IL-10 prevents liver necrosis during murine infection with Trichinella spiralis

Higher frequency of circulating Vδ1 γδT cells in patients with advanced schistosomiasis

Gamma‐delta (γδ) T cells are the bridge between natural and adaptive immunity. In the present study, peripheral blood was collected from 13 patients with advanced schistosomiasis (schistosomiasis group) and 13 uninfected people (control group) to investigate the γδ T cells and their subtypes in human schistosomiasis. Compared with the control group, the proportion of Vδ1 cells and CD27⁺Vδ1⁺ cells in the schistosomiasis group increased significantly, while CD27⁻ cells and CD27⁻Vδ1⁻ cells decreased. Only the level of IL‐17A differed between the groups, being significantly decreased in the schistosomiasis group. In the schistosomiasis group, there were no correlations between the liver fibrosis and subsets of γδ T cells, or the level of cytokines. Additionally, the level of IL‐17A correlated positively with the proportion of CD27⁻ Vδ1⁻ cells. Thus, there was a higher frequency of circulating Vδ1 γδT cells in patients with advanced schistosomiasis. The decreased IL‐17A might be related to the reduction in CD27⁻Vδ1⁻ cell.

EPA plus DHA improves survival related to a decrease of injury after extended liver ischemia in Sprague-Dawley rats

INTRODUCTION AND OBJECTIVES

The omega-3 fatty acids (ω3), EPA and DHA, have been described for their beneficial effects on metabolism and inflammation. In addition, they are interesting tools in the treatment of acute liver disease. This investigation was conducted to assess the effect of EPA+DHA administration before partial ischemia (IR) on survival and liver injury.

MATERIALS AND METHODS

Male Sprague-Dawley rats were supplemented for 7 days with ω3 [EPA (270mg/kg) and DHA (180mg/kg)]; controls received saline solution. After EPA+DHA supplementation, liver IR was induced by temporarily occluding the blood supply for 1h, followed up by 48h of reperfusion. Control animals were subjected to sham laparotomy.

RESULTS

Previous to IR, the EPA+DHA administration improved the rate and prolonged the survival time by decreasing the AST and ALT levels and improving liver degenerative changes generated by the IR, which decreased TNF-α and IL-1β. In addition, IL-10 increased at 20h with a tendency to normalize at 48h. The IR group had no differences in the IL-10 levels compared to controls.

CONCLUSIONS

The ω3 supplementation could prevent and promote the restoration of the liver tissue and significantly improve the survival rate in rats at 48h.

The acidified drinking water-induced changes in the behavior and gut microbiota of wild-type mice depend on the acidification mode

Acidification of drinking water to a pH between 2.5 and 3.0 is widely used to prevent the spread of bacterial diseases in animal colonies. Besides hydrochloric acid (HCl), sulfuric acid (H₂SO₄) is also used to acidify drinking water. Here we examined the effects of H₂SO₄-acidified drinking water (pH = 2.8) received from weaning (postnatal day 21) on the behavior and gut microflora of 129S6/SvEv mice, a mouse strain commonly used in transgenic studies. In contrast to HCl-acidified water, H₂SO₄-acidified water only temporarily impaired the pole-descending ability of mice (at 3 months of age), and did not change the performance in an accelerating rotarod test. As compared to 129S6/SvEv mice receiving non-acidified or HCl-acidified drinking water, the gut microbiota of 129S6/SvEv mice on H₂SO₄-acidified water displayed significant alterations at every taxonomic level especially at 6 months of age. Our results demonstrate that the effects of acidified drinking water on the behavior and gut microbiota of 129S6/SvEv mice depends on the acid used for acidification. To shed some light on how acidified drinking water affects the physiology of 129S6/SvEv mice, we analyzed the serum and fecal metabolomes and found remarkable, acidified water-induced alterations.

The Role of the Anti-Inflammatory Cytokine Interleukin-10 in Tissue Fibrosis

Significance: Fibrosis is the endpoint of chronic disease in multiple organs, including the skin, heart, lungs, intestine, liver, and kidneys. Pathologic accumulation of fibrotic tissue results in a loss of structural integrity and function, with resultant increases in morbidity and mortality. Understanding the pathways governing fibrosis and identifying therapeutic targets within those pathways is necessary to develop novel antifibrotic therapies for fibrotic disease. Recent Advances: Given the connection between inflammation and fibrogenesis, Interleukin-10 (IL-10) has been a focus of potential antifibrotic therapies because of its well-known role as an anti-inflammatory mediator. Despite the apparent dissimilarity of diseases associated with fibrotic progression, pathways involving IL-10 appear to be a conserved molecular theme. More recently, many groups have worked to develop novel delivery tools for recombinant IL-10, such as hydrogels, and cell-based therapies, such as ex vivo activated macrophages, to directly or indirectly modulate IL-10 signaling. Critical Issues: Some efforts in this area, however, have been stymied by IL-10's pleiotropic and sometimes conflicting effects. A deeper, contextual understanding of IL-10 signaling and its interaction with effector cells, particularly immune cells, will be critical to future studies in the field. Future Directions: IL-10 is clearly a gatekeeper of fibrotic/antifibrotic signaling. The development of novel therapeutics and cell-based therapies that capitalize on targets within the IL-10 signaling pathway could have far-reaching implications for patients suffering from the consequences of organ fibrosis.

Changes in motor behavior, neuropathology, and gut microbiota of a Batten disease mouse model following administration of acidified drinking water

CLN3 mutations cause the fatal neurodegenerative disorder, CLN3 Batten disease. The Cln3^−/− mouse model displays characteristic features of the human disease including motor deficits. When mice received acidified drinking water (pH 2.5–2.9) instead of normal tap water (pH 8.4) for several generations, the motor skills of Cln3^−/− mice normalized to control levels, indicating a disease-modifying effect of acidified water. Here we investigated if acidified water administered from postnatal day 21 has therapeutic benefits in Cln3^−/− mice. Indeed, acidified water temporarily attenuated the motor deficits, had beneficial effects on behavioral parameters and prevented microglial activation in the brain of Cln3^−/− mice. Interestingly, in control mice, acidified drinking water caused brain region-specific glial activation and significant changes in motor performance. Since the gut microbiota can influence neurological functions, we examined it in our disease model and found that the gut microbiota of Cln3^−/− mice was markedly different from control mice, and acidified water differentially changed the gut microbiota composition in these mice. These results indicate that acidified water may provide therapeutic benefit to CLN3 Batten disease patients, and that the pH of drinking water is a major environmental factor that strongly influences the results of murine behavioral and pathological studies.

Hepatoprotective immune response during Trichinella spiralis infection in mice

Infections with gastrointestinal nematodes provoke immune and inflammatory responses mediated by cytokines released from T-helper type-2 (Th2) cells. Infections with Trichinella species have been reported to differ by the host species. Previously, in rats, we observed acute liver inflammation in response to infection with Trichinella spiralis, and the rat hosts showed a series of biochemical changes characterized by a decrease in serum paraoxonase (PON) 1 activity associated with the down-regulation of hepatic PON1 synthesis. In the present study, we investigated the effect(s) of species differences on the immune response against T. spiralis infection by analyzing serum PON1 activity and the associated inflammatory/anti-inflammatory mediators in mice. There were inconsistent changes in the serum PON1 activity of mice infected with T. spiralis, and these changes were associated with significant increases in the serum levels of interleukin (IL)-2, IL-4, IL-10, IL-12 (p70), granulocyte-macrophage colony-stimulating factor, and tumor necrosis factor α during the enteric phase of the infection, while the levels of IL-5 and interferon γ were significantly increased throughout the entire experimental period. Moreover, T. spiralis infection in mice was associated with little inflammatory cell infiltration in hepatic tissues. Given the zoonotic prevalence of T. spiralis, further mechanistic research in this area is warranted.

Biomolecular Changes and Cortical Neurodegenerative Lesions in Trichinella Spiralis Infected BALB/c Mice: A Preliminary Study Elucidating a Potential Relationship Between Systemic Helminthic Infections and Idiopathic Parkinson's

Idiopathic Parkinson's (IP) is a neurodegenerative disease that is suspected to be due to exposure to infections during early life. Toxoplasmosishas been the only suspected parasitic infection in IP (Celik et al., 2010). Recently, some non-central nervous system bacterial and viral infections have been incriminated in IP (Çamcı & Oğuz, 2016). So in the current study, we tried to explore if the systemic inflammatory reactions triggered by some helminths like Trichinella spiralis can induce Parkinsonian lesions in the brain, especially that the cerebral complications have been reported in 10-20% of Trichinella spiralis infected patients . An experimental study was designed to assess the neurodegenerative and biomolecular changes that may occur in Trichinella spiralis infected BALB/C mice in comparison to rotenone induced PD model and apparently healthy ones. The motor affection was significantly lesser in the Trichinella infected mice than the Parkinson's model, but when the catalepsy score was calculated (through the grid and bar tests) it was found to be significantly higher in the infected mice than in the healthy ones. A significant increase in the blood advanced oxidative protein products (AOPP), IFN-γ, TGF-β, and brain DNA fragmentation was also detected in the Trichinella spiralis infected mice. After histopathological examination, a significant increase in the cortical apoptotic neurons and Lewy's body were observed in the Trichinella infected and the rotenone induced Parkinson's model sections. A significant decrease in the immunohistochemical expression of the tyrosine hydroxylase expression in the brain sections and the ELISA measured dopamine level in the brain homogenate was also reported in the infected mice group. This study findings may collectively suggest that the systemic inflammatory reactions and the oxidative stresses associated with some systemic helminthic infections like trichinellosis are possible to precipitate neurodegenerative lesions and biomolecular changes in the brain , and manifest with IPD later in life.

Paraoxonase-1 activity is related to Trichinella spiralis-induced hepatitis in rats

BACKGROUND

Little is known about the potential adverse effects of a chronic zoonotic nematode Trichinella spiralis infection on hepatic inflammation and its relationship to paraoxonase (PON)-1 and butyrylcholinesterase (BuChE) activities. Therefore, we aimed to examine the effects of T. spiralis infection on hepatic synthesis of PON1.

METHODS

Wistar rats were infected with 2500 first-stage larvae (L1) of T. spiralis, and serum PON1 and BuChE activities were evaluated. Hepatic expression levels of PON1, BuChE and various cytokines and chemokines [interleukin (IL)-1, IL-4, IL-6, IL-10, tumour necrosis factor (TNF)-α, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1α, and transforming growth factor (TGF)-β1] were evaluated for up to 9 weeks post-infection (p.i.). The effect of these changes on the degree of hepatic apoptosis was also investigated.

RESULTS

Trichinella spiralis infection in rats induced significant decreases in serum PON1 activities from day 2 until week 7 p.i. and BuChE activity starting from day 4 until 2 weeks p.i. Moreover, T. spiralis infection increased serum pro-inflammatory cytokines IL-1, IL-6 and TNF-α as well as chemokines MCP-1, MIP-1α and TGF-β1 during the enteral phase of the parasite life cycle. The anti-inflammatory cytokines IL-4 and IL-10 showed significant increases during the enteral phase for the former and the muscle phase for the latter. These were associated with hepatic inflammation and apoptosis. These events typically decreased hepatic PON1 and BuChE mRNA expression.

CONCLUSIONS

Immune responses mounted against T. spiralis infection in rats were associated with hepatic inflammation and a subsequent decrease in serum PON1 and BuChE activities.

Eosinophils in Helminth Infection: Defenders and Dupes

Eosinophilia is a central feature of the host response to helminth infection. Larval stages of parasitic worms are killed in vitro by eosinophils in the presence of specific antibodies or complement. These findings established host defense as the paradigm for eosinophil function. Recently, studies in eosinophil-ablated mouse strains have revealed an expanded repertoire of immunoregulatory functions for this cell. Other reports document crucial roles for eosinophils in tissue homeostasis and metabolism, processes that are central to the establishment and maintenance of parasitic worms in their hosts. In this review, we summarize current understanding of the significance of eosinophils at the host-parasite interface, highlighting their distinct functions during primary and secondary exposure.

Interleukins in chronic liver disease: lessons learned from experimental mouse models

Interleukins represent a class of immunomodulatory cytokines, small intercellular signaling proteins, that are critically involved in the regulation of immune responses. They are produced in large amounts by various cell types during inflammatory reactions, and the balance of cytokines determines the outcome of an immune response. Therefore, cytokines are regarded as interesting therapeutic targets for the treatment of patients with liver diseases. Mouse models provide a good tool for in vivo studies on cytokine function, as human and mouse cytokines share many homologies. Sophisticated mouse models either mimicking distinct pathological conditions or targeting cytokines and cytokine-signaling pathways in the liver or even in distinct cellular compartments have provided enormous insight into the different functions of interleukins during hepatic inflammation. Interleukins may have pro- as well as anti-inflammatory functions in chronic liver diseases, some interleukins even both, dependent on the inflammatory stimulus, the producing and the responding cell type. IL-17, for example, promotes hepatic fibrogenesis through activation of hepatic stellate cells and facilitates development of liver cancer through recruitment of myeloid-derived suppressor cells. IL-22, on the other hand, protects from development of fibrosis or steatohepatitis. IL-12 balances T-helper (Th)-1 and Th2 cell responses in infectious disease models. IL-13 and IL-33, two cytokines related to Th2 cells and innate lymphoid cells, promote fibrotic responses in the liver. IL-10 is the prototypic anti-inflammatory interleukin with tissue-protective functions during chronic liver injury and fibrogenesis. Despite its critical role for inducing the acute-phase response in the liver, IL-6 signaling is protective during fibrosis progression, but promotes hepatocellular carcinoma. Experimental studies in mice help to define the exact influence of a specific cytokine on the outcome of chronic liver diseases and to identify useful therapeutic targets.

In vivo time-lapse imaging shows diverse niche engagement by quiescent and naturally activated hematopoietic stem cells

Hematopoietic stem cells (HSCs) maintain the turnover of mature blood cells during steady state and in response to systemic perturbations such as infections. Their function critically depends on complex signal exchanges with the bone marrow (BM) microenvironment in which they reside, but the cellular mechanisms involved in HSC-niche interactions and regulating HSC function in vivo remain elusive. We used a natural mouse parasite, Trichinella spiralis, and multipoint intravital time-lapse confocal microscopy of mouse calvarium BM to test whether HSC-niche interactions may change when hematopoiesis is perturbed. We find that steady-state HSCs stably engage confined niches in the BM whereas HSCs harvested during acute infection are motile and therefore interact with larger niches. These changes are accompanied by increased long-term repopulation ability and expression of CD44 and CXCR4. Administration of a CXCR4 antagonist affects the duration of HSC-niche interactions. These findings suggest that HSC-niche interactions may be modulated during infection.

Influence of fish to soybean oil ratio on hepatic mononuclear cell function and survival after intraportal bacterial challenge in parenterally fed mice

BACKGROUND

Parenteral nutrition (PN) is indispensable for meeting the caloric and substrate needs of patients who cannot receive adequate amounts of enteral nutrition. However, PN decreases hepatic mononuclear cell (MNC) numbers and impairs their functions. We examined the effects of various ratios of ω-3 to ω-6 polyunsaturated fatty acids on hepatic MNC number and function in a murine model. We focused on serum liver enzymes, lipid metabolism, cytokine production, histopathology, and the outcomes of an intraportal bacterial challenge.

MATERIAL AND METHODS

In experiment 1, male Institute of Cancer Research mice were randomized to CHOW, 67%, 33%, 16%, 8%, 4%, and 0% fish oil (FO)-PN groups. After receiving their respective diets for 5 days, 1.0 × 10(7) Pseudomonas aeruginosa were delivered by intraportal injection. Survival was observed ≤ 7 days after injection. Liver histologies after intraportal bacterial challenge were examined in the CHOW, 33%, 8%, and 0% FO-PN groups. In experiment 2, the mice were divided into 4 groups: CHOW, 33%, 8%, and 0% FO-PN. After the mice had been fed for 5 days, MNC were isolated. Hepatic MNC were counted and cytokine productions (tumor necrosis factor [TNF]-α and interleukin [IL]-10) by MNC in response to lipopolysaccharide (LPS) were measured. Blood samples were analyzed for lipid metabolism and hepatobiliary biochemical parameters. Liver histologies were also examined.

RESULTS

In experiment 1, survival times were significantly shorter in the 4% and 0% FO-PN groups than in the CHOW group. Survival rates at 168 hours were 100%, 64%, 86%, 73%, 67%, 11%, and 13% in the CHOW, 67%, 33%, 16%, 8%, 4%, and 0% FO-PN groups, respectively. At 72 hours after intraportal bacterial challenge, the 0% FO-PN group showed severe tissue damage, whereas such damage was reduced in the 8% and 33% FO-PN groups. In experiment 2, the CHOW, 33%, 8%, and 0% FO-PN groups showed LPS dose-dependent increases in TNF-α levels. IL-10 levels were also LPS dose-dependently increased in the CHOW and 33% FO-PN groups. However, no marked changes were observed in response to LPS stimulation in either the 8% or the 0% FO-PN group. There were no differences in serum levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, or total bilirubin among these 4 groups. In the 0% FO-PN group, serum total cholesterol levels were greater than those in the 8% and 33% FO-PN groups. Without bacterial challenge, livers from the 0% FO-PN group showed steatosis, but these changes were attenuated in the 8% and 33% FO-PN groups.

CONCLUSION

The 30-40% ratio of FO to soybean oil with 20% of total calories supplied by lipid seems to be the best PN for preservation of hepatic MNC number and function.

An essential role for TH2-type responses in limiting acute tissue damage during experimental helminth infection

Helminths induce potent Th2-type immune responses that can mediate worm expulsion but the importance of this response in controlling acute tissue damage caused by migrating multi-cellular parasites through vital tissues remains uncertain. We used a helminth infection model where parasitic nematode larvae migrate transiently through the lung causing damage resulting in hemorrhage and inflammation. Our findings showed initial elevations in IL-17 contributed to inflammation and lung damage while subsequent IL-4R signaling controlled IL-17 elevations, enhanced expression of insulin-like growth factor 1 and IL-10 and stimulated development of M2 cells, each of which contributed to rapid resolution of tissue damage. These studies indicate an essential role for the Th2-type immune response in mediating acute wound healing during helminth infection.

Helminths and dendritic cells: sensing and regulating via pattern recognition receptors, Th2 and Treg responses

The classical reaction of the host to helminth infections is the induction of Th2 immune responses with a regulatory component. DC, as central players in the induction and maintenance of immune responses, play a prominent role in both these processes, and in recent years considerable progress has been made in elucidating the mechanisms behind the interplay between DC and helminths. It is becoming increasingly clear that helminths modulate DC function not only via direct interactions but also indirectly via host-derived cues. Furthermore, while studies have until recently focused on receptor signaling-mediated DC modulation by helminths, evidence is emerging that DC may also respond to helminth infections by sensing stress signals or tissue damage inflicted by the worms or their products. Here, we will discuss these new insights and will link them to the origin and importance of Th2 and regulatory immune responses with respect to the survival of both parasite and host.

Combinatorial effects of interleukin 10 and interleukin 4 determine the progression of hepatic inflammation following murine enteric parasitic infection

Mice lacking the immunoregulatory cytokine interleukin 10 (IL-10) develop necrotizing hepatitis after infection with Trichinella spiralis, and inflammation is dependent on the migration of intestinally activated CD4(+) T cells into the liver. Hepatic production of IL-4 is elevated in these mice, and we hypothesized that it plays a role in the development of hepatic pathology. Wild-type (WT), IL-10 knockout (KO), IL-4 KO, and IL-10/IL-4 KO mice were orally infected, and disease progression was followed by histological examination, alanine aminotransferase assays, and flow cytometric analysis of hepatocellular content. Both IL-10 KO and IL-10/IL-4 KO mice experienced hepatocellular injury, but only IL-10 KO mice advanced to a necrotic phase. Hepatic CD4(+) T cells were the major source of IL-4, and IL-10 regulated the number of intestinally-derived CD4(+)IL-4(+) cells. Sequestration of activated neutrophils in the liver required IL-4, and neutrophil depletion prevented progression to overt necrosis. Adoptive transfer of intestinal WT CD4(+) T cells inhibited neutrophil accumulation and inflammation, but their regulatory effects did not require IL-10 signaling.

CONCLUSION

The absence of IL-10 led to hepatocyte injury during infection, but IL-4 was necessary for the development of neutrophil-dependent necrosis. These studies provide new insight into the combinatorial role of these cytokines and their targets in the generation and progression of hepatic inflammation.

A subset of IL-10-producing gammadelta T cells protect the liver from Listeria-elicited, CD8(+) T cell-mediated injury

Although gammadelta T cells play a role in protecting tissues from pathogen-elicited damage to bacterial, viral and parasitic pathogens, the mechanisms involved in the damage and in the protection have not been clearly elucidated. This has been addressed using a murine model of listeriosis, which in mice lacking gammadelta T cells (TCRdelta(-/-)) is characterised by severe and extensive immune-mediated hepatic necrosis. We show that these hepatic lesions are caused by Listeria-elicited CD8(+) T cells secreting high levels of TNF-alpha that accumulate in the liver of Listeria-infected TCRdelta(-/-) mice. Using isolated populations of gammadelta T cells from wild-type and cytokine-deficient strains of mice to reconstitute TCRdelta(-/-) mice, the TCR variable gene 4 (Vgamma4)(+) subset of gammadelta T cells was shown to protect against liver injury. Hepatoprotection was dependent upon their ability to produce IL-10 after TCR-mediated interactions with Listeria-elicited macrophages and CD8(+) T cells. IL-10-producing Vgamma4(+) T cells also contribute to controlling CD8(+) T cell expansion and to regulating and reducing TNF-alpha secretion by activated CD8(+) T cells. This effect on TNF-alpha production was directly attributed to IL-10. These findings identify a novel mechanism by which pathogen-elicited CD8(+) T cells are regulated via interactions with, and activation of, IL-10-producing hepatoprotective gammadelta T cells.

IL-10 Regulates Movement of Intestinally Derived CD4+T Cells to the Liver

Diseases that affect the intestine may have hepatic manifestations, but the mechanisms involved in establishing hepatic disease secondarily remain poorly understood. We previously reported that IL-10 knockout (KO) mice developed severe necrotizing hepatitis following oral infection with Trichinella spiralis. In this study, we used this model of intestinal inflammation to further examine the role of IL-10 in regulating hepatic injury. Hepatic damage was induced by migrating newborn larvae. By delivering the parasite directly into the portal vein, we demonstrated that an ongoing intestinal immune response was necessary for the development of hepatitis. Intestinally derived CD4+ cells increased in the livers of IL-10 KO mice, and Ab-mediated blockade of MAdCAM-1 inhibited the accumulation of CD4+alpha(4)beta(7)+ cells in the liver. Moreover, adoptive transfer of intestinally primed CD4+ T cells from IL-10 KO mice caused hepatitis in infected immunodeficient animals. Conversely, transfer of wild-type donor cells reduced the severity of hepatic inflammation in IL-10 KO recipients, demonstrating regulatory activity. Our results revealed that IL-10 prevented migration of intestinal T cells to the liver and inhibited the development of hepatitis.

Coordinated control of immunity to muscle stage Trichinella spiralis by IL-10, regulatory T cells, and TGF-beta

We previously demonstrated that IL-10 is critical in the control of acute inflammation during development of Trichinella spiralis in the muscle. In this study, we use gene-targeted knockout mice, adoptive transfer of specific T cell populations, and in vivo Ab treatments to determine the mechanisms by which inflammation is controlled and effector T cell responses are moderated during muscle infection. We report that CD4(+)CD25(-) effector T cells, rather than CD4(+)CD25(+) regulatory T cells, suppress inflammation by an IL-10-dependent mechanism that limits IFN-gamma production and local inducible NO synthase induction. Conversely, we show that depletion of regulatory T cells during infection results in exaggerated Th2 responses. Finally, we provide evidence that, in the absence of IL-10, TGF-beta participates in control of local inflammation in infected muscle and promotes parasite survival.

Differential roles of the co-stimulatory molecules GITR and CTLA-4 in the immune response to Trichinella spiralis

We investigated the roles of the regulatory molecules glucocorticoid-induced TNF receptor family-related protein (GITR) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) in murine infection with the nematode parasite Trichinella spiralis. Expression of GITR and CTLA-4 was rapidly upregulated on cells in the mesenteric lymph nodes and spleen, with approximately 80% of CD4+ lymphocytes expressing GITR by day 7 post-infection, coinciding with release and dissemination of newborn larvae. As the infection progressed to the chronic muscle phase, expression of GITR returned to normal, whereas CTLA-4 was sustained as late as day 60. Mice treated with anti-GITR antibodies rapidly developed higher titres of parasite-specific IgG1, IgG2a, IgG2b and IgM than controls. This was accompanied by elevated background lymphocyte proliferation, but parasite establishment in the intestine or the muscle was unaffected. In contrast, treatment with anti-CTLA-4 antibody resulted in elevated serum IgE, enhanced production of interleukin-4 and interleukin-10, and lower numbers of parasites recovered from skeletal muscle. These results reveal different temporal and regulatory roles for CTLA-4 and GITR in immune responses to helminth infection.

Amelioration of influenza-induced pathology in mice by coinfection with Trichinella spiralis

Illness due to respiratory virus infection is often induced by excessive infiltration of cells into pulmonary tissues, leading to airway occlusion. We show here that infection with Trichinella spiralis results in lower levels of tumor necrosis factor in bronchoalveolar lavage fluid and inhibits cellular recruitment into the airways of mice coinfected with influenza A virus. Infiltration of neutrophils and CD4+ and CD8+ lymphocytes was reduced, resulting in animals gaining weight more rapidly following the initial phase of infection. Influenza resulted in a generalized increase in vascular permeability in pulmonary tissues, and this was suppressed by parasite infection, although the effects were restricted to the early phase of trichinosis. Moreover, the number of cells producing interleukin-10 (IL-10), and the local levels of this cytokine, were reduced, suggesting that amelioration of pulmonary pathology by parasite infection occurs independently of IL-10 production.

Synthesis of syndecan-1 by skeletal muscle cells is an early response to infection with Trichinella spiralis but is not essential for nurse cell development

Trichinella spiralis creates a unique intracellular habitat in striated muscle. We report that a proteoglycan, syndecan-1, is induced early in infection yet is not essential for habitat development and exerts a modest influence on the immune response. This report is the first to address the requirement for a specific muscle protein in trichinellosis by using mice deficient in the relevant gene.

Comparative dynamics and phenotype of the murine immune response to Trichinella spiralis and Trichinella pseudospiralis

Infection of NIH mice with Trichinella spiralis and Trichinella pseudospiralis results in qualitatively comparable immune responses. Antigen-specific proliferation by mesenteric lymph node cells was transient and temporally associated with intestinal infection, but in contrast was sustained throughout infection by splenocytes. Early cytokine production by mesenteric lymph node cells was dominated by interleukin 10, but also IL-5 and IL-4, with rapid resolution following parasite expulsion from the gut. Splenocytes showed a mixed profile of cytokine production, although again dominated by IL-10 and sustained over 60 days of infection. All antibody classes were evident, with early production of IgA and IgG1, and subsequent secretion of other subclasses including IgG2a. Granulocytic infiltration of the spleen was significantly greater in T. spiralis infection. The concentration of serum corticosterone generally remained within normal boundaries, although was raised by day 60 in T. spiralis-infected mice. We conclude that the systemic suppression of inflammation reported for T. pseudospiralis does not result from selective induction of regulatory cytokines, or a major difference in the immune response to infection with T. spiralis.

Interleukin-10 limits local and body cavity inflammation during infection with muscle-stage Trichinella spiralis

The aim of this study was to characterize cellular responses to muscle-stage Trichinella spiralis. From its intracellular habitat in muscle, T. spiralis secretes potent glycoprotein antigens that elicit a strong systemic host immune response. Despite the magnitude and prolonged nature of this response, nurse cells are rarely destroyed by infiltrating cells. We tested the hypothesis that the anti-inflammatory cytokine interleukin-10 (IL-10) moderates cellular responses to muscle-stage parasites. Trichinella larvae colonize the diaphragm in large numbers, prompting us to evaluate regional responses in body cavities in addition to local responses in muscle. Mice deficient in IL-10 demonstrated an exaggerated inflammatory response around nurse cells and in the pleural cavity. The effect of IL-10 was most evident 20 days following muscle infection. The increased intensity of the response in IL-10-deficient mice did not affect parasite establishment or survival. Between 20 and 50 days postinfection, the inflammatory response was diminished in both wild-type and IL-10-deficient mice. Muscle infection also elicited an antibody response, characterized initially by mixed isotypes directed at somatic larval antigens and changing to an immunoglobulin G1-dominated response directed at tyvelose-bearing excreted or secreted antigens. We conclude that IL-10 limits local and regional inflammation during the early stages of muscle infection but that chronic inflammation is controlled by an IL-10-independent mechanism that is coincident with a Th2 response.