Recognition of microbial viability via TLR8 drives TFH cell differentiation and vaccine responses.

Live attenuated vaccines are generally highly efficacious and often superior to inactivated vaccines, yet the underlying mechanisms of this remain largely unclear. Here we identify recognition of microbial viability as a potent stimulus for follicular helper T cell (TFH cell) differentiation and vaccine responses. Antigen-presenting cells (APCs) distinguished viable bacteria from dead bacteria through Toll-like receptor 8 (TLR8)-dependent detection of bacterial RNA. In contrast to dead bacteria and other TLR ligands, live bacteria, bacterial RNA and synthetic TLR8 agonists induced a specific cytokine profile in human and porcine APCs, thereby promoting TFH cell differentiation. In domestic pigs, immunization with a live bacterial vaccine induced robust TFH cell and antibody responses, but immunization with its heat-killed counterpart did not. Finally, a hypermorphic TLR8 polymorphism was associated with protective immunity elicited by vaccination with bacillus Calmette-Guérin (BCG) in a human cohort. We have thus identified TLR8 as an important driver of TFH cell differentiation and a promising target for TFH cell-skewing vaccine adjuvants.

Parasites of the liver - epidemiology, diagnosis and clinical management in the European context.

Parasites in the liver cause significant global morbidity and mortality, as they can lead to recurrent cholangitis, cirrhosis, liver failure and cancer. Due to climate change and globalisation, their incidence is increasing, especially in Europe. The correct diagnosis of a hepatic parasite is often delayed because clinicians are unfamiliar with respective entities. Therefore, in this review, we aim to provide clinicians with a comprehensive clinical picture of hepatic parasites and to bring these neglected parasitic liver diseases to the wider attention of hepatology stakeholders in Europe and around the world.

Interaction of TLR4 and TLR8 in the Innate Immune Response against Mycobacterium Tuberculosis.

The interaction and crosstalk of Toll-like receptors (TLRs) is an established pathway in which the innate immune system recognises and fights pathogens. In a single nucleotide polymorphisms (SNP) analysis of an Indian cohort, we found evidence for both TLR4-399T and TRL8-1A conveying increased susceptibility towards tuberculosis (TB) in an interdependent manner, even though there is no established TLR4 ligand present in Mycobacterium tuberculosis (Mtb), which is the causative pathogen of TB. Docking studies revealed that TLR4 and TLR8 can build a heterodimer, allowing interaction with TLR8 ligands. The conformational change of TLR4-399T might impair this interaction. With immunoprecipitation and mass spectrometry, we precipitated TLR4 with TLR8-targeted antibodies, indicating heterodimerisation. Confocal microscopy confirmed a high co-localisation frequency of TLR4 and TLR8 that further increased upon TLR8 stimulation. The heterodimerisation of TLR4 and TLR8 led to an induction of IL12p40, NF-κB, and IRF3. TLR4-399T in interaction with TLR8 induced an increased NF-κB response as compared to TLR4-399C, which was potentially caused by an alteration of subsequent immunological pathways involving type I IFNs. In summary, we present evidence that the heterodimerisation of TLR4 and TLR8 at the endosome is involved in Mtb recognition via TLR8 ligands, such as microbial RNA, which induces a Th1 response. These findings may lead to novel targets for therapeutic interventions and vaccine development regarding TB.

A SNP upstream of the cyclic GMP-AMP synthase (cGAS) gene protects from relapse and extra-pulmonary TB and relates to BCG vaccination status in an Indian cohort.

Tuberculosis (TB) caused by Mycobacterium tuberculosis (M.tb) is a major health care threat worldwide causing over a million deaths annually. Host-pathogen interaction is complex, and a strong genetic contribution to disease susceptibility has been proposed. We have investigated single-nucleotide polymorphisms (SNPs) within cGAS/STING in Indian TB patients and healthy cohorts from India and Germany by Lightcycler®480 genotyping technique. The cGAS/STING pathway is an essential defense pathway within the cytosol after M.tb is internalized and mycobacterial DNA is released inducing the production of type I IFNs. We found that the rs311686 SNP upstream of cGAS provides protection from getting TB overall and is differently distributed in pulmonary TB patients compared with extra-pulmonary and particularly relapse cases. This SNP furthermore differs in distribution when comparing individuals with respect to BCG vaccination status. Taken together, our results show that the presence of the rs311686 SNP influences the course of TB significantly. However, structural conformation changes were found only for the cGAS rs610913 SNP. These findings underscore the importance of M.tb DNA recognition for TB pathogenesis and may eventually help in risk stratification of individuals. This may ultimately help in prevention of disease and aid in developing new vaccination and treatment strategies.

Salvage Therapy for Alveolar Echinococcosis-A Case Series.

Benzimidazoles are the only approved drugs for the treatment of inoperable human alveolar echinococcosis but may be limited due to intolerance or, rarely, ineffectiveness. A medical second-line or salvage therapy is not available, though it is urgently needed. We report long-term follow-up data from 14 patients who underwent salvage therapy with repurposed drugs with cumulatively 53.25 patient-years. Treatment response was evaluated by both clinical outcome and image studies, preferably PET/CT. Eleven patients received amphotericin B, and 70% of evaluable cases showed some positive treatment response, but side effects often limited therapy. Five patients received nitazoxanide, of which two showed clear progression but one achieved a lasting stable disease. One patient was treated with mefloquine combination therapy in advanced disease, and overall, a positive treatment response could not be assessed. Furthermore, we report on one patient receiving pembrolizumab for a concomitant malignancy, which did not result in a reduction of echinococcal manifestation. In summary, current options of salvage therapy can sometimes induce persistent disease control, although with potentially significant side effects and high treatment costs, and mortality remains high. No clear recommendation for a salvage therapy can be given; treatment remains highly experimental, and non-pharmaceutical interventions have to be considered.

Experienced stigma and applied coping strategies during the COVID-19 pandemic in Germany: a mixed-methods study.

OBJECTIVE: Health-related stigma is considered a social determinant of health equity and a hidden burden of disease. This study aimed to assess the level and dimensions of stigma and respective coping mechanisms in COVID-19 survivors. METHODS: A mixed-methods study with sequential explanatory design was conducted at the University Hospital of Ulm, Germany. Stigma was assessed using the Social Impact Scale (SIS) including adult COVID-19 survivors with mild-to-severe disease. Subsequently, 14 participants were sampled with regard to gender, age and severity of disease for in-depth interviews to understand how stigma was experienced and coping strategies were applied. The questionnaire was analysed using descriptive statistics, t-test and analysis of variance. Content analysis was used for qualitative data. RESULTS: From 61 participants, 58% were men and mean age was 51 years. The quantitative analysis of the SIS indicated an intermediate level of experienced stigma. Participants experienced stigma mainly as 'social rejection' (M=14.22, SD=4.91), followed by 'social isolation' (M=10.17, SD=4.16) and 'internalised shame' (M=8.39, SD=3.32). There was no significant difference in experienced stigma regarding gender, education, occupational status or residual symptoms. However, participants between 30 and 39 years of age experienced higher levels of stigma than other age groups (p=0.034). The qualitative analysis revealed how stigma seemed to arise from misconceptions creating irrational fear of infection, leading to stereotyping, vilification, discrimination and social exclusion of COVID-19 survivors, leaving them feeling vulnerable. Stigma cut through all social levels, from the individual level at the bottom to the institutional and societal level at the top. Social networks protected from experiencing stigma. CONCLUSION: COVID-19-related stigma is a relevant burden in the ongoing pandemic. Providing accurate information and exposing misinformation on disease prevention and treatment seems key to end COVID-19-related stigma.

Initial Risk Assessment in Patients with Alveolar Echinococcosis-Results from a Retrospective Cohort Study.

Background: Alveolar echinococcosis (AE) is a potentially lethal parasitosis with a broad spectrum of disease dynamics in affected patients. To guide clinical management, we assessed initial prognostic factors for both progressive and controlled AE based on initial staging. Methods: A retrospective cohort study was conducted, examining 279 patients assigned to different clinical groups: cured, stable with and without the need for benzimidazole treatment, and progressive disease. Univariate analysis compared demographic and clinical variables. Significant variables were subsequently entered into two separate logistic regression models for progressive and controlled disease. Results: Based on the multivariate analysis, a large AE lesion (OR = 1.02 per millimetre in size; 95%CI 1.004-1.029), PNM staging (OR = 2.86; 95%CI 1.384-5.911) and especially the involvement of neighbouring organs (OR = 3.70; 95%CI 1.173-11.653) remained significant risk factors for progressive disease. A negative Em2+ IgG (OR = 0.25; 95%CI 0.072-0.835) and a small AE lesion (OR = 0.97; 95%CI 0.949-0.996) were significant protective factors. Conclusions: Patients with large lesions and advanced stages should be monitored closely and most likely require long-term treatment with benzimidazoles if curative resection is not feasible. Patients with small lesions and negative Em2+ IgG seem able to control the disease to a certain extent and a less strict treatment regimen might suffice.

Echinococcus multilocularis specific antibody, systemic cytokine, and chemokine levels, as well as antigen-specific cellular responses in patients with progressive, stable, and cured alveolar echinococcosis: A 10-year follow-up.

BACKGROUND: The infestation with Echinococcus multilocularis larvae may persist in humans for up to decades without evident clinical symptoms. Longitudinal investigations are needed to understand the dynamic immunological processes in alveolar echinococcosis (AE) patients associated with an active and progressive, a stable or a regressive course of disease. METHODOLOGY/PRINCIPAL FINDINGS: This study evaluated the E. multilocularis specific antibody responses, systemic cytokine, and chemokine serum levels over a 10-year follow-up period, as well as cellular responsiveness in AE patients. Our results demonstrate a rapid decrease in antibodies against E. multilocularis specific antigen Em2+. Especially in cured patients, these antibodies remained negative, making them a significant predictor for cured AE. E. multilocularis specific IgG4, and indirect hemagglutination IHA decreased later in time, after around 5 years. While total IgE did not show significant dynamics over the course of disease, E. multilocularis specific IgE decreased after one to two years, and increasing levels were a significant predictor of progressive disease. There was no significant change in systemic IL-8, IL-9, CCL18 or CCL20 serum levels over time. Univariate analysis across groups indicated lower IL-8 levels in cured patients; however, this result could not be confirmed by multivariate analysis. Levels of CCL17 decreased during treatment, especially in cured patients, and thus might serve as a predictive or risk factor for progressive disease. Levels of IL-10 and CCL13 decreased during disease, especially after five and ten years of intervention. The E. multilocularis antigen (EmAg) inducible cellular productions of MCP1(CCL13), TARC(CCL17) and PARC(CCL18) were lowest in patients with cured AE and infection-free controls, while the EmAg inducible cellular production of IFN-γ increased after cure. Significant positive cytokine and chemokine correlations were observed in AE patients for IL-9, IL-10, CCL13(MCP-4), CCL17(TARC) and CCL20(LARC)(for all p<0.001). E. multilocularis specific IgG4 response correlated positively with TARC (p<0.001). Both markers enhanced over time in progressive disease and decreased after cure. The levels of IL-8, IL-10, MCP4 and LARC enhanced with AE regression. CONCLUSIONS/SIGNIFICANCE: Repeated biomarker surveys are advisable to evaluate progression or regression of disease during longitudinal follow-up and such analyses can support imaging techniques and improve staging of AE patients.

RNA Sensing of Mycobacterium tuberculosis and Its Impact on TB Vaccination Strategies.

Tuberculosis (TB) is still an important global threat and although the causing organism has been discovered long ago, effective prevention strategies are lacking. Mycobacterium tuberculosis (MTB) is a unique pathogen with a complex host interaction. Understanding the immune responses upon infection with MTB is crucial for the development of new vaccination strategies and therapeutic targets for TB. Recently, it has been proposed that sensing bacterial nucleic acid in antigen-presenting cells via intracellular pattern recognition receptors (PRRs) is a central mechanism for initiating an effective host immune response. Here, we summarize key findings of the impact of mycobacterial RNA sensing for innate and adaptive host immunity after MTB infection, with emphasis on endosomal toll-like receptors (TLRs) and cytosolic sensors such as NLRP3 and RLRs, modulating T-cell differentiation through IL-12, IL-21, and type I interferons. Ultimately, these immunological pathways may impact immune memory and TB vaccine efficacy. The novel findings described here may change our current understanding of the host response to MTB and potentially impact clinical research, as well as future vaccination design. In this review, the current state of the art is summarized, and an outlook is given on how progress can be made.

Toll-like receptor 1 variations influence susceptibility and immune response to Mycobacterium tuberculosis.

BACKGROUND: Tuberculosis (TB), a disease caused by Mycobacterium tuberculosis (MTB) infection, is still a global public health problem. TB susceptibility varies greatly in infected individuals, and mycobacterial recognition by the innate immune system likely affects disease course and outcome. This research describes a single nucleotide polymorphism in the Toll-like receptor (TLR) 1 gene that functionally alters the innate immune response to MTB and is associated with TB susceptibility in India. METHODS: 206 TB patients and 239 healthy controls from Hyderabad, India were analyzed for SNPs in the TLR1 and TLR2 genes, which were subsequently correlated to TB susceptibility. To test individual responses to MTB lysates, we stimulated PBMCs from genotyped healthy German individuals, as well as HEK cells transfected with TLR1/2 variants. TNF production and NF-kB activation were assessed respectively. RESULTS: Cohort analysis associated the TLR1-248N SNP (RS4833095) with TB protection. TLR1-248N expressing PBMCs from healthy controls exhibited an increased TNF response to MTB lysates. In addition to this, functional studies using HEK cell lines transfected with TLR1-248N and stimulated with MTB showed an increased NF-kB activation. CONCLUSION: SNP TLR1-248N is associated with TB protection in an Indian population and exhibits an increased immune response to MTB lysate in vitro.