IL-1β production through the NLRP3 inflammasome by hepatic macrophages links hepatitis C virus infection with liver inflammation and disease

Chronic hepatitis C virus (HCV) infection is a leading cause of liver disease. Liver inflammation underlies infection-induced fibrosis, cirrhosis and liver cancer but the processes that promote hepatic inflammation by HCV are not defined. We provide a systems biology analysis with multiple lines of evidence to indicate that interleukin-1β (IL-1β) production by intrahepatic macrophages confers liver inflammation through HCV-induced inflammasome signaling. Chronic hepatitis C patients exhibited elevated levels of serum IL-1β compared to healthy controls. Immunohistochemical analysis of healthy control and chronic hepatitis C liver sections revealed that Kupffer cells, resident hepatic macrophages, are the primary cellular source of hepatic IL-1β during HCV infection. Accordingly, we found that both blood monocyte-derived primary human macrophages, and Kupffer cells recovered from normal donor liver, produce IL-1β after HCV exposure. Using the THP-1 macrophage cell-culture model, we found that HCV drives a rapid but transient caspase-1 activation to stimulate IL-1β secretion. HCV can enter macrophages through non-CD81 mediated phagocytic uptake that is independent of productive infection. Viral RNA triggers MyD88-mediated TLR7 signaling to induce IL-1β mRNA expression. HCV uptake concomitantly induces a potassium efflux that activates the NLRP3 inflammasome for IL-1β processing and secretion. RNA sequencing analysis comparing THP1 cells and chronic hepatitis C patient liver demonstrates that viral engagement of the NLRP3 inflammasome stimulates IL-1β production to drive proinflammatory cytokine, chemokine, and immune-regulatory gene expression networks linked with HCV disease severity. These studies identify intrahepatic IL-1β production as a central feature of liver inflammation during HCV infection. Thus, strategies to suppress NLRP3 or IL-1β activity could offer therapeutic actions to reduce hepatic inflammation and mitigate disease.

Hepatitis C virus (HCV) causes chronic infection of the liver and is a leading cause of liver inflammation, cirrhosis and liver cancer in nearly 200 million people worldwide. Importantly, hepatic inflammation during chronic HCV infection is considered to be the primary catalyst for progressive liver disease and development of liver cancer. However, the underlying molecular mechanism(s) of HCV-mediated hepatic inflammation are not well understood. The goal of this study was to determine the mechanisms of HCV-induced inflammation. We found that serum IL-1β levels are elevated in chronic hepatitis C patients. Furthermore, we found that hepatic macrophages or Kupffer cells are the major IL-1β-producing cell population within HCV infected livers. Our studies, using the THP1 cell culture model of HCV exposure, reveal that exposure of macrophages to HCV induces IL-1β through a process of infection-independent phagocytic virus uptake that triggers signaling through MyD88/TLR7 and NLRP3 inflammasome pathways to drive IL-1β expression and maturation/secretion, respectively. RNA sequencing (RNA-seq) analysis of patient liver biopsies shows that viral triggering of these signaling pathways drives an inflammatory response linked with liver disease in patients with chronic hepatitis C. Our results identify HCV-induced IL-1β production by hepatic macrophages as a critical and central process that promotes liver inflammation and disease.

IL-7 licenses activation of human liver intrasinusoidal mucosal-associated invariant T cells

Human mucosal-associated invariant T (MAIT) cells are a T cell population characterized by the expression of a semi-invariant TCR capable of recognizing bacterial products in the context of MR1. MAIT cells are enriched in the human liver, which is constantly exposed to bacterial products from the intestine. Whether this specific parenchymal localization influences their function remains unknown. We analyzed MAIT cells resident in the vascular bed of livers and showed that they represented the majority of T cells expressing NK markers and the dominant IL-17A(+) T cell subset in the human liver sinusoids. In comparison with MAIT cells purified from peripheral blood, intrasinusoidal MAIT cells expressed markers of T cell activation; however, TCR-mediated cytokine production was equally suppressed in both circulating and intrasinusoidal MAIT cells. MAIT cells also expressed high levels of IL-7R, and we showed that IL-7, a cytokine produced by hepatocytes during inflammation, regulated TCR-mediated activation of MAIT cells, licensing them to dramatically increase Th1 cytokines and IL-17A production. Our quantitative and functional data indicate that MAIT cells are a specialized cell population highly adapted to exert their immune functions in the vascular network of the liver.

Preserved T-cell function in children and young adults with immune-tolerant chronic hepatitis B

BACKGROUND & AIMS

Chronic hepatitis B (CHB) infection acquired perinatally or in early childhood has been associated with a prolonged phase of immune tolerance from viral exposure into early adulthood. The immune-tolerant phase of the disease is characterized by high levels of hepatitis B virus (HBV) DNA and normal liver biochemistry, with minimal or no fibrosis. We investigated whether the age of patients with CHB affects their antiviral immunity and whether children and young adults have a veritable state of immunologic tolerance.

METHODS

We isolated T cells from different age groups of patients with CHB and used flow cytometric methods to measure production of effector and inflammatory cytokines (interferon, tumor necrosis factor, interleukin [IL]-17A, IL-22, and IL-8), T-helper (Th)2 cytokines (IL-10, IL-4), Th1 cytokines (IL-2 and IL-21), and the CC chemokine CCL3 (MIP-1). We also measured markers of T-cell exhaustion or inhibition (PD-1, LAG-3, TIM3, LAIR-1, and CTLA-4) and HBV-specific T cells.

RESULTS

Young patients with CHB have a Th1-cell cytokine profile and a partial profile of T-cell exhaustion. Direct quantification of the HBV-specific T-cell response showed that young patients with CHB have more HBV-specific T cells with the ability to proliferate and produce cytokines than adult patients with CHB.

CONCLUSIONS

HBV infection in younger patients is not associated with an immune profile of T-cell tolerance. On the contrary, children and young adults with chronic HBV infection have an HBV-specific immune profile that is less compromised than that observed in older patients.

Toll-like receptor 8 agonist and bacteria trigger potent activation of innate immune cells in human liver

The ability of innate immune cells to sense and respond to impending danger varies by anatomical location. The liver is considered tolerogenic but is still capable of mounting a successful immune response to clear various infections. To understand whether hepatic immune cells tune their response to different infectious challenges, we probed mononuclear cells purified from human healthy and diseased livers with distinct pathogen-associated molecules. We discovered that only the TLR8 agonist ssRNA40 selectively activated liver-resident innate immune cells to produce substantial quantities of IFN-γ. We identified CD161^Bright mucosal-associated invariant T (MAIT) and CD56^Bright NK cells as the responding liver-resident innate immune cells. Their activation was not directly induced by the TLR8 agonist but was dependent on IL-12 and IL-18 production by ssRNA40-activated intrahepatic monocytes. Importantly, the ssRNA40-induced cytokine-dependent activation of MAIT cells mirrored responses induced by bacteria, i.e., generating a selective production of high levels of IFN-γ, without the concomitant production of TNF-α or IL-17A. The intrahepatic IFN-γ production could be detected not only in healthy livers, but also in HBV- or HCV-infected livers. In conclusion, the human liver harbors a network of immune cells able to modulate their immunological responses to different pathogen-associated molecules. Their ability to generate a strong production of IFN-γ upon stimulation with TLR8 agonist opens new therapeutic opportunities for the treatment of diverse liver pathologies.

The ability of human pathogens, like HBV, HCV or Plasmodium spp. to infect the liver might be influenced by its tolerogenic features. However, hepatic tolerance is not absolute since protective immunity can be triggered. Our goal was to define how to deliberately elicit an intrahepatic protective immune response. To achieve this, we purified immune cells residing in the vascular bed of human livers and we probed their reactivity against different pathogen-associated molecules, mimicking signature components of viruses or bacteria. We found that robust production of anti-viral cytokine IFN-γ was induced only by the TLR8 agonist ssRNA40. Mechanistically, ssRNA40 triggered hepatic monocytes to produce IL-12 and IL-18 cytokines, which stimulated IFN-γ production by liver-resident CD161^Bright MAIT and CD56^Bright NK cells. We also demonstrated that ssRNA40-mediated activation could occur in pathologic (HBV- or HCV-chronically infected) livers and that a similar cytokine-mediated activation of intrahepatic cells could also be triggered upon bacterial infection. Thus, we showed that the liver immune cells can respond vigorously to specific pathogen-associated molecules. The selective production of IFN-γ by liver-resident cells could have therapeutic implications for the treatment of chronic liver infections.

Analysis of CD8+ T-cell-mediated inhibition of hepatitis C virus replication using a novel immunological model

BACKGROUND & AIMS

Virus-specific CD8+ T cells are required for the control of hepatitis C virus (HCV) infection. We investigated the extent to which different effector functions of CD8+ T cells contribute to the inhibition of viral replication.

METHODS

We developed a novel immunologic model by stably transducing the HLA-A2 gene into the replicon system, matching the epitope sequence of the replicon to the sequence targeted by an HCV-specific CD8+ T-cell clone. Luciferase activity was then measured to quantitate HCV RNA replication.

RESULTS

HCV-specific CD8+ T cells strongly inhibited viral replication, through cytolytic and noncytolytic mechanisms, in a dose-dependent manner. HCV replication was almost completely inhibited at an effector-to-target ratio of 1:1 with significant cytotoxicity; however, >95% viral inhibition occurred at ratios as low as 1:100. Importantly, no cytotoxicity was observed at low effector-to-target ratios, indicating a dominant effect of noncytolytic effector functions that was confirmed by Transwell experiments. Neutralization experiments revealed that interferon gamma mediates the noncytolytic inhibition.

CONCLUSIONS

Only a very few HCV-specific CD8+ T cells are required to inhibit HCV replication; inhibition occurs primarily by noncytolytic effector functions.

Intrahepatic CD206+ macrophages contribute to inflammation in advanced viral-related liver disease

BACKGROUND & AIMS

Liver inflammation is key in the progression of chronic viral hepatitis to cirrhosis and hepatocellular carcinoma. The magnitude of viral replication and the specific anti-viral immune responses should govern the degree of inflammation, but a direct correlation is not consistently found in chronic viral hepatitis patients. We aim to better define the mechanisms that contribute to chronic liver inflammation.

METHODS

Intrahepatic CD14⁺ myeloid cells from healthy donors (n=19) and patients with viral-related liver cirrhosis (HBV, HBV/HDV or HCV; n=15) were subjected to detailed phenotypic, molecular and functional characterisation.

RESULTS

Unsupervised analysis of multi-parametric data showed that liver disease was associated with the intrahepatic expansion of activated myeloid cells mainly composed of pro-inflammatory CD14⁺HLA-DR^hiCD206⁺ cells, which spontaneously produced TNFα and GM-CSF. These cells only showed heightened pro-inflammatory responses to bacterial TLR agonists and were more refractory to endotoxin-induced tolerance. A liver-specific enrichment of CD14⁺HLA-DR^hiCD206⁺ cells was also detected in a humanised mouse model of liver inflammation. This accumulation was abrogated following oral antibiotic treatment, suggesting a direct involvement of translocated gut-derived microbial products in liver injury.

CONCLUSIONS

Viral-related chronic liver inflammation is driven by the interplay between non-endotoxin-tolerant pro-inflammatory CD14⁺HLA-DR^hiCD206⁺ myeloid cells and translocated bacterial products. Deciphering this mechanism paves the way for the development of therapeutic strategies specifically targeting CD206⁺ myeloid cells in viral-related liver disease patients. Lay summary: Viral-related chronic liver disease is driven by intrahepatic pro-inflammatory myeloid cells accumulating in a gut-derived bacterial product-dependent manner. Our findings support the use of oral antibiotics to ameliorate liver inflammation in these patients.

Activated macrophages promote hepatitis C virus entry in a tumor necrosis factor-dependent manner

Macrophages are critical components of the innate immune response in the liver. Chronic hepatitis C is associated with immune infiltration and the infected liver shows a significant increase in total macrophage numbers; however, their role in the viral life cycle is poorly understood. Activation of blood-derived and intrahepatic macrophages with a panel of Toll-like receptor agonists induce soluble mediators that promote hepatitis C virus (HCV) entry into polarized hepatoma cells. We identified tumor necrosis factor α (TNF-α) as the major cytokine involved in this process. Importantly, this effect was not limited to HCV; TNF-α increased the permissivity of hepatoma cells to infection by Lassa, measles and vesicular stomatitis pseudoviruses. TNF-α induced a relocalization of tight junction protein occludin and increased the lateral diffusion speed of HCV receptor tetraspanin CD81 in polarized HepG2 cells, providing a mechanism for their increased permissivity to support HCV entry. High concentrations of HCV particles could stimulate macrophages to express TNF-α, providing a direct mechanism for the virus to promote infection.

CONCLUSION

This study shows a new role for TNF-α to increase virus entry and highlights the potential for HCV to exploit existing innate immune responses in the liver to promote de novo infection events.

Identification of peptides with tolerogenic potential in a hydrolysed whey-based infant formula

BACKGROUND

Failure to induce oral tolerance may result in food allergy. Hydrolysed cow's milk-based infant formulas are recommended in subjects with a high risk of developing allergic disease. Presentation of T cell epitopes is a prerequisite to generate regulatory T cells that could contribute to oral tolerance.

OBJECTIVE

To investigate whether a specific hydrolysed whey-based infant formula contains peptides that function as T cell epitopes to support the development of oral tolerance to whey.

METHODS

First, a novel liquid chromatography-mass spectrometry (LC-MS) method was developed to characterize β-lactoglobulin-derived peptides present in a specific infant formula with a focus on region AA#13-48 of β-lactoglobulin, which has previously been described to contain T cell epitopes with tolerogenic potential. Second, the formula was subjected to the ProImmune ProPresent^® antigen presentation assay and MHC class II binding algorithm to identify relevant HLA-DRB1-restricted peptides. Third, identified peptides were tested on human cow's milk protein-specific T cell lines to determine T cell recognition.

RESULTS

Thirteen peptides of minimal 9AAs long that overlap with AA#13-48 of β-lactoglobulin were identified. Six of them were found across all batches analysed. It was further confirmed that these peptides were processed and presented by human dendritic cells. The identified HLA-DRB1-restricted peptides were correlated to AA#11-30 and AA#23-39 of β-lactoglobulin. Importantly, the proliferation assay showed that the synthetic peptides were recognized by cow's milk protein-specific T cell lines and induced T cell proliferation.

CONCLUSION AND CLINICAL RELEVANCE

This study demonstrates that the tested hydrolysed infant formula contains functional HLA-DRB1-restricted T cell epitopes, which can potentially support the development of oral tolerance to whey.

Role of cellular immunity in cow's milk allergy: pathogenesis, tolerance induction, and beyond

Food allergy is an aberrant immune-mediated reaction against harmless food substances, such as cow's milk proteins. Due to its very early introduction, cow's milk allergy is one of the earliest and most common food allergies. For this reason cow's milk allergy can be recognized as one of the first indications of an aberrant inflammatory response in early life. Classically, cow's milk allergy, as is true for most other allergies as well, is primarily associated with abnormal humoral immune responses, that is, elevation of specific immunoglobulin E levels. There is growing evidence indicating that cellular components of both innate and adaptive immunity play significant roles during the pathogenesis of cow's milk allergy. This is true for the initiation of the allergic phenotype (stimulation and skewing towards sensitization), development and outgrowth of the allergic disease. This review discusses findings pertaining to roles of cellular immunity in allergic inflammation, and tolerance induction against cow's milk proteins. In addition, a possible interaction between immune mechanisms underlying cow's milk allergy and other types of inflammation (infections and noncommunicable diseases) is discussed.

Experimental models to study the immunobiology of hepatitis C virus

Effective host immune responses are essential for the control of hepatitis C virus (HCV) infection and persistence of HCV has indeed been attributed to their failure. In recent years, several in vitro and in vivo experimental models have allowed studies of host immune responses against HCV. Numerous observations derived from these models have improved our understanding of the mechanisms responsible for the host's ability to clear the virus as well as of the mechanisms responsible for the host's failure to control HCV replication. Importantly, several findings obtained with these model systems have been confirmed in studies of acutely or chronically HCV-infected individuals. Collectively, several mechanisms are used by HCV to escape host immune responses, such as poor induction of the innate immune response and escaping/impairing adaptive immunity. In this review, we summarize current findings from experimental models available for studies of the immune response targeting HCV and discuss the relevance of these findings for the in vivo situation in HCV-infected humans.

Low perforin expression of early differentiated HCV-specific CD8+ T cells limits their hepatotoxic potential

BACKGROUND & AIMS

Perforin plays a central role in the immunopathogenesis of different viral infections. However, its role in hepatitis C virus (HCV) infection has not been fully understood. Here, we analyzed two closely related questions: first, is CD8+ T cell-mediated killing of HCV-replicating human hepatoma cells mediated by perforin? Second, if so, do HCV-specific CD8+ T cells obtained from chronically HCV infected patients express and upregulate perforin?

METHODS

Susceptibility of HCV-replicating human hepatoma cells to the cytotoxic pathway was tested in vitro by addition of perforin substitute streptolysin O and granzyme B and by co-culture experiments with a perforin-expressing HCV-specific CD8+ T cell clone in the presence of perforin or caspase inhibitors. HCV-specific CD8+ T cells were obtained and analyzed for perforin expression and differentiation markers ex vivo from 12 chronically infected patients and 12 patients with resolved HCV infection.

RESULTS

HCV-replicating human hepatoma cells were susceptible to cytotoxic killing in vitro and a dominant role of perforin in HCV-specific CD8+ T cell-mediated cytolysis was observed. However, HCV-specific CD8+ T cells obtained ex vivo from chronically HCV infected patients expressed only low levels of perforin and showed an impaired ability to upregulate perforin. This was tightly linked to the distinct differentiation stage of HCV-specific CD8+ T cell differentiation ex vivo since early and intermediate differentiated HCV-specific CD8+ T cells only showed weak perforin expression in contrast to late differentiated CD8+ T cells that displayed strong perforin expression.

CONCLUSIONS

Our results suggest that perforin plays a dominant role in CD8+ T cell-mediated lysis of HCV-replicating human hepatoma cells but that lysis may be limited in human chronic viral infection by the low perforin expression of early/intermediate differentiated HCV-specific CD8+ T cells.

Fibrinolytic characteristics of Bacillus subtilis G8 isolated from natto

Due to the high prevalence of vascular obstructive diseases, discovering potent, safe, and affordable fibrinolytic agents is of importance. There is particular interest concerning the use of functional foods that have a fibrinolytic activity, such as natto, a Japanese fermented soy-based product made with Bacillus subtilis (natto) strain BEST195. We recently isolated another bacterial strain from natto commercialized in Indonesia, B. subtilis G8, which has proven to exert fibrinolytic activity. Herein, a further characterization of B. subtilis G8 was assessed through a comparison with commercialized nattokinase, the major fibrinolytic enzyme of B. subtilis, by utilizing various in vitro fibrinolytic assays, namely whole blood clot lysis, euglobulin clot lysis, the fibrin plate method, and zymography. Both nattokinase and B. subtilis G8 were able to dissolve both whole blood and euglobulin clots. Furthermore, both nattokinase and B. subtilis G8 were able to lyse blood clots, presumably due to their ability to directly lyse fibrin. Finally, a crude extract of B. subtilis G8 displayed six zymogram bands of approximately 42.0, 35.5, 30.8, 26.7, 20.0, and 13.7 kDa, with the strongest activity observed at 20.0 kDa. This indicates that B. subtilis G8 contained several fibrinolytic enzymes, which might have comprised nattokinase and other fibrinolytic enzymes. In summary, we demonstrated that a crude extract of B. subtilis G8 has potent fibrinolytic activity and that the activity was mediated by various fibrinolytic enzymes.

Growth Patterns of Indonesian Infants with Cow's Milk Allergy and Fed with Soy-Based Infant Formula

PURPOSE

The use of soy-based infant formula has increased widely in infants with cow's milk allergy (CMA). This study aimed to provide evidence on the growth pattern of CMA infants fed with soy-based infant formula in an Indonesian setting.

METHODS

A multi-site, intervention study was conducted among full-term and normal birth weight CMA infants. Within six months, the subjects were provided with a soy-based infant formula. Weight, height, and head circumference were measured at baseline, weeks 4, 8, 12, 16, 20, and 24. Adverse events were recorded by scoring atopic dermatitis and symptom-based clinical scores.

RESULTS

Based on the World Health Organization growth chart, we found that most of subjects had normal nutritional status for weight-for-age, length-for-age, weight-for-length, and head-circumference-for-age. There were statistically significant differences between baseline and end-line for weight-for-age, length-for-age, weight-for-length, and head circumference-for-age nutritional status. No allergic symptoms or intolerance toward soy formula were observed at the end of the intervention period.

CONCLUSION

These results show that infants fed with soy-based infant formula have a normal pattern of growth.

Lactose Intolerance versus Cow's Milk Allergy in Infants: A Clinical Dilemma

Due to its very early introduction, cow's milk is one of the first foods that can cause adverse reactions in human beings. Lactose intolerance (LI) and cow's milk allergy (CMA) are the most common adverse reactions to cow's milk. While LI is due to insufficient small intestinal lactase activity and/or a large quantity of ingested lactose, CMA is an aberrant immune reaction to cow's milk proteins, particularly casein or β-lactoglobulin. However, the clinical manifestations of LI and CMA, particularly their gastrointestinal signs and symptoms, are very similar, which might lead to misdiagnosis or delayed diagnosis as well as nutritional risks due to inappropriate dietary interventions or unnecessary dietary restriction. Formula-fed infants with LI should be treated with formula with reduced or no lactose, while those with CMA should be treated with formula containing extensive hydrolyzed cow's milk protein or amino acids. This review is therefore written to assist clinicians to better understand the pathophysiologies of LI and CMA as well as to recognize the similarities and differences between clinical manifestations of LI and CMA.

Relationship Between Insulin-Receptor Substrate 1 and Langerhans' Islet in a Rat Model of Type 2 Diabetes Mellitus

BACKGROUND/AIM

In vivo studies on pathogenesis of type 2 diabetes mellitus (T2DM) have been reported, however, the relationship between insulin-receptor substrate 1 (IRS1) and the area of Langerhans' islets was unknown. Therefore, a correlation between both parameters was assessed.

MATERIALS AND METHODS

Diabetic groups were fed with a high-fat diet (HFD) and injected with three different doses of streptozotocin, namely 25, 35 and 45 mg/kg, and compared to a control group after 9 weeks.

RESULTS

Administration of HFD/streptozotocin increased the level of fasting blood glucose but reduced the level of IRS1 and the area of Langerhans' islets in diabetic groups. The coefficient of correlation between IRS1 and area of Langerhans' islets was 0.259 (p=0.232). In addition, the coefficient of correlation for fasting blood glucose with the area of Langerhans' islets and IRS1 was -0.520 (p=0.011) and -0.603 (p=0.002), respectively.

CONCLUSION

The reduction of IRS1 was weakly correlated with the destruction of Langerhans' islets, suggesting there is an intermediate step between both parameters.

Whole-genome analysis of Bacillus subtilis G8 isolated from natto

Abstract. Dikson, Victor H, Jong D, Sanjaya A, Samantha A, Jo J, Pinontoan R. 2022. Whole-genome analysis of Bacillus subtilis G8 isolated from natto. Biodiversitas 23: 1293-1300. Bacillus subtilis-fermented soy-based food is associated with multiple health benefits. Various bacterial strains have been isolated from it, includingB. subtilisG8, recent isolation from Japanese natto commercially available in Indonesia. Both 16S rRNA gene sequencing and fibrinolytic activity characterization have been performed and published in prior studies. After comparison to the genome of a natto-isolated reference strain (i.e., B. subtilisBEST195), the B. subtilis G8 genome showed a similar guanine-cytosine (GC) content, predicted number of coding sequences (CDS) and predicted number of tRNA genes, but had a shorter sequence length and fewer predicted rRNA genes. Further analysis using multiple genome alignment with Mauve, average nucleotide identity (ANI) matrix calculation, and phylogenetic inference indicated that B. subtilis G8 was more related to natto-derived B. subtilis than to cheonggukjang-derived B. subtilis and B. subtilis 168. Finally, sequence analyses of a gene encoding nattokinase as well as two genes regulating poly-gamma-glutamic acid (?-PGA) production in B. subtilis G8, B. subtilis BEST195 and B. subtilis 168 clearly indicated that B. subtilis G8 is able to produce nattokinase and ?-PGA, which both contribute to natto’s fermentation process. Therefore, it is proposed that B. subtilis G8 should be reclassified as B. subtilis subsp. natto G8 to reflect that it is a natto-derived B. subtilis strain.

Regular Consumption of Fortified Growing-up Milk Attenuates Upper Respiratory Tract Infection among Young Children in Indonesia: A Retrospective Cohort Study

Introduction

A Growing-up Milk (GUM) supplemented with short-chain Galacto-oligosaccharides (scGOS), long-chain Fructo-oligosaccharides (lcFOS), and omega-3 Long-chain Polyunsaturated Fatty Acids (n-3 LCPUFAs) could support the development of the immune system to prevent the Upper Respiratory Tract Infection (URTI) and associated morbidities. It is of interest to assess whether a daily consumption of scGOS/lcFOS/n-3 LCPUFAs-fortified GUM for a minimum of 6 months reduces URTI incidences within the subsequent 3 months among young children in Indonesia.

Methods

A total of 154 children aged 18 to 36 months were recruited in this retrospective cohort study and categorized into exposed and non-exposed groups (78 and 76 children, respectively). A guided interview was conducted with each subject’s parent. Demographic and clinical information was collected, including incidence of URTI within the past three months, duration of URTI, as well as the frequency of medical visits when contracting URTI. The bivariate analysis via chi-square test as well as the multivariate analysis via binary logistic regression were performed.

Results

The overall characteristics were similar between groups with certain distinctions. The bivariate analysis indicated the exposed group to have better protection against URTI within the past 3 months as compared to the non-exposed group (RR=0.62; 95% CI=0.41-0.92; P<0.05). The multivariate analysis reinforced the finding by reporting that the exposed group was indeed protected against URTI (adjusted RR=0.42; 95% CI=0.21-0.85; P<0.05).

Conclusion

A routine consumption of scGOS/lcFOS/n-3 LCPUFAs-fortified GUM for a minimum of 6 months among Indonesian young children protected against URTI up to 58%, suggesting that fortified GUM consumption supports proper development of the immune system.

Assessment on anti-SARS-CoV-2 receptor-binding domain antibodies among CoronaVac-vaccinated Indonesian adults

The immunogenicity of CoronaVac among Indonesian adults at the academic premises was investigated. Two doses of CoronaVac vaccine induced a complete seroconversion on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) naïve adults with titers of anti-SARS-CoV-2 receptor-binding domain (RBD) antibodies ranging from 9.1 to 151.9 U/mL. The median value was lower than the one observed in recovered adults with mild coronavirus disease 2019 (38.7 vs. 114.5 U/mL). Nonetheless, 93.6% of the vaccinated adults, in contrast to 76.5% of the recovered adults, displayed inhibition rates above the cut-off to block RBD-angiotensin-converting enzyme 2 binding. This suggests that two doses of CoronaVac were immunogenic and likely to be protective among Indonesian adults.

Gastrointestinal Health and Immunity of Milk Formula Supplemented with a Prebiotic Mixture of Short-Chain Galacto-oligosaccharides and Long-Chain Fructo-Oligosaccharides (9:1) in Healthy Infants and Toddlers: A Systematic Review with Meta-Analysis

Prebiotics are substrates selectively utilized by microorganisms to confer health benefits to their hosts. Various prebiotics have been supplemented in standard milk formulas for infants who cannot be exclusively breastfed, aiming to provide benefits similar to those of breast milk. One of the most commonly used prebiotics is a mixture of 90% short-chain galacto-oligosaccharides and 10% long-chain fructo-oligosaccharides (scGOS/lcFOS [9:1]). Systematic review and meta-analysis were conducted to determine the effectiveness of scGOS:lcFOS (9:1) supplementation in standard milk formula for improving gastrointestinal health and immunity among healthy infants and toddlers, using parameters such as stool pH and intestinal colonization with beneficial bacteria. This systematic review was prepared in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Randomized clinical trials comparing scGOS/lcFOS (9:1)-supplemented formula versus placebo- or non-supplemented formula milk were eligible for inclusion. Related studies on gastrointestinal health and immunity among healthy infants up to five years old were searched from the earliest available date until February 29, 2024. Eighteen publications (number of participants=1,675) were selected for the systematic review, of which 11 were subsequently subjected to a meta-analysis. Results showed that the standard formula supplemented with scGOS/lcFOS (9:1) was well tolerated and conferred various gastrointestinal health and immunity to healthy infants and toddlers. These findings support the supplementation of standard milk formula with scGOS/lcFOS (9:1) for healthy infants and toddlers.

Evaluation of anti-diphtheria toxoid antibody persistence in school-age children in Jakarta, Indonesia

Background Diphtheria can be effectively prevented by adequate immunization. A combined vaccine against diphtheria toxoid, pertussis, and tetanus toxoid (DPT) is currently used in routine pediatric immunizations. Outbreaks of diphtheria could emerge in Indonesia as a consequence of declining routine vaccination during the COVID-19 pandemic. Objective To analyze the impact of the first (administered at 18-24 months of age ) and second diphtheria boosters (administered at 5-7 years of age ) in retaining protective levels of anti-diphtheria toxoid antibodies. We also investigated for relevant factors associated with anti-diphtheria toxoid antibody titers. Methods This cross-sectional study was conducted in the Senen District of Jakarta, Indonesia. The inclusion criteria were healthy children aged 6 to 7 years  with documented history of DPT vaccination. Primary vaccination defined as 3 doses of DPT at age less than 1 year , first booster  was DPT vaccination at 18-24 years of age, and second booster was diphtheria-tetanus (DT) vaccination received at 5 to 7 years of age. Peripheral blood specimens were obtained from participating children, after informed consent was provided by their parents. Antibodies against diphtheria in sera specimens were assessed by commercial anti-diphtheria toxoid immunoglobulin G (IgG) enzyme-linked immunosorbent assay. Results There were 154 children included in the study, with a female majority (61%). Overall, specific humoral immunity against diphtheria was observed in 113 children (73.4%). There was no statistical difference in immunity level between genders. Importantly, children who received the first and second diphtheria booster had significantly higher anti-diphtheria antibody level than those who did not receive both diphtheria booster (P<0.001). Conclusion Booster vaccinations are crucial among school-age children in Indonesia to improve their anti-diphtheria immunity and to minimize a risk of diphtheria outbreaks.

Genomic Characterization and Safety Assessment of Bifidobacterium breve BS2-PB3 as Functional Food

Our group had isolated Bifidobacterium breve strain BS2-PB3 from human breast milk. In this study, we sequenced the whole genome of B. breve BS2-PB3, and with a focus on its safety profile, various probiotic characteristics (presence of antibiotic resistance genes, virulence factors, and mobile elements) were then determined through bioinformatic analyses. The antibiotic resistance profile of B. breve BS2-PB3 was also evaluated. The whole genome of B. breve BS2-PB3 consisted of 2,268,931 base pairs with a G-C content of 58.89% and 2,108 coding regions. The average nucleotide identity and whole-genome phylogenetic analyses supported the classification of B. breve BS2-PB3. According to our in silico assessment, B. breve BS2-PB3 possesses antioxidant and immunomodulation properties in addition to various genes related to the probiotic properties of heat, cold, and acid stress, bile tolerance, and adhesion. Antibiotic susceptibility was evaluated using the Kirby-Bauer disk-diffusion test, in which the minimum inhibitory concentrations for selected antibiotics were subsequently tested using the Epsilometer test. B. breve BS2-PB3 only exhibited selected resistance phenotypes, i.e., to mupirocin (minimum inhibitory concentration/MIC >1,024 μg/ml), sulfamethoxazole (MIC >1,024 μg/ml), and oxacillin (MIC >3 μg/ml). The resistance genes against those antibiotics, i.e., ileS, mupB, sul4, mecC and ramA, were detected within its genome as well. While no virulence factor was detected, four insertion sequences were identified within the genome but were located away from the identified antibiotic resistance genes. In conclusion, B. breve BS2-PB3 demonstrated a sufficient safety profile, making it a promising candidate for further development as a potential functional food.

Factors associated with parental intention to vaccinate their preschool children against COVID-19: a cross-sectional survey in urban area of Jakarta, Indonesia

Purpose

We reported a survey-based study assessing the parental intention to vaccinate children of 5 to 7 years old against coronavirus disease 2019 (COVID-19). The aim of this study is to assess factors influencing the parental intention to vaccinate their children against COVID-19.

Materials and Methods

This study adopted a cross-sectional design, held at the public health center of Senen district, Jakarta, Indonesia from November 1-30, 2022. The off-line questionnaires were distributed via the school administrator to all eligible parents. Factors associated with intention to vaccinate were analyzed with the regression logistic models.

Results

Of the 435 parents in this study, 215 had already vaccinated their children against COVID-19 (49.4%), and the overall intention of the participants to vaccinate was 69.7%. Factors associated with intention to vaccinate the children against COVID-19 were parental employment status, parental COVID-19 vaccine status and concern of contracting COVID-19. Parents who are employed, had completed vaccines with COVID-19 booster vaccine, and had concern of their children contracting COVID-19 were more likely to vaccinate their children (odds ratio [OR], 2.10; 95% confidence interval [CI], 1.22-3.69; p=0.011; OR, 2.15; 95% CI, 1.21-3.83; p=0.013; OR, 2.40; 95% CI, 1.34-4.30; p=0.004, respectively). Concern on the vaccine's side effects was negatively associated with the willingness to vaccinate.

Conclusion

This study showed that childhood COVID-19 vaccine only covered half of the population, with parental intentions for childhood COVID-19 vaccination being high, reaching almost two-thirds of the study participants. Factors influencing parental intentions were employment status, parental COVID-19 vaccine status, concerns about COVID-19 and concerns about vaccine side effects.

SARS-CoV-2 Breakthrough Infection after mRNA-1273 Booster among CoronaVac-Vaccinated Healthcare Workers

It remains unknown whether the Indonesian healthcare workers (HCWs) who had received two doses of CoronaVac vaccine and one dose of mRNA-1273 booster could be protected during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron wave. In total, 125 infection-naïve and 10 previously infected HCWs were recruited. The mRNA-1273 booster substantially increased titer of anti-SARS-CoV-2 spike protein receptor-binding domain antibodies. However, the monitoring revealed that 34 out of 125 infection-naïve (27.2%) and 3 out of 10 previously infected HCWs (30.0%) were infected during the Omicron wave. All infected HCWs were either asymptomatic or having mild coronavirus disease 2019 (COVID-19) and subsequently fully recovered, supporting the heterologous prime-boost strategy against COVID-19.

Heterologous prime-boost with the mRNA-1273 vaccine among CoronaVac-vaccinated healthcare workers in Indonesia

Purpose

This study was performed to investigate humoral immune response and adverse events upon the heterologous prime-boost with a single dose of the mRNA-1273 vaccine among fully CoronaVac-vaccinated, infection-naïve healthcare workers in Indonesia.

Materials and Methods

One hundred twenty-five eligible healthcare workers were recruited from one hospital for this prospective cohort study. Blood collection was conducted twice, i.e., on 7 days before and 28 days after the booster vaccination. The titer of anti-SARS-CoV-2 receptor-binding domain (RBD) antibodies was quantified accordingly. The post-vaccination adverse event was recorded for both CoronaVac and mRNA-1273 vaccinations. Any breakthrough infection was monitored during the follow-up period. Wilcoxon matched-pairs signed rank test was used to test differences between groups.

Results

A significant increase was observed in the titer of anti-SARS-CoV-2 RBD antibodies upon receiving the mRNA-1273 booster (geometric mean titers of 65.57 and 47,445 U/mL in pre- and post-booster, respectively), supporting the argument to use heterologous prime-boost vaccination to improve the protection against COVID-19 in a high-risk population. The mRNA-1273 vaccine, however, caused a higher frequency of adverse events than the CoronaVac vaccine. Nonetheless, the adverse events were considered minor medical events and temporary as all subjects were not hospitalized and fully recovered. Of note, no breakthrough infection was observed during the follow-up to 12 weeks post-booster.

Conclusion

The heterologous prime-boost vaccination of healthcare workers with a single dose of the mRNA-1273 vaccine generated a significant elevation in humoral immune response towards RBD of SARS-CoV-2 and was associated with a higher frequency, but minor and transient, adverse events.