CD4 + T cells are found within endemic Burkitt lymphoma and modulate Burkitt lymphoma precursor cell viability and expression of pathogenically relevant Epstein-Barr virus genes.

Endemic Burkitt lymphoma (eBL) is an aggressive B cell cancer characterized by an IgH/c-myc translocation and the harboring of Epstein-Barr virus (EBV). Evidence accumulates that CD4 + T cells might contribute to eBL pathogenesis. Here, we investigate the presence of CD4 + T cells in primary eBL tissue and their potential dichotomous impact on an EBV-infected pre-eBL cell model using ex vivo material and in vitro co-cultures. In addition, we establish a novel method to study the effect of IgH/c-myc translocation in primary B cells by employing a CRISPR/Cas9 knock-in approach to introduce and tag de novo translocation. We unprecedently document that CD4 + T cells are present in primary eBL tumor tissue. Furthermore, we demonstrate that CD4 + T cells on the one hand suppress eBL development by killing pre-eBL cells lacking IgH/c-myc translocation in vitro and on the other hand indirectly promote eBL development by inducing crucial EBV Latency III to Latency I switching in pre-eBL cells. Finally, we show that while the mere presence of an IgH/c-myc translocation does not suffice to escape CD4 + T-cell-mediated killing in vitro, the CD4 + T-cell-mediated suppression of EBV's Latency III program in vivo may allow cells harboring an IgH/c-myc translocation and additional mutations to evade immune control and proliferate by means of deregulated c-myc activity, resulting in neoplasia. Thus, our study highlights the dichotomous effects of CD4 + T cells and the mechanisms involved in eBL pathogenesis, suggests mechanisms of their impact on eBL progression, and provides a novel in vitro model for further investigation of IgH/c-myc translocation.

Support of BCP-ALL-cells by autologous bone marrow Th-cells involves induction of AID expression but not widespread AID off-target mutagenesis.

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is the most common childhood malignancy. The two-step BCP-ALL pathogenesis requires in utero-induced chromosomal aberrations and additional mutagenic events for overt leukemia. In mouse models, activation-induced cytidine deaminase (AID/AICDA) was suggested to contribute to BCP-ALL pathogenesis by off-target mutagenic activity. The role of AID in patients, however, remains unclear. Moreover, AID is usually not expressed in precursor B-cells but in germinal center B-cells, where it is induced upon T-helper (Th) cell stimulation. We have previously demonstrated that autologous Th-cells supportively interacted with BCP-ALL-cells. Here, we hypothesize that this interaction additionally induces AID expression in BCP-ALL-cells, leading to off-target mutagenic activity. We show that co-culture with autologous bone marrow Th-cells induced high AICDA expression in primary BCP-ALL-cells. This induction was mediated by a mechanism similar to the induction in mature B-cells involving IL-13/Stat6, CD40L/NF-κB and TGFß/Smad2/3 signaling. Even though Th-cell-induced AID seemed to be active in vitro in a BCP-ALL reporter cell line, extensive mutational signature analysis revealed no major contribution of AID activity to the mutational landscape in BCP-ALL patients. AID activity was neither detected in mutation clusters nor in known AID targets. Moreover, no recurrently mutated gene showed a relevant enrichment of mutations in the AID motif. Together, the lack of AID-induced mutational consequences argues towards a Th-cell-promoted yet AID-independent BCP-ALL pathogenesis and favors therapeutic research focusing on Th-cell-derived support of BCP-ALL-cells rather than AID-induced effects.

Deficiencies in paediatric research applications delaying ethics committee approval.

BACKGROUND: A clinical research application must be submitted for approval by a competent ethics committee (EC) before a study can be executed. There is very limited information on how such submissions could be optimised, especially regarding research in children and adolescents, which requires particular caution and age-adapted patient information. METHODS: We assessed all research applications from the University Children’s Hospital Zurich submitted to the EC of the Canton of Zurich in 2014–2015, i.e., in the first two years after Switzerland’s new Human Research Act came into effect. Moreover, we validated our findings by assessing a randomly selected sample of applications from the same hospital in 2018–2019. RESULTS: We assessed a total of 86 applications from 2014–2015, originating from 29 departments and sub-specialties. The EC judged that it was not responsible for three applications and declined an assessment for another three because the studies had already been conducted. Thus, we included 80 applications in the present analysis (18 clinical trials, 52 research projects, 10 further use projects). Applicants withdrew four applications before the EC’s final decision and the EC rejected two after assessment. The EC had objections in 46 (62%) of the remaining 74 applications. Formal, including formal legal, objections (n = 503) and legal objections (n = 287) accounted for the vast majority of objections. There were also 71 ethical and 82 scientific objections. The most frequent formal and formal legal objections were incomplete or missing age-adapted patient information (49%) and incorrect templates for informed consent and signature forms (46%). A review of the 20 randomly selected applications from 2018–2019 confirmed that four out of the five most frequent deficiencies relating to informed consent were identical to those observed in the 2014–2015 applications. CONCLUSIONS: Careful preparation of submission documents by the investigators and close adherence to formal and legal requirements have the potential to considerably optimise and expedite the EC review process, and thus the commencement of the clinical research.    .

39·0°C versus 38·5°C ear temperature as fever limit in children with neutropenia undergoing chemotherapy for cancer: a multicentre, cluster-randomised, multiple-crossover, non-inferiority trial.

BACKGROUND: Fever in neutropenia is the most frequent complication of chemotherapy for cancer. The temperature limit defining fever used clinically varies. A higher limit can avoid unnecessary diagnoses in patients spontaneously recovering from fever. This trial primarily aimed to determine if a limit of 39·0°C ear temperature is non-inferior to 38·5°C regarding safety. METHODS: This cluster-randomised, multiple crossover, non-blinded, non-inferiority trial was done in six Swiss Paediatric Oncology Group centres (clusters) in Switzerland. Patients (aged 1 to <18 years) with any malignancy and treated with myelosuppressive chemotherapy expected to last 2 months or more were repeatedly randomly assigned (1:1), at the cluster level, to either monthly 39·0°C or 38·5°C ear temperature limits for diagnosis of fever in neutropenia. Diagnosis below the randomised limit was allowed for clinical reasons. Such a diagnosis implied emergency hospitalisation, examinations (including blood culture), as-needed antipyretics, and empirical intravenous broad-spectrum antibiotics. The primary outcome was the rate of fever in neutropenia with safety relevant events (SRE) per chemotherapy year; we also assessed efficacy in terms of rate of fever in neutropenia. The non-inferiority margin was 1·33 for safety, and for effiacy, the superiority margin was 1·00. This trial is registered at ClinicalTrials.gov, number NCT02324231. FINDINGS: 269 patients were recruited between April 28, 2016, to Aug 27, 2018, until the trial was stopped for success after the second interim analysis. Patients were repeatedly randomly assigned, with 1210 (48%) of 2547 randomisation periods and 92 (47%) of 195 chemotherapy years randomised to 39·0°C. SREs were diagnosed in 72 (20%) of 360 fever in neutropenia episodes (zero deaths, 16 intensive care unit admissions, 22 cases of severe sepsis, and 56 cases of bacteraemia). In 92 chemotherapy years randomised to the 39·0°C fever limit, 151 episodes of fever with neutropenia were diagnosed (1·64 per year), including 22 (15%) with SRE (0·24 per year). In 103 chemotherapy years randomised to 38·5°C, 209 episodes were diagnosed (2·03 per year), including 50 (24%) with SRE (0·49 per year). The mixed Poisson regression rate ratio (RR) of fever in neutropenia with SRE in 39·0°C versus 38·5°C was 0·56 (95% upper confidence bound 0·72). The corresponding RR of fever in neutropenia was 0·83 (95% upper confidence bound 0·98). INTERPRETATION: In children with neutropenia and chemotherapy for cancer, 39·0°C ear temperature was safe and seemed efficacious. For Switzerland and comparable settings, 39·0°C can be recommended as new evidence-based standard fever limit except for patients with acute myeloid leukaemia or haematopoietic stem cell transplantation. FUNDING: Swiss Cancer League (KLS-3645-02-2015).

Burden and Timeline of Infectious Diseases in the First Year After Solid Organ Transplantation in the Swiss Transplant Cohort Study.

BACKGROUND: The burden and timeline of posttransplant infections are not comprehensively documented in the current era of immunosuppression and prophylaxis. METHODS: In this prospective study nested within the Swiss Transplant Cohort Study (STCS), all clinically relevant infections were identified by transplant-infectious diseases physicians in persons receiving solid organ transplant (SOT) between May 2008 and December 2014 with ≥12 months of follow-up. RESULTS: Among 3541 SOT recipients, 2761 (1612 kidney, 577 liver, 286 lung, 213 heart, and 73 kidney-pancreas) had ≥12 months of follow-up; 1520 patients (55%) suffered 3520 infections during the first year posttransplantation. Burden and timelines of clinically relevant infections differed between transplantations. Bacteria were responsible for 2202 infections (63%) prevailing throughout the year, with a predominance of Enterobacteriaceae (54%) as urinary pathogens in heart, lung, and kidney transplant recipients, and as digestive tract pathogens in liver transplant recipients. Enterococcus spp (20%) occurred as urinary tract pathogens in kidney transplant recipients and as digestive tract pathogens in liver transplant recipients, and Pseudomonas aeruginosa (9%) in lung transplant recipients. Among 1039 viral infections, herpesviruses predominated (51%) in kidney, liver, and heart transplant recipients. Among 263 fungal infections, Candida spp (60%) prevailed as digestive tract pathogens in liver transplant recipients. Opportunistic pathogens, including Aspergillus fumigatus (1.4%) and cytomegalovirus (6%), were rare, scattering over 12 months across all SOT recipients. CONCLUSIONS: In the current era of immunosuppression and prophylaxis, SOT recipients experience a high burden of infections throughout the first year posttransplantation, with rare opportunistic pathogens and a predominance of bacteria.

Survey by TEDDY European Network of Excellence for Paediatric Clinical Research demonstrates potential for Europe-wide trials.

AIM: The European Network of Excellence for Paediatric Clinical Research, known as the TEDDY Network, carried out a survey to determine the capacity and competence of paediatric centres to perform research studies. METHODS: A cross-sectional, web-based pilot survey was conducted from October 2016 to April 2017 with paediatric clinical research centres in 11 countries: Albania, Austria, Belgium, Denmark, Iceland, Ireland, Italy, Norway, Spain, Switzerland and the United Kingdom. All were registered with the TEDDY Network database. RESULTS: We approached 107 centres and 63 provided data on their experiences and expertise in paediatric clinical trials. Four groups of performance indicators were identified, referring to scientific experience, trial readiness, trial competence, regulatory issues, ethics and patients. Most centres were actively involved in paediatric clinical research: 53 centres (84.1%) had received funds for more than five paediatric studies in the last 5 years, and 42 (66.7%) had a specific clinical trial unit and dedicated study coordinators. We concluded that the European centres we studied had the capability and capacity to conduct paediatric trials, but there was still room for improvement, including enhanced collaboration. CONCLUSION: This pilot survey demonstrated that there is potential for performing paediatric trials across Europe, but improvements are possible.

CD8+ T cells retain protective functions despite sustained inhibitory receptor expression during Epstein-Barr virus infection in vivo.

Epstein Barr virus (EBV) is one of the most ubiquitous human pathogens in the world, persistently infecting more than 90% of the adult human population. It drives some of the strongest human CD8+ T cell responses, which can be observed during symptomatic primary infection known as infectious mononucleosis (IM). Despite high viral loads and prolonged CD8+ T cell stimulation during IM, EBV enters latency and is under lifelong immune control in most individuals that experience this disease. We investigated whether changes in T cell function, as frequently characterized by PD-1 up-regulation, occur during IM due to the prolonged exposure to high antigen levels. We readily detected the expansion of PD-1 positive CD8+ T cells together with high frequencies of Tim-3, 2B4, and KLRG1 expression during IM and in mice with reconstituted human immune system components (huNSG mice) that had been infected with a high dose of EBV. These PD-1 positive CD8+ T cells, however, retained proliferation, cytokine production, and cytotoxic abilities. Multiple subsets of CD8+ T cells expanded during EBV infection, including PD-1+Tim-3+KLRG1+ cells that express CXCR5 and TCF-1 germinal center homing and memory markers, and may also contain BATF3. Moreover, blocking the PD-1 axis compromised EBV specific immune control and resulted in virus-associated lymphomagenesis. Finally, PD-1+, Tim-3+, and KLRG1+ CD8+ T cell expansion coincided with declining viral loads during low dose EBV infection. These findings suggest that EBV infection primes PD-1 positive CD8+ T cell populations that rely on this receptor axis for the efficient immune control of this ubiquitous human tumor virus.

Cyclin-dependent kinase 1 and survivin as potential therapeutic targets against nasal natural killer/T-cell lymphoma.

Nasal natural killer/T-cell lymphoma (NNKTL) is closely associated with Epstein-Barr virus (EBV) and is characterized by poor prognosis, resulting from rapid progression of lesions in the affected organs. Recent data have shown that NNKTL is associated with the aberrant expression of cyclin-dependent kinase 1 (CDK1) and its downstream target survivin, but little is known about the functional roles of CDK1 and survivin in NNKTL. In the current study, we show that knockdown of the EBV-encoded oncoprotein latent membrane protein 1 (LMP1) induces downregulation of CDK1 and survivin in NNKTL cells. Immunohistochemistry detected CDK1 and survivin expression in LMP1-positive cells of NNKTL biopsy specimens. Inhibition of CDK1 and survivin in NNKTL cells with several inhibitors led to a dose-dependent decrease in cell proliferation. In addition, the Sp1 inhibitor mithramycin, which can downregulate both CDK1 and survivin, significantly suppressed the growth of established NNKTL in a murine xenograft model. Our results suggest that LMP1 upregulation of CDK1 and survivin may be essential for NNKTL progression. Furthermore, targeting CDK1 and survivin with Sp1 inhibitors such as mithramycin may be an effective approach to treat NNKTL, which is considered to be a treatment-refractory lymphoma.

Bone marrow T helper cells with a Th1 phenotype induce activation and proliferation of leukemic cells in precursor B acute lymphoblastic leukemia patients.

Precursor B cell acute lymphoblastic leukemia (BCP-ALL) constitutes the leading cause of cancer-related death in children. While chromosomal alterations contribute to BCP-ALL pathogenesis, they are insufficient for leukemia development. Epidemiological data and evidence from a mouse model suggest that immune responses to infections may trigger the emergence of leukemia, but the mechanisms remain unclear. Here, we show that T helper (Th) cells from bone marrow of pediatric BCP-ALL patients can be attracted and activated by autologous BCP-ALL cells. Bone-marrow Th cells supportively interacted with BCP-ALL cells, inducing upregulation of important surface molecules and BCP-ALL cell proliferation. These Th cells displayed a Th1-like phenotype and produced high levels of IFN-γ. IFN-γ was responsible for the upregulation of CD38 in BCP-ALL cells, a molecule which we found to be associated with early relapse, and accountable for the production of IP-10, a chemokine involved in BCP-ALL migration and drug resistance. Thus, our data provide mechanistic support for an involvement of Th cell immune responses in the propagation of BCP-ALL and suggest that BCP-ALL cell-supportive Th cells may serve as therapeutic target.

Is breastfeeding an equipoise option in effectively treated HIV-infected mothers in a high-income setting?

Combined antiretroviral treatment (cART) has reduced mother-to-child transmission (MTCT) of the human immunodeficiency virus (HIV) to virtually zero in industrialised countries, where strictly bottle feeding is recommended for HIV-infected mothers, and to as low as 0.7% after 12 months in low-resource settings, where breastfeeding is strongly encouraged. Given the theoretically very low risk of transmission by breastfeeding with cART, and the advantages and benefits of breastfeeding, also in industrialised countries, the strong recommendation to HIV-infected mothers to refrain from breastfeeding in this setting may no longer be justified. We have evaluated risks of breastfeeding for HIV MTCT in the light of accessible cART, the general benefits of breastfeeding, and the women's autonomy to consent to any intervention. As we found no evidence in the literature of HIV MTCT via breastfeeding whilst on effective cART, we identified a situation of clinical equipoise. We propose how to proceed in Switzerland when HIV-infected women consider breastfeeding. We advocate a shared decision-making process and suggest a list of topics on which to provide unbiased information for the HIV-infected mother to enable her comprehensive understanding of one or the other decision. Although breastfeeding still should not be actively recommended in Switzerland, any HIV-infected mother, regardless of her geographical and cultural background, who decides to breastfeed should be supported by the best strategy to achieve optimal medical care for both herself and her child. This includes continuous support of cART adherence and regular maternal HIV plasma viral load monitoring.

IRAK4 is essential for TLR9-induced suppression of Epstein-Barr virus BZLF1 transcription in Akata Burkitt's lymphoma cells.

Burkitt's lymphoma (BL) is the most common childhood cancer in equatorial Africa, and is endemic to areas where people are chronically co-infected with Epstein-Barr virus (EBV) and the malaria pathogen Plasmodium falciparum. The contribution of these pathogens in the oncogenic process remains poorly understood. We showed earlier that the activation of Toll-like receptor (TLR) 9 by hemozoin, a disposal product formed from the digestion of blood by P. falciparum, suppresses the lytic reactivation of EBV in BL cells. EBV lytic reactivation is regulated by the expression of transcription factor Zta (ZEBRA), encoded by the EBV gene BZLF1. Here, we explore in the BL cell line Akata, the mechanism involved in repression by TLR9 of expression of BZLF1. We show that BZLF1 repression is mediated upon TLR9 engagement by a mechanism that is largely independent of de novo protein synthesis. By CRISPR/Cas9-induced inactivation of TLR9, MyD88, IRAK4 and IRAK1 we confirm that BZLF1 repression is dependent on functional TLR9 and MyD88 signaling, and identify IRAK4 as an essential element for TLR9-induced repression of BZLF1 expression upon BCR cross-linking. Our results unprecedentedly show that TLR9-mediated inhibition of lytic EBV is largely independent of new protein synthesis and demonstrate the central roles of MyD88 and IRAK4 in this process contributing to EBV's persistence in the host's B-cell pool.

Pediatric precursor B acute lymphoblastic leukemia: are T helper cells the missing link in the infectious etiology theory?

Precursor B acute lymphoblastic leukemia (BCP-ALL), the most common childhood malignancy, arises from an expansion of malignant B cell precursors in the bone marrow. Epidemiological studies suggest that infections or immune responses to infections may promote such an expansion and thus BCP-ALL development. Nevertheless, a specific pathogen responsible for this process has not been identified. BCP-ALL cells critically depend on interactions with the bone marrow microenvironment. The bone marrow is also home to memory T helper (Th) cells that have previously expanded during an immune response in the periphery. In secondary lymphoid organs, Th cells can interact with malignant cells of mature B cell origin, while such interactions between Th cells and malignant immature B cell in the bone marrow have not been described yet. Nevertheless, literature supports a model where Th cells-expanded during an infection in early childhood-migrate to the bone marrow and support BCP-ALL cells as they support normal B cells. Further research is required to mechanistically confirm this model and to elucidate the interaction pathways between leukemia cells and cells of the tumor microenvironment. As benefit, targeting these interactions could be included in current treatment regimens to increase therapeutic efficiency and to reduce relapses.

Two alternate strategies for innate immunity to Epstein-Barr virus: One using NK cells and the other NK cells and γδ T cells.

Most humans become infected with Epstein-Barr virus (EBV), which then persists for life. Infrequently, EBV infection causes infectious mononucleosis (IM) or Burkitt lymphoma (BL). Type I EBV infection, particularly type I BL, stimulates strong responses of innate immune cells. Humans respond to EBV in two alternative ways. Of 24 individuals studied, 13 made strong NK and γδ T cell responses, whereas 11 made feeble γδ T cell responses but stronger NK cell responses. The difference does not correlate with sex, HLA type, or previous exposure to EBV or cytomegalovirus. Cohorts of EBV+ children and pediatric IM patients include both group 1 individuals, with high numbers of γδ T cells, and group 2 individuals, with low numbers. The even balance of groups 1 and 2 in the human population points to both forms of innate immune response to EBV having benefit for human survival. Correlating these distinctive responses with the progress of EBV infection might facilitate the management of EBV-mediated disease.

Tonsillar CD56brightNKG2A+ NK cells restrict primary Epstein-Barr virus infection in B cells via IFN-γ.

Natural killer (NK) cells constitute the first line of defense against viruses and cancers cells. Epstein-Barr virus (EBV) was the first human virus to be directly implicated in carcinogenesis, and EBV infection is associated with a broad spectrum of B cell lymphomas. How NK cells restrict EBV-associated oncogenesis is not understood. Here, we investigated the efficacies and mechanisms of distinct NK cell subsets from tonsils, the portal of entry of EBV, in limiting EBV infection in naïve, germinal center-associated and memory B cells. We found that CD56bright and NKG2A expression sufficiently characterizes the potent anti-EBV capacity of tonsillar NK cells. We observed restriction of EBV infection in B cells as early as 18 hours after infection. The restriction was most efficient in naïve B cells and germinal center-associated B cells, the B cell subsets that exhibited highest susceptibility to EBV infection in vitro. IFN-γ release by and partially NKp44 engagement of CD56bright and NKG2A positive NK cells mediated the restriction that eventually inhibited B-cell transformation. Thus, harnessing CD56brightNKG2A+ NK cell function might be promising to improve treatment strategies that target EBV-associated B cell lymphomas.

Activation of ATR-Chk1 pathway facilitates EBV-mediated transformation of primary tonsillar B-cells.

Primary infection of the immunocompromised host with the oncovirus Epstein-Barr virus (EBV) that targets mainly B-cells is associated with an increased risk for EBV-associated tumors. The early events subsequent to primary infection with potential for B-cell transformation are poorly studied. Here, we modeled in vitro the primary infection by using B-cells isolated from tonsils, the portal of entry of EBV, since species specificity of EBV hampers modeling in experimental animals. Increasing evidence indicates that the host DNA damage response (DDR) can influence and be influenced by EBV infection. Thus, we inoculated tonsillar B-cells (TBCs) with EBV-B95.8 and investigated cell proliferation and the DDR during the first 96 hours thereafter. We identified for the first time that EBV infection of TBCs induces a period of hyperproliferation 48-96 hours post infection characterized by the activation of ataxia telangiectasia and Rad3-releated (ATR) and checkpoint kinase-1 (Chk1). Whereas inhibition of Chk1 did not affect B-cell transformation, the specific inhibition of ATR robustly decreased the transformation efficiency of EBV. Our results suggest that activation of ATR is key for EBV-induced B-cell transformation. Thus, targeting the interaction between ATR/Chk1 and EBV could offer new options for the treatment of EBV-associated malignancies.

Update of the Swiss guidelines on post-treatment Lyme disease syndrome.

Lyme borreliosis is caused by Borrelia burgdorferi sensu lato infection, which responds well to antibiotic therapy in the overwhelming majority of cases. However, despite adequate antibiotic treatment some patients report persisting symptoms which are commonly summarised as post-treatment Lyme disease syndrome (PTLDS). In 2005, the Swiss Society of Infectious Diseases published a case definition for PTLDS. We aimed to review the scientific literature with a special emphasis on the last 10 years, questioning whether the definitions from 2005 are still valid in the light of current knowledge. Furthermore, we describe the clinical history of infection with Borrelia burgdorferi sensu lato, the estimated prevalence of PTLDS, the possible pathogenesis of PTLDS, and treatment options with an emphasis on clinical studies. In summary, we were unable to find a scientific reason for modification of the PTLDS definitions published in 2005. Thus, the diagnostic criteria remain unchanged, namely documented clinical and laboratory evidence of previous infection with B. burgdorferi, a completed course of appropriate antibiotic therapy, symptoms including fatigue, arthralgia, myalgia, cognitive dysfunction or radicular pain persisting for >6 months, a plausible timely association between documented B. burgdorferi infection and onset of symptoms (i.e., persistent or recurrent symptoms that began within 6 months of completion of a recommended antibiotic therapy for early or late Lyme borreliosis), and exclusion of other somatic or psychiatric causes of symptoms. The main therapeutic options remain cognitive behavioural therapy and low-impact aerobic exercise programmes. Growing and unequivocal evidence confirms that prolonged or repeated antibiotic therapy for PTLDS is not beneficial, but potentially harmful and therefore contraindicated. The Guidelines of the Swiss Society of Infectious Diseases offer an evidence based, diagnostic and therapeutic framework for physicians caring for patients suffering from presumptive PTLDS in Switzerland.

Infection with and Carriage of Mycoplasma pneumoniae in Children.

"Atypical" pneumonia was described as a distinct and mild form of community-acquired pneumonia (CAP) already before Mycoplasma pneumoniae had been discovered and recognized as its cause. M. pneumoniae is detected in CAP patients most frequently among school-aged children from 5 to 15 years of age, with a decline after adolescence and tapering off in adulthood. Detection rates by polymerase chain reaction (PCR) or serology in children with CAP admitted to the hospital amount 4-39%. Although the infection is generally mild and self-limiting, patients of every age can develop severe or extrapulmonary disease. Recent studies indicate that high rates of healthy children carry M. pneumoniae in the upper respiratory tract and that current diagnostic PCR or serology cannot discriminate between M. pneumoniae infection and carriage. Further, symptoms and radiologic features are not specific for M. pneumoniae infection. Thus, patients may be unnecessarily treated with antimicrobials against M. pneumoniae. Macrolides are the first-line antibiotics for this entity in children younger than 8 years of age. Overall macrolides are extensively used worldwide, and this has led to the emergence of macrolide-resistant M. pneumoniae, which may be associated with severe clinical features and more extrapulmonary complications. This review focuses on the characteristics of M. pneumoniae infections in children, and exemplifies that simple clinical decision rules may help identifying children at high risk for CAP due to M. pneumoniae. This may aid physicians in prescribing appropriate first-line antibiotics, since current diagnostic tests for M. pneumoniae infection are not reliably predictive.

Infectious Mononucleosis Triggers Generation of IgG Auto-Antibodies against Native Myelin Oligodendrocyte Glycoprotein.

A history of infectious mononucleosis (IM), symptomatic primary infection with the Epstein Barr virus, is associated with the development of autoimmune diseases and increases the risk to develop multiple sclerosis. Here, we hypothesized that immune activation during IM triggers autoreactive immune responses. Antibody responses towards cellular antigens using a HEp-2 based indirect immunofluorescence assay and native myelin oligodendrocyte glycoprotein (MOG) using a flow cytometry-based assay were determined in 35 patients with IM and in 23 control subjects. We detected frequent immunoglobulin M (IgM) reactivity to vimentin, a major constituent of the intermediate filament family of proteins, in IM patients (27/35; 77%) but rarely in control subjects (2/23; 9%). IgG autoantibodies binding to HEp-2 cells were absent in both groups. In contrast, IgG responses to native MOG, present in up to 40% of children with inflammatory demyelinating diseases of the central nervous system (CNS), were detectable in 7/35 (20%) patients with IM but not in control subjects. Normalization of anti-vimentin IgM levels to increased total IgM concentrations during IM resulted in loss of significant differences for anti-vimentin IgM titers. Anti-MOG specific IgG responses were still detectable in a subset of three out of 35 patients with IM (9%), even after normalization to increased total IgG levels. Vimentin-specific IgM and MOG-specific IgG responses decreased following clinical resolution of acute IM symptoms. We conclude from our data that MOG-specific memory B cells are activated in subset of patients with IM.

Swiss national prospective surveillance of paediatric Mycoplasma pneumoniae-associated encephalitis.

OBJECTIVE: To assess the presence of Mycoplasma pneumoniae-associated encephalitis in children in Switzerland and its likely pathogenesis. METHODS: M. pneumoniae-associated encephalitis cases seen at a single-centre during 2010-2013 were reviewed, and the Swiss Paediatric Surveillance Unit (SPSU) prospectively conducted a nationwide surveillance 2013-2015. Case definition included confirmed, probable and possible cases. RESULTS: Seven patients (median age 8.7 years, range 4.7-10.1 years) with confirmed or possible M. pneumoniae-associated encephalitis were observed. All patients manifested prodromal respiratory symptoms over at least 5 days and five out of the six who had a chest radiograph, showed pulmonary infiltrates. M. pneumoniae DNA in cerebrospinal fluid was negative in all patients. Intrathecally synthesised M. pneumoniae-specific immunoglobulin (IgM and IgG) were investigated and found positive in one patient (confirmed case). M. pneumoniae DNA in respiratory specimens and/or M. pneumoniae-specific IgM and IgG in serum were detected in the other six patients (possible cases). One confirmed and two possible cases had neurological sequelae at 4-19 months follow-up. CONCLUSION: The lack of detectable M. pneumoniae DNA in cerebrospinal fluid of our encephalitis patients suggests a likely immune-mediated pathogenesis ignited by a respiratory inflammatory process including pneumonia.