Breast Cancer knowledge, perceptions and practices in a rural Community in Coastal Kenya

Background

Data on breast healthcare knowledge, perceptions and practice among women in rural Kenya is limited. Furthermore, the role of the male head of household in influencing a woman’s breast health seeking behavior is also not known. The aim of this study was to assess the knowledge, perceptions and practice of breast cancer among women, male heads of households, opinion leaders and healthcare providers within a rural community in Kenya. Our secondary objective was to explore the role of male heads of households in influencing a woman’s breast health seeking behavior.

Methods

This was a mixed method cross-sectional study, conducted between Sept 1st 2015 Sept 30th 2016. We administered surveys to women and male heads of households. Outcomes of interest were analysed in Stata ver 13 and tabulated against gender. We conducted six focus group discussions (FGDs) and 22 key informant interviews (KIIs) with opinion leaders and health care providers, respectively. Elements of the Rapid Assessment Process (RAP) were used to guide analysis of the FGDs and the KIIs.

Results

A total of 442 women and 237 male heads of households participated in the survey. Although more than 80% of respondents had heard of breast cancer, fewer than 10% of women and male heads of households had knowledge of 2 or more of its risk factors.

More than 85% of both men and women perceived breast cancer as a very serious illness. Over 90% of respondents would visit a health facility for a breast lump.

Variable recognition of signs of breast cancer, limited decision- autonomy for women, a preference for traditional healers, lack of trust in the health care system, inadequate access to services, limited early-detection services were the six themes that emerged from the FGDs and the KIIs. There were discrepancies between the qualitative and quantitative data for the perceived role of the male head of household as a barrier to seeking breast health care.

Conclusions

Determining level of breast cancer knowledge, the characteristics of breast health seeking behavior and the perceived barriers to accessing breast health are the first steps in establishing locally relevant intervention programs.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-6464-3) contains supplementary material, which is available to authorized users.

Policy, System and Environmental Correlates of Fruit and Vegetable Consumption in a Low-Income African American Population in the Southeast

Objective

The current study seeks to identify policy, system and environmental (PSE) correlates of fruit and vegetable consumption among a sample of low-income African Americans in two counties in Alabama (Jefferson and Mobile) and one county in Mississippi (Forrest).

Design

A modified Behavioral Risk Factor Surveillance System (BRFFS) survey, which included multi-level ecological factors, was used to evaluate nutritional habits at the pre-intervention stage of a multi-state research study. We surveyed a total of 256 participants between May and August 2015. Local community coalitions established in each of the counties were instrumental in the planning and administration of the baseline survey.

Results

Univariate analyses revealed that whether participants met the daily recommendation for fruit/vegetable consumption may be correlated with whether participants had children who attended schools/day care centers with health policies in place, received food assistance, and observed media campaigns related to nutrition. Further, results of multivariate analysis indicated that meeting fruit/vegetable recommendations was correlated with personally participating or having a family member who participated in a health policy meeting in the past two years.

Conclusion

These findings suggest that policy-based interventions have the potential to improve health outcomes among priority populations, such as low-income African Americans, who are at high risk of developing chronic diseases.

Introduction: Impacting the Social Determinants of Health through a Regional Academic-Community Partnership: The Experience of the Mid-South Transdisciplinary Collaborative Center for Health Disparities Research

Objective

The purpose of this article is to describe the background and experience of the Academic-Community Engagement (ACE) Core of the Mid-South Transdisciplinary Collaborative Center for Health Disparities Research (Mid-South TCC) in impacting the social determinants of health through the establishment and implementation of a regional academic-community partnership.

Conceptual Framework

The Mid-South TCC is informed by three strands of research: the social determinants of health, the socioecological model, and community-based participatory research (CBPR). Combined, these elements represent a science of engagement that has allowed us to use CBPR principles at a regional level to address the social determinants of health disparities.

Results

The ACE Core established state coalitions in each of our founding states-Alabama, Louisiana, and Mississippi-and an Expansion Coalition in Arkansas, Tennessee, and Kentucky. The ACE Core funded and supported a diversity of 15 community engaged projects at each level of the socioecological model in our six partner states through our community coalitions.

Conclusion

Through our cross-discipline, cross-regional infrastructure developed strategically over time, and led by the ACE Core, the Mid-South TCC has established an extensive infrastructure for accomplishing our overarching goal of investigating the social, economic, cultural, and environmental factors driving and sustaining health disparities in obesity and chronic illnesses, and developing and implementing interventions to ameliorate such disparities.

Using Community Feedback to Improve Community Interventions: Results From the Deep South Network for Cancer Control Project

The Deep South Network for Cancer Control (DSNCC), initiated in 2000, is a dual-state, community-based participatory research infrastructure composed of academic and community partners committed to reducing cancer disparities among underserved African Americans in 12 designated counties of the Alabama Black Belt and the Mississippi Delta, 2 historically underserved areas of the country. Local residents trained as Community Health Advisors as Research Partners implemented a 3-tier community action plan (CAP) focused on promoting cancer screening, physical activity, and nutrition. Breast, cervical and colorectal cancer screening, healthy eating habits, and physical activity levels increased among many, but not all, African American women in the 12-county DSNCC coverage area. Seeking to improve our reach to include participants who reported they had never heard of the DSNCC or participated in the CAP, we conducted in-depth conversations with community residents about reasons for selective nonparticipation and ways to improve participation in the DSNCC community health interventions. Three patterns and their associated themes described ways to improve the penetration of CAP strategies and tailor them to effectively reach underserved African Americans in the intervention counties. We conclude with lessons learned for future interventions.

IL-21 receptor signalling partially mediates Th2-mediated allergic airway responses

BACKGROUND

Interleukin-21 (IL-21) has been implicated in the development of Th2-mediated immune responses; however, the exact role it plays in allergic diseases is not well understood.

OBJECTIVE

To elucidate the contribution of IL-21 receptor signalling to Th2-dependent immune responses in the lung.

METHODS

We compared allergic airway responses in wild-type BALB/c and Il21r-deficient mice exposed to local airway challenge with house dust mite (HDM).

RESULTS

We demonstrate that IL-21R-deficiency reduces HDM-driven airway hyperresponsiveness (AHR) with only partial effects on airway inflammation. Concomitant with the reduction in AHR in Il21r-deficient mice, significant suppression was observed in protein levels of the Th2 cytokines IL-4, and IL-13. In contrast, IL-21R-deficiency was associated with an increase in PBS- and allergen-driven IgE levels, while IgG1 and IgG2a levels were decreased. Moreover, our results suggest that IL-21 may contribute to AHR through its ability to both directly induce Th2 cell survival and to impair regulatory T-cell suppression of Th2 cytokine production. Importantly, we show that IL-21-positive cells are increased in the bronchial mucosa of asthmatics compared with non-asthmatics.

CONCLUSION

These results suggest that IL-21 plays an important role in the allergic diathesis by enhancing Th2 cytokine production through multiple mechanisms including the suppression of Treg inhibitory effects on Th2 cell cytokine production.

African American organ donor registration: a mixed methods design using the theory of planned behavior

CONTEXT

A large racial disparity exists in organ donation.

OBJECTIVE

To identify factors associated with becoming a registered organ donor among African Americans in Alabama.

METHODS

Concurrent mixed methods design guided by the Theory of Planned Behavior to analyze African Americans' decisions to become a registered organ donor by using both qualitative (focus groups) and quantitative (survey) methods.

RESULTS

The sample consisted of 22 registered organ donors and 65 non registered participants from 6 focus groups completed in urban (n = 3) and rural (n = 3) areas. Participants emphasized the importance of the autonomy to make one's own organ donation decision and have this decision honored posthumously. One novel barrier to becoming a registered organ donor was the perception that organs from African Americans were often unusable because of the high prevalence of chronic medical conditions such as diabetes and hypertension. Another novel theme discussed as an advantage to becoming a donor was the subsequent motivation to take responsibility for one's health. Family and friends were the most common groups of persons identified as approving and disapproving of the decision to become a donor. The most common facilitator to becoming a donor was information, whereas fear and the lack of information were the most common barriers. In contrast, religious beliefs, mistrust, and social justice themes were infrequently referenced as barriers to becoming a donor.

CONCLUSION

Findings from this study may be useful for prioritizing organ donation community-based educational interventions in campaigns to increase donor registration.

Adaptation of innate lymphoid cells to a micronutrient deficiency promotes type 2 barrier immunity

How the immune system adapts to malnutrition to sustain immunity at barrier surfaces, such as the intestine, remains unclear. Vitamin A deficiency is one of the most common micronutrient deficiencies and is associated with profound defects in adaptive immunity. Here, we found that type 3 innate lymphoid cells (ILC3s) are severely diminished in vitamin A-deficient settings, which results in compromised immunity to acute bacterial infection. However, vitamin A deprivation paradoxically resulted in dramatic expansion of interleukin-13 (IL-13)-producing ILC2s and resistance to nematode infection in mice, which revealed that ILCs are primary sensors of dietary stress. Further, these data indicate that, during malnutrition, a switch to innate type 2 immunity may represent a powerful adaptation of the immune system to promote host survival in the face of ongoing barrier challenges.

Using community-based participatory approaches to mobilize communities for policy change

The Racial and Ethnic Approaches to Community Health (REACH) Alabama Breast and Cervical Cancer Coalition used community-based participatory research principles to address breast and cervical cancer disparities among Alabama's most vulnerable African American communities. With funding from the Centers for Disease Control and Prevention, the Alabama Breast and Cervical Cancer Coalition implemented a multilevel action plan, which entailed disseminating evidence-based strategies to community organizations interested in addressing cancer and other health disparities. Based on the Alabama Breast and Cervical Cancer Coalition's technical assistance on advocacy, an independent, community-led coalition was formed. This article uses a case study approach to document the steps taken by this empowered coalition to mobilize their community to impact cancer disparities using community-based participatory research principles as a tool to change tobacco and breast and cervical cancer legislation.

Development of a spiritually based educational intervention to increase informed decision making for prostate cancer screening among church-attending African American men

One way of developing culturally relevant health communication in the African American church setting is to develop spiritually based interventions, in which the health message is framed by relevant spiritual themes and scripture. In this article we describe the development of a community health advisor(CHA)-led intervention aimed at increasing informed decision making (IDM) for prostate cancer screening among church-attending African American men. Full-color print educational booklets were developed and pilot tested with extensive community participation of church-attending African American men age-eligible for screening. The intervention development phase consisted of ideas solicited from an advisory panel of African American men (N = 10), who identified core content and developed the spiritual themes. In the intervention pilot testing phase, prototypes of the intervention materials were pilot tested for graphic appeal in two focus groups (N = 16), and content was tested for acceptability and comprehension using individual cognitive response interviews (N = 10). Recommendations were made for project branding and logo and for use of graphics of real people in the educational materials. Significant feedback was obtained from the focus groups, on the graphics, colors, fonts, continuity, titles, and booklet size/shape. The importance of working closely with the community when developing interventions is discussed, as well as the importance of pilot testing of educational materials.

A comparison of a spiritually based and non-spiritually based educational intervention for informed decision making for prostate cancer screening among church-attending African-American men

INTRODUCTION

Health communication interventions have been modestly effective for increasing informed decision making for prostate cancer screening among African-American men; however, knowledge and informed decision making is still questionable even with screening. Church-based programs may be more effective if they are spiritually based in nature.

OBJECTIVE

The aims of the present study were to implement and provide an initial evaluation of a spiritually based prostate cancer screening informed decision making intervention for African-American men who attend church, and determine its efficacy for increasing informed decision making.

DESIGN AND METHOD

Churches were randomized to receive either the spiritually based or the non-spiritual intervention. Trained community health advisors, who were African-American male church members, led an educational session and distributed educational print materials. Participants completed baseline and immediate follow-up surveys to assess the intervention impact on study outcomes.

RESULTS

The spiritually based intervention appeared to be more effective in areas such as knowledge, and men read more of their materials in the spiritually based group than in the non-spiritual group.

CONCLUSIONS

Further examination of the efficacy of the spiritually based approach to health communication is warranted.

Religious involvement and prostate cancer screening behaviors among southeastern African American men

This study examined the relationship between religious involvement and prostate cancer screening behavior among a probability sample of 199 African American men. Religious involvement was assessed by telephone via a multidimensional instrument. Engaging in religious behaviors was predictive of reporting a digital rectal examination (DRE) within the past year. Religious beliefs and behaviors were predictive of behavioral intention for DRE in the next 6 months. Religious behaviors were predictive of reporting an appointment for a DRE in the next 6 months. All analyses were controlled for age, education, and marital status. None of the predictions were significant for prostate-specific antigen testing. Understanding the role of religious involvement in cancer beliefs and screening is important. Such knowledge can inform educational interventions for this group, which is disproportionately affected by prostate cancer.

Cellular and molecular mechanisms of fibrosis

Fibrosis is defined by the overgrowth, hardening, and/or scarring of various tissues and is attributed to excess deposition of extracellular matrix components including collagen. Fibrosis is the end result of chronic inflammatory reactions induced by a variety of stimuli including persistent infections, autoimmune reactions, allergic responses, chemical insults, radiation, and tissue injury. Although current treatments for fibrotic diseases such as idiopathic pulmonary fibrosis, liver cirrhosis, systemic sclerosis, progressive kidney disease, and cardiovascular fibrosis typically target the inflammatory response, there is accumulating evidence that the mechanisms driving fibrogenesis are distinct from those regulating inflammation. In fact, some studies have suggested that ongoing inflammation is needed to reverse established and progressive fibrosis. The key cellular mediator of fibrosis is the myofibroblast, which when activated serves as the primary collagen-producing cell. Myofibroblasts are generated from a variety of sources including resident mesenchymal cells, epithelial and endothelial cells in processes termed epithelial/endothelial-mesenchymal (EMT/EndMT) transition, as well as from circulating fibroblast-like cells called fibrocytes that are derived from bone-marrow stem cells. Myofibroblasts are activated by a variety of mechanisms, including paracrine signals derived from lymphocytes and macrophages, autocrine factors secreted by myofibroblasts, and pathogen-associated molecular patterns (PAMPS) produced by pathogenic organisms that interact with pattern recognition receptors (i.e. TLRs) on fibroblasts. Cytokines (IL-13, IL-21, TGF-beta1), chemokines (MCP-1, MIP-1beta), angiogenic factors (VEGF), growth factors (PDGF), peroxisome proliferator-activated receptors (PPARs), acute phase proteins (SAP), caspases, and components of the renin-angiotensin-aldosterone system (ANG II) have been identified as important regulators of fibrosis and are being investigated as potential targets of antifibrotic drugs. This review explores our current understanding of the cellular and molecular mechanisms of fibrogenesis.

A novel and sensitive ELISA reveals that the soluble form of IL-13R-alpha2 is not expressed in plasma of healthy or asthmatic subjects

BACKGROUND

IL-13 plays a key regulatory role in asthmatic responses and immunity to parasitic infection. In vivo, IL-13R-alpha2 is a critical modulator of IL-13 bioactivity. When inducibly expressed on the surface of fibroblasts and other cell types under inflammatory conditions, IL-13R-alpha2 contributes to resolution of IL-13 responses. A soluble form of IL-13R-alpha2 (sIL-13R-alpha2) can be detected in murine circulation, and functions as a regulator of IL-13 bioactivity. In humans, sIL-13R-alpha2 has been more difficult to detect. Recently, novel assay systems have been described to quantitate sIL-13R-alpha2 in human circulation, and revealed unexpectedly high levels of sIL-13R-alpha2 in healthy subjects.

OBJECTIVE

To verify sIL-13R-alpha2 quantitation in human plasma samples under stringent conditions of signal verification and false-positive detection.

METHODS

A standard ELISA protocol was evaluated for specificity using false-positive detection reagents. A more stringent ELISA protocol was developed by optimizing the composition of blocking and dilution buffers.

RESULTS

Using the stringent assay protocol, endogenous sIL-13R-alpha2 was undetectable in plasma samples from a total of 120 asthmatics and 20 healthy subjects, and in bronchoalveolar lavage fluid from 10 asthmatics and eight healthy subjects undergoing allergen challenge.

CONCLUSION

These results underscore the necessity to perform rigorous assay controls in the biological matrix to be tested. Because the soluble form could not be demonstrated, our findings question a role for sIL-13R-alpha2 in the regulation of IL-13 bioactivity, and highlight the potentially important contribution of the membrane-bound form of IL-13R-alpha2 in humans.

Perceptions of the religion--health connection among African Americans in the southeastern United States: sex, age, and urban/rural differences

Extensive literature reviews suggest that religiousness is positively associated with health. Much less understood is the particular nature of the religion-health connection. Religion and the church play a central role in the lives of many African Americans. This study used a mixed-methods approach to examine perceptions of the religion-health connection among African Americans in urban and rural areas. Four hundred participants were randomly selected and interviewed by telephone, answering open-ended questions about their perceptions of the role of religiousness in their health. Data were analyzed using an open-coding technique. Codes were arranged into families involving the role of a higher power, health behavior, physical factors, social support, mental health, and contextual factors in determining physical health, as well as the potential negative role of religiousness. Quantitative analysis revealed the stronger presence of themes among women, older participants, and those in rural counties. Applications for theory and health promotion are discussed.

Characterization of the divergent eosinophil ribonuclease, mEar 6, and its expression in response to Schistosoma mansoni infection in vivo

The eosinophil-associated ribonucleases (Ears) are rapidly evolving proteins found in multigene clusters that are unique to each rodent species. Of the 15 independent genes in the Mus musculus cluster, only mEars 1 and 2 are expressed at significant levels at homeostasis. Here we characterize the expression of mEar 6 in the liver and spleen in mice in response to infection with the helminthic parasite, Schistosoma mansoni. Interestingly, expression of mEar 6 is not directly related to the elevated levels of serum IL-5 or tissue eosinophilia characteristic of this disease, as no mEar 6 transcripts were detected in the liver or the spleen from uninfected IL-5-transgenic mice. The coding sequence of mEar 6 has diverged under positive selection pressure (K(a)/K(s) > 1.0) and has a unique unpaired cysteine near the carboxy-terminus of the protein. The high catalytic efficiency of recombinant mEar 6 (k(cat)/K(m) = 0.9 x 10(6)/M/s) is similar to that of the cluster's closest human ortholog, eosinophil-derived neurotoxin (EDN/RNase 2). In summary, we have identified mEar 6 as one of only two RNase A superfamily ribonucleases known to be expressed specifically in response to pathophysiologic stress in vivo.

African American community health advisors trained as research partners: recruitment and training

The African American community has played an influential role in generating change. Grass-roots organizations and concerned individuals can be included in programs designed to increase cancer awareness and cancer early detection practices to ultimately eliminate cancer disparities. The utilization of a formalized Community Health Advisors program can be an infrastructure by which effective cancer prevention and control programs can be conducted in underserved African American communities. The purpose of this article is to outline the steps necessary to develop an infrastructure for recruitment and training of grass-root African Americans to serve as Community Health Advisors trained as Research Partners.

Community health advisors as research partners: an evaluation of the training and activities

The feasibility of training large numbers of community health advisors as research partners (CHARPs) was evaluated using talking circles data and cancer activity questionnaires and logs. The talking circles data indicated that the CHARPs (n=108) valued their training and believed they learned necessary research partner skills. A review of contacts (n=7,956) provided evidence that CHARPs (n=883) could work as a team to deliver a variety of services over time to the community. The findings suggested that implementing a large scale intervention with CHARPs has the potential to increase the dissemination of cancer information and to reduce cancer disparities.

The development of a community action plan to reduce breast and cervical cancer disparities between African-American and White women

The purpose of this project was to establish a coalition of academic, state, and community-based organizations to develop a community action plan (CAP) to eliminate breast and cervical cancer morbidity and mortality disparities between African-American (AA) and Caucasian women. The project targeted rural and urban low-income AA women in Alabama. Based on the logic model, community capacity building was implemented, followed by the development of a community-driven CAP. For community capacity building, a coalition comprising 12 organizations was established, and a network of 84 community volunteers was formed. Community needs assessments identified 3 levels of barriers to breast and cervical cancer screening: 1) individual, 2) community systems, and 3) healthcare provider. Based on these findings, a community-driven CAP was developed. Our results indicate that a coalition of diverse organizations can partner and develop CAPs to improve the health of their communities.

Regulation of hepatic fibrosis and extracellular matrix genes by the th response: new insight into the role of tissue inhibitors of matrix metalloproteinases

Hepatic fibrosis is the hallmark of Schistosoma mansoni infection and often results in portal hypertension and bleeding from esophageal varices. The fibrotic process is highly dependent on type 2 cytokines, yet their role in the regulation of extracellular matrix remodeling genes remains largely unknown. Here, we examined the expression of matrix metalloproteases (MMP) -2, -3, -9, -12, and -13 and their inhibitors, tissue inhibitor of metalloproteases (TIMP) -1, -2, and -3, in the livers of infected mice and correlated their expression profiles with fibrosis and type 2 cytokine production. Expression of MMP-2, -3, -9, -12, and -13 and of TIMP-1 and -2 mRNA rapidly increased at the onset of egg laying in infected mice, while TIMP-3 was unchanged. Because TIMP are presumed to be important regulators of the extracellular matrix, and their expression correlated with the development of fibrosis, we studied their role in fibrogenesis by infecting TIMP-1- and TIMP-2-deficient mice. Strikingly, our data revealed no role for TIMP-1 or -2 in the fibrotic pathology induced by S. mansoni eggs. Because of these findings, we infected IL-10/IFN-gamma-deficient mice that develop an exaggerated fibrotic response to determine whether changes in type 2 cytokine dominance influence the pattern of MMP and TIMP expression. Fibrosis and type 2 cytokine production correlated with increased MMP-2/MMP-9 vs TIMP-1/TIMP-2 expression. These data, in addition to our knockout studies, demonstrate that TIMP-1/TIMP-2 play no essential role in fibrogenesis in schistosomiasis. Indeed, our findings suggest that inhibiting profibrotic cytokines or specific MMP may be a more effective strategy to ameliorate fibrotic pathology.

Differential regulation of nitric oxide synthase-2 and arginase-1 by type 1/type 2 cytokines in vivo: granulomatous pathology is shaped by the pattern of L-arginine metabolism

Type 2 cytokines regulate fibrotic liver pathology in mice infected with Schistosoma mansoni. Switching the immune response to a type 1-dominant reaction has proven highly effective at reducing the pathologic response. Activation of NOS-2 is critical, because type 1-deviated/NO synthase 2 (NOS-2)-deficient mice completely fail to control their response. Here, we demonstrate the differential regulation of NOS-2 and arginase type 1 (Arg-1) by type 1/type 2 cytokines in vivo and for the first time show a critical role for arginase in the pathogenesis of schistosomiasis. Using cytokine-deficient mice and two granuloma models, we show that induction of Arg-1 is type 2 cytokine dependent. Schistosome eggs induce Arg-1, while Mycobacterium avium-infected mice develop a dominant NOS-2 response. IFN-gamma suppresses Arg-1 activity, because type 1 polarized IL-4/IL-10-deficient, IL-4/IL-13-deficient, and egg/IL-12-sensitized animals fail to up-regulate Arg-1 following egg exposure. Notably, granuloma size decreases in these type-1-deviated/Arg-1-unresponsive mice, suggesting an important regulatory role for Arg-1 in schistosome egg-induced pathology. To test this hypothesis, we administered difluoromethylornithine to block ornithine-aminodecarboxylase, which uses the product of arginine metabolism, L-ornithine, to generate polyamines. Strikingly, granuloma size and hepatic fibrosis increased in the ornithine-aminodecarboxylase-inhibited mice. Furthermore, we show that type 2 cytokine-stimulated macrophages produce proline under strict arginase control. Together, these data reveal an important regulatory role for the arginase biosynthetic pathway in the regulation of inflammation and demonstrate that differential activation of Arg-1/NOS-2 is a critical determinant in the pathogenesis of granuloma formation.

The role of interleukin (IL)-10 in the persistence of Leishmania major in the skin after healing and the therapeutic potential of anti-IL-10 receptor antibody for sterile cure

Some pathogens (e.g., Mycobacterium tuberculosis, Toxoplasma gondii, Leishmania spp) have been shown to persist in their host after clinical cure, establishing the risk of disease reactivation. We analyzed the conditions necessary for the long term maintenance of Leishmania major in genetically resistant C57BL/6 mice after spontaneous healing of their dermal lesions. Interleukin (IL)-10 was found to play an essential role in parasite persistence as sterile cure was achieved in IL-10-deficient and IL-4/IL-10 double-deficient mice. The requirement for IL-10 in establishing latency associated with natural infection was confirmed in IL-10-deficient mice challenged by bite of infected sand flies. The host-parasite equilibrium was maintained by CD4+ and CD8+ T cells which were each able to release IL-10 or interferon (IFN)-gamma, and were found to accumulate in chronic sites of infection, including the skin and draining lymph node. A high frequency of the dermal CD4+ T cells released both IL-10 and IFN-gamma. Wild-type mice treated transiently during the chronic phase with anti-IL-10 receptor antibodies achieved sterile cure, suggesting a novel therapeutic approach to eliminate latency, infection reservoirs, and the risk of reactivation disease.

Patterns of chemokine expression in models of Schistosoma mansoni inflammation and infection reveal relationships between type 1 and type 2 responses and chemokines in vivo

To explore the roles of chemokines in type 1 and type 2 responses in vivo, we examined mRNA expression for a panel of up to 17 chemokines in experimental mouse models using Schistosoma mansoni. These studies revealed that Mig (monokine induced by gamma interferon), cytokine-responsive gene 2/10-kDa interferon-inducible protein, RANTES, lymphotactin, macrophage inflammatory protein 1beta (MIP-1beta), JE/monocyte chemoattractant protein 1, and MIP-2 are associated with type 1 egg-induced responses and that thymus-derived chemotactic agent 3 (TCA3), eotaxin, MIP-1alpha, and MIP-1gamma are associated with type 2 egg-induced responses. After cercarial infection, both type 1-associated and type 2-associated chemokines were elevated in the livers of infected mice presensitized with eggs and recombinant interleukin-12 (rIL-12), a regimen that diminishes pathology. Neutralization of IL-12 or gamma interferon during egg deposition reversed the effects of prior treatment with rIL-12, leading to a return to larger granulomas; persistently elevated expression of TCA3, eotaxin, and MIP-1alpha; and a marked reduction in the expression of type 1-associated chemokines despite the maintenance of a dominant type 1 cytokine response in the draining lymph nodes. Our findings suggest that there are patterns of coordinate chemokine expression characteristic of type 1 and type 2 responses in vivo; that the cells recruited by a given pattern of chemokines may differ, depending on the composition of peripheral populations; and that patterns of tissue expression of chemokines may determine the character of an inflammatory response independently of the dominant pattern of differentiation of antigen-specific T cells. Our data reveal new relationships between chemokines and polarized immune responses and suggest that end organ inflammation might be altered by chemokine blockade without necessitating reversal of the phenotype of the majority of differentiated T cells.

Disease fingerprinting with cDNA microarrays reveals distinct gene expression profiles in lethal type 1 and type 2 cytokine-mediated inflammatory reactions

Development of polarized immune responses controls resistance and susceptibility to many microorganisms. However, studies of several infectious, allergic, and autoimmune diseases have shown that chronic type-1 and type-2 cytokine responses can also cause significant morbidity and mortality if left unchecked. We used mouse cDNA microarrays to molecularly phenotype the gene expression patterns that characterize two disparate but equally lethal forms of liver pathology that develop in Schistosoma mansoni infected mice polarized for type-1 and type-2 cytokine responses. Hierarchical clustering analysis identified at least three groups of genes associated with a polarized type-2 response and two linked with an extreme type-1 cytokine phenotype. Predictions about liver fibrosis, apoptosis, and granulocyte recruitment and activation generated by the microarray studies were confirmed later by traditional biological assays. The data show that cDNA microarrays are useful not only for determining coordinated gene expression profiles but are also highly effective for molecularly "fingerprinting" diseased tissues. Moreover, they illustrate the potential of genome-wide approaches for generating comprehensive views on the molecular and biochemical mechanisms regulating infectious disease pathogenesis.

Studies of murine schistosomiasis reveal interleukin-13 blockade as a treatment for established and progressive liver fibrosis

In several allergic, autoimmune, and infectious diseases, fibrosis is a major cause of morbidity and mortality. Here, using a model of infection-induced liver fibrosis, we show that interleukin (IL)-13 is required at all stages of Schistosomiasis mansoni infection to induce fibrosis. IL-4 production was preserved in IL-13-deficient mice, yet failed to significantly contribute to the fibrotic response in either acute or chronic infection. Significant fibrosis develops in all infected mice, although the magnitude of the response varies widely in inbred mice. C3H/HeN, BALB/c, and C57BL/6 mice develop high, intermediate, and low levels of fibrosis, respectively. Despite these differences, IL-13 antagonism resulted in a marked amelioration of fibrosis in all strains. The fibrotic mechanism in the high- and low-responder strains was unrelated to their tissue eosinophil or mast cell responses, but did correlate with their patterns of IL-13, IL-10, and interferon gamma (IFN-gamma) mRNA expression. Indeed, severe fibrosis correlated with a high IL-13 and low IFN-gamma/IL-10 mRNA response. Because fibrotic diseases are typically progressive disorders, an important issue was to determine whether IL-13 inactivation might be used to treat an established and ongoing fibrotic disease. Here, IL-13 antagonism was highly efficacious, even after fibrosis and the Th2 cytokine response were firmly established. These studies demonstrate the central role played by IL-13 in fibrogenesis and suggest that therapeutic approaches aimed at disrupting the IL-13 pathway will be highly effective at preventing fibrotic disease caused by chronic Th2-mediated inflammatory reactions.

Helicobacter hepaticus-induced colitis in interleukin-10-deficient mice: cytokine requirements for the induction and maintenance of intestinal inflammation

We have previously shown that specific-pathogen-free interleukin-10 (IL-10)-deficient (IL-10 KO) mice reconstituted with Helicobacter hepaticus develop severe colitis associated with a Th1-type cytokine response. In the present study, we formally demonstrate that IL-12 is crucial for disease induction, because mice deficient for both IL-10 and IL-12 p40 show no intestinal pathology following H. hepaticus infection. By using monoclonal antibodies (MAbs) to IL-12, gamma interferon (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha), we have further analyzed the role of these cytokines in the maintenance of the Th1 response and inflammation in IL-10 KO mice with established H. hepaticus-induced colitis. Treatment of infected colitic IL-10 KO mice with anti-IL-12 p40 resulted in markedly reduced intestinal inflammation, colonic IFN-gamma, TNF-alpha, and inducible nitric oxide synthase (iNOS) mRNA levels, and H. hepaticus-specific IFN-gamma secretion by mesenteric lymph node (MLN) cells compared to the findings in control MAb-treated mice. Moreover, the diminished pathology was associated with decreased numbers of colonic CD3(+) T cells and significantly reduced frequencies of Helicobacter-reactive CD4(+) Th1 cells in MLN. In contrast, anti-IFN-gamma and/or anti-TNF-alpha had no effect on intestinal inflammation in IL-10 KO mice with established colitis. Using IL-10/IFN-gamma double-deficient mice, we further show that IFN-gamma is not required for the development of colitis following H. hepaticus infection. MLN cells from infected IL-10/IFN-gamma KO animals secreted elevated amounts of IL-12 and TNF-alpha following bacterial antigen stimulation, indicating alternative pathways of disease induction. Taken together, our results demonstrate a crucial role for IL-12 in both inducing and sustaining intestinal inflammation through recruitment and maintenance of a pool of pathogenic Th1 cells.

Cutting edge: Stat6-dependent substrate depletion regulates nitric oxide production

The cytokines IL-4 and IL-13 inhibit the production of NO from activated macrophages through an unresolved molecular mechanism. We show here that IL-4 and IL-13 regulate NO production through depletion of arginine, the substrate of inducible NO synthase (iNOS). Inhibition of NO production from murine macrophages stimulated with LPS and IFN-gamma by IL-4 or IL-13 was dependent on Stat6, cell density in the cultures, and pretreatment for at least 6 h. IL-4/IL-13 did not interfere with the expression or activity of iNOS but up-regulated arginase I (the liver isoform of arginase) in a Stat6-dependent manner. Addition of exogenous arginine completely restored NO production in IL-4-treated macrophages. Furthermore, impaired killing of the intracellular pathogen Toxoplasma gondii in IL-4-treated macrophages was overcome by supplementing L-arginine. The simple system of regulated substrate competition between arginase and iNOS has implications for understanding the physiological regulation of NO production.

The guanine protein coupled receptor rhodopsin is developmentally regulated in the free-living stages of Schistosoma mansoni

Schistosoma mansoni parasites inhabit three distinct environments including water, intermediate molluscan hosts, and definitive vertebrate hosts. Determining how schistosomes interact with these environments may be one mechanism by which suitable vaccines or novel chemotherapeutic targets will be identified. Towards this end, we describe the identification of a 36-kDa S. mansoni protein that shares extensive sequence similarity to light absorbing rhodopsin guanine protein coupled receptors (GPCRs). This protein, S. mansoni rhodopsin (SmRHO), is the first molecularly characterized GPCR described in schistosomes. Sequence analysis reveals that SmRHO shares extensive phylogenetic conservation among rhodopsins/opsins expressed in water-dwelling invertebrates, possibly indicative of orthology. We demonstrate here that SmRHO is expressed in the free-living, light responsive miracidia and cercaria stages and is down-regulated in the adult, vertebrate residing forms. Moreover, we show that SmRHO is localized to sub-tegumental structures found towards the anterior end of cercariae. As SmRHO may be implicated in schistosome photoreception processes, we have begun a search for additional parasite encoded GPCR super-family members, which may be associated with chemoreception, chemotaxis, and olfaction. Identifying and characterizing new GPCRs may uncover hidden aspects of parasite biology useful towards the development of novel intervention strategies.

Defining a schistosomiasis vaccination strategy - is it really Th1 versus Th2?

Successful vaccine development for schistosomiasis has been hindered by a lack of consensus on the type of immune response that would provide maximum levels of protective immunity and incomplete knowledge of the key antiparasite effector mechanisms. Many vaccine studies conducted in mice support type-1-cytokine-mediated effector mechanisms, while acquired resistance in humans correlates with type-2-cytokine-mediated responses. However, recent data from cytokine-knockout mice suggest that choosing between these opposing pathways may be less important than previously hypothesized, as discussed here by Thomas Wynn and Karl Hoffmann.

NOS-2 mediates the protective anti-inflammatory and antifibrotic effects of the Th1-inducing adjuvant, IL-12, in a Th2 model of granulomatous disease

Mice sensitized with SCHISTOSOMA: mansoni eggs and IL-12 develop liver granulomas, on subsequent infection, which are smaller and less fibrotic than those in nonsensitized mice. The protective response is accompanied by a shift in the type-2 cytokine profile to one dominated by type-1 cytokines. The deviated response is associated with marked increases in inducible nitric oxide synthase (NOS-2) activity. Here, we demonstrate, by using NOS-2-deficient mice, that the anti-inflammatory and anti-fibrotic effects of the type-1 response are completely NOS-2-dependent. Strikingly, despite developing a polarized type-1 cytokine response that was similar in magnitude, the egg/IL-12-sensitized NOS-deficient mice developed granulomas 8 times larger than WT mice did. There was also no decrease in hepatic fibrosis in the sensitized mutant animals. Interferon-gamma-deficient mice failed to exhibit the exacerbated inflammatory response, despite displaying a marked deficiency in nitric oxide production. However, immune deviation was unsuccessful in the latter animals, which suggested that the increase in inflammation in NOS-deficient mice resulted from a polarized but nitric oxide-deficient type-1 response. These results reveal a beneficial role for NOS-2 in the regulation of inflammation and suggest that the ultimate success of Th2-to-Th1 immune deviation strategies will rely on the efficient activation of NOS-2 expression in downstream effector cells.

IL-10 and the dangers of immune polarization: excessive type 1 and type 2 cytokine responses induce distinct forms of lethal immunopathology in murine schistosomiasis

To dissect the controversial roles of type 1 and type 2 cytokines to the pathogenesis of schistosomiasis, we generated IL-10/IL-4- and IL-10/IL-12-deficient mice that develop highly polarized type 1 and type 2 cytokine responses, respectively. Interestingly, the Th1-polarized IL-10/IL-4-deficient mice rapidly lost weight at the onset of egg-laying and displayed 100% mortality by wk 9 postinfection. This acute mortality was linked to overexpression of the proinflammatory mediators IFN-gamma, TNF-alpha, and inducible NO and the formation of nonfibrotic granulomas. Elevated serum aspartate transaminase levels confirmed that mortality was in part attributable to acute hepatotoxicity. In contrast, the Th2-polarized IL-10/IL-12-deficient mice developed a progressive wasting disease that correlated with increased hepatic fibrosis, formation of large eosinophil-rich granulomas, a 10-fold increase in IL-4 and IL-13, and significant mortality during the chronic stages of infection. Surprisingly, IL-10-deficient mice displayed pathological features that were characteristic of both extremes, while wild-type mice developed relatively successful long term chronic infections. These data demonstrate that IL-10 significantly suppresses type 1 and type 2 cytokine development in IL-4- and IL-12-deficient mice, respectively, thereby impeding the development of severe egg-induced pathology in the single cytokine-deficient animals. Together, these findings reveal the central regulatory role of IL-10 in the pathogenesis of schistosomiasis and illustrate that excessive type 1 and type 2 cytokine responses trigger distinct, but equally detrimental, forms of pathology following infection.

CpG oligonucleotides can prophylactically immunize against Th2-mediated schistosome egg-induced pathology by an IL-12-independent mechanism

Using a Schistosoma mansoni egg-induced granuloma model, we examined the ability of CpG oligodeoxynucleotides (ODN) to suppress Th2-type cytokine expression and to prophylactically immunize against Th2-dependent pulmonary pathology. The mechanism was examined by studying Th2 response regulation in cytokine-deficient mice. Surprisingly, our findings revealed several functions of CpG DNA that were completely IL-12 independent. Most striking was the marked suppression in Th2 cytokine expression and granulomatous inflammation observed in egg/CpG-sensitized IL-12-deficient mice. Immune deviation was not dependent on NK or B cells. However, a role for IL-10, B7.1, and CD40 expression in Th2 response inhibition was suggested. Indeed, CpG ODN up-regulated all three elements in both wild-type and IL-12-deficient mice. The role of IL-10 was demonstrated in mice exhibiting combined deficiencies in IL-12 and IL-10. Here, a marked increase in egg-specific IL-4/IL-5-producing cells confirmed a role for both cytokines in Th2 response inhibition. Nevertheless, the frequency of Th2-producing cells was again reduced by CpG ODN. However, in marked contrast to IL-12-deficient animals, a significant increase in IFN-gamma-producing cells likely explains the reduced Th2 response in IL-10/IL-12-deficient mice. Thus, a novel IL-12-independent type 1-inducing pathway was revealed in the combined absence of IL-12 and IL-10. Together, these data demonstrate 1) that the Th1-promoting activity of CpG DNA is controlled by IL-12 and IL-10, and 2) that Th2 response inhibition by CpG ODN involves IL-12-independent changes in IL-10 and costimulatory molecule expression. These findings illustrate the utility of CpG DNA as adjuvants for vaccines designed to prevent Th2-dependent immunopathology.

An IL-13 inhibitor blocks the development of hepatic fibrosis during a T-helper type 2-dominated inflammatory response

In schistosomiasis, chronic parasite egg-induced granuloma formation can lead to tissue destruction and fibrosis, which causes much of the morbidity and mortality associated with this disease. Here we show the importance of IL-13 in the pathogenesis of schistosomiasis, and demonstrate, perhaps for the first time, the therapeutic efficacy of an IL-13 inhibitor, sIL-13Ralpha2-Fc, in the control of hepatic fibrosis. T-helper type 2 (Th2) cytokines dominate the immune response in mice infected with Schistosoma mansoni, yet the specific contributions of IL-13 and IL-4 to the development of fibrosis were not previously investigated. Our studies demonstrate that both cytokines play redundant roles in granuloma formation, which explains the ability of IL-4-deficient mice to form granulomas around eggs. More importantly, however, these studies demonstrate that IL-13 is the dominant Th2-type cytokine regulating fibrosis. IL-13 stimulated collagen production in fibroblasts, and procollagen I and procollagen III mRNA expression was decreased in sIL-13Ralpha2-Fc-treated mice. Moreover, the reduction in fibrosis observed in IL-4-deficient mice was much less pronounced than that in sIL-13Ralpha2-Fc-treated animals. Fibrosis is a major pathological manifestation of a number of allergic, autoimmune, and infectious diseases. Thus, our findings provide evidence that IL-13 inhibitors may be of general therapeutic benefit in preventing damaging tissue fibrosis resulting from Th2-dominated inflammatory responses.

Interleukin-12 can directly induce T-helper 1 responses in interferon-gamma (IFN-gamma) receptor-deficient mice, but requires IFN-gamma signalling to downregulate T-helper 2 responses

An in vivo model of pulmonary granuloma formation around embolized schistosome eggs was investigated as an environment in which to analyse a role for interleukin-12 (IL-12) in the differentiation of T-helper 1 (Th1) and Th2 subsets. Specifically, mice deficient for the interferon-gamma receptor (IFN-gammaR-/-) were used to determine the role for IL-12 in the absence of IFN-gamma-mediated signalling. We show that recombinant IL-12 administered to IFN-gammaR-/- mice caused the up-regulation of mRNA for IFN-gamma in lung tissue, and the secretion of abundant IFN-gamma by in vitro-cultured lymph node cells in response to egg antigens. This indicates that IL-12 can act independently of IFN-gamma to induce the development of Th1 cells. Administration of rIL-12 to wild-type mice markedly reduced the secretion of Th2-associated cytokines, IL-4 and IL-5. However, these cytokines were not dramatically reduced in IFN-gammaR-/- mice treated with IL-12. We conclude that inhibition of these cytokines by IL-12 is primarily dependent upon effective IFN-gamma signalling, although abrogation of T-cell derived IL-10 appeared to be dependent upon IL-12. We also show that increases in mRNA for the beta2 subunit of the IL-12 receptor and the p40 subunit of IL-12 after rIL-12 treatment were lower in IFN-gammaR-/- mice, compared to wild-type mice, indicating that their expression was primarily dependent upon IFN-gamma with only a minor role for IL-12.

The role of IL-13 in helminth-induced inflammation and protective immunity against nematode infections

Helminth infections induce the production of type 2 cytokines, which contribute both to expulsion of the worms and inflammatory responses that can either protect or damage the host. Although IL-4 has been considered the most critical cytokine for both inflammation and protective immunity, recent observations indicate that IL-13 - a related cytokine - can have equal or even greater importance than IL-4 in inflammatory responses and host protection against infection.

Studies with double cytokine-deficient mice reveal that highly polarized Th1- and Th2-type cytokine and antibody responses contribute equally to vaccine-induced immunity to Schistosoma mansoni

A fundamental obstacle to vaccine development in schistosomiasis mansoni is a lack of understanding of what type of an immune response should be invoked. We have addressed this central issue by using the radiation-attenuated cercariae vaccine in mice genetically engineered to exhibit highly polarized type 1 (IL-10/IL-4-deficient) or type 2 (IL-10/IL-12-deficient) cytokine and Ab phenotypes. Our data show that while significant differences in immunity exist after a single vaccination with irradiated cercariae in double cytokine-deficient vs wild-type mice, these differences disappear after two vaccinations. The most important finding of these studies, however, was revealed in vaccinated IL-10-deficient mice. These mice developed a mixed and elevated type 1- and type 2-associated immune response and developed anti-schistosome immunity at levels equal to or better than those in wild-type mice. This immunity in IL-10-deficient mice correlated with higher parasite-specific Ab titers, greater proliferative capacity of lymphocytes, increased frequency of IFN-gamma- and IL-4-secreting cells, elevated perivascular/peribronchial inflammatory responses in the lung, and greater in vitro schistosomulacidal capacity of parasite Ag-elicited cells. These results suggest that optimal vaccine-induced immunity against schistosomes is linked not to the development of a highly polarized response, but, rather, to the induction of both type 1- and type 2-associated immune responses.

Cytokine production in acute versus chronic human Schistosomiasis mansoni: the cross-regulatory role of interferon-gamma and interleukin-10 in the responses of peripheral blood mononuclear cells and splenocytes to parasite antigens

The contribution of interleukin (IL)-10 and interferon (IFN)-gamma to the regulation of type 1 and type 2 cytokine responses was investigated in Brazilians with different clinical forms of schistosomiasis mansoni. Cells from members of a family with acute intestinal schistosomiasis responded to schistosomal soluble egg antigen (SEA) or soluble adult worm antigen preparation (SWAP) with greater amounts of IFN-gamma than did cells from several patients with chronic intestinal schistosomiasis; IL-10 levels were similar. Neutralization of IL-10 had no effect on the SEA-specific IFN-gamma response in patients with acute infection, whereas SWAP-induced IFN-gamma was increased in both groups. Anti-IL-10 also up-regulated SEA-specific IFN-gamma protein and mRNA responses in most splenocyte cultures from hepatosplenic schistosomiasis patients but had no effect on antigen-specific IL-4 or IL-5 production. Neutralization of IFN-gamma resulted in a comparable increase in SWAP-specific IL-10 and IL-5, while IL-4 was not affected. These studies demonstrate that early disease in schistosomiasis is associated with a significant IFN-gamma response and that IL-10 contributes to the suppression of that response during both early and chronic infection.

Egg laying is delayed but worm fecundity is normal in SCID mice infected with Schistosoma japonicum and S. mansoni with or without recombinant tumor necrosis factor alpha treatment

Mice with severe combined immunodeficiency (SCID mice) lack functional B and T cells. Egg laying by Schistosoma mansoni and S. japonicum was delayed in SCID mice, but in a matter of weeks worm fecundity was equivalent to that in intact mice. SCID mice formed smaller hepatic granulomas and showed less fibrosis than did intact mice. The reduction in egg-associated pathology in SCID mice correlated with marked reductions in interleukin-4 (IL-4), IL-5, IL-13, and gamma interferon mRNA expression in the liver. S. mansoni infections were frequently lethal for SCID mice infected for more than 9 weeks, while S. japonicum-infected SCID mice died at the same rate as infected intact mice. We were unable to affect hepatic granuloma formation or egg laying by worms in SCID mice by administration of recombinant murine tumor necrosis factor alpha (TNF-alpha). In fact, SCID and BALB/c mice appeared to express nearly equivalent levels of TNF-alpha mRNA in their granulomatous tissues, suggesting that there is little or no deficit in TNF-alpha expression in infected SCID mice. The data indicate that TNF-alpha may be in large part derived from a non-T-cell source. Together, these findings provide little evidence that TNF-alpha alone can reconstitute early fecundity, granuloma formation, or hepatic fibrosis in schistosome-infected SCID mice.

The p47(phox-/-) mouse model of chronic granulomatous disease has normal granuloma formation and cytokine responses to Mycobacterium avium and Schistosoma mansoni eggs

Chronic granulomatous disease (CGD) is a genetic disorder of NADPH oxidase in which phagocytes are defective in generating reactive oxidants. CGD patients suffer from recurrent infections and exuberant and persistent tissue granuloma formation. We hypothesized that abnormal granulomata in CGD may result from aberrant T-cell-mediated cytokine responses. To assess Th-1-type cytokine responses and granulomata, we challenged p47(phox-/-) and wild-type mice with avirulent (SmD) or virulent (SmT) variants of Mycobacterium avium 2-151. To assess Th-2-type cytokine responses and granulomata, we used Schistosoma mansoni eggs (SME). Mononuclear cells were harvested, and cytokine responses were determined by enzyme-linked immunosorbent assay or reverse transcriptase PCR. Following SmD or SmT challenge, splenocytes from p47(phox-/-) and wild-type mice generated similar polar Th-1 responses (increased levels of gamma interferon and basal levels of interleukin 4 [IL-4] and IL-5). By 8 weeks after SmT challenge, exuberant splenic granulomata developed in p47(phox-/-) and wild-type mice. After SME challenge, thoracic lymph node mononuclear cells from p47(phox-/-) and wild-type mice generated similar mixed Th-1 and Th-2 cytokine responses to SME antigen and concanavalin A. Peak lung granuloma sizes and rates of regression were similar in p47(phox-/-) and wild-type mice. These results suggest that exuberant granulomatous inflammation in CGD is probably not the result of skewing of T-cell responses toward the Th-1 or Th-2 pole. Appropriate regression of established tissue granulomata in p47(phox-/-) mice challenged with SME suggests that abnormal granuloma formation in CGD is stimulus dependent and is not an invariant feature of the disease.

Role of cytokines in the formation and downregulation of hepatic circumoval granulomas and hepatic fibrosis in Schistosoma mansoni-infected mice

Schistosoma mansoni infections are associated with a strong Th2 cytokine response. Treatment of mice with IL-12 or anti-IL-2 or anti-IL-4 before i.v. injection of eggs increased IFN-gamma production and downregulated Th2 responses and pulmonary granuloma size. Conversely, anti-IFN-gamma antibody treatment increased Th2 responses and granuloma size. Similar manipulation produced less dramatic results in infected mice. However, sensitization of mice with eggs + IL-12 before infection augmented the Th1 response and decreased Th2 cytokines, granuloma size and fibrosis. Antisera to IFN-gamma, TNF-alpha or IL-12 during IL-12-egg immunization partly restored granuloma size and fibrosis following infection. Variations in the size of granulomas in acute (8 week) infections may be influenced primarily by the number and state of activation of T cells. In chronic (12-16 week) infections immunologic downmodulation proceeded normally in mice without functional CD8+ cells and in IFN-gamma KO mice but not in B cell KO (microMT) mice or in mice deficient in FcR expression in spite of the fact that these mice downregulated their T cell and cytokine responses. It is evident that the participation of cytokines in granuloma formation and regulation is complicated and that the mechanisms controlling both these phenomena are likely to involve both T cells and antibody/FcR interactions.

IL-13 is a key regulatory cytokine for Th2 cell-mediated pulmonary granuloma formation and IgE responses induced by Schistosoma mansoni eggs

Schistosoma mansoni egg-induced pulmonary granuloma formation is a cell-mediated inflammatory response associated with dominant Th2-type cytokine expression, tissue eosinophilia, and high levels of serum IgE. In the present study, we show that in vivo blockade of the Th2 cytokine IL-13, using soluble IL-13R alpha2-Fc fusion protein, significantly reduced the size of pulmonary granulomas in unsensitized as well as egg-sensitized mice. Blocking IL-13 also significantly reduced total serum IgE levels. Interestingly, however, IL-13 blockade did not affect the evolving egg-induced Th2-type cytokine response. IL-4, IL-5, as well as IL-13 responses were indistinguishable in control-Fc- and soluble IL-13R alpha2-Fc fusion protein-treated animals. The smaller granulomas were also phenotypically like the control Fc-treated mice, displaying a similar eosinophil content. Additional studies in IL-4-deficient mice demonstrated that IL-13 was produced, but at much lower levels than in wild-type mice, while IL-4 expression was completely independent of IL-13. Moreover, while granuloma formation was partially reduced in IL-4-deficient mice, blocking IL-13 in these animals almost completely abrogated granuloma development and the pulmonary eosinophilia, while it simultaneously increased IFN-gamma production. Together, these data demonstrate that IL-13 serves as an important mediator of Th2-mediated inflammation and plays a role in eliciting IgE responses triggered by schistosome eggs.

Optimal vaccination against Schistosoma mansoni requires the induction of both B cell- and IFN-gamma-dependent effector mechanisms

Mice immunized with radiation-attenuated cercariae of Schistosoma mansoni display resistance to challenge infection, which increases with multiple boosting. Protection in animals receiving a single vaccination is thought to involve a primarily cell-mediated, IFN-gamma-dependent mechanism, while humoral immunity has been shown to contribute to challenge rejection in multiply (three times) immunized mice. To better understand the respective contribution of the B lymphocyte- and IFN-gamma-dependent effector arms in host resistance, we compared vaccine-induced immunity in B cell-deficient (muMT) and IFN-gamma knockout (GKO) animals. Unexpectedly, after a single vaccination, B cell knockout (KO) mice displayed reduced protection against challenge infection, although they developed a normal IFN-gamma-dominated cytokine response. This defect in resistance was equivalent to that displayed by GKO animals. Moreover, whereas two additional vaccinations significantly increased the level of immunity in wild-type mice, the protection in B cell KO animals remained unchanged. In contrast, multiple vaccination resulted in increased but, nevertheless, defective resistance in GKO mice. Since FcR gamma KO mice, which lack functional FcgammaRI, FcgammaRIII, and FcepsilonRI, show no defects in vaccine-induced resistance after immunization either one or three times, the B cell-dependent mechanism of protection involved does not appear to require FcR signaling. Together, these findings indicate that effective vaccination against schistosomes depends on the simultaneous induction of both humoral and cell-mediated immunity, a conclusion that may explain the limited success of most subunit vaccine protocols designed to preferentially induce either B cell- or IFN-gamma-dependent protective mechanisms.

IFN-gamma, IL-12, and TNF-alpha are required to maintain reduced liver pathology in mice vaccinated with Schistosoma mansoni eggs and IL-12

The development of hepatic fibrosis and portal hypertension is the principal cause of morbidity and mortality in schistosomiasis mansoni. Nevertheless, relatively little is known about the mechanisms that lead to excessive collagen deposition during infection with Schistosoma mansoni. In the murine model, infection leads to significant egg-induced granuloma formation, tissue eosinophilia, and hepatic fibrosis. The pathology has been linked to dominant type 2 cytokine expression, and our recent studies showed that sensitizing animals to egg Ags in combination with IL-12, before infection, led to a highly significant reduction in egg-induced immunopathology. In this study, we demonstrate that in contrast with egg/IL-12-sensitized animals that showed marked decreases in pathology, mice similarly sensitized but depleted of IFN-gamma, IL-12, or TNF-alpha at the time of egg laying developed granulomas that were similar to the non-IL-12-treated control group. Although all three anti-cytokine-treated groups exhibited a dominant type 1 response in lymph node cells restimulated ex vivo, the expression of type 2 cytokine mRNA was markedly restored at the site of granuloma formation, which suggests that all three cytokines are required to maintain the suppressed type 2 pattern. Moreover, egg/IL-12-sensitized mice depleted of IFN-gamma or IL-12 displayed a partial reduction in IFN-gamma production, suggesting that multiple type 1 cytokines were required to maintain polarized type 1 responses to chronic type 2-inducing stimuli. Together, these data reveal key roles for IFN-gamma, IL-12, and TNF-alpha in the protective effects mediated by this IL-12-based vaccine to prevent pathology.

The debate over the effector function of eosinophils in helminth infection: new evidence from studies on the regulation of vaccine immunity by IL-12

The production of Th1-type cytokines is associated with strong cell-mediated immunity while Th2-type cytokines are typically involved in the generation of humoral immune responses. In mice vaccinated a single time (1X) with attenuated cercariae of Schistosoma mansoni, the immunity induced is highly dependent on CD4+ T cells and IFN-gamma. In contrast, mice vaccinated multiple times (3X) have decreased IFN-gamma expression, develop a more dominant Th2-type cytokine response as well as protective antibodies which can passively transfer immunity to naive recipients. Previously, we demonstrated the ability of IL-12, a potent IFN-gamma-inducing cytokine to enhance (1X) schistosome cell-mediated saline-treated mice demonstrated a 70 immunity when administered during the period of immunization. More recently, we asked what effects IL-12 would have on the development humoral-based immunity. While multiply-immunized/ saline-treated mice demonstrated a 70-80% reduction in parasite burden, 3X/IL-12-vaccinated animals displayed an even more striking > 90% reduction in challenge infection, with many mice in the later group demonstrating complete protection. Analysis of pulmonary cytokine mRNA responses demonstrated that control challenged mice elicited a dominant Th2-type response, 3X/saline-vaccinated produced a mixed Th1/Th2-type cytokine response, while 3X/IL-12-immunized animals displayed a dominant Th1-type response. The IL-12-treated group also showed a marked reduction in total serum IgE and tissue eosinophilia while SWAP-specific IgG2a and IgG2b Abs were elevated. Interestingly, animals vaccinated with IL-12 also showed a highly significant increase in total Ig titers specific for IrV, a known protective antigen. More importantly, 3X/IL-12 serum transferred significantly less protection. Nevertheless, animals vaccinated in the presence of IL-12 also develop macrophages with enhanced nitric oxide dependent killing activity against the parasites. Together, these observation suggest that IL-12, initially described as an adjuvant for cell-mediated immunity, may also be used as an adjuvant for promoting both humoral and cell-mediated protective responses.

Mice deficient for 5-lipoxygenase, but not leukocyte-type 12-lipoxygenase, display altered immune responses during infection with Schistosoma mansoni

Periovular granuloma formation during Schistosoma mansoni infection is a complex, multifaceted immunologic response. Products of arachidonic acid metabolism have been shown to contribute to this response through studies in which general inhibitors of lipoxygenase function reduce granulomatous inflammation. To determine which lipoxygenases are important for granuloma development in schistosomiasis, wild type mice or mice deficient for 5-lipoxygenase (5-LO) or "leukocyte-type" 12-lipoxygenase (12-LO) were infected with S. mansoni and studied for responses to schistosome eggs and egg antigens. At the acute stage of infection, when granuloma formation is usually maximal, 5-LO deficient mice developed smaller granulomas around liver-deposited schistosome eggs compared with wild type or 12-LO deficient mice. 5-LO mice also displayed less antibody-mediated (5 h) and cell-mediated, delayed-type (24 h) hypersensitivity to schistosome egg antigens than did the other two infection groups. In an attempt to determine possible mechanisms for the reduced inflammatory responses, we also measured hepatic mRNA levels of cytokines that have been shown to influence granuloma size (IL-4, IL-10, and IFN-gamma). The mRNA levels for IL-10 were significantly lower in 5-LO-deficient mice, but SEA-stimulated spleen cells did not demonstrate a significant difference in IL-10 production between wild type and 5-LO mice. These data suggest that 5-LO plays a role in host responses to schistosomiasis via a mechanism that cannot be explained solely by changes in expression of these cytokines.

Inducible nitric oxide synthase-deficient mice develop enhanced type 1 cytokine-associated cellular and humoral immune responses after vaccination with attenuated Schistosoma mansoni cercariae but display partially reduced resistance

High levels of nitric oxide (NO) are produced by inducible nitric oxide synthase (iNOS) in response to activating signals from Th1-associated cytokines and play an important role in cytotoxicity and cytostasis against many pathogenic microorganisms. In addition to its direct effector function, NO serves as a potent immunoregulatory factor. NO produced by gamma interferon-activated macrophages immobilizes and kills Schistosoma mansoni larvae, and several studies have indicated a role for this pathway in protective immunity against this parasite. The potential regulatory influence of NO in immunity to S. mansoni is less well understood. In this study, we have used iNOS-deficient mice to determine the role of NO in mice vaccinated with irradiated cercariae of S. mansoni. We show by enzyme-linked immunosorbent assay and reverse transcriptase PCR analysis that vaccinated iNOS-deficient mice develop exacerbated type 1 cytokine responses in the lungs, the site where resistance to infection is primarily manifested. In addition, parasite-specific immunoglobulin G2a (IgG2a) and IgG2b antibody responses were significantly increased in vaccinated iNOS-deficient animals and total IgE antibody levels in serum were decreased relative to those in wild-type controls. Surprisingly, since resistance in this vaccine model is largely Th1 dependent and since Th1-related cellular and humoral immune responses were found to be exacerbated in vaccinated iNOS-deficient mice, vaccine-elicited protective immunity against challenge infection was found to be reduced. These findings demonstrate that iNOS plays a paradoxical role in immunity to S. mansoni, both in the effector mechanism of resistance and in the down regulation of the type 1 cytokine response, which is ultimately required for NO production.