Microbial ecosystem assessment and hydrogen oxidation potential of newly discovered vent systems from the Central and South-East Indian Ridge

In order to expand the knowledge of microbial ecosystems from deep-sea hydrothermal vent systems located on the Central and South-East Indian Ridge, we sampled hydrothermal fluids, massive sulfides, ambient water and sediments of six distinct vent fields. Most of these vent sites were only recently discovered in the course of the German exploration program for massive sulfide deposits and no previous studies of the respective microbial communities exist. Apart from typically vent-associated chemosynthetic members of the orders Campylobacterales, Mariprofundales, and Thiomicrospirales, high numbers of uncultured and unspecified Bacteria were identified via 16S rRNA gene analyses in hydrothermal fluid and massive sulfide samples. The sampled sediments however, were characterized by an overall lack of chemosynthetic Bacteria and the presence of high proportions of low abundant bacterial groups. The archaeal communities were generally less diverse and mostly dominated by members of Nitrosopumilales and Woesearchaeales, partly exhibiting high proportions of unassigned Archaea. Correlations with environmental parameters were primarily observed for sediment communities and for microbial species (associated with the nitrogen cycle) in samples from a recently identified vent field, which was geochemically distinct from all other sampled sites. Enrichment cultures of diffuse fluids demonstrated a great potential for hydrogen oxidation coupled to the reduction of various electron-acceptors with high abundances of Hydrogenovibrio and Sulfurimonas species. Overall, given the large number of currently uncultured and unspecified microorganisms identified in the vent communities, their respective metabolic traits, ecosystem functions and mediated biogeochemical processes have still to be resolved for estimating consequences of potential environmental disturbances by future mining activities.

Prevalence of Fecal Incontinence in Normal Pressure Hydrocephalus: A Prospective Evaluation of 100 Patients

BACKGROUND

Normal pressure hydrocephalus (NPH) is a frequent disease in elderly patients. The main symptoms are gait disturbance, urine incontinence, and cognitive decline. Fecal urgency and incontinence are described as rare additional symptoms; however, no exact numbers are known. The aim of this study was to investigate the prevalence of fecal disturbances in NPH patients.

METHODS

Patients who presented to our department with confirmed diagnosis of NPH between January and December 2021 were interviewed prospectively about fecal function. Additionally, the extent of gait disturbance, cognitive decline, ventriculomegaly (EvansIndex), disproportionate enlarged subarachnoid space hydrocephalus (DESH presence), age, gender, and length of history were documented. In those who were operated with a hydrocephalus shunt postoperative development of stool incontinence was followed up.

RESULTS

One hundred patients were evaluated (67 males, 33 females, medium age 77.5 years, medium Evans Index: 0.37; 87 with disproportionate enlarged subarachnoid space hydrocephalus). 97 patients showed gait disturbance, 84 cognitive decline, and 87 bladder dysfunctions. 78 patients had the complete Hakim triad. 32 patients complained about fecal incontinence (20 with urge incontinence, 12 with complete incontinence). Twenty nine patients were shunted, of which 17 (57%) recovered completely, 9 (31%) partially, and 3 (10%) did not show any change.

CONCLUSIONS

Fecal urgency and incontinence is a frequent finding in NPH (32%) and is essential for the quality of life. In the general population, fecal incontinence in elderly is found in up to 15%. The more than two-fold higher prevalence in NPH patients and the high percentage of postshunted improvement suggests that NPH causes often directly fecal disturbance.

Taxonomic diversity of microbial communities in sub-seafloor hydrothermal sediments of the active Santorini-Kolumbo volcanic field

Introduction

Active hydrothermal vents of volcanic origin provide a remarkable manifestation of life on Earth under extreme conditions, which may have consequences for our understanding of habitability on other terrestrial bodies as well.

Methods

Here, we performed for the first time Illumina sequencing of bacterial and archaeal communities on sub-seafloor samples collected from the Santorini-Kolumbo volcanic field. A total of 19 (3-m long) gravity corers were collected and processed for microbial community analysis.

Results

From a total of 6,46,671 produced V4 sequences for all samples, a total of 10,496 different Operational Taxonomic Units (OTUs) were identified that were assigned to 40 bacterial and 9 archaeal phyla and 14 candidate divisions. On average, the most abundant phyla in all samples were Chloroflexi (Chloroflexota) (24.62%), followed by Proteobacteria (Pseudomonadota) (11.29%), Firmicutes (Bacillota) (10.73%), Crenarchaeota (Thermoproteota) (8.55%), and Acidobacteria (Acidobacteriota) (8.07%). At the genus level, a total of 286 known genera and candidate genera were mostly dominated by members of Bacillus, Thermoflexus, Desulfatiglans, Pseudoalteromonas, and Pseudomonas.

Discussion

In most of the stations, the Chao1 values at the deeper layers were comparable to the surface sediment samples denoting the high diversity in the subsurface of these ecosystems. Heatmap analysis based on the 100 most abundant OTUs, grouped the sampling stations according to their geographical location, placing together the two hottest stations (up to 99°C). This result indicates that this specific area within the active Kolumbo crater create a distinct niche, where microorganisms with adaptation strategies to withstand heat stresses can thrive, such as the endospore-forming Firmicutes.

Decision curve analysis confirms higher clinical utility of multi-domain versus single-domain prediction models in patients with open abdomen treatment for peritonitis

BACKGROUND

Prediction modelling increasingly becomes an important risk assessment tool in perioperative systems approaches, e.g. in complex patients with open abdomen treatment for peritonitis. In this population, combining predictors from multiple medical domains (i.e. demographical, physiological and surgical variables) outperforms the prediction capabilities of single-domain prediction models. However, the benefit of these prediction models for clinical decision-making remains to be investigated. We therefore examined the clinical utility of mortality prediction models in patients suffering from peritonitis with a decision curve analysis.

METHODS

In this secondary analysis of a large dataset, a traditional logistic regression approach, three machine learning methods and a stacked ensemble were employed to examine the predictive capability of demographic, physiological and surgical variables in predicting mortality under open abdomen treatment for peritonitis. Calibration was examined with calibration belts and predictive performance was assessed with the area both under the receiver operating characteristic curve (AUROC) and under the precision recall curve (AUPRC) and with the Brier Score. Clinical utility of the prediction models was examined by means of a decision curve analysis (DCA) within a treatment threshold range of interest of 0-30%, where threshold probabilities are traditionally defined as the minimum probability of disease at which further intervention would be warranted.

RESULTS

Machine learning methods supported available evidence of a higher prediction performance of a multi- versus single-domain prediction models. Interestingly, their prediction performance was similar to a logistic regression model. The DCA demonstrated that the overall net benefit is largest for a multi-domain prediction model and that this benefit is larger compared to the default "treat all" strategy only for treatment threshold probabilities above about 10%. Importantly, the net benefit for low threshold probabilities is dominated by physiological predictors: surgical and demographics predictors provide only secondary decision-analytic benefit.

CONCLUSIONS

DCA provides a valuable tool to compare single-domain and multi-domain prediction models and demonstrates overall higher decision-analytic value of the latter. Importantly, DCA provides a means to clinically differentiate the risks associated with each of these domains in more depth than with traditional performance metrics and highlighted the importance of physiological predictors for conservative intervention strategies for low treatment thresholds. Further, machine learning methods did not add significant benefit either in prediction performance or decision-analytic utility compared to logistic regression in these data.

Pit picking vs. Limberg flap vs. primary open method to treat pilonidal sinus disease – A cohort of 327 consecutive patients

Background

Minimally invasive methods in pilonidal sinus disease (PSD) surgery are becoming standard. Although long-term results are available for some techniques, long-term outcome data of patients after pit picking is lacking. We aimed at investigating perioperative and long-term outcomes of patients undergoing pit picking, Limberg flap or primary open surgery to treat PSD.

Methods

In a single-centre observational study, we evaluated the outcomes of 327 consecutive patients undergoing PSD surgery between 2011 and 2020.

Results

PSD had recurred in 22% of Limberg flap patients and 62% of pit picking patients at 5 years (p=0.0078; log rank test). Previous pilonidal surgeries, smoking, body mass index, immunodeficiency, and diabetes did not significantly influence the long-term recurrence rate. Primary open treatment was performed for 72% of female patients presenting with primary disease.

Conclusions

Due to its especially dismal long-term results, pit picking should be abandoned, and Limberg flap should be promoted instead, even for primary disease and in females.

Comparison of the prognostic value of stress and rest pulmonary transit time estimation using myocardial perfusion CMR

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation Clinical Research Training Fellowship

Background

Pulmonary transit time (PTT) is a quantitative biomarker of cardiopulmonary status. Rest PTT was previously shown to predict outcomes in specific disease models, but clinical adoption is hindered but challenges in data acquisition. Whether evaluation of PTT during stress encodes incremental prognostic information has not been previously investigated as scale.

Objectives

To compare the prognostic value of stress and rest PTT derived from a fully automated, in-line method of estimation using perfusion CMR, in a large patient cohort.

Methods

A retrospective two-center study of patients referred clinically for adenosine stress myocardial perfusion assessment using CMR. Analysis of right and left ventricular cavity arterial input function curves from first pass perfusion was performed automatically, allowing the in-line estimation of both rest and stress PTT. Association with major adverse cardiovascular events (MACE) was evaluated. MACE was defined as a composite outcome of myocardial infarction, stroke, heart failure admission and ventricular tachycardia or appropriate ICD treatment (including ICD shock and/or anti-tachycardia pacing).

Results

985 patients (67% male, median age 62 years (IQR 52,71)) were included, with median left ventricular ejection fraction (LVEF) of 62% (IQR 54-69). Median stress PTT was shorter than rest PTT 6.2 (IQR 5.1, 7.7) seconds versus 7.7 (IQR, 6.4, 9.2) seconds. Stress and rest PTT were highly correlated (r = 0.69; p < 0.001). Stress PTT also correlated with LVEF (r=-0.37), stress MBF (r=-0.31), LVEDVi (r = 0.24), LA area index (r = 0.32) (p < 0.001 for all). Over a median follow-up period of 28.6 (IQR, 22.6 35,7) months, MACE occurred in 61 (6.2%) patients. After adjusting for prognostic factors, both rest and stress PTT, independently predicted MACE, but not all-cause mortality. For every 1xSD (2.39s) increase in rest PTT the adjusted hazard ratio (HR) for MACE was 1.43 (95% CI 1.10-1.85, p = 0.007). The hazard ratio for one standard deviation (2.64s) increase in stress PTT was 1.34 (95% CI 1.048-1.723; p = 0.020) after adjusting for age, LVEF, hypertension, diabetes, sex and presence of LGE

Conclusions

In this 2-center study of 985 patients, we deploy a fully automated method of PTT estimation using perfusion mapping with CMR and show that both stress and rest PTT are independently associated with adverse cardiovascular outcomes. In this patient cohort, there is no clear incremental prognostic value of stress PTT, over its evaluation during rest.

Figure 1. Stress and Rest Pulmonary Transit Time estimation using myocardial perfusion CMR

Figure 2. Event-free survival curves for major adverse cardiovascular events (Heart failure hospitalization, myocardial infarction, stroke and ventricular tachycardia/ICD treatment) according to mean rest PTT (8.05seconds) and mean stress PTT (6.7seconds). Log-rank for both p < 0.05

A cost analysis of cardiac magnetic resonance imaging in the diagnostic pathway of a population with unexplained acute myocardial injury and normal coronary angiography

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): National Institute for Health Research (NIHR) Biomedical Research Centre at St Bartholomew"s Hospital London. Irish Cardiac Society

OnBehalf

European Association of Cardiovascular Imaging (EACVI) -Task Force for Cost Effectiveness.

Background

Acute presentations with myocardial injury that occur despite culprit-free coronary angiography were first reported over 70 years ago, with a prevalence between 5-9%.  1-3 There is increasing evidence that a more accurate diagnosis is available and that CMR is a key tool to determine the underlying pathology. This is reflected with the most recent international guidelines advocating for the use of CMR in the diagnostic pathways of this heterogeneous population.  However, to date there is no formal assessment of the financial implications of adopting these new guidelines.

Purpose

To determine the financial impact of implementing cardiac magnetic resonance imaging in the diagnostic pathway of a population with unexplained acute myocardial injury and normal coronary angiography in comparison to existing clinical practice.

Methods

We performed a focused cost-benefit analysis using a hypothetical population of 2,000 patients with unexplained acute myocardial injury and normal coronary angiography.  The population was split evenly into two groups of either standard, or CMR guided management, and extrapolated over a ten-year period. Standard management was defined as 66% of the population receiving dual antiplatelet therapy (ticagrelor and aspirin) for one year followed by aspirin for life, and the remaining 34% of the population receiving aspirin for life. CMR guided management determined antiplatelet therapy according to the imaging findings. This analysis focused on CMR’s ability to accurately identify those patients who may have had an MI and facilitate tailored treatment with evidence based dual antiplatelet therapy. Costs and rates were defined in Table 1. A one-way sensitivity analysis was also performed to determine the variables with largest impact on the costs. Each variable was varied by +/- 20% and the change in cost determined at year 10.

Results

Using CMR in the diagnostic pathway resulted in an increased cost of £72,656 in the first year. After year 7, CMR guided practice becomes cost neutral, resulting in cost saving of £24,054 over a ten-year period in a population of 1000 patients. Figure 1. Utilizing CMR in this population also resulted in 7 fewer myocardial infarctions and 14 fewer major bleeding events over a ten-year time horizon.

The three most sensitive variables were, in decreasing order, the cost of CMR, the cost of ticagrelor and the percentage of the population with MI requiring DAPT. A 20% change from baseline resulted in a 320%, 247% and 162% change in costs at 10 years, respectively.

Conclusion

Utilizing CMR in this population may be associated with reduced costs in the medium to long term. The initial increased cost of CMR is offset over time, by delivering a more personalised, higher quality level of care to patients.

InterCarb: A Community Effort to Improve Interlaboratory Standardization of the Carbonate Clumped Isotope Thermometer Using Carbonate Standards

Increased use and improved methodology of carbonate clumped isotope thermometry has greatly enhanced our ability to interrogate a suite of Earth-system processes. However, interlaboratory discrepancies in quantifying carbonate clumped isotope (Δ47) measurements persist, and their specific sources remain unclear. To address interlaboratory differences, we first provide consensus values from the clumped isotope community for four carbonate standards relative to heated and equilibrated gases with 1,819 individual analyses from 10 laboratories. Then we analyzed the four carbonate standards along with three additional standards, spanning a broad range of δ47 and Δ47 values, for a total of 5,329 analyses on 25 individual mass spectrometers from 22 different laboratories. Treating three of the materials as known standards and the other four as unknowns, we find that the use of carbonate reference materials is a robust method for standardization that yields interlaboratory discrepancies entirely consistent with intralaboratory analytical uncertainties. Carbonate reference materials, along with measurement and data processing practices described herein, provide the carbonate clumped isotope community with a robust approach to achieve interlaboratory agreement as we continue to use and improve this powerful geochemical tool. We propose that carbonate clumped isotope data normalized to the carbonate reference materials described in this publication should be reported as Δ47 (I-CDES) values for Intercarb-Carbon Dioxide Equilibrium Scale.

Rethinking the causes of pilonidal sinus disease: a matched cohort study

Our understanding of pilonidal sinus disease (PSD) is based on a paper published 29 years ago by Karydakis. Since then, surgeons have been taught that hair more easily penetrates wet skin, leading to the assumption that sweating promotes PSD. This postulate, however, has never been proven. Thus we used pilocarpine iontophoresis to assess sweating in the glabella sacralis. 100 patients treated for PSD and 100 controls were matched for sex, age and body mass index (BMI). Pilocarpine iontophoresis was performed for 5 min, followed by 15 min of sweat collection. PSD patients sweated less than their matched pairs (18.4 ± 1.6 µl vs. 24.2 ± 2.1 µl, p = 0.03). Men sweated more than women (22.2 ± 1.2 µl vs. 15.0 ± 1.0 µl in non-PSD patients (p < 0.0001) and 20.0 ± 1.9 µl vs. 11.9 ± 2.0 µl in PSD patients (p = 0.051)). And regular exercisers sweated more than non-exercisers (29.1 ± 2.9 µl vs. 18.5 ± 1.6 µl, p = 0.0006 for men and 20.7 ± 2.3 µl vs. 11.4 ± 1.4 µl, p = 0.0005 for women). PSD patients sweat less than matched controls. Thus sweating may have a protective effect in PSD rather than being a risk factor.

[Wound Healing Disorders after Excision and Open Treatment for Pilonidal Sinus]

INTRODUCTION

Pilonidalis sinus disease is a mostly chronic selective infection of the hairy skin in the area of skin wrinkles, mainly in the area of the natal cleft. Open treatment is still the most common recommended therapy. Nevertheless, there may be healing disorders within the framework of open wound treatment, which can significantly complicate the course.

METHODS

The following is an overview of wound healing disorders after excision of pilonidalis sinus. Healing time and frequency are determined on the basis of current data and the causes of the healing disorder are evaluated. In addition, possible treatment options are presented and treatment recommendations are made.

RESULTS

The evaluation of published data on wound healing period showed that the wound usually heals after a mean of two months. The results of the German forces cohort study show by way of example that almost all wounds have healed in the period up to three months. However, a small percentage of non-healing wounds remain. The frequency of significantly delayed wound healing is given in the literature as 2 - 5%. The influencing factors for wound healing after sinus pilonidalis excision are not only the size and symmetry of the excision wound but also other details of open wound treatment. In addition to intensification of the previous open wound treatment, the new excision and refreshment of the wound are mentioned as treatment options in the event of a lack of wound healing. Furthermore, changes in strategy for plastic-reconstructive procedures or other surface treatment are also recommended.

CONCLUSION

The excision wound of pilonidalis sinus should be healed after three to four months at the latest, after which the wound can be regarded as a wound with significantly delayed healing or as a wound healing disorder. Around this time, the findings should be re-evaluated and, if necessary, a change in the treatment concept should be made.

Transverse vs. median laparotomy in peritonitis and staged lavage: a single center case series

Background: Staged lavage was first introduced in the 1970s and now serves as a therapeutic option for septic patients with peritonitis. A central aspect of this treatment concept is leaving the abdomen open after a wide incision. To evaluate the influence of transverse vs. median access to the abdomen in staged lavage, data from the authors’ patients were analyzed.

Methods: To evaluate patients with peritonitis, prospective intensive care data were examined together with data on the surgical details. The main aspects covered here were the surgical details of the lavage (namely, transverse vs. median laparotomy), number of lavages, fascia closure, wound-healing disorders, and observed lethality, in combination with the preoperatively evaluated SAPS-II score, expected hospital lethality, patient age, and the Mannheim Peritonitis Index.

Results: Between January 2008 and December 2018, 522 patients were treated with open abdomen and staged lavage. The mean age of the patients was 66.0 years (standard deviation (SD) 15.9 years). A median incision was used in 140 cases, and transverse laparotomy was performed in 382. The mean SAPS-II score was 46.5 (SD 15.7), expected lethality was 39.6% (SD 26.3%), and observed lethality was 19.9%. On average, two lavages were performed after the index operation. Transverse incision was significantly less likely to cause wound-healing disorder (p=0.03), and fascial dehiscence was observed less frequently in the transverse laparotomies group than in median incisions in the statistical trend (p=0.06).

Conclusion: In summary, staged lavage reduced expected lethality in patients with peritonitis. Transverse incision caused wound-healing disorders and fascial dehiscence less often. Therefore, the indication for transverse laparotomy should be generous, as this form of treatment is advantageous in case of peritonitis.

A prospective study evaluating the integration of a multifaceted evidence-based medicine curriculum into early years in an undergraduate medical school

BACKGROUND

The importance of ensuring medical students are equipped with the skills to be able to practice evidence-based medicine (EBM) has been increasingly recognized in recent years. However, there is limited information on an effective EBM curriculum for undergraduate medical schools. This study aims to test the feasibility of integrating a multifaceted EBM curriculum in the early years of an undergraduate medical school. This was subsequently evaluated using the validated Fresno test and students' self-reported knowledge and attitudes as they progressed through the curriculum.

METHODS

EBM was integrated horizontally and vertically into the curriculum into the first 2 years of undergraduate medical school. First year medical students were recruited to participate in the study. The 212-point Fresno test was administered along with a locally developed questionnaire at baseline before EBM teaching in year one and at the end of EBM teaching in year two.

RESULTS

Thirty-one students participated at baseline and 55 students participated at the end of second year EBM teaching. For the 18 students who completed the Fresno at both time points, the average score increased by 38.7 marks (p < 0.001) after EBM teaching. Students felt confident in formulating clinical questions and in critically appraising journal articles after EBM teaching. EBM was perceived to be important to their future practice as a doctor and for improving patient outcomes at both time points.

CONCLUSIONS

It has been feasible to integrate a multifaceted, EBM curriculum from the first year of an undergraduate medical program. Early evaluation of the curriculum using the Fresno test has shown a significant increase in students' EBM knowledge. The curriculum also demonstrated an increase in students' perceptions of the clinical relevance of EBM in their developing practice.

[Pilonidal Sinus Disease; What is the Best Treatment Option?]

INTRODUCTION

Sinus pilonidalis is a chronic infection of the hairy skin in the area of skin wrinkles, with the most common localization in the natal cleft. The disease often has a significant impact on the quality of life of the affected person; the treatment may be complex and needs to be adapted to the patient's needs.

METHODS

Below is an overview of the origin as well as the treatment alternatives and their peculiarities. The following aspects are presented: early post-operative results, wound healing disorder and long-term results.

RESULTS

The pathomechanism of pilonidal sinus disease has still not been conclusively clarified; it must continue to be assumed that the hair in the natal cleft contributes significantly to the formation. However, recent findings indicate that the large tufts of hair that are repeatedly found in the wound cavity are most likely to come from the hairy scalp. Three essential treatment options can be distinguished: The standard treatment of excision and subsequent open wound treatment, has a low recurrence rate, but requires considerable effort in wound treatment and thus leads to protracted time off work. Relatively new treatments include locally destructive treatment that essentially preserves the skin. Important representatives are so-called pit picking, fistuloscopy and other forms of treatment, such as phenol injection and/or laser treatment. In these treatment options, the final evaluation of the results is still pending. The third treatment group is excision and plastic reconstruction. These procedures are technically demanding, often involve inpatient treatment but lead to relatively good results in the long term.

CONCLUSION

Treatment of pilonidal disease requires patient-oriented therapy planning. The patient must be taught the different treatment options and a treatment recommendation must be given to the patient. Excision and open granulation continues to serve as a standard procedure with which other treatment options can be compared.

Microbial metal-sulfide oxidation in inactive hydrothermal vent chimneys suggested by metagenomic and metaproteomic analyses

Metal‐sulfides are wide‐spread in marine benthic habitats. At deep‐sea hydrothermal vents, they occur as massive sulfide chimneys formed by mineral precipitation upon mixing of reduced vent fluids with cold oxygenated sea water. Although microorganisms inhabiting actively venting chimneys and utilizing compounds supplied by the venting fluids are well studied, only little is known about microorganisms inhabiting inactive chimneys. In this study, we combined 16S rRNA gene‐based community profiling of sulfide chimneys from the Manus Basin (SW Pacific) with radiometric dating, metagenome (n = 4) and metaproteome (n = 1) analyses. Our results shed light on potential lifestyles of yet poorly characterized bacterial clades colonizing inactive chimneys. These include sulfate‐reducing Nitrospirae and sulfide‐oxidizing Gammaproteobacteria dominating most of the inactive chimney communities. Our phylogenetic analysis attributed the gammaproteobacterial clades to the recently described Woeseiaceae family and the SSr‐clade found in marine sediments around the world. Metaproteomic data identified these Gammaproteobacteria as autotrophic sulfide‐oxidizers potentially facilitating metal‐sulfide dissolution via extracellular electron transfer. Considering the wide distribution of these gammaproteobacterial clades in marine environments such as hydrothermal vents and sediments, microbially accelerated neutrophilic mineral oxidation might be a globally relevant process in benthic element cycling and a considerable energy source for carbon fixation in marine benthic habitats.

H1N1 vaccination in Sjögren's syndrome triggers polyclonal B cell activation and promotes autoantibody production

OBJECTIVES

Vaccination of patients with rheumatic disease has been reported to result in lower antibody titres than in healthy individuals. However, studies primarily include patients on immunosuppressive therapy. Here, we investigated the immune response of treatment-naïve patients diagnosed with primary Sjögren's syndrome (pSS) to an H1N1 influenza vaccine.

METHODS

Patients with Sjögren's syndrome without immunomodulatory treatment and age-matched and gender-matched healthy controls were immunised with an H1N1 influenza vaccine and monitored for serological and cellular immune responses. Clinical symptoms were monitored with a standardised form. IgG class switch and plasma cell differentiation were induced in vitro in purified naïve B cells of untreated and hydroxychloroquine-treated patients and healthy controls. Gene expression was assessed by NanoString technology.

RESULTS

Surprisingly, treatment-naïve patients with Sjögren's syndrome developed higher H1N1 IgG titres of greater avidity than healthy controls on vaccination. Notably, off-target B cells were also triggered resulting in increased anti-EBV and autoantibody titres. Endosomal toll-like receptor activation of naïve B cells in vitro revealed a greater propensity of patient-derived cells to differentiate into plasmablasts and higher production of class switched IgG. The amplified plasma cell differentiation and class switch could be induced in cells from healthy donors by preincubation with type 1 interferon, but was abolished in hydroxychloroquine-treated patients and after in vitro exposure of naïve B cells to chloroquine.

CONCLUSIONS

This comprehensive analysis of the immune response in autoimmune patients to exogenous stimulation identifies a mechanistic basis for the B cell hyperactivity in Sjögren's syndrome, and suggests that caution is warranted when considering vaccination in non-treated autoimmune patients.