Macrophage-derived human resistin is induced in multiple helminth infections and promotes inflammatory monocytes and increased parasite burden

Resistin - A Plausible Therapeutic Target in the Pathogenesis of Psoriasis

Resistin, a cytokine hormone predominantly secreted by adipose tissue, is elevated in various metabolic disorders such as obesity, type 2 diabetes, and cardiovascular disease. In addition to its involvement in metabolic regulation, resistin has been implicated in the pathogenesis of psoriasis, a chronic inflammatory skin disorder. Numerous studies have reported increased resistin levels in psoriatic skin lesions, suggesting a possible association between resistin and psoriasis. Recent studies have suggested the potential involvement of resistin in the development and progression of certain cancers. Resistin is overexpressed in breast, colorectal, and gastric cancers. This suggests that it may play a role in the development of these cancers, possibly by inducing inflammation and cell growth. The link between resistin and cancer raises the possibility of shared underlying mechanisms driving the pathogenesis of psoriasis. Chronic inflammation, one such mechanism, is a hallmark of psoriasis and cancer. Further research is needed to fully understand the relationship between resistin and psoriasis. Identifying potential therapeutic targets is crucial for effective management of psoriasis. By doing so, we may be able to develop more effective treatment options for individuals living with psoriasis and ultimately improve their quality of life. Ultimately, a more comprehensive understanding of the mechanisms underlying the impact of resistin on psoriasis is essential for advancing our knowledge and finding new ways to treat and manage this challenging condition.

Predictive value of adipokines for the severity of acute pancreatitis: a meta-analysis

BACKGROUND

Severe acute pancreatitis (SAP) is a dangerous condition with a high mortality rate. Many studies have found an association between adipokines and the development of SAP, but the results are controversial. Therefore, we performed a meta-analysis of the association of inflammatory adipokines with SAP.

METHODS

We screened PubMed, EMBASE, Web of Science and Cochrane Library for articles on adipokines and SAP published before July 20, 2023. The quality of the literature was assessed using QUADAS criteria. Standardized mean differences (SMD) with 95% confidence intervals (CI) were calculated to assess the combined effect. Subgroup analysis, sensitivity analysis and publication bias tests were also performed on the information obtained.

RESULT

Fifteen eligible studies included 1332 patients with acute pancreatitis (AP). Pooled analysis showed that patients with SAP had significantly higher serum levels of resistin (SMD = 0.78, 95% CI:0.37 to 1.19, z = 3.75, P = 0.000). The difference in leptin and adiponectin levels between SAP and mild acute pancreatitis (MAP) patients were not significant (SMD = 0.30, 95% CI: -0.08 to 0.68, z = 1.53, P = 0.127 and SMD = 0.11, 95% CI: -0.17 to 0.40, z = 0.80, P = 0.425, respectively). In patients with SAP, visfatin levels were not significantly different from that in patients with MAP (SMD = 1.20, 95% CI: -0.48 to 2.88, z = 1.40, P = 0.162).

CONCLUSION

Elevated levels of resistin are associated with the development of SAP. Resistin may serve as biomarker for SAP and has promise as therapeutic target.

Integrated Analyses of Single-Cell Transcriptome and Mendelian Randomization Reveal the Protective Role of Resistin in Sepsis Survival in Intensive Care Unit

The high morbidity and mortality rates associated with sepsis highlight the challenges of finding specific remedies for this condition in the intensive care unit (ICU). This study aimed to explore the differentially expressed genes (DEGs) specific to cell types in sepsis and investigate the role of resistin in the survival of sepsis patients through Mendelian randomization (MR) analyses. We used single-cell and bulk transcriptome data to identify cell type-specific DEGs between sepsis and healthy controls. MR analyses were then conducted to investigate the causal relationships between resistin (one of the identified DEGs) levels and the survival of sepsis patients. Additionally, we utilized meQTL (methylation quantitative trait loci) to identify cytosine-phosphate-guanine (CpG) sites that may directly affect sepsis. We identified 560 cell type-specific DEGs between sepsis and healthy controls. Notably, we observed the upregulation of resistin levels in macrophages during sepsis. In bulk transcriptome, RETN is also upregulated in sepsis samples compared with healthy controls. MR analyses revealed a negative association existed between the expression of resistin, at both gene and protein levels, and the mortality or severity of sepsis patients in ICU. Moreover, there were no associations observed between resistin levels and death or organ failure due to other causes. We also identified three methylation CpG sites, located in RETN or its promoter region-cg06633066, cg22322184, and cg02346997-that directly affected both resistin protein levels and sepsis death in the ICU. Our findings suggest that resistin may provide feasible protection for sepsis patients, particularly those with severe cases, without serious side effects. Therefore, resistin could be a potential drug candidate for sepsis treatment. Additionally, we identified two CpG sites, cg06633066 and cg22322184, that were associated with RETN protein levels and sepsis death, providing novel insights into the underlying mechanisms of sepsis.

Genetic Variants Associated with Acne Vulgaris

Acne vulgaris (AV) ranks among the common chronic inflammatory disorders that impact the sebaceous components of hair follicles. Acne vulgaris is characterised by cardinal manifestations such as the presence of pimples, nodules, pustules, and cysts, which have the potential to lead to the development of acne scarring and pigmentation. The phenomenon is influenced by polygenic inheritance or can be ascribed to the interplay between multiple genes and environmental factors. In recent years, some researchers have found that some genes (such as IL, TNF, RETN, CYP family, MMPs and TIMPs genes et al) are associated with acne vulgaris and may affect the progression and prognosis of the disease. The number of reviews addressing acne-associated genetic variants, however, is limited. In that case, we have compiled a list of prevalent genes associated with acne in recent times. This helps us understand acne's genetic basis and lets us step in early for people prone to severe acne, lowering the chance of acne scars.

The Role of Adipokines in the Pathogenesis of Psoriasis

Psoriasis is a chronic and immune-mediated skin condition characterized by pro-inflammatory cytokines and keratinocyte hyperproliferation. Dendritic cells, T lymphocytes, and keratinocytes represent the main cell subtypes involved in the pathogenesis of psoriasis, while the interleukin-23 (IL-23)/IL-17 pathway enhances the disease progression. Human adipose tissue is an endocrine organ, which secretes multiple proteins, known as adipokines, such as adiponectin, leptin, visfatin, or resistin. Current evidence highlights the immunomodulatory roles of adipokines, which may contribute to the progression or suppression of psoriasis. A better understanding of the complexity of psoriasis pathophysiology linked with adipokines could result in developing novel diagnostic or therapeutic strategies. This review aims to present the pathogenesis of psoriasis and the roles of adipokines in this process.

Evaluation of Potential Inflammatory Markers for Cystic Echinococcosis: P-selectin and Resistin

OBJECTIVE

Cystic echinococcosis (CE) is one of the most common zoonotic diseases worldwide. Diagnosis of CE is predominantly based on imaging techniques and serological tests are used in cases of non-characteristic imaging findings as diagnostic reference. However, serological test results cannot be completely reliable as they are affected by multi-factors. P-selectin and resistin are inflammatory markers that are altered during the acute stages of infection. In this purpose, inflammatory markers as P-selectin and resistin have been investigated for a potential diagnostic reference for CE diagnosis.

METHODS

A total of 60 patients who were diagnosed with CE and twenty-five healthy individuals were included in this study. Blood samples were obtained from all participants. Obtained sera were evaluated using the P-selectin and resistin ELISA kits for protein levels. Additionally, the relative expression of SELP (P-selectin) and RETN (resistin) genes were determined using the comparative CT (ΔΔCT) method between groups as CE patients with active and inactive cysts, CE patients and healthy controls.

RESULTS

SELP (13.9-fold change, p<0.05) and RETN (8.1-fold change, p<0.05) were differentially expressed in CE patients compared in the control group. Whereas resistin protein levels were significantly higher in CE patients than the healthy controls (p<0.001), the difference in P-selectin protein levels was not significant (p>0.05). There was no difference between active and inactive CE patients in terms of P-selectin and resistin in gene and protein levels (p>0.05).

CONCLUSION

Although there was no difference between the active and inactive CE patients, the good differentiation between the healthy controls and the CE patients suggested that resistin is a potential inflammatory diagnostic reference.

Resistin Associated With Cytokines and Endothelial Cell Adhesion Molecules Is Related to Worse Outcome in COVID-19

Introduction

Resistin is reported to form a cytokine network and cause endothelial damage. The pathogenesis of coronavirus disease 2019 (COVID-19) remains unknown, but the association between cytokine storm and endothelial damage is crucial. This study aimed to evaluate resistin in COVID-19 pathogenesis compared with sepsis.

Materials and Methods

First, we evaluated the association of plasma resistin levels and disease severity and clinical outcome in two large cohorts: a publicly available cohort including 306 COVID-19 patients in the United States (MGH cohort) and our original cohort including only intubated 113 patients in Japan (Osaka cohort 1). Second, to understand pathogenesis, we evaluate resistin, cytokines and endothelial cell adhesion molecules in COVID-19 compared with sepsis. Blood samples were collected from 62 ICU-treated COVID-19 patients and 38 sepsis patients on day 1 (day of ICU admission), days 2-3, days 6-8, and from 18 healthy controls (Osaka cohort 2). The plasma resistin, inflammatory cytokines (IL-6, IL-8, MCP-1 and IL-10) and endothelial cell adhesion molecules (ICAM-1 and VCAM-1) were compared between patients and control. Correlations among resistin, inflammatory cytokines and endothelial cell adhesion molecules were evaluated in COVID-19 and sepsis.

Results

In the MGH cohort, the day 1 resistin levels were associated with disease severity score. The non-survivors showed significantly greater resistin levels than survivors on days 1, 4 and 8. In the Osaka cohort 1, 28-day non-survivors showed significantly higher resistin levels than 28-day survivors on days 6-8. Patients with late recovery (defined as the day of weaning off mechanical ventilation >12 or death) had significantly higher resistin levels than those with early recovery on day 1 and days 6-8. In the Osaka cohort 2, plasma resistin levels were elevated in COVID-19 and sepsis patients compared to controls at all measurement points and were associated with inflammatory cytokines and endothelial cell adhesion molecules.

Conclusion

Resistin was elevated in COVID-19 patients and was associated with cytokines and endothelial cell adhesion molecules. Higher resistin levels were related to worse outcome.

P38 MAPK pathway regulates the expression of resistin in porcine alveolar macrophages via Ets2 during Haemophilus parasuis stimulation

Haemophilus parasuis is a widespread bacterial pathogen causing acute systemic inflammation and leading to the sudden death of piglets. Resistin, a multifunctional peptide hormone previously demonstrated to influence the inflammation in porcine, was extremely increased in H. parasuis-infected tissues. However, the mechanism of resistin expression regulation in porcine, especially during pathogen infection, remains unclear. In the present study, we explored for the first time the transcription factor and signaling pathway mediating the expression of pig resistin during H. parasuis stimulation. We found that H. parasuis induced the expression of pig resistin in a time- and dose-dependent manner via the transcription factor Ets2 in porcine alveolar macrophages during H. parasuis stimulation. Moreover, the expression of Ets2 was mediated by the activation of the p38 MAPK pathway induced by H. parasuis, thus promoting resistin production. These results revealed a novel view of the molecular mechanism of pig resistin production during acute inflammation induced by pathogenic bacteria.

Trickle infection with Heligmosomoides polygyrus results in decreased worm burdens but increased intestinal inflammation and scarring

Introduction

Intestinal roundworms cause chronic debilitating disease in animals, including humans. Traditional experimental models of these types of infection use a large single-dose infection. However, in natural settings, hosts are exposed to parasites on a regular basis and when mice are exposed to frequent, smaller doses of Heligmosomoides polygyrus, the parasites are cleared more quickly. Whether this more effective host response has any negative consequences for the host is not known.

Results

Using a trickle model of infection, we found that worm clearance was associated with known resistance-related host responses: increased granuloma and tuft cell numbers, increased levels of granuloma IgG and decreased intestinal transit time, as well as higher serum IgE levels. However, we found that the improved worm clearance was also associated with an inflammatory phenotype in and around the granuloma, increased smooth muscle hypertrophy/hyperplasia, and elevated levels of Adamts gene expression.

Discussion

To our knowledge, we are the first to identify the involvement of this protein family of matrix metalloproteinases (MMPs) in host responses to helminth infections. Our results highlight the delicate balance between parasite clearance and host tissue damage, which both contribute to host pathology. When continually exposed to parasitic worms, improved clearance comes at a cost.

Macrophage regulation & function in helminth infection

Macrophages are innate immune cells with essential roles in host defense, inflammation, immune regulation and repair. During infection with multicellular helminth parasites, macrophages contribute to pathogen trapping and killing as well as to tissue repair and the resolution of type 2 inflammation. Macrophages produce a broad repertoire of effector molecules, including enzymes, cytokines, chemokines and growth factors that govern anti-helminth immunity and repair of parasite-induced tissue damage. Helminth infection and the associated type 2 immune response induces an alternatively activated macrophage (AAM) phenotype that - beyond driving host defense - prevents aberrant Th2 cell activation and type 2 immunopathology. The immune regulatory potential of macrophages is exploited by helminth parasites that induce the production of anti-inflammatory mediators such as interleukin 10 or prostaglandin E₂ to evade host immunity. Here, we summarize current insights into the mechanisms of macrophage-mediated host defense and repair during helminth infection and highlight recent progress on the immune regulatory crosstalk between macrophages and helminth parasites. We also point out important remaining questions such as the translation of findings from murine models to human settings of helminth infection as well as long-term consequences of helminth-induced macrophage reprogramming for subsequent host immunity.

FIZZ2 as a Biomarker for Acute Exacerbation of Chronic Obstructive Pulmonary Disease

PURPOSE

Found in inflammatory zone 2 (FIZZ2) is associated with lung inflammation. The aim of the study was to investigate the expression and utility of FIZZ2 as a marker for chronic obstructive pulmonary disease (COPD).

METHODS

Immunohistochemistry was used to detect the expression of FIZZ2 in COPD. The serum concentration of FIZZ2 was measured by enzyme-linked immunosorbent assay and the episodes of acute exacerbations of COPD (AECOPD) in the following year were recorded.

RESULTS

FIZZ2 expression was elevated in bronchial epithelial cells (0.217 ± 0.021 vs 0.099 ± 0.010, p < 0.0001) and negatively correlated with the pulmonary function (FEV1/FVC%) (p = 0.0149) and positively correlated with the smoking index (p = 0.0241). Serum level of FIZZ2 in COPD were significantly higher than that in healthy controls (561.6 ± 70.71 vs 52.24 ± 20.52 pg/ml, p < 0.0001) and increased with the COPD severity. Serum levels of FIZZ2 negatively correlated with the pulmonary function [Forced Vital Capacity (FVC), Forced Expiratory Volume (FEV1), FEV1%, FEV1/FVC) (r =  - 0.3086, - 0.3529, - 0.3343, and - 0.2676, respectively, p = 0.0003, p < 0.0001, p < 0.0001, p = 0.0014). The expression of human serum FIZZ2 was positively correlated with the smoking index (r = 0.2749, p = 0.0015). There was a positive correlation between the FIZZ2 concentration and the frequency of AECOPD episodes in the following year (r = 0.7291, p < 0.0001).

CONCLUSION

FIZZ2 expression was elevated in patients with COPD and its serum concentration might be a potential biomarker for AECOPD.

Is resistin the master link between inflammation and inflammation-related chronic diseases?

Resistin has been firstly discovered in mice and was identified as an adipose tissue-secreted hormone or adipokine linking obesity and insulin resistance. In humans, resistin has been characterized as a hormone expressed and secreted by Immune cells especially by macrophages, and was linked to many inflammatory responses including inflammation of adipose tissue due to macrophages' infiltration. Human and mouse resistin display sequence and structural similarities and also dissimilarities that could explain their different expression pattern. In mice, strong pieces of evidence clearly associated high resistin plasma levels to obesity and insulin resistance suggesting that resistin could play an important role in the onset and progression of obesity and insulin resistance via resistin-induced inflammation. In humans, the link between resistin and obesity/insulin resistance is still a matter of debate and needs more epidemiological studies. Also, resistin has been linked to other chronic diseases such as cardiovascular diseases and cancers where resistin has been proposed in many studies as a biological marker.

Resistin, a Novel Host Defense Peptide of Innate Immunity

Resistin, a cysteine-rich protein, expressed in adipocytes, was initially proposed as a link between obesity and diabetes in mice. In humans, resistin is considered to be a pro-inflammatory molecule expressed in immune cells, which plays a regulatory role in many chronic inflammatory diseases, metabolic diseases, infectious diseases, and cancers. However, increasing evidence shows that resistin functions as a host defense peptide of innate immunity, in terms of its wide-spectrum anti-microbial activity, modulation of immunity, and limitation of microbial product-induced inflammation. To date, the understanding of resistin participating in host defense mechanism is still limited. The review aims to summarize current knowledge about the biological properties, functions, and related mechanisms of resistin in host defense, which provides new insights into the pleiotropic biological function of resistin and yields promising strategies for developing new antimicrobial therapeutic agents.

Cannabinoid Receptor Subtype-1 Regulates Allergic Airway Eosinophilia During Lung Helminth Infection

Introduction: Over 1 billion humans carry infectious helminth parasites that can lead to chronic comorbidities such as anemia and growth retardation in children. Helminths induce a T-helper type 2 (Th2) immune response in the host and can cause severe tissue damage and fibrosis if chronic. We recently reported that mice infected with the soil-transmitted helminth, Nippostrongylus brasiliensis, displayed elevated levels of endocannabinoids (eCBs) in the lung and intestine. eCBs are lipid-signaling molecules that control inflammation; however, their function in infection is not well defined. Materials and Methods: A combination of pharmacological approaches and genetic mouse models was used to investigate roles for the eCB system in inflammatory responses and lung injury in mice during parasitic infection with N. brasiliensis. Results: Hemorrhaging of lung tissue in mice infected with N. brasiliensis was exacerbated by inhibiting peripheral cannabinoid receptor subtype-1 (CB1Rs) with the peripherally restricted CB1R antagonist, AM6545. In addition, these mice exhibited an increase in nonfunctional alveolar space and prolonged airway eosinophilia compared to vehicle-treated infected mice. In contrast to mice treated with AM6545, infected cannabinoid receptor subtype-2-null mice (Cnr2-/-) did not display any changes in these parameters compared to wild-type mice. Conclusions: Roles for the eCB system in Th2 immune responses are not well understood; however, increases in its activity in response to infection suggest an immunomodulatory role. Moreover, these findings suggest a role for eCB signaling at CB1Rs but not cannabinoid receptor subtypes-2 in the resolution of Th2 inflammatory responses, which become host destructive over time.

Resistin: Potential biomarker and therapeutic target in atherosclerosis

Resistin, a cysteine-rich secretory protein, has a pleiotropic role in humans. Resistin usually presents as trimer or hexamer in plasma, and targets specific receptors Toll Like Receptor 4 (TLR4) or Adenylyl Cyclase-Associated Protein 1 (CAP1). Upon binding to TLR4 and CAP1, resistin can trigger various intracellular signal transduction pathways to induce vascular inflammation, lipid accumulation, and plaque vulnerability. These pro-atherosclerotic effects of resistin appear in various cell types, including endothelial cells, vessel smooth muscle cells and macrophages, which cause diverse damages to cardiovascular system from dyslipidemia, atherosclerosis rupture and ventricular remodeling. In this review, we gather recent evidence about the pro- atherosclerotic effects of resistin and highlight it as a candidate therapeutic or diagnostic target for cardiovascular disease.

The role of resistin and myeloperoxidase in severe sepsis and septic shock: Results from the ALBIOS trial

BACKGROUND

Inflammatory biomarkers are useful in detecting patients with sepsis. The prognostic role of resistin and myeloperoxidase (MPO) has been investigated in sepsis.

MATERIALS AND METHODS

Plasma resistin and MPO were measured on days 1, 2 and 7 in 957 patients enrolled in the Albumin Italian Outcome Sepsis (ALBIOS) trial. The association between resistin and MPO levels on day 1, 2 and 7 and 90-day mortality was assessed.

RESULTS

Plasma resistin and MPO concentrations were higher at day 1 and decreased until day 7. Both biomarkers were positively correlated with each other and with physiological parameters. Higher levels of resistin and MPO on day 1 were associated with the development of new organ failures. Patients experiencing death at 90 days showed higher levels of resistin and MPO compared with survivors. At day 1, only MPO in the 4th quartile (Q4), but not resistin, was found to predict 90-day death (adjusted hazard ratio [aHR] 1.55 vs Q1). At day 2, resistin in the Q3 and Q4 predicted a > 40% increase in mortality as also did MPO in the Q4. On day 7, Q4 resistin was able to predict 90-day mortality, while all quartiles of MPO were not.

CONCLUSIONS

High levels of MPO, but not of resistin, on day 1 were able to predict 90-day mortality. These findings may either suggest that early hyper-activation of neutrophils is detrimental in patients with sepsis or reflect the burden of the inflammatory process caused by sepsis. Further studies are warranted to deepen these aspects (ALBIOS ClinicalTrials.gov Identifier: NCT00707122).

Resistin family proteins in pulmonary diseases

The family of resistin-like molecules (RELMs) consists of four members in rodents (RELMα/FIZZ1/HIMF, RELMβ/FIZZ2, Resistin/FIZZ3, and RELMγ/FIZZ4) and two members in humans (Resistin and RELMβ), all of which exhibit inflammation-regulating, chemokine, and growth factor properties. The importance of these cytokines in many aspects of physiology and pathophysiology, especially in cardiothoracic diseases, is rapidly evolving in the literature. In this review article, we attempt to summarize the contribution of RELM signaling to the initiation and progression of lung diseases, such as pulmonary hypertension, asthma/allergic airway inflammation, chronic obstructive pulmonary disease, fibrosis, cancers, infection, and other acute lung injuries. The potential of RELMs to be used as biomarkers or risk predictors of these diseases also will be discussed. Better understanding of RELM signaling in the pathogenesis of pulmonary diseases may offer novel targets or approaches for the development of therapeutics to treat or prevent a variety of inflammation, tissue remodeling, and fibrosis-related disorders in respiratory, cardiovascular, and other systems.

The Network of Colonic Host Defense Peptides as an Innate Immune Defense Against Enteropathogenic Bacteria

Host defense peptides, abundantly secreted by colonic epithelial cells and leukocytes, are proposed to be critical components of an innate immune response in the colon against enteropathogenic bacteria, including Shigella spp., Salmonella spp., Clostridium difficile, and attaching and effacing Escherichia coli and Citrobacter rodentium. These short cationic peptides are bactericidal against both Gram-positive and -negative enteric pathogens, but may also exert killing effects on intestinal luminal microbiota. Simultaneously, these peptides modulate numerous cellular responses crucial for gut defenses, including leukocyte chemotaxis and migration, wound healing, cytokine production, cell proliferation, and pathogen sensing. This review discusses recent advances in our understanding of expression, mechanisms of action and microbicidal and immunomodulatory functions of major colonic host defense peptides, namely cathelicidins, β-defensins, and members of the Regenerating islet-derived protein III (RegIII) and Resistin-like molecule (RELM) families. In a theoretical framework where these peptides work synergistically, aspects of pathogenesis of infectious colitis reviewed herein uncover roles of host defense peptides aimed to promote epithelial defenses and prevent pathogen colonization, mediated through a combination of direct antimicrobial function and fine-tuning of host immune response and inflammation. This interactive host defense peptide network may decode how the intestinal immune system functions to quickly clear infections, restore homeostasis and avoid damaging inflammation associated with pathogen persistence during infectious colitis. This information is of interest in development of host defense peptides (either alone or in combination with reduced doses of antibiotics) as antimicrobial and immunomodulatory therapeutics for controlling infectious colitis.

Interactions between macrophages and helminths

Macrophages, the major population of tissue-resident mononuclear phagocytes, contribute significantly to the immune response during helminth infection. Alternatively activated macrophages (AAM) are induced early in the anti-helminth response following tissue insult and parasite recognition, amplifying the early type 2 immune cascade initiated by epithelial cells and ILC2s, and subsequently driving parasite expulsion. AAM also contribute to functional alterations in tissues infiltrated with helminth larvae, mediating both tissue repair and inflammation. Their activation is amplified and occurs more rapidly following reinfection, where they can play a dual role in trapping tissue migratory larvae and preventing or resolving the associated inflammation and damage. In this review, we will address both the known and emerging roles of tissue macrophages during helminth infection, in addition to considering both outstanding research questions and new therapeutic strategies.

Elevation of C-reactive protein, P-selectin and Resistin as potential inflammatory biomarkers of urogenital Schistosomiasis exposure in preschool children

Background

Schistosomiasis is known to induce inflammatory immune responses. C-reactive protein (CRP), resistin and P-selectin are serological inflammatory markers that rise during the acute stages of infection. Here, we propose such inflammatory biomarkers have a potential for use in urogenital schistosomiasis diagnostic screening for exposure and infection in preschool-aged children.

Methods

As part of a larger study on urogenital schistosomiasis, 299 preschool children aged 1–5 years were included in this cross-sectional study. Parasitological diagnosis was conducted using urine filtration for Schistosoma haemtobium infection, and Kato Katz for S. mansoni infection. Serum levels of P-selectin, resistin, CRP, and antibodies against S. haematobium cercarial antigen preparation (CAP) and soluble worm antigen preparation (SWAP) were measured by ELISA.

Results

Of the 299 participants, 14% were egg positive for S. haematobium. Serology showed 46 and 9% of the participants to have been exposed to S. haematobium cercarial antigens and adult worm antigens, respectively. Levels of P-selectin were significantly higher in participants infected with S. haematobium (egg-positive) than in uninfected participants (p = 0.001). Levels of P-selectin were also higher in those exposed to cercarial antigen than in unexposed participants (p = 0.019). There was a positive correlation between P-selectin and infection intensity (r = 0.172; p = 0.002), as well as with IgM responses to CAP and SWAP (r = 0.183; p = 0.001); (r = 0.333; p < 0.0001) respectively. CRP significantly correlated with IgM responses to CAP (r = 0.133; p = 0.029) while resistin correlated with IgM responses to CAP and SWAP (r = 0.127; p = 0.016); (r = 0.197; p = 0.0004). CRP levels were higher in those exposed to cercarial and adult worm antigens than unexposed participants (p = 0.035); (p = 0.002) respectively, while resistin was higher in participants exposed to cercarial antigen than unexposed participants (p = 0.024).

Conclusion

In this preschool population, P-selectin is significantly associated with urogenital schistosome infection and intensity; hence a potential biomarker for infection diagnosis and disease monitoring. The inflammatory biomarkers (P-selectin, Resistin and CRP) were significantly higher in participants exposed to cercarial antigens than unexposed individuals indicating an underlying inflammatory environment.

Eosinophils and Macrophages within the Th2-Induced Granuloma: Balancing Killing and Healing in a Tight Space

Granuloma formation is a key host immune response generated to confine invading pathogens and limit extensive host damage. It consists of an accumulation of host immune cells around a pathogen. This host response has been extensively studied in the context of inflammatory diseases. However, there is much less known about Th2-type granulomas generated in response to parasitic worms. Based on in vitro data, innate immune cells within the granuloma are thought to immobilize and kill parasites but also act to repair damaged tissue. Understanding this dual function is key. The two billion people and many livestock/wild animals infected with helminths demonstrate that granulomas are not effective at clearing infection. However, the lack of high mortality highlights their importance in ensuring that parasite migration/tissue damage is restricted and wound healing is effective. In this review, we define two key cellular players (macrophages and eosinophils) and their associated molecular players involved in Th2 granuloma function. To date, the underlying mechanisms remain poorly understood, which is in part due to a lack of conclusive studies. Most have been performed in vitro rather than in vivo, using cells that have not been obtained from granulomas. Experiments using genetically modified mouse strains and/or antibody/chemical-mediated cell depletion have also generated conflicting results depending on the model. We discuss the caveats of previous studies and the new tools available that will help fill the gaps in our knowledge and allow a better understanding of the balance between immune killing and healing.

Resistin directly inhibits bacterial killing in neutrophils

Background

Sepsis-induced immunosuppression is a key factor contributing to the morbidity and mortality of critically ill patients, and polymorphonuclear neutrophil dysfunction is believed to be a hallmark of this immunosuppression. Circulating myeloid cells produce the cytokine resistin (RETN), which has been associated with poor outcomes in sepsis/septic shock and can directly inhibit neutrophil function. We previously demonstrated that resistin caused a dose-dependent impairment in neutrophil migration, reactive oxygen species production, and bacterial clearance in neutrophil cell lines. However, the relative antimicrobial responses of other innate immune cells to Gram-positive and Gram-negative infections in the presence of elevated levels of resistin have not been evaluated. We hypothesized that resistin directly contributes to sepsis-induced immunosuppression by selectively targeting the neutrophil component of the innate cellular immune system. Thus, the goal of the present study was to compare the effect of resistin on bacterial killing using monocultures or co-cultures of monocyte and neutrophil cell lines, as well as to extend our findings to primary immune cells.

Results

Our results indicate that human resistin impairs the ability of neutrophils to kill the Gram-negative bacterium Pseudomonas aeruginosa and the Gram-positive bacterium Staphylococcus aureus. In contrast, with the exception of macrophages incubated with P. aeruginosa, resistin did not affect the ability of macrophages or monocytes to kill either Gram-positive or Gram-negative organisms. Furthermore, co-incubation of neutrophils with increasing proportions of monocytes did not enhance bacterial killing. Resistin blocked bactericidal activity through partial reduction of F-actin polymerization and suppression of the oxidative burst in neutrophils.

Conclusions

Our studies indicate that resistin selectively impairs neutrophil bacterial killing. These findings further support the notion that resistin can mimic cell type-dependent immunosuppressive effects. This is consistent with its putative role in the pathogenesis of bacterial sepsis.

Associations between soil-transmitted helminthiasis and viral, bacterial, and protozoal enteroinfections: a cross-sectional study in rural Laos

Background

Humans are susceptible to over 1400 pathogens. Co-infection by multiple pathogens is common, and can result in a range of neutral, facilitative, or antagonistic interactions within the host. Soil-transmitted helminths (STH) are powerful immunomodulators, but evidence of the effect of STH infection on the direction and magnitude of concurrent enteric microparasite infections is mixed.

Methods

We collected fecal samples from 891 randomly selected children and adults in rural Laos. Samples were analyzed for 5 STH species, 6 viruses, 9 bacteria, and 5 protozoa using a quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay. We utilized logistic regression, controlling for demographics and household water, sanitation, and hygiene access, to examine the effect of STH infection on concurrent viral, bacterial, and protozoal infection.

Results

We found that STH infection was associated with lower odds of concurrent viral infection [odds ratio (OR): 0.48, 95% confidence interval (CI): 0.28–0.83], but higher odds of concurrent bacterial infections (OR: 1.81, 95% CI: 1.06–3.07) and concurrent protozoal infections (OR: 1.50, 95% CI: 0.95–2.37). Trends were consistent across STH species.

Conclusions

The impact of STH on odds of concurrent microparasite co-infection may differ by microparasite taxa, whereby STH infection was negatively associated with viral infections but positively associated with bacterial and protozoal infections. Results suggest that efforts to reduce STH through preventive chemotherapy could have a spillover effect on microparasite infections, though the extent of this impact requires additional study. The associations between STH and concurrent microparasite infection may reflect a reverse effect due to the cross-sectional study design. Additional research is needed to elucidate the exact mechanism of the immunomodulatory effects of STH on concurrent enteric microparasite infection.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3471-2) contains supplementary material, which is available to authorized users.

Host- and Helminth-Derived Endocannabinoids That Have Effects on Host Immunity Are Generated during Infection

Helminths have coevolved with their hosts, resulting in the development of specialized host immune mechanisms and parasite-specific regulatory products. Identification of new pathways that regulate helminth infection could provide a better understanding of host-helminth interaction and may identify new therapeutic targets for helminth infection. Here we identify the endocannabinoid system as a new mechanism that influences host immunity to helminths. Endocannabinoids are lipid-derived signaling molecules that control important physiologic processes, such as feeding behavior and metabolism. Following murine infection with Nippostrongylus brasiliensis, an intestinal nematode with a life cycle similar to that of hookworms, we observed increased levels of endocannabinoids (2-arachidonoylglycerol [2-AG] or anandamide [AEA]) and the endocannabinoid-like molecule oleoylethanolamine (OEA) in infected lung and intestine. To investigate endocannabinoid function in helminth infection, we employed pharmacological inhibitors of cannabinoid subtype receptors 1 and 2 (CB₁R and CB₂R). Compared to findings for vehicle-treated mice, inhibition of CB₁R but not CB₂R resulted in increased N. brasiliensis worm burden and egg output, associated with significantly decreased expression of the T helper type 2 cytokine interleukin 5 (IL-5) in intestinal tissue and splenocyte cultures. Strikingly, bioinformatic analysis of genomic and transcriptome sequencing (RNA-seq) data sets identified putative genes encoding endocannabinoid biosynthetic and degradative enzymes in many parasitic nematodes. To test the novel hypothesis that helminth parasites produce their own endocannabinoids, we measured endocannabinoid levels in N. brasiliensis by mass spectrometry and quantitative PCR and found that N. brasiliensis parasites produced endocannabinoids, especially at the infectious larval stage. To our knowledge, this is the first report of helminth- and host-derived endocannabinoids that promote host immune responses and reduce parasite burden.

Here, there and everywhere: Resistin-like molecules in infection, inflammation, and metabolic disorders

The Resistin-Like Molecules (RELM) α, β, and γ and their namesake, resistin, share structural and sequence homology but exhibit significant diversity in expression and function within their mammalian host. RELM proteins are expressed in a wide range of diseases, such as: microbial infections (eg. bacterial and helminth), inflammatory diseases (eg. asthma, fibrosis) and metabolic disorders (eg. diabetes). While the expression pattern and molecular regulation of RELM proteins are well characterized, much controversy remains over their proposed functions, with evidence of host-protective and pathogenic roles. Moreover, the receptors for RELM proteins are unclear, although three receptors for resistin, decorin, adenylyl cyclase-associated protein 1 (CAP1), and Toll-like Receptor 4 (TLR4) have recently been proposed. In this review, we will first summarize the molecular regulation of the RELM gene family, including transcription regulation and tissue expression in humans and mouse disease models. Second, we will outline the function and receptor-mediated signaling associated with RELM proteins. Finally, we will discuss recent studies suggesting that, despite early misconceptions that these proteins are pathogenic, RELM proteins have a more nuanced and potentially beneficial role for the host in certain disease settings.

Activation of the porcine alveolar macrophages via toll-like receptor 4/NF-κB mediated pathway provides a mechanism of resistin leading to inflammation

Resistin, a previously discovered cysteine-rich adipokine known to regulate glucose metabolism, has been emerged as a mediator in inflammation and immunity. Its level was supposed to be related to the expression of indicators, such as interleukin-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α) in inflammation. Toll-like receptor 4 (TLR4) was reported to be a receptor for resistin in cells, like leukocytes and peripheral blood mononuclear cells (PBMC). However, the pro-inflammatory role of resistin and its intracellular mechanisms in alveolar macrophages have not been thoroughly validated. Here we found that the pro-inflammatory cytokine expression in porcine alveolar macrophages (PAMs) was positively correlated with resistin. Our results also showed that resistin induced the expression of TLR4, intracellular molecules myeloid differentiation primary response protein 88 (MyD88), TRIF-related adaptor molecule (TRAM) and nuclear factor κB (NF-κB) in PAMs. In contrast, inhibition of TLR4, MyD88, TRAM and NF-κB abrogated the pro-inflammatory effect of resistin on PAMs. Additionally, the associations among TLR4, MyD88/TRAM and NF-κB were investigated by introducing TLR4-siRNA, MyD88-siRNA and TRAM-siRNA respectively into PAMs prior to the treatment with resistin. Taken together, our findings demonstrated that resistin promoted the production of pro-inflammatory cytokine in PAMs via TLR4/NF-κB-mediated pathway (TLR4/MyD88/TRAM/NF-κB).

Human resistin protects against endotoxic shock by blocking LPS-TLR4 interaction

Helminths trigger multiple immunomodulatory pathways that can protect from sepsis. Human resistin (hRetn) is an immune cell-derived protein that is highly elevated in helminth infection and sepsis. However, the function of hRetn in sepsis, or whether hRetn influences helminth protection against sepsis, is unknown. Employing hRetn-expressing transgenic mice (hRETNTg⁺) and recombinant hRetn, we identify a therapeutic function for hRetn in lipopolysaccharide (LPS)-induced septic shock. hRetn promoted helminth-induced immunomodulation, with increased survival of Nippostrongylus brasiliensis (Nb)-infected hRETNTg⁺ mice after a fatal LPS dose compared with naive mice or Nb-infected hRETNTg^- mice. Employing immunoprecipitation assays, hRETNTg⁺Tlr4^-/- mice, and human immune cell culture, we demonstrate that hRetn binds the LPS receptor Toll-like receptor 4 (TLR4) through its N terminal and modulates STAT3 and TBK1 signaling, triggering a switch from proinflammatory to anti-inflammatory responses. Further, we generate hRetn N-terminal peptides that are able to block LPS proinflammatory function. Together, our studies identify a critical role for hRetn in blocking LPS function with important clinical significance in helminth-induced immunomodulation and sepsis.

Effect of anthelmintic treatment on leptin, adiponectin and leptin to adiponectin ratio: a randomized-controlled trial

Emerging evidence suggests that helminths might confer protection against the development of type 2 diabetes. We aimed to assess the role of adipokines in mediating the effect of helminths on insulin resistance. Serum samples were obtained from a randomized-controlled trial of anthelmintic treatment in an area endemic for soil-transmitted helminths (STH), Flores Island, Indonesia. In STH-infected subjects, anthelmintic treatment significantly increased the ratio of leptin to adiponectin (treatment effect factor (95% confidence interval (CI)), P-value for interaction: 1.20 (1.06-1.35), P=0.010), which largely stemmed from a significant reduction in adiponectin (0.91 (0.85-0.98), P=0.020) and a trend for an increase in leptin level (1.10 (1.00-1.21), P=0.119). No significant effect on resistin level was observed. This increase in leptin to adiponectin ratio seemed to contribute to the observed effect of deworming on increased insulin resistance (IR) as adjustment for leptin to adiponectin ratio attenuated the effect on IR from 1.07 (1.01-1.14, P=0.023) to 1.05 (0.99-1.11, P=0.075). Anthelmintic treatment in STH-infected subjects increases leptin to adiponectin ratio which may in small part contribute to the modest increase in IR. Further studies will be needed to assess the effect of the changes in adipokine levels on the host immune response and metabolism.

Resistin-like molecule β is a bactericidal protein that promotes spatial segregation of the microbiota and the colonic epithelium

The mammalian intestine is colonized by trillions of bacteria that perform essential metabolic functions for their hosts. The mutualistic nature of this relationship depends on maintaining spatial segregation between these bacteria and the intestinal epithelial surface. This segregation is achieved in part by the presence of a dense mucus layer at the epithelial surface and by the production of antimicrobial proteins that are secreted by epithelial cells into the mucus layer. Here, we show that resistin-like molecule β (RELMβ) is a bactericidal protein that limits contact between Gram-negative bacteria and the colonic epithelial surface. Mouse and human RELMβ selectively killed Gram-negative bacteria by forming size-selective pores that permeabilized bacterial membranes. In mice lacking RELMβ, Proteobacteria were present in the inner mucus layer and invaded mucosal tissues. Another RELM family member, human resistin, was also bactericidal, suggesting that bactericidal activity is a conserved function of the RELM family. Our findings thus identify the RELM family as a unique family of bactericidal proteins and show that RELMβ promotes host-bacterial mutualism by regulating the spatial segregation between the microbiota and the intestinal epithelium.

Resistin Gene Expression is Downregulated in CD4(+) T Helper Lymphocytes and CD14(+) Monocytes in Rheumatoid Arthritis Responding to TNF-α Inhibition

Rheumatoid arthritis (RA) is caused by complex interactions between immune cells and sustained by Th1 response cytokines. Resistin [resistance to insulin; (RETN)] is an inflammatory cytokine, first discovered in murine adipocytes. In man, RETN is mainly secreted by monocytes. The distinct role of RETN in the immune reaction is uncertain; however, RETN has pro-inflammatory, pro-fibrotic and possibly tolerogenic properties. The aim was to assess the reaction of RETN gene expression to TNF-α inhibition (I) in pathogenetic immune cell subsets in RA, in the context of Th1, inflammatory and regulatory cytokine gene expressions. Accordingly, we measured RETN, IFN-γ, TNF-β, IL-1β, TNF-α, TGF-β and IL-10 gene expressions in CD14(+) monocytes, CD4(+) T helper (Th) lymphocytes (ly), CD8(+) T cytotoxic (Tc) ly and CD19(+) B ly in active RA before and 3 months after start of TNF-αI. Leucocyte subsets were separated by specific monoclonal antibody-covered beads, RNA extracted and levels of RETN, Th1 response, inflammatory and regulatory cytokine mRNAs measured by quantitative reverse transcription-polymerase chain reaction technique. We found that TNF-αI caused a significant downregulation of RETN gene expression in CD14(+) monocytes and CD4(+) Th ly and was unchanged in CD8(+) Tc ly and CD19(+) B ly. Both in active RA and during TNF-αI, RETN mRNA levels were significantly higher in CD14(+) monocytes than in all other examined cell types. In monocytes, fold change in RETN and TGF-β gene expressions upon TNF-αI correlated significantly. Our findings indicate that RETN has pro-inflammatory as well as proresolving roles in active RA.

Cytokine profiles in patients with toxoplasmic lymphadenitis in the setting of pregnancy

INTRODUCTION

Majority of Toxoplasma gondii infections are benign and asymptomatic; however, some patients experience toxoplasmic lymphadenitis (TL). Factors associated as to whether infection will be symptomatic or not are unknown.

METHODS

Dye test titers of patients with acute toxoplasmosis (pregnant and not pregnant) with TL (TL+) were compared with those in patients with asymptomatic acute infection (TL-). Additionally, mean levels of 62 serum cytokines were compared between TL+ and TL- pregnant women and between TL+ pregnant and non-pregnant women.

RESULTS

During acute infection, mean dye test titer was higher in TL+ than in TL- patients (p=0.021). In addition, out of 62 cytokines, CXCL9andCXCL10 levels were higher (p<0.05) and resistin mean levels were lower (p<0.05) in pregnant women with TL+ compared to TL-. Among patients with TL+, levels of VCAM1andCCL2 were lower (p<0.05) in pregnant women than in non-pregnant women.

CONCLUSION

Here we report differences in dye test titers in patients with acute infection. Cytokine responses vary according to the presence of TL+ and to the pregnancy status. Factors underlying these differences are presently unknown and require further studies to define individual and combined roles of cytokines in TL+.

Immune polarization by hookworms: taking cues from T helper type 2, type 2 innate lymphoid cells and alternatively activated macrophages

Cellular and molecular investigation of parasitic helminth infections has greatly accelerated the understanding of type 2 immune responses. However, there remains considerable debate regarding the specific leucocytes that kill parasites and whether these mechanisms are distinct from those responsible for tissue repair. Herein, we chronicle discoveries over the past decade highlighting current paradigms in type 2 immunity with a particular emphasis upon how CD4(+) T helper type 2 cells, type 2 innate lymphoid cells and alternatively activated macrophages coordinately control helminth-induced parasitism. Primarily, this review will draw from studies of the murine nematode parasite Nippostrongylus brasiliensis, which bears important similarities to the human hookworms Ancylostoma duodenale and Necator americanus. Given that one or more hookworm species currently infect millions of individuals across the globe, we propose that vaccine and/or pharmaceutical-based cure strategies targeting these affected human populations should incorporate the conceptual advances outlined herein.

RELMs in the Realm of Helminths

Resistin-like molecule (RELM) proteins are essential for immunity to helminths. Recently, Chen and collaborators identified a dominant role for RELMα over RELMβ in host immunity to Nippostrongylus brasiliensis using a double knockout system. The study highlighted how important and yet divergent the contributions of these proteins are in the control of helminth infections.

Comparison of RELMα and RELMβ Single- and Double-Gene-Deficient Mice Reveals that RELMα Expression Dictates Inflammation and Worm Expulsion in Hookworm Infection

Resistin-like molecules (RELMs) are highly expressed following helminth infection, where they impact both the host and helminth. While RELMα (Retnla) impairs helminth expulsion by inhibiting protective Th2 immunity, RELMβ (Retnlb) can promote its expulsion. We employed Retnla(-/-) and Retnlb(-/-) mice to delineate the function of both proteins following infection with Nippostrongylus brasiliensis, a hookworm that infects the lung and intestine. Whereas wild-type (WT) and Retnlb(-/-)mice exhibited equivalent infection-induced inflammation, Retnla(-/-) mice suffered a heightened inflammatory response, including increased mortality, weight loss, and lung inflammation. In the intestine, Retnla(-/-)mice had low parasite egg burdens compared to those of WT mice, while Retnlb(-/-) mice exhibited high egg burdens, suggesting that RELMα and RELMβ have functionally distinct effects on immunity and inflammation to N. brasiliensis To test the importance of both proteins, we generated Retnla(-/-) Retnlb(-/-) mice. Infected Retnla(-/-)Retnlb(-/-) mice exhibited similar responses to Retnla(-/-) mice, including increased mortality and lung inflammation. This inflammatory response in Retnla(-/-) Retnlb(-/-) mice negatively impacted N. brasiliensis fitness, as demonstrated by significantly lower worm ATP levels and decreased intestinal worm burden and fecundity. Lung cytokine analysis revealed that Retnla(-/-) and Retnla(-/-) Retnlb(-/-) mice expressed significantly increased levels of interleukin-4 (IL-4). Finally, we generated Retnla(-/-) mice on the Rag(-/-) background and observed that the effects of RELMα were abrogated in the absence of adaptive immunity. Together, these data demonstrate that RELMα but not RELMβ significantly impacts the immune response toN. brasiliensis infection by downregulating the Th2 adaptive immune response in the lung, which protects the host but allows improved parasite fitness.

Strongyloides stercoralis, Eosinophilia, and Type 2 Diabetes Mellitus: The Predictive Value of Eosinophilia in the Diagnosis of S stercoralis Infection in an Endemic Community

Background.  This study examines the predictive value of eosinophilia for Strongyloides stercoralis infection, as measured by enzyme-linked immunosorbent assay (ELISA) testing, in an endemic community. In remote communities, eosinophilia is frequently used as a proxy test for the presence of helminth infections. Past studies of eosinophilia and Strongyloides infection have been conducted in specific groups such as immigrants and refugees, or in subpopulations of nonendemic communities, rather than in endemic communities. Methods.  We conducted a cross-sectional study of the relationship between eosinophilia and Strongyloides ELISA serology, as part of a study into the relationship between S stercoralis infection and type 2 diabetes mellitus (T2DM) in an Indigenous community in northern Australia. Results.  Two hundred thirty-nine adults had their eosinophil count and S stercoralis ELISA serology measured in 2012 and 2013, along with other biometric and metabolic data. Eosinophilia was found to have a relatively poor sensitivity (60.9%), specificity (71.1%), positive predictive value (54.6%), and negative predictive value (76.1%) for S stercoralis ELISA positivity in this group. However, there was a more constant relationship between eosinophilia and S Stercoralis ELISA positivity in patients with T2DM (negative predictive value 87.5%). Conclusion.  This study suggests that the presence or absence of eosinophilia is not an adequate proxy test for S stercoralis infection in a community where the infection is prevalent, and that the association between eosinophilia and S stercoralis ELISA positivity is more constant in patients with T2DM.

Hypoxia-Inducible Factor 1α Is a Critical Downstream Mediator for Hypoxia-Induced Mitogenic Factor (FIZZ1/RELMα)-Induced Pulmonary Hypertension

OBJECTIVE

Pulmonary hypertension (PH) is characterized by progressive elevation of pulmonary vascular resistance, right ventricular failure, and ultimately death. We have shown that in rodents, hypoxia-induced mitogenic factor (HIMF; also known as FIZZ1 or resistin-like molecule-β) causes PH by initiating lung vascular inflammation. We hypothesized that hypoxia-inducible factor-1 (HIF-1) is a critical downstream signal mediator of HIMF during PH development.

APPROACH AND RESULTS

In this study, we compared the degree of HIMF-induced pulmonary vascular remodeling and PH development in wild-type (HIF-1α(+/+)) and HIF-1α heterozygous null (HIF-1α(+/-)) mice. HIMF-induced PH was significantly diminished in HIF-1α(+/-) mice and was accompanied by a dysregulated vascular endothelial growth factor-A-vascular endothelial growth factor receptor 2 pathway. HIF-1α was critical for bone marrow-derived cell migration and vascular tube formation in response to HIMF. Furthermore, HIMF and its human homolog, resistin-like molecule-β, significantly increased interleukin (IL)-6 in macrophages and lung resident cells through a mechanism dependent on HIF-1α and, at least to some extent, on nuclear factor κB.

CONCLUSIONS

Our results suggest that HIF-1α is a critical downstream transcription factor for HIMF-induced pulmonary vascular remodeling and PH development. Importantly, both HIMF and human resistin-like molecule-β significantly increased IL-6 in lung resident cells and increased perivascular accumulation of IL-6-expressing macrophages in the lungs of mice. These data suggest that HIMF can induce HIF-1, vascular endothelial growth factor-A, and interleukin-6, which are critical mediators of both hypoxic inflammation and PH pathophysiology.

Type 2 Diabetes Mellitus Is Associated with Strongyloides stercoralis Treatment Failure in Australian Aboriginals

Objective

To explore the efficacy of ivermectin in the treatment of serologically diagnosed cases of Strongyloides stercoralis (S. stercoralis) infection in an Aboriginal community and to describe factors that may influence the outcome of treatment.

Methods

Longitudinal study of a group of 92 individuals with serologically diagnosed S. stercoralis treated with ivermectin and followed up over a period of approximately 6 months. Main outcomes were serological titers pre and post treatment, diabetic status, and duration of follow up.

Findings

Treatment success was achieved in 62% to 79% of cases dependent on the methods employed for the diagnosis of infection and assessment of treatment outcome. Type 2 Diabetes Mellitus (T2DM) was found to be significantly associated with treatment failure in this group for two of the three methods employed.

Interpretation

Ivermectin has been confirmed as an effective treatment for S stercoralis infection in this setting. T2DM appears to be an independent risk factor for treatment failure in this population, and plausible mechanisms to explain this observation are presented.

In this study we examine the treatment of the intestinal worm infection Strongyloides stercoralis, a soil transmitted helminth that is common in the developing world and in the Aboriginal communities of northern Australia. Oral ivermectin is generally accepted as the treatment of choice for this condition. We screened an Aboriginal community for Strongyloides infection over the course of 2 years and measured the outcome of treatment in the 92 cases we found. This study measures the success or otherwise of treatment, and looks at whether there are any factors that could influence the rate of treatment failure. The results suggest that ivermectin is an effective treatment for Strongyloides in this setting, and that pre-existing Type 2 Diabetes Mellitus is a risk factor for treatment failure, an observation of great interest in Aboriginal communities where the prevalence of both conditions is very high. We discuss some possible mechanisms to help explain this previously unknown relationship.

Goblet Cell Derived RELM-β Recruits CD4+ T Cells during Infectious Colitis to Promote Protective Intestinal Epithelial Cell Proliferation

Enterohemorrhagic Escherichia coli and related food and waterborne pathogens pose significant threats to human health. These attaching/effacing microbes infect the apical surface of intestinal epithelial cells (IEC), causing severe diarrheal disease. Colonizing the intestinal luminal surface helps segregate these microbes from most host inflammatory responses. Based on studies using Citrobacter rodentium, a related mouse pathogen, we speculate that hosts rely on immune-mediated changes in IEC, including goblet cells to defend against these pathogens. These changes include a CD4⁺ T cell-dependent increase in IEC proliferation to replace infected IEC, as well as altered production of the goblet cell-derived mucin Muc2. Another goblet cell mediator, REsistin-Like Molecule (RELM)-β is strongly induced within goblet cells during C. rodentium infection, and was detected in the stool as well as serum. Despite its dramatic induction, RELM-β’s role in host defense is unclear. Thus, wildtype and RELM-β gene deficient mice (Retnlb^-/-) were orally infected with C. rodentium. While their C. rodentium burdens were only modestly elevated, infected Retnlb^-/- mice suffered increased mortality and mucosal ulceration due to deep pathogen penetration of colonic crypts. Immunostaining for Ki67 and BrDU revealed Retnlb^-/- mice were significantly impaired in infection-induced IEC hyper-proliferation. Interestingly, exposure to RELM-β did not directly increase IEC proliferation, rather RELM-β acted as a CD4⁺ T cell chemoattractant. Correspondingly, Retnlb^-/- mice showed impaired CD4⁺ T cell recruitment to their infected colons, along with reduced production of interleukin (IL)-22, a multifunctional cytokine that directly increased IEC proliferation. Enema delivery of RELM-β to Retnlb^-/- mice restored CD4⁺ T cell recruitment, concurrently increasing IL-22 levels and IEC proliferation, while reducing mucosal pathology. These findings demonstrate that RELM-β and goblet cells play an unexpected, yet critical role in recruiting CD4⁺ T cells to the colon to protect against an enteric pathogen, in part via the induction of increased IEC proliferation.

Food and water-borne bacterial pathogens such as enterohemorrhagic Escherichia coli (EHEC) target the epithelial cells that line the inner surface of their host’s intestines, causing inflammation and diarrhea. While professional immune cells including T lymphocytes are well known for promoting host defense, we hypothesized that as the cells in closest contact with these bacterial pathogens, intestinal epithelial cells also play an active and essential role in protecting the host during infection. Infecting mice with Citrobacter rodentium, a mouse specific relative of EHEC, we noted a dramatic upregulation in the expression and secretion of the mediator RELM-β by a subset of epithelial cells called goblet cells. Compared to wildtype mice, mice lacking RELM-β showed less epithelial cell proliferation and suffered significantly more intestinal damage during infection. Rather than directly causing epithelial cell proliferation, we found RELM-β instead recruited T lymphocytes to the infected intestine. Upon reaching the intestine, the T lymphocytes produced the cytokine interleukin-22, which directly increased epithelial cell proliferation. Taken together, these findings indicate that epithelial/goblet cells play a critical role in orchestrating the host response to an intestinal pathogen, by recruiting T lymphocytes and by promoting epithelial proliferation to limit the intestinal damage suffered during infection.

Non-traditional cytokines: How catecholamines and adipokines influence macrophages in immunity, metabolism and the central nervous system

Catecholamines and adipokines function as hormones; catecholamines as neurotransmitters in the sympathetic nervous system, and adipokines as mediators of metabolic processes. It has become increasingly clear, however, that both also function as immunomodulators of innate and adaptive immune cells, including macrophages. Macrophages can respond to, as well as produce their own catecholamines. Dopamine, noradrenaline, and adrenaline are the most abundant catecholamines in the body, and can induce both pro-inflammatory and anti-inflammatory immune responses in macrophages, as well as non-immune processes such as thermogenesis. Though they are responsive to adipokines, particularly lipoproteins, leptin, and adiponectin, macrophages generally do not synthesize their own adipokines, with the exception being resistin-like molecules. Adipokines contribute to adverse metabolic and immune responses by stimulating lipid accumulation, foam cell formation and pro-inflammatory cytokine production in macrophages. Adipokines can also promote balance or resolution during metabolic and immune processes by promoting reverse lipid transport and expression of Th2 cytokines. This review will explore the mechanisms by which catecholamines and adipokines influence macrophage function in neural pathways, immunity and metabolism.