer cell cytotoxicity was increased with pycnogenol treatment.     

Helminth infection impairs autophagy-mediated killing of bacterial enteropathogens by macrophages

Autophagy is an important mechanism used by macrophages to kill intracellular pathogens. The results reported in this study demonstrate that autophagy is also involved in the macrophage killing of the extracellular enteropathogen Citrobacter rodentium after phagocytosis. The process was significantly impaired in macrophages isolated from mice chronically infected with the helminth parasite Heligmosomoides polygyrus. The H. polygyrus-mediated inhibition of autophagy was Th2 dependent because it was not observed in macrophages isolated from helminth-infected STAT6-deficient mice. Moreover, autophagy of Citrobacter was inhibited by treating macrophages with IL-4 and IL-13. The effect of H. polygyrus on autophagy was associated with decreased expression and processing of L chain protein 3 (LC3), a key component of the autophagic machinery. The helminth-induced inhibition of LC3 expression and processing was STAT6 dependent and could be recapitulated by treatment of macrophages with IL-4 and IL-13. Knockdown of LC3 significantly inhibited autophagic killing of Citrobacter, attesting to the functional importance of the H. polygyrus-mediated downregulation of this process. These observations reveal a new aspect of the immunosuppressive effects of helminth infection and provide mechanistic insights into our earlier finding that H. polygyrus significantly worsens the in vivo course of Citrobacter infection.