Eosinophil-mediated signalling attenuates inflammatory responses in experimental colitis

OBJECTIVE

Eosinophils reside in the colonic mucosa and increase significantly during disease. Although a number of studies have suggested that eosinophils contribute to the pathogenesis of GI inflammation, the expanding scope of eosinophil-mediated activities indicate that they also regulate local immune responses and modulate tissue inflammation. We sought to define the impact of eosinophils that respond to acute phases of colitis in mice.

DESIGN

Acute colitis was induced in mice by administration of dextran sulfate sodium, 2,4,6-trinitrobenzenesulfonic acid or oxazolone to C57BL/6J (control) or eosinophil deficient (PHIL) mice. Eosinophils were also depleted from mice using antibodies against interleukin (IL)-5 or by grafting bone marrow from PHIL mice into control mice. Colon tissues were collected and analysed by immunohistochemistry, flow cytometry and reverse transcription PCR; lipids were analysed by mass spectroscopy.

RESULTS

Eosinophil-deficient mice developed significantly more severe colitis, and their colon tissues contained a greater number of neutrophils, than controls. This compensatory increase in neutrophils was accompanied by increased levels of the chemokines CXCL1 and CXCL2, which attract neutrophils. Lipidomic analyses of colonic tissue from eosinophil-deficient mice identified a deficiency in the docosahexaenoic acid-derived anti-inflammatory mediator 10, 17- dihydroxydocosahexaenoic acid (diHDoHE), namely protectin D1 (PD1). Administration of an exogenous PD1-isomer (10S, 17S-DiHDoHE) reduced the severity of colitis in eosinophil-deficient mice. The PD1-isomer also attenuated neutrophil infiltration and reduced levels of tumour necrosis factor-α, IL-1β, IL-6 and inducible NO-synthase in colons of mice. Finally, in vitro assays identified a direct inhibitory effect of PD1-isomer on neutrophil transepithelial migration.

CONCLUSIONS

Eosinophils exert a protective effect in acute mouse colitis, via production of anti-inflammatory lipid mediators.

Epithelial HIF-1α/claudin-1 axis regulates barrier dysfunction in eosinophilic esophagitis

Epithelial barrier dysfunction is a significant factor in many allergic diseases, including eosinophilic esophagitis (EoE). Infiltrating leukocytes and tissue adaptations increase metabolic demands and decrease oxygen availability at barrier surfaces. Understanding of how these processes impact barrier is limited, particularly in allergy. Here, we identified a regulatory axis whereby the oxygen-sensing transcription factor HIF-1α orchestrated epithelial barrier integrity, selectively controlling tight junction CLDN1 (claudin-1). Prolonged experimental hypoxia or HIF1A knockdown suppressed HIF-1α-dependent claudin-1 expression and epithelial barrier function, as documented in 3D organotypic epithelial cultures. L2-IL5OXA mice with EoE-relevant allergic inflammation displayed localized eosinophil oxygen metabolism, tissue hypoxia, and impaired claudin-1 barrier via repression of HIF-1α/claudin-1 signaling, which was restored by transgenic expression of esophageal epithelial-targeted stabilized HIF-1α. EoE patient biopsy analysis identified a repressed HIF-1α/claudin-1 axis, which was restored via pharmacologic HIF-1α stabilization ex vivo. Collectively, these studies reveal HIF-1α's critical role in maintaining barrier and highlight the HIF-1α/claudin-1 axis as a potential therapeutic target for EoE.

Autophagy mediates epithelial cytoprotection in eosinophilic oesophagitis

OBJECTIVE

The influence of eosinophilic oesophagitis (EoE)-associated inflammation upon oesophageal epithelial biology remains poorly understood. We investigated the functional role of autophagy in oesophageal epithelial cells (keratinocytes) exposed to the inflammatory EoE milieu.

DESIGN

Functional consequences of genetic or pharmacological autophagy inhibition were assessed in endoscopic oesophageal biopsies, human oesophageal keratinocytes, single cell-derived ex vivo murine oesophageal organoids as well as a murine model recapitulating EoE-like inflammation and basal cell hyperplasia. Gene expression, morphological and functional characterisation of autophagy and oxidative stress were performed by transmission electron microscopy, immunostaining, immunoblotting, live cell imaging and flow cytometry.

RESULTS

EoE-relevant inflammatory conditions promoted autophagy and basal cell hyperplasia in three independent murine EoE models and oesophageal organoids. Inhibition of autophagic flux via chloroquine treatment augmented basal cell hyperplasia in these model systems. Oesophageal keratinocytes stimulated with EoE-relevant cytokines, including tumour necrosis factor-α and interleukin-13 exhibited activation of autophagic flux in a reactive oxygen species-dependent manner. Autophagy inhibition via chloroquine treatment or depletion of Beclin-1 or ATG-7, augmented oxidative stress induced by EoE-relevant stimuli in murine EoE, oesophageal organoids and human oesophageal keratinocytes. Oesophageal epithelia of paediatric EoE patients with active inflammation displayed increased autophagic vesicle content compared with normal and EoE remission subjects. Functional flow cytometric analysis revealed autophagic flux in human oesophageal biopsies.

CONCLUSIONS

Our findings reveal for the first time that autophagy may function as a cytoprotective mechanism to maintain epithelial redox balance and homeostasis under EoE inflammation-associated stress, providing mechanistic insights into the role of autophagy in EoE pathogenesis.

Ultrastructural features of eosinophilic oesophagitis: impact of treatment on desmosomes

AIMS

A growing body of evidence suggests a role for altered epithelial barrier function in the pathophysiology of eosinophilic oesophagitis (EoE), but few have described the epithelial structure during inflammation. The purpose of this study was to define ultrastructural features of active, inactive EoE and control subject's oesophageal epithelia.

METHODS

We prospectively enrolled patients undergoing diagnostic upper endoscopy for evaluation of EoE. Mucosal pinch biopsies were obtained from the distal oesophagus and processed for routine histology and electron microscopic assessment. Clinical features of enrolled subjects were analysed and subjects were divided into four groups: normal, gastroesophageal reflux disease (GERD), inactive EoE and active EoE. Representative photomicrographs of the basal and superficial epithelia were reviewed for abnormalities. Desmosomes were quantified on the surface of epithelia three to four prickle-cell layers above the basal layer.

RESULTS

Twenty-nine paediatric cases (ages 2-18 years) were enrolled in the study. We observed a significant decrease in the number of desmosomes per cell (DPC) of subjects with active EoE compared with inactive EoE, GERD and normal epithelia. With respect to DPC, no significant differences were found between inactive EoE compared with GERD or normal subjects. Additional ultrastructural features observed included epithelial microplicae and evidence of eosinophil transmigration, degranulation, and sombrero formation.

CONCLUSIONS

Consistent with clinical and molecular findings, our ultrastructural data provide support for an altered oesophageal barrier in paediatric cases with active EoE, which may improve following treatment.

Clinical evidence for repurposing chloroquine and hydroxychloroquine as antiviral agents: a systematic review

BACKGROUND

Repurposing hydroxychloroquine (HCQ) and chloroquine (CQ) as antiviral agents is a re-emerging topic with the advent of new viral epidemics.

AIMS

To summarize evidence from human clinical studies for using HCQ or CQ as antiviral agents for any viral infection.

SOURCES

PubMed, EMBASE, Scopus, Web of Science for published studies without time or language restrictions; Cochrane Clinical Trial Registry and Chinese Clinical Trials Registry for trials registered after 2015; MedRxiv for preprints within the last 12 months.

CONTENT

Study eligibility criteria were interventional and prospective observational studies (with or without a control group). Participants were adults and children with a confirmed viral infection. Interventions included the use of CQ or HCQ as antiviral agent in one or more groups of the study. Two authors independently screened abstracts, and all authors agreed on eligible studies. A meta-analysis was planned if studies were available which were similar in terms of participants, intervention, comparator and outcomes. Nineteen studies (including two preprints) were eligible (HIV 8, HCV 2, dengue 2, chikungunya 1, COVID-19 6). Nine and ten studies assessed CQ and HCQ respectively. Benefits of either drug for viral load suppression in HIV are inconsistent. CQ is ineffective in curing dengue (high-certainty evidence) and may have little or no benefit in curing chikungunya (low-certainty evidence). The evidence for COVID-19 infection is rapidly evolving but at this stage we are unsure whether either CQ or HCQ has any benefit in clearing viraemia (very-low-certainty evidence).

IMPLICATIONS

Using HCQ or CQ for HIV/HCV infections is now clinically irrelevant as other effective antivirals are available for viral load suppression (HIV) and cure (HCV). There is no benefit of CQ in dengue, and the same conclusion is likely for chikungunya. More evidence is needed to confirm whether either HCQ or CQ is beneficial in COVID-19 infection.

Imported malaria: a possible threat to the elimination of malaria from Sri Lanka?

OBJECTIVE

To discuss epidemiological aspects of imported malaria and the potential impact of imported malaria cases reported in Sri Lanka 2008-2011 in terms of a possible resurgence of the disease.

METHODS

The national malaria database was used to assess details regarding country where the infection was possibly acquired, species of Plasmodium, number of days lapsed between disembarkation in Sri Lanka and diagnosis, compliance with national treatment guidelines including percentage of patients followed up as per the national guidelines.

RESULTS

After the strengthening of malaria surveillance, during the 4-year period, 152 imported malaria cases were recorded: an increase of 176% in the number of cases. Most of the imported malaria infections were acquired by Sri Lankan Nationals mainly from South Asia, especially India. Plasmodium vivax accounted for 64% of the infections. Approximately 50% of the cases were diagnosed in the Western Province. The average period from disembarkation in Sri Lanka to malaria diagnosis was 3.6 days. Patients were managed and treated according to the national guidelines. 82% of the patients were followed up for 28 days to ensure parasite clearance.

CONCLUSIONS

There is a possible increasing risk of re-introduction of malaria to the country from imported cases. Enhanced surveillance activities and the increase in international travel have contributed to an increase in recorded case numbers. There is a need to further strengthen surveillance, especially for monitoring and timely addressing of imported malaria, if the country is to prevent the re-establishment of transmission within. The importance of having an efficient response mechanism to deal with imported malaria is also highlighted.

Evaluation of a rapid whole blood immunochromatographic assay for the diagnosis of Plasmodium falciparum and Plasmodium vivax malaria

OBJECTIVE

Microscopic examination of blood smears is the 'gold standard' for malaria diagnosis, but is labour intensive and requires skilled operators. Plasmodium vivax malaria accounts for up to 70% of infections in Sri Lanka. The objective of this study was to determine the effectiveness of an immunochromatographic test which can detect both the species of Plasmodium, P. vivax and P. falciparum, present in Sri Lanka.

DESIGN

Prospective study from May 2001 to March 2002.

SETTING AND METHODS

All persons above 5 years of age who presented to the Malaria Research Station, Kataragama or the Anti-malaria Clinic, Kurunegala, with a history of fever were recruited to the study. Thick and thin blood smears were examined for malarial parasites. The rapid diagnostic test (RDT), ICT Malaria P.f/P.v (AMRAD ICT, Australia) was performed simultaneously by an independent investigator. The severity of clinical disease of all patients was evaluated.

RESULTS

The study sample comprised 328 individuals of whom 126 (38%) were infected, 102 with P. vivax (31.1%) and 24 with P. falciparum (7.3%). The RDT was found to be highly sensitive (100%) and specific (100%) for the diagnosis of P. falciparum when compared with field microscopy. The sensitivity for the diagnosis of P. vivax malaria was only 70%. When P. vivax parasitaemia was greater than 5000 parasites/microL the RDT was 96.2% sensitive. A significant association was noted between the band intensity on the dipstick and both peripheral blood parasitaemia (p < 0.001) and clinical severity of disease with P. vivax (p = 0.011).

CONCLUSIONS

The ICT Malaria P.f/P.v test can be used in Sri Lanka in the absence of microscopists.

The health and nutritional status of school children in two rural communities in Sri Lanka

There is growing evidence of considerable burden of morbidity and mortality due to infectious diseases and undernutrition in school children. This study describes the nutritional status and parasitic infections of school children in two areas of rural Sri Lanka. All children in four primary schools in the Moneragala district of Sri Lanka were included in the study. The height and weight of children were measured and anthropometric indices calculated. Stool and blood samples were examined for evidence of intestinal helminthiasis, malaria and anaemia. A greater proportion of boys than girls were underweight, wasted and stunted. Over 80% of the children were anaemic but did not apparently have iron deficiency anaemia according to their blood picture. The prevalence of parasitic infections such as hookworm and Plasmodium spp that may contribute to anaemia was low.

A cost analysis of the use of the rapid, whole-blood, immunochromatographic P.f/P.v assay for the diagnosis of Plasmodium vivax malaria in a rural area of Sri Lanka

Between May 2001 and March 2002, a prospective study was conducted in a malaria-endemic area of Sri Lanka, to determine the cost implications of using the immunochromatographic P.f/P.v test to detect Plasmodium vivax infection. All consecutive subjects aged >5 years who presented with a history of fever were recruited. Each was checked for P. vivax infection by the standard microscopical examination of bloodsmears and by the immunochromatographic test (ICT). The costs of diagnosis using each method and the sensitivity, specificity and predictive values of the ICT (with bloodsmear examination used as the 'gold standard') were estimated, the costs/case detected being simulated for different slide positivity 'rates' and ICT sensitivities. In the detection of P. vivax, the ICT had a sensitivity of 70% and a specificity of 99%. The costs of the ICT per subject investigated and per case detected were, respectively, approximately 14 and 20 times more than those of bloodsmear examination. The costs of the ICT per case detected would fall as the sensitivity of the test increased. The ICT gave relatively few false-positive results. The current, relatively high cost of the ICT is the most important barrier to its routine operational use in the diagnosis of malaria. The test is already useful, however, in specific situations.

Candidate gene study of susceptibility to cutaneous leishmaniasis in Sri Lanka

OBJECTIVES

To investigate the association between selected single nucleotide polymorphisms (SNPs) in TNF, LTA and SLC11A1 genes and risk of endemic cutaneous leishmaniasis (CL) in Sri Lanka through a case-control disease association study.

METHODS

An anonymized DNA resource representative of the Sri Lankan population was genotyped initially to establish baseline parameters. This was followed up by genotyping 200 patients and 200 matched controls. Published or modified PCR/RFLP methods were employed for genotyping.

RESULTS

Comparison of the different ethnic groups showed the distribution of alleles of LTA +252 A>G to differ significantly in Tamils and Moors when compared with Sinhalese. The differences seen at allele level were also reflected in the haplotypes defined by these SNPs at the TNF locus. The case-control analysis did not show an association between the SNPs or the haplotypes investigated and CL. The distribution of these variant alleles in other populations, where they are positively associated with leishmaniasis, differed significantly from the Sri Lankan study cohort.

CONCLUSIONS

The selected polymorphisms do not predispose to CL in the Sri Lankan population. The study of extended haplotypes at these loci using a sufficiently powered sample collection would elaborate the findings of this study. In the face of an evolving disease pattern in the country with other forms of leishmaniasis now being reported, prevalence of polymorphisms predisposing to these forms calls for heightened surveillance and preparedness.

Use of Bacillus thuringiensis israelensis in integrated vector control of Aedes sp. in Sri Lanka: a prospective controlled effectiveness study

OBJECTIVES

The annual incidence of dengue has been increasing over the last few years in Sri Lanka with seasonal epidemics. Biological control of the vector has not been part of the integrated vector control implemented by the public health authorities of Sri Lanka so far. This pilot study assessed the effectiveness of using Bacillus thuringiensis israelensis (Bti) spray to control the Aedes mosquito vector population density.

METHODS

Prospective controlled effectiveness study in three administrative divisions of Colombo. Study areas were selected from urban, semiurban and rural administrative divisions within the district, and they were compared with two matching controls from the same division. Test areas received three cycles of Bti spraying 1 month apart. Control areas were not sprayed with Bti. Ovitrap and larval indices were calculated at baseline and 2 weeks after each spray cycle.

RESULTS

There was a significant improvement in the adult vector population (ovitrap index) in the test areas after three spray cycles, but this effect had disappeared after 8 weeks (no residual effect). There was no consistent positive impact on larval indices (premise, container and Breteau indices) after each spray cycle.

CONCLUSION

Bti might have a moderate impact on adult vector populations mediated via transient reductions in larval populations. However, this effect is not sustained probably due to rapid re-infestation. Bti spray, if implemented, can only play a supplementary role to other vector control methods.

Diagnosis and treatment of malaria by health care providers: findings from a post conflict district in Sri Lanka

This study determines whether 72 health care providers in a previously conflict-affected district in Sri Lanka adhere to the recommendations of the Anti Malaria Campaign with regard to diagnosis, prescribing antimalarials and reporting of a positive case. All patients suspected of clinically having malaria are being referred for laboratory confirmation, indicating that presumptive treatment is not practiced. The knowledge amongst health care providers regarding accurate management and reporting of a malaria positive case needs to be improved.

Antibodies to hepatitis C virus in patients who have had multiple transfusions in Sri Lanka

OBJECTIVE

To determine the prevalence of antibodies to hepatitis C virus (HCV) in patients who have had multiple transfusions in Sri Lanka.

SETTING

University Medical Unit at the National Hospital, Colombo, the Cancer Institute, Maharagama, and the Lady Ridgeway Children's Hospital, Colombo.

PATIENTS

One to 5 ml of blood for serology was collected from 200 multiply transfused patients (those who have received five or more blood transfusions).

METHOD

The sera were tested for HCV specific antibodies using a third generation anti-HCV enzyme immuno-assay (EIA) kit. All sera giving positive or intermediate EIA results were re-tested by a commercial HCV Western blot confirmatory test.

RESULTS

Of the 200 patients, 10 (5%) were repeatedly positive and confirmed by the Western blot. 33% (7/21) of haemophiliacs and 10% (3/31) of thalassaemics were positive for antibodies to HCV. Antibodies were not detected in other groups of multiply transfused patients (haemolytic disease, aplastic anemias, chronic renal failure, haematological and other malignancies). Of the 200 patients, those who have had more than 80 blood transfusions had a significantly higher prevalence of antibodies to HCV. The frequency of HCV infection was also higher among those who had received factor concentrates.

CONCLUSION

33% of haemophiliacs and 10% of thalassaemics who have received multiple transfusions were infected with HCV. These findings warrant a larger study among blood donors, and justify screening and decontamination of blood and blood products given to haemophiliacs and thalassaemics in Sri Lanka.

Anthelmintic prescribing patterns of a sample of general practitioners from selected areas in the Colombo district of Sri Lanka

General Practitioners (GPs) provide first contact care of children and pregnant mothers in the community. This study ascertained the prescribing pattern of anthelmintics to children and pregnant women by a sample of GPs from the district of Colombo. Two hundred medical practitioners engaged in full-time General Practice (100 urban and 100 rural), were selected randomly. A pre-tested interviewer-administered questionnaire was used to collect data. A total of 183 GPs aged between 26 and 72 years (median 38) participated with 94 coming from urban areas. Seventy percent of the GPs were male. Almost 13% of GPs from urban areas had a Postgraduate degree in comparison to 4.5% from the rural areas (P < 0.05). Over 50% of GPs had 6-20 years of service and over 30% treated 16-30 patients daily. Seventy-three percent of GPs from rural areas accessed health-related reading material either daily or weekly in contrast to only 40% from urban areas (P < 0.001). All GPs prescribed anthelmintics to children. Pyrantel pamoate was the preferred anthelmintic used for children by both groups. Approximately 55% and 64% of GPs from urban and rural areas, respectively, prescribed anthelmintics during pregnancy. A majority of GPs prescribed drugs after the first trimester. However, 25% from urban areas gave drugs during any trimester (P < 0.001). Regression analysis revealed that GPs with postgraduate qualifications, those having frequent access to health-related material and those seeing more than 30 patients daily, prescribed anthelmintics to pregnant women more often. Although routine de-worming of pregnant women and children should occur through government antenatal and well-baby clinics, and through the schools de-worming programme, it may not happen due to various reasons. Thus, GPs play a vital role in achieving good coverage of anthelmintics among children and pregnant women. Making available clear national guidelines on prescribing anthelmintics in Sri Lanka would improve the prescribing patterns of anthelmintics among GPs.

Geo-helminth infections in a rural area of Sri Lanka

School children carry the heaviest burden of morbidity due to intestinal helminth infection. The objective of this investigation was to study geo-helminth infections in 349 school children aged 6 to 13 years living in a rural area of Sri Lanka. Stool samples were examined by direct saline smear in an initial survey to determine the prevalence of intestinal parasitic infections and thereafter the children were followed up over a two year period with cross sectional surveys of stool samples being carried out at yearly intervals. Following collection of a stool sample, all the subjects were treated with mebendazole 500 mg as a single dose. Weights and heights were measured using standardized procedures. 2 ml of venous blood were collected from each subject under aseptic conditions to determine hematological indices. The prevalence of geo-helminth infections was low, and the prevalence declined during the two-year period from 5.4% in 1997 to 2.2% in 1998 and 2.0% in 1999 following yearly mass anti-helminth treatment. The incidence density was 0.021 cases per child year. The reduction in the prevalence from the baseline to the second survey is probably due to the reduction of the reservoir of infection among children as a result of mass treatment at baseline. The prevalence of infection during the second and third surveys were almost the same probably due to infections originating from other segments of the untreated population.

A histochemical study of adenosine triphosphatase in neuroglia

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The impact of repeated malaria attacks on the school performance of children

The impact of repeated malarial infections on the school performance of children was investigated in 571 school children 6-14 years of age in a malaria-endemic area in southern Sri Lanka where both Plasmodium falciparum and P. vivax infections are prevalent. Malaria infections confirmed by microscopy were monitored over a six-year period. School performance was assessed by two specially designed, school grade-specific, test papers for Sinhala language and mathematics. The scores for Sinhala language and mathematics for each school term test for the year 1997 were obtained. Malarial infections were a major predictor of children's performance in language and mathematics after controlling for parent's education, monthly family income, and house type. The education of the father predicted language scores but not mathematics scores. A child who experienced more than five attacks of malaria scored approximately 15% less than a child who experienced less than three attacks of malaria. The data suggest that repeated attacks of malaria have an adverse impact on the school performance of children.

Epidemiological aspects and risk factors of toxocariasis in a pediatric population in Sri Lanka

This cross-sectional study, carried out over a period of 11 months, investigated the relationship between Toxocara seropositivity, socio-demographic and environmental variables in a pediatric population. Risk factors for Toxocara infection were assessed by direct interview of parent or guardian using a structured pre-tested questionnaire. Eosinophilia and presence of helminth eggs or protozoan cysts in a fecal smear were recorded. Diagnosis of Toxocara seropositivity in children was based on IgG Toxocara Microwell Serum Elisa Kits. The ELISA test was regarded as positive if the optical density was 0.3 units or above. Unadjusted and adjusted odds ratios were calculated to determine risk factors for disease. The proportion of children who were positive for Toxocara antibodies in the study population was 20%. Children being exposed to a puppy of less than 3 months at home, visiting a playground frequently, living in a poorly constructed house and dogs having access to playgrounds were significant risk factors on univariate analysis. Of these four variables, only the first three variables (OR 19, OR 4 and OR 3, respectively) remained significant risk factors on the multivariate model. Presence of eosinophilia in seropositive children was significantly higher than the seronegative group (77% vs 40%; p < 0.001). This study indicates that dogs contribute significantly to children being seropositive for toxocariasis in Sri Lanka. Implementation of public health programs specifically focused on anti-parasitic treatment of dogs is recommended.