An immunomodulating peptide with potential to suppress tumour growth and autoimmunity

Cancers and autoimmune diseases commonly co-exist and immune checkpoint inhibitor therapy (ICI) exacerbates autoimmune pathologies. We recently described a lipidic peptide, designated IK14004, that promotes expansion of immunosuppressive T regulatory (Treg) cells and uncouples interleukin-2 from interferon-gamma production while activating CD8+ T cells. Herein, we report IK14004-mediated inhibition of Lewis lung cancer (LLC) growth and re-invigoration of splenocyte-derived exhausted CD4+ T cells. In human immune cells from healthy donors, IK14004 modulates expression of the T cell receptor α/β subunits, induces Type I IFN expression, stimulates natural killer (NK) cells to express NKG2D/NKp44 receptors and enhances K562 cytotoxicity. In both T and NK cells, IK14004 alters the IL-12 receptor β1/β2 chain ratio to favour IL-12p70 binding. Taken together, this novel peptide offers an opportunity to gain further insight into the complexity of ICI immunotherapy so that autoimmune responses may be minimised without promoting tumour evasion from the immune system.

An immunomodulating peptide to counteract solar radiation-induced immunosuppression and DNA damage

Ultraviolet radiation (UVR) induces immunosuppression and DNA damage, both of which contribute to the rising global incidence of skin cancer including melanoma. Nucleotide excision repair, which is activated upon UVR-induced DNA damage, is linked to expression of interleukin-12 (IL-12) which serves to limit immunosuppression and augment the DNA repair process. Herein, we report an immunomodulating peptide, designated IK14800, that not only elicits secretion of IL-12, interleukin-2 (IL-2) and interferon-gamma (IFN-γ) but also reduces DNA damage in the skin following exposure to UVR. Combined with re-invigoration of exhausted CD4+ T cells, inhibition of UVR-induced MMP-1 release and suppression of B16F10 melanoma metastases, IK14800 offers an opportunity to gain further insight into mechanisms underlying the development and progression of skin cancers.

Abstract 5586: Demonstrating restoration of T cell function in exhausted T cells with IKZF3 small molecule inhibitor, Lenalidomide

CD8+ T cell exhaustion as a result of prolonged antigenic stimulation in the tumour microenvironment is thought to be a major mechanism by which tumours can escape immune surveillance. T cell exhaustion is characterised by co-expression of checkpoint inhibitor molecules such as PD-1, LAG-3 and TIM-3; reduced proliferative capacity; and diminished production of pro-inflammatory cytokines such as IL-2, IFN-γ and TNF-α and treatment with checkpoint inhibitor blockade such as Nivolumab (anti-PD-1) have shown great promise in the treatment of a subset of individuals and tumour types. However, resistance to these approaches is prevalent and there is a need to identify novel targets to provide alternative options for the rescue of T cell exhaustion and cancer treatment for use alone or potentially in combination with checkpoint inhibitor modulation. One such target is IKZF3, a transcription factor that is increased in murine models of T cell exhaustion and reduces IL-2 expression. Previously we presented an in vitro human T cell exhaustion assay whereby in vitro stimulated T cells phenotypically and functionally recapitulate the exhausted T cells found within the tumour microenvironment and now we demonstrate that exhaustion can be partially rescued by treatment with the IKZF3 small molecule inhibitor, Lenalidomide, alone and in combination with checkpoint inhibitor blockade. The use of small molecule inhibitors offers new avenues for reversing T cell exhaustion in cases of checkpoint inhibitor resistance and this platform delivers a robust assay allowing for assessment of small molecules or checkpoint inhibitors both individually and in combination.

Citation Format: Joanne Hay, Francis Acklam, Darryl Turner, Mark Barbour, Preeti Singh, Courtney Grant, Hayley Gooding, Rhoanne McPherson, Justyna Rzepecka. Demonstrating restoration of T cell function in exhausted T cells with IKZF3 small molecule inhibitor, Lenalidomide [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5586.

251 The use of small molecule inhibitors to target novel pathways in exhausted T cells for immuno-oncology therapeutic intervention

Background

The ability to reverse exhaustion in CD8+ T cells holds great promise for therapeutic intervention in oncology. Indeed, treatment with therapeutics targeted at checkpoint inhibitors, such as Nivolumab (anti-PD-1), have shown great promise in the treatment of a subset of individuals and tumour types. However, pre-clinical success does not always translate to success in clinical trials and resistance to these approaches is prevalent. As such, there is a pressing need to develop novel approaches that target alternative pathways for use alone or potentially in combination with checkpoint inhibitor modulation. A secondary need is the requirement for advanced assays that accurately recapitulate the pathways and cell phenotypes prevalent in the tumour environment.

Methods

Here we describe the characteristics of an in vitro human T cell exhaustion assay whereby in vitro stimulated T cells phenotypically and functionally recapitulate the exhausted T cells found within the tumour microenvironment. We also demonstrate the effect of checkpoint blockade as well as small molecule inhibition of a novel target on the exhausted T cell phenotype.

Results

In this assay, exhaustion can be partially but not fully reversed by treatment with anti-PD-1 alone. In addition, we demonstrate the effect of a small molecule inhibitor targeting IKZF3, a transcription factor shown to be upregulated in T cell exhaustion, on reversing T cell exhaustion alone and in combination with checkpoint inhibitor blockade.

Conclusions

These assays and approaches enable investigation into the ability of compounds to influence reversal of T cell exhaustion where anti-PD-1 treatment does not fully reverse the exhausted phenotype and offers the ability to test combination therapy approaches.

Acknowledgements

This work was aided by the valuable input and insight of Professor Stephen Anderton.

Ethics Approval

The study obtained ethics approval from West Midlands – Black Country Research Ethics Committee under IRAS project ID 270936. All donors gave informed consent before taking part.

Abstract LB158: Implications of Targeting Novel Pathways in Exhausted T Cells for Immuno-Oncology Therapeutic Intervention

The induction of CD8+ T cell exhaustion, driven by the tumor microenvironment, is thought to be a major mechanism by which tumors can escape immune surveillance and are able to persist and progress. T cell exhaustion is typically characterized by the expression of co-inhibitory markers such as PD-1, LAG-3 and TIM-3 and a reduced capacity for pro-inflammatory cytokine production. Whilst treatment with therapeutics targeted at checkpoint inhibitors, such as Nivolumab (anti-PD-1), have shown great promise in the treatment of a subset of individuals and tumor types, resistance to these approaches is prevalent. As such, novel approaches are required in order to provide alternative options for the rescue of T cell exhaustion and cancer treatment.

Here we describe the characteristics of an in vitro human T cell exhaustion assay whereby in vitro stimulated T cells phenotypically and functionally recapitulate the exhausted T cells found within the tumor microenvironment and where exhaustion can be partially rescued by treatment with anti-PD-1. Furthermore, we demonstrate the effect of treatment with an inhibitor of a novel target identified in exhausted T cells on T cell function; both through analysis of pro-inflammatory cytokine production and the ability to kill tumor cells. These assays and approaches enable investigation into the ability of compounds to influence reversal of T cell exhaustion where anti-PD-1 treatment does not fully reverse the exhausted phenotype and offers the ability to test combination therapy approaches.

Citation Format: Rhoanne McPherson, Francis Acklam, Joanne Hay, Mark Barbour, Courtney Grant, Preeti Singh, Adriana Gambardella, Justyna Rzepecka, Stephen Anderton, Hayley Gooding. Implications of Targeting Novel Pathways in Exhausted T Cells for Immuno-Oncology Therapeutic Intervention [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB158.

Abstract 3877: MPL-5821, a macrophage targeted ESMTM p38 MAPK inhibitor, inhibits the production of TLR agonist induced IL-10 whilst sparing T-cell functionality

Compensatory release of immunosuppressive cytokines, such as IL-10, by macrophages present in the tumor microenvironment has been implicated as a mechanism for adaptive resistance to a number of immunotherapies. Our drug discovery effort utilises Esterase Motif TechnologyTM (ESMTM) which selectively targets myelomonocytic cells sparing the concomitant lymphocyte anti-tumor immune response. TLR agonists are known to be stimulators of the immune response, a key component of which is the production of myeloid cell IL-12p70. However, their therapeutic potential has been limited by their accompanying induction of IL-10 and other factors. MPL-5821 is an ESMTM p38 MAPK inhibitor which not only inhibits IL-10 but also enhances LPS stimulated IL-12p70 and in contrast to conventional p38 MAPK inhibitors provides enhancement of lymphocyte IFNγ production.

The present studies contrast MPL-5821 with multiple non-targeted agents, including inhibitors of HDAC, JAK, PI3K, MEK and CSF-1R, in human PBMC assays. These demonstrated the benefit of ESMTM-targeting as applied to p38 MAP kinase inhibition to not only inhibit TLR agonist induced immunosuppression but also enhance IFNγ due to its sparing of the myeloid-lymphocyte axis. None of the other modalities were able to achieve the effects observed for MPL-5821.

Having established the unique ability of MPL-5281 to inhibit LPS induced IL-10 production whilst still maintaining lymphocyte IFNγ production, we extended our studies to human cancer ex vivo models. We chose to evaluate MPL-5821 in combination with TLR agonists in ex vivo assays using tissue and ascites derived from ovarian and cervical cancer patients. A single cell suspension was prepared from cervical cancer tumor draining lymph nodes and incubated with MPL-5821 +/- the TLR 7/8 agonist R848 for 24 and 48 hours. MPL-5821 potently inhibited the R848 induced IL-10 production as measured by Cytometric Bead Array and in contrast to a conventional p38 MAP inhibitor LY2228820 also enhanced IFNγ production.

We studied MPL-5821 in cell suspensions prepared from human ovarian tumor and ascites. For the tumor sample, a single cell homogenate was prepared by mechanical and enzymatic digestion and for the ascites the cells were isolated by centrifugation. The cell populations were then analysed by flow cytometry and the cell preparation cultured for 72 hours with anti-CD3 or TLR agonist in the presence of test compound. Cytokine production was measured after 72 hours by ELISA or Luminex bead array. MPL-5821 again showed potent inhibition of TLR agonist induced IL-10 with concomitant enhancement of IFNγ production. We conclude that application of ESMTM technology to macrophage selective delivery of p38 MAPK inhibitors has the potential to inhibit TLR agonist induction of IL-10, which is implicated in limiting the performance of TLR agonists in the clinic.

Citation Format: David Moffat, Martin Perry, A. Marijne Heeren, Tanja D. de Gruijl, Justyna Rzepecka, Lucia Janicova, Anastasia Nika, Darryl Turner, Clare Doris, Claire Tebbutt, Kathryn Chapman, Gary Newton, Stephen Anderton. MPL-5821, a macrophage targeted ESMTM p38 MAPK inhibitor, inhibits the production of TLR agonist induced IL-10 whilst sparing T-cell functionality [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3877.

Testing small molecule analogues of the Acanthocheilonema viteae immunomodulator ES-62 against clinically relevant allergens

ES-62 is a glycoprotein secreted by the filarial nematode Acanthocheilonema viteae that protects against ovalbumin (OVA)-induced airway hyper-responsiveness in mice by virtue of covalently attached anti-inflammatory phosphorylcholine (PC) residues. We have recently generated a library of small molecule analogues (SMAs) of ES-62 based around its active PC moiety as a starting point in novel drug development for asthma and identified two compounds - termed 11a and 12b - that mirror ES-62's protective effects. In this study, we have moved away from OVA, a model allergen, to test the SMAs against two clinically relevant allergens - house dust mite (HDM) and cockroach allergen (CR) extract. We show that both SMAs offer some protection against development of lung allergic responses to CR, in particular reducing eosinophil infiltration, whereas only SMA 12b is effective in protecting against eosinophil-dependent HDM-induced allergy. These data therefore suggest that helminth molecule-induced protection against model allergens may not necessarily translate to clinically relevant allergens. Nevertheless, in this study, we have managed to demonstrate that it is possible to produce synthetic drug-like molecules based on a parasitic worm product that show therapeutic potential with respect to asthma resulting from known triggers in humans.

Prophylactic and therapeutic treatment with a synthetic analogue of a parasitic worm product prevents experimental arthritis and inhibits IL-1β production via NRF2-mediated counter-regulation of the inflammasome

Rheumatoid arthritis (RA) remains a debilitating autoimmune condition as many patients are refractory to existing conventional and biologic therapies, and hence successful development of novel treatments remains a critical requirement. Towards this, we now describe a synthetic drug-like small molecule analogue, SMA-12b, of an immunomodulatory parasitic worm product, ES-62, which acts both prophylactically and therapeutically against collagen-induced arthritis (CIA) in mice. Mechanistic analysis revealed that SMA-12b modifies the expression of a number of inflammatory response genes, particularly those associated with the inflammasome in mouse bone marrow-derived macrophages and indeed IL-1β was the most down-regulated gene. Consistent with this, IL-1β was significantly reduced in the joints of mice with CIA treated with SMA-12b. SMA-12b also increased the expression of a number of genes associated with anti-oxidant responses that are controlled by the transcription factor NRF2 and critically, was unable to inhibit expression of IL-1β by macrophages derived from the bone marrow of NRF2(-/-) mice. Collectively, these data suggest that SMA-12b could provide the basis of an entirely novel approach to fulfilling the urgent need for new treatments for RA.

The parasitic worm product ES-62 targets myeloid differentiation factor 88-dependent effector mechanisms to suppress antinuclear antibody production and proteinuria in MRL/lpr mice

Objective

The hygiene hypothesis suggests that parasitic helminths (worms) protect against the development of autoimmune disease via a serendipitous side effect of worm-derived immunomodulators that concomitantly promote parasite survival and limit host pathology. The aim of this study was to investigate whether ES-62, a phosphorylcholine-containing glycoprotein secreted by the filarial nematode Acanthocheilonema viteae, protects against kidney damage in an MRL/lpr mouse model of systemic lupus erythematosus (SLE).

Methods

MRL/lpr mice progressively produce high levels of autoantibodies, and the resultant deposition of immune complexes drives kidney pathology. The effects of ES-62 on disease progression were assessed by measurement of proteinuria, assessment of kidney histology, determination of antinuclear antibody (ANA) production and cytokine levels, and flow cytometric analysis of relevant cellular populations.

Results

ES-62 restored the disrupted balance between effector and regulatory B cells in MRL/lpr mice by inhibiting plasmablast differentiation, with a consequent reduction in ANA production and deposition of immune complexes and C3a in the kidneys. Moreover, by reducing interleukin-22 production, ES-62 may desensitize downstream effector mechanisms in the pathogenesis of kidney disease. Highlighting the therapeutic importance of resetting B cell responses, adoptive transfer of purified splenic B cells from ES-62–treated MRL/lpr mice mimicked the protection afforded by the helminth product. Mechanistically, this reflects down-regulation of myeloid differentiation factor 88 expression by B cells and also kidney cells, resulting in inhibition of pathogenic cross-talk among Toll-like receptor–, C3a-, and immune complex–mediated effector mechanisms.

Conclusion

This study provides the first demonstration of protection against kidney pathology by a parasitic worm–derived immunomodulator in a model of SLE and suggests therapeutic potential for drugs based on the mechanism of action of ES-62.

Small molecule analogues of the immunomodulatory parasitic helminth product ES-62 have anti-allergy properties

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Small molecule analogues of the helminth immunomodulator ES-62 have been produced.

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Two analogues inhibit mast cell functions and prevent airway hypersensitivity.

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The analogues are drug-like and could be considered for treatment of human allergy.

ES-62, a glycoprotein secreted by the filarial nematode Acanthocheilonema viteae, exhibits anti-inflammatory properties by virtue of covalently attached phosphorylcholine moieties. Screening of a library of ES-62 phosphorylcholine-based small molecule analogues (SMAs) revealed that two compounds, termed 11a and 12b, mirrored the helminth product both in inhibiting mast cell degranulation and cytokine responses in vitro and in preventing ovalbumin-induced Th2-associated airway inflammation and eosinophil infiltration of the lungs in mice. Furthermore, the two SMAs inhibited neutrophil infiltration of the lungs when administered therapeutically. ES-62-SMAs 11a and 12b thus represent starting points for novel drug development for allergies such as asthma.

Impact of worms and their products on eosinophils and neutrophils in experimental asthma

Prolonged existence of helminth parasites in their mammalian hosts has led to the establishment of a very particular immunological microenvironment that supports the fitness of both the pathogen and the host. The modern way of living in developed societies has interrupted this tight relationship by almost completely removing helminths from the human population. It is believed that, as a consequence of this process, a rapid increase in the incidence of asthma and other inflammatory disorders has occurred. Data derived from experimental models clearly show that worms and their products can ameliorate asthma-like disease in mice. This review will concentrate on the effects of helminth-driven regulatory mechanisms on the function of eosinophils and neutrophils in experimental asthma. Eosinophils and neutrophils are major effector cells driving pathology in the lung, therefore learning how to control their exacerbated activation in asthma might aid in creating much needed novel therapeutics to combat this common inflammatory disorder.

Designing anti-inflammatory drugs from parasitic worms: a synthetic small molecule analogue of the Acanthocheilonema viteae product ES-62 prevents development of collagen-induced arthritis

In spite of increasing evidence that parasitic worms may protect humans from developing allergic and autoimmune diseases and the continuing identification of defined helminth-derived immunomodulatory molecules, to date no new anti-inflammatory drugs have been developed from these organisms. We have approached this matter in a novel manner by synthesizing a library of drug-like small molecules based upon phosphorylcholine, the active moiety of the anti-inflammatory Acanthocheilonema viteae product, ES-62, which as an immunogenic protein is unsuitable for use as a drug. Following preliminary in vitro screening for inhibitory effects on relevant macrophage cytokine responses, a sulfone-containing phosphorylcholine analogue (11a) was selected for testing in an in vivo model of inflammation, collagen-induced arthritis (CIA). Testing revealed that 11a was as effective as ES-62 in protecting DBA/1 mice from developing CIA and mirrored its mechanism of action in downregulating the TLR/IL-1R transducer, MyD88. 11a is thus a novel prototype for anti-inflammatory drug development.

The parasitic helminth product ES-62 suppresses pathogenesis in collagen-induced arthritis by targeting the interleukin-17-producing cellular network at multiple sites

OBJECTIVE

Among many survival strategies, parasitic worms secrete molecules that modulate host immune responses. One such product, ES-62, is protective against collagen-induced arthritis (CIA), a model of rheumatoid arthritis (RA). Since interleukin-17 (IL-17) has been reported to play a pathogenic role in the development of RA, this study was undertaken to investigate whether targeting of IL-17 may explain the protection against CIA afforded by ES-62.

METHODS

DBA/1 mice progressively display arthritis following immunization with type II collagen. The protective effects of ES-62 were assessed by determination of cytokine levels, flow cytometric analysis of relevant cell populations, and in situ analysis of joint inflammation in mice with CIA.

RESULTS

ES-62 was found to down-regulate IL-17 responses in mice with CIA. First, it acted to inhibit priming and polarization of IL-17 responses by targeting a complex IL-17-producing network, involving signaling between dendritic cells and γ/δ or CD4+ T cells. In addition, ES-62 directly targeted Th17 cells by down-regulating myeloid differentiation factor 88 expression to suppress responses mediated by IL-1 and Toll-like receptor ligands. Moreover, ES-62 modulated the migration of γ/δ T cells and this was reflected by direct suppression of CD44 up-regulation and, as evidenced by in situ analysis, dramatically reduced levels of IL-17-producing cells, including lymphocytes, infiltrating the joint. Finally, there was strong suppression of IL-17 production by cells resident in the joint, such as osteoclasts within the bone areas.

CONCLUSION

Our findings indicate that ES-62 treatment of mice with CIA leads to unique multisite manipulation of the initiation and effector phases of the IL-17 inflammatory network. ES-62 could be exploited in the development of novel therapeutics for RA.

The helminth product, ES-62, protects against airway inflammation by resetting the Th cell phenotype

We previously demonstrated inhibition of ovalbumin-induced allergic airway hyper-responsiveness in the mouse using ES-62, a phosphorylcholine-containing glycoprotein secreted by the filarial nematode, Acanthocheilonema viteae. This inhibition correlated with ES-62-induced mast cell desensitisation, although the degree to which this reflected direct targeting of mast cells remained unclear as suppression of the Th2 phenotype of the inflammatory response, as measured by eosinophilia and IL-4 levels in the lungs, was also observed. We now show that inhibition of the lung Th2 phenotype is reflected in ex vivo analyses of draining lymph node recall cultures and accompanied by a decrease in the serum levels of total and ovalbumin-specific IgE. Moreover, ES-62 also suppresses the lung infiltration by neutrophils that is associated with severe asthma and is generally refractory to conventional anti-inflammatory therapies, including steroids. Protection against Th2-associated airway inflammation does not reflect induction of regulatory T cell responses (there is no increased IL-10 or Foxp3 expression) but rather a switch in polarisation towards increased Tbet expression and IFNγ production. This ES-62-driven switch in the Th1/Th2 balance is accompanied by decreased IL-17 responses, a finding in line with reports that IFNγ and IL-17 are counter-regulatory. Consistent with ES-62 mediating its effects via IFNγ-mediated suppression of pathogenic Th2/Th17 responses, we found that neutralising anti-IFNγ antibodies blocked protection against airway inflammation in terms of pro-inflammatory cell infiltration, particularly by neutrophils, and lung pathology. Collectively, these studies indicate that ES-62, or more likely small molecule analogues, could have therapeutic potential in asthma, in particular for those subtypes of patients (e.g. smokers, steroid-resistant) who are refractory to current treatments.

Calreticulin from the intestinal nematode Heligmosomoides polygyrus is a Th2-skewing protein and interacts with murine scavenger receptor-A

Helminth infections are commonly associated with a Th2 immune response, yet only a few parasite molecules involved in triggering such immune responses have been identified. Here, we describe the Th2-skewing property of calreticulin of Heligmosomoides polygyrus (HpCRT). HpCRT is a secreted protein most abundantly expressed by tissue invasive larvae (L4). Native HpCRT purified from adult worm extract (nHpCRT) stimulated robust IL-4 release from CD4(+) T cells of H. polygyrus infected mice. Interestingly, CD4(+) T cells also produced significant amounts of IL-10 while IFN-gamma was not detectable. Likewise, immunization with recombinant HpCRT (rHpCRT) without extrinsic adjuvant led predominantly to a specific IL-4 production implying the innate ability of HpCRT to drive Th2 responses. The triggering of a Th2-skewed immune response to rHpCRT is corroborated by the induction of HpCRT-specific IgG1 and IgE antibodies. Furthermore, rHpCRT bound to scavenger receptor type A (SR-A) on dendritic cells, and interaction of HpCRT with SR-A led to internalization of HpCRT that could be partially blocked by competition with SR-A ligands as well as with an anti-SR-A monoclonal antibody. Hence, our data imply that nematode calreticulin interacts with a mammalian scavenger receptor and at the same time induces a Th2 response.

Heligmosomoides polygyrus: Decreased apoptosis in fast responder FVB mice during infection

Primary infection with Heligmosomoides polygyrus in some strains of mice is chronic although fast responder mouse strains eliminate the parasite in a short period of time. The reason for the differences is unknown. In this study apoptosis, proliferation, IL-2 and IL-6 production of mesenteric lymph node (MLN) and spleen cells in vitro from fast (FVB) and slow (C57Bl/6) responder mice were compared during H. polygyrus infection. FVB cells showed decreased apoptosis, more proliferation and more cytokine production than cells from C57Bl/6 mice during infection. At the beginning of infection in C57Bl/6 mice the apoptosis of CD4(+) but not CD8(+) cells significantly increased in MLN and spleen cell cultures. Apoptosis, when the first immune signal is given by infective larvae, might play an important role in the modulation of the response in slow responder mice.

Heligmosomoides polygyrus infection down-regulates eotaxin concentration and CCR3 expression on lung eosinophils in murine allergic pulmonary inflammation

There is growing evidence that helminth infections might suppress allergic responses by mechanisms potentially involving regulatory T lymphocytes, cytokines, helminth molecules and polyclonal IgE. Heligmosomoides polygyrus infection in mice is associated with reduced local and systemic immune responses, thus providing an excellent model to study the mechanisms of immune regulation. In this research, we examined the way that nematode infection modulates the influx of eosinophils into the airways of asthmatic mice. We observed a reduction in the total number and percentage of lung eosinophils that coincided with decreased levels of eotaxin in bronchoalveolar lavage fluid (BALF), lower expression of the CCR3 receptor on eosinophils and impaired chemotaxis of these cells toward eotaxin. We conclude that allergen-induced immune response was down-regulated as production of Th1 (IFN-gamma)-, Th2 (IL-4, IL-5)- and Treg (IL-10)-related cytokines as well as IL-6 and TNF-alpha was diminished upon nematode infection. We postulate that attenuation of allergic inflammation during H. polygyrus infection is a consequence of the dichotomy of the immune response in the face of concurrent antigenic challenge.

Reduced apoptosis in BALB/c mice infected with Heligmosomoides polygyrus

We evaluated levels of apoptosis and the immune response ex vivo in BALB/c mice infected with Heligmosomoides polygyrus. Cell proliferation, apoptosis and cytokine production were measured in mesenteric lymph nodes (MLN) without exposure to H. polygyrus antigens in culture. The inhibited apoptosis and cytokine production reported might reflect a state of cell hyporesponsiveness in the prepatent phase of infection. These changes were accompanied by changes in the percentage of CD4+ cells in MLN and popliteal lymph nodes (PLN). The prolonged reduction in apoptosis coexisted with induced cell proliferation, elevated TNF-alpha, IL-12p70, IFN-gamma, IL-6, IL-10 and TGF-beta synthesis, but lowered IL-4 and IL-2 levels. In the chronic phase of infection an increasing production of IFN-gamma, monocyte chemotactic protein-1 (MCP-1), IL-10 and TGF-beta with decreasing concentrations of other cytokines resulted in restored apoptosis. The cytokine response in serum showed moderate production of TNF-alpha, temporary involvement of IL-12p70, induction of IFN-gamma and IL-10 synthesis, as well as growing IL-6 and MCP-1 production. It is suggested that a synchronized synthesis of distinct cytokines is accompanied by different levels of inhibited apoptosis during the prepatent and chronic phases of H. polygyrus infection in BALB/c mice. We suggest that immunosuppression provoked by the nematode is not the outcome of parasite-induced apoptosis, but rather results from a hyporesponsiveness experienced by cells during H. polygyrus infection.

[Regulation of the immune response in BALb/c mice infected with Heligmosomoides polygyrus]

The aim of the studies was to identify the regulatory mechanisms that act at different levels of the ongoing immune response in BALB/c mice infected with intestinal nematode H. polygyrus. The role of TGF-beta during the course of H. polygyrus infection and an immunosuppressive action of the nematode against eosinophil response in allergic pulmonary inflammation has been studied. An attempt to identify the immunoregulatory proteins of the parasite has been performed as well. The obtained results proved: (1) for the first time the direct role of TGF-beta in the regulation of the immune response during helminth infections. Neutralization of TGF-beta in vivo increased concentration of IL-12, TNF-alpha and IL-10 in serum of infected mice and restored the control number of eosinophils in the intestinal mucosa. The mobilization of the immune response after neutralization of TGF-beta led to persistent decrease of nematode egg production and faster rejection of the worm from mouse intestine; (2) for the first time it was shown that the reduction of eosinophil number was due to the lower production of eotaxin and reduced expression of CCR3 receptor, playing an essential role in the chemotaxis of these leukocytes in Ova-related asthma; (3) significant decrease of T cell proliferation by one of the H. polygyrus protein fraction. With the use of mass spectrometry seven proteins have been identified: two heat shock proteins, disulfide isomerase, calreticulin, calumenin, fructose-bisphosphate aldolase, glyceraldehyde-3-phosphate dehydrogenase. From the bibliographic data it may be supposed that calreticulin could mediate the downregulation of lymphocytes proliferation. The fraction with calreticulin stimulated also production of specific IgE.

Screening for immunomodulatory proteins of the intestinal parasitic nematode Heligmosomoides polygyrus

Parasitic nematodes are constantly exposed to the immune effector mechanisms of their hosts. One strategy of the worms to cope with these defence reactions is the secretion of modulatory proteins that down-regulate cell-mediated immune responses. We analysed the proliferation of mesenteric lymph node cells of mice infected with Heligmosomoides polygyrus and showed that cellular proliferation was strongly suppressed in the chronic phase of infection. To identify proteins of H. polygyrus that are involved in parasite-induced immunomodulation, worm extract and culture supernatant of adult H. polygyrus were fractionated by gel chromatography and activity of each fraction was determined. One of the fractions (fraction 9) of worm extract as well as worm secretory products inhibited the antigen-specific cellular proliferation by about 40%. This reduced cellular reactivity coincided with a down-regulation of inducible nitric oxide production of mouse macrophages by 57%. Furthermore, fraction 9 contained antigens that were recognized by IgE antibodies of H. polygyrus-infected mice and induced degranulation of an IgE-sensitized basophil cell line. Single proteins of fraction 9 were analysed by mass spectrometry. These data suggest that antigens that are recognised by IgE antibodies might play an important role in immunomodulation exerted by nematode infections.

The role of TGF-β in mice infected with Heligmosomoides polygyrus

Hyporesponsiveness induced by Heligmosomoides polygyrus was quantified and the relationship between TGF-beta and inflammation was identified in BALB/c mice. The immune response and pathological changes modified by neutralization of TGF-beta were characterized in vivo. Nine and twelve days following infection, BALB/c mice were injected intraperitoneally with anti-TGF-beta (1,2,3) antibodies, isotype control antibodies or isosmotic solution. We assessed both Th1 and Th2 related cytokines production ex vivo and in vitro, IgA, the number of CD4+ cells, and eosinophils in the lamina propria and the villus : crypt ratio in the small intestine 6 weeks after infection. The pattern of cytokine production differed in the intestine, peritoneal fluid and serum. In mice infected with H. polygyrus the concentrations of IL-5, IL-12, TNF-alpha and IL-10 were raised in the intestine, but in serum the level of cytokines was diminished below the value observed in uninfected mice. The neutralization of TGF-beta converted the pattern of immune response induced by H. polygyrus. The elevation of cytokines in serum coincided with the reduction of cytokine concentration in the intestine or peritoneum. Neutralization of TGF-beta restored infiltration of eosinophils into the lamina propria of the intestine despite the low level of IL-5. We conclude that H. polygyrus infection suppresses the immune response through pathways involving TGF-beta production or activity and that the Th2 related immune response was not affected by neutralization.

[Apoptosis in the regulation of immune response in mice infected with Heligmosomoides polygyrus]

An unbalanced Th1 and Th2 cell subsets response was proposed as the main downregulating mechanisms operating in mice infected with H. polygyrus. During worm infections nonspecific inflammatory and specific immune reactions which might be regulated by apoptosis, coordinate the host protective response. The intensity of apoptosis and proliferation of lymphocytes, the concentration of Th1 and Th2 related cytokines were measured in BALB/c and C57BL6 mice on day 3, 6, 12, 24, 30 after infection with H. polygyrus. Mesenteric lymph nodes (MLN) and popliteal lymph nodes (PLN) lymphocytes underwent an apoptosis, with a different kinetics to the proliferation. Interleukine 5 and IL-6 concentrations increased on time when apoptosis was reduced. No changes in the level of IL-12 were related to intensity of proliferation or apoptosis in both examined strains of mice.

[Changes in the immune response of BALB/c mice coinfected with Heligmosomoides polygyrus and Trichinella spiralis]

The influence of Heligmosomoides polygyrus on infection with Trichinella spiralis was studied in BALB/c mice. Mice coinfected with T. spiralis and previously given H. polygyrus harboured both nematode species till day 34. The number of T. spiralis muscle larvae was greater in mice coinfected with H. polygyrus/T. spiralis or T. spiralis/H. polygyrus than after infection with T. spiralis alone. Infection with H. polygyrus did not enhance eosinophil and IL-5 levels induced by T. spiralis. Additionally, the production of IgG1 specific to L1 T. spiralis was inhibited by co-infection. Changes in the levels of IFN-gamma and IgG2a implicated a disturbance in Th2 cell activation during protective response and resulted in the greater number of T. spiralis muscle larvae in coinfected mice.