Preadmission course and management of severe pediatric group A streptococcal infections during the 2022-2023 outbreak: a single-center experience.

PURPOSE: The massive increase of infections with Group A Streptococcus (GAS) in 2022-2023 coincided in Switzerland with a change of the recommendations for the management of GAS pharyngitis. Therefore, the objective of the present study was to investigate whether the clinical manifestations and management before hospitalization for GAS infection differed in 2022-2023 compared with 2013-2022. METHODS: Retrospective study of GAS infections requiring hospitalization in patients below 16 years. Preadmission illness (modified McIsaac score), oral antibiotic use, and outcome in 2022-2023 were compared with 2013-2022. Time series were compared with surveillance data for respiratory viruses. RESULTS: In 2022-2023, the median modified McIsaac score was lower (2 [IQR 2-3] vs. 3 [IQR 2-4], p = < 0.0001) and the duration of preadmission illness was longer (4 days [3-7] vs. 3 [2-6], p = 0.004) than in 2013-2022. In both periods, withholding of preadmission oral antibiotics despite a modified McIsaac score ≥ 3 (12% vs. 18%, n.s.) or ≥ 4 (2.4% vs. 10.0%, p = 0.027) was rare. Respiratory disease, skeletal/muscle infection, and invasive GAS disease were significantly more frequent in 2022-2023, but there were no differences in clinical outcome. The time course of GAS cases in 2022-2023 coincided with the activity of influenza A/B. CONCLUSION: We found no evidence supporting the hypothesis that the 2022-2023 GAS outbreak was associated with a change in preadmission management possibly induced by the new recommendation for GAS pharyngitis. However, clinical manifestations before admission and comparative examination of time-series strongly suggest that viral co-circulation played an important role in this outbreak.

Postpandemic fluctuations of regional respiratory syncytial virus hospitalization epidemiology: potential impact on an immunization program in Switzerland.

RSV hospitalization epidemiology is subject to rapid changes brought about by the COVID-19 pandemic and the prospect of vaccine prevention. The purpose of this report is to characterize recent epidemiologic and clinical fluctuations and to analyze their potential impact on an immunization program with nirsevimab. This is a 2018-2024 retrospective analysis of all hospitalizations caused by RSV in patients below 16 years of age occurring at an academic Children's Hospital that serves a defined population. We simulated the vaccine impact against RSV hospitalization by applying the expected effects of the infant immunization program with nirsevimab proposed in Switzerland to observed case counts. We analyzed 1339 hospitalizations. The consecutive occurrence of two major epidemics in 2022-2023 and 2023-2024 had never been recorded previously. The 2023-2024 season witnessed a major shift to older age. Only 61% of patients were below 12 months of age, while prepandemic long-term surveillance since 1997 found a range between 64 and 85% (median, 73%). Age below 3 months, prematurity, airway anomalies, congenital heart disease, and neuromuscular disorders were independently associated with ICU admission. Simulation of the vaccine impact using two scenarios of coverage and efficacy (scenario 1, 50% and 62%, respectively; scenario 2, 90% and 90%) and three different age distributions resulted in an infant vaccine impact of 31.0% (scenario 1) and 81.0% (scenario 2), respectively. Vaccine impact for all patients below 16 years ranged from 22.7 to 24.9% (scenario 1) and 54.2 to 68.8% (scenario 2). CONCLUSION: RSV hospitalization epidemiology was characterized by substantial variability in patient age on admission. As the proposed RSV immunization program primarily targets infants, year-to-year fluctuation of cases among older children will cause a variability of vaccine impact of approximately 15%. This information may be useful for physicians and hospital administrators when they anticipate the resources needed during the winter season. WHAT IS KNOWN: • RSV hospitalization epidemiology was subject to massive disturbances during the COVID-19 pandemic. • Extended half-life monoclonal antibodies and active maternal immunization offer new means of passive protection of infants against severe RSV disease. WHAT IS NEW: • We demonstrate substantial year-to-year fluctuation of the age distribution at the time of RSV hospitalization. • Up to 40% of annual RSV hospitalizations in a given season occur in children above 12 months of age who do not benefit from maternal RSV immunization and may not be eligible for receipt of a monoclonal antibody.

Transfer of antiretroviral drugs into breastmilk: a prospective study from the Swiss Mother and Child HIV Cohort Study.

INTRODUCTION: In 2018, Switzerland changed its guidelines to support women living with HIV wishing to breastfeed. The exposure of antiretroviral drugs (ARVs) in breastmilk and the ingested daily dose by the breastfed infant are understudied, notably for newer ARVs. This study aimed to quantify ARV concentrations in maternal plasma and breastmilk to determine the milk/plasma ratio, to estimate daily infant ARV dose from breastfeeding and to measure ARV concentrations in infants. METHODS: All women wishing to breastfeed were included, regardless of their ARV treatment. Breastmilk and maternal plasma samples were mostly collected at mid-dosing interval. RESULTS: Twenty-one mother/child pairs were enrolled; of those several were on newer ARVs including 10 raltegravir, 1 bictegravir, 2 rilpivirine, 2 darunavir/ritonavir and 3 tenofovir alafenamide. No vertical HIV transmission was detected (one infant still breastfed). The median milk/plasma ratios were 0.96/0.39 for raltegravir once/twice daily, 0.01 for bictegravir, 1.08 for rilpivirine, 0.12 for darunavir/ritonavir and 4.09 for tenofovir alafenamide. The median estimated infant daily dose (mg/kg) from breastfeeding was 0.02/0.25 for raltegravir once/twice daily, 0.01 for bictegravir, 0.02 for rilpivirine, 0.05 for darunavir/ritonavir and 0.007 for tenofovir alafenamide, resulting in relative infant dose <10% exposure index for all ARVs. CONCLUSIONS: ARVs were transferred to a variable extent in breastmilk. Nevertheless, the estimated daily ARV dose from breastfeeding remained low. Differential ARV exposure was observed in breastfed infants with some ARVs being below/above their effective concentrations raising the concern of resistance development if HIV infection occurs. More data on this potential risk are warranted to better support breastfeeding.

Infected cephalhaematoma in a five-week-old infant - case report and review of the literature.

BACKGROUND: A cephalhaematoma is usually a benign condition which resolves spontaneously. Nevertheless, there is a small risk of primary or secondary infection and diagnosis of this condition is challenging. The purpose of this article is to summarise risk factors, clinical criteria, pathogenesis, appropriate investigations and treatment methods for infected cephalhaematomas in infants. CASE PRESENTATION: A 5-week-old infant presented with fever and a non-tender cephalhaematoma without local signs of inflammation. The inflammatory markers in blood were elevated. Urine, blood and cerebrospinal fluid cultures were sterile. The raised inflammatory markers did not decrease under antibiotic treatment. An aspirate of the cephalhaematoma grew Escherichia coli. A debridement and evacuation of the haematoma was performed and the infant was treated with antibiotics for 11 days. The infant did not show any sequelae on follow-up visits. CONCLUSIONS: We present a case of an infected cephalhaematoma with Escherichia coli in a 5-week-old infant. Diagnosis of an infected cephalhaematoma is challenging. Infection should be suspected if infant present with secondary enlargement of the haematoma, erythema, fluctuance, skin lesions or signs of systemic infection. Inflammatory markers and imaging have limited diagnostic power. The main associations with infection of cephalhaematomas are instrumental assisted deliveries and sepsis, followed by the use of scalp electrodes, skin abrasions and prolonged rupture of membranes. Although, aspiration is contraindicated in treatment of cephalhaematomas, it needs to be performed when an infection is suspected. Escherichia coli are the most frequently isolated bacteria from infected cephalhaematomas.

Seroepidemiology of Human Tularemia-Systematic Review and Meta-analysis of Seroprevalence Studies.

Background: Seroepidemiologic studies of human tularemia have been conducted throughout the northern hemisphere. The purposes of this study were (1) to provide an overview of Francisella tularensis seroprevalence data, and (2) to generate an estimate of the proportion of study participants whose infection remained subclinical. Methods: We conducted a systematic review of F tularensis seroprevalence studies according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. We searched PubMed, Embase, and Web of Science covering the period from 1951 to 2023. Results: The weighted pooled seroprevalence among 44 486 participants recruited in 52 studies was 3.7% (95% confidence interval [CI], 2.7-5.1). Reported seroprevalences ranged between 0.2% and 31.3%. Occupational activities associated with an increased likelihood of exposure (risk ratio, 3.51 [95% CI, 3.2-3.86]) and studies from North America versus Europe and Asia (4.53 [4.15-4.94]) were associated with significantly increased seropositive rates. Twenty-eight data sets (47%) reported clinical information on a total of 965 seropositive participants. The weighted pooled estimate for subclinical seropositivity was 84.4% (95% CI, 72.9%-991.7%). Studies from F tularensis type A areas (risk ratio, 0.37 [95% CI, .27-.51) and studies from sites where pulmonary tularemia prevailed (0.38 [.28-.51]) reported lower subclinical seropositivity rates than studies from type B areas and from areas of predominance of (ulcero)glandular or oropharyngeal tularemia, respectively. Conclusions: Throughout the northern hemisphere, only a small proportion of study participants showed serologic evidence of exposure to F tularensis. Eight of 10 seropositive participants had no historical evidence of past clinical tularemia.

Ongoing Excess Hospitalizations for Severe Pediatric Group A Streptococcal Disease in 2023-2024-A Single-Center Report.

A Europe-wide outbreak of invasive pediatric group A streptococcal infections (iGAS) began in fall 2022. Here, we report the evolution of GAS hospitalizations in children and adolescents during the second outbreak year in 2023-2024 at a tertiary center in Switzerland. Using prospective monitoring of all in-patient GAS cases below 16 years of age, including those with iGAS, we compared case frequencies and clinical characteristics in three time periods (2013-2020; 2022-2023; 2023-2024). Annual GAS hospitalizations increased from a median of 25 cases (range 11-28) in 2013-2020 to 89 and 63 cases, respectively, in 2022-2023 and 2023-2024. iGAS cases evolved similarly (2013-2020, 4 cases (3-8); 2022-2023, 32 cases; 2023-2024, 21 cases). The decline in cases from 2022-2023 to 2023-2024 included all types of GAS organ involvement, except suppurative infections in the head area, which remained largely unchanged (48 vs. 45 cases). Pleural empyema declined from 13 to 7 cases, possibly explained by a poor overlap of the GAS and influenza curves, respectively, in 2023-2024 compared to 2022-2023. These data document the prolongation of the GAS outbreak into its second winter season in 2023-2024.

Clinical Characteristics and Management of Children and Adolescents Hospitalized With Pyomyositis.

BACKGROUND: Pyomyositis, a bacterial muscle infection, is an important differential diagnosis in children and adolescents with musculoskeletal pain. In contrast to tropical regions, it is rarely recognized in temperate countries, but incidence is increasing and major studies are missing. METHODS: This retrospective multicenter study included patients <18 years of age hospitalized with pyomyositis in 11 Swiss children's hospitals between January 2010 and December 2022. Cases were identified by ICD-10 code (Myositis; M60-M60.9), and data was extracted from electronic hospital records. RESULTS: Of 331 patients identified, 102 fulfilled the case definition. Patient age at presentation ranged from 2 weeks to 17 years (median 8 years). The majority had no underlying illness and all presented with fever and localized pain. At the respective site of pyomyositis, 100 (98%) had impaired movement and 39 (38%) presented with local swelling. Pelvic (57%) and leg (28%) muscles were mostly affected. Blood or tissue cultures were obtained in 94 (92%) and 59 (57%) patients, respectively. Of those, 55 (58%) blood and 52 (88%) tissue cultures were positive, mainly for Staphylococcus aureus (35 and 19, respectively) and Streptococcus pyogene s (12 and 15, respectively). All patients received antibiotic treatment during hospitalization for a median of 10 days (interquartile range: 7-17), followed by outpatient treatment for a further median of 16 days (interquartile range: 11-22) in 95 (93%) patients. Fifty-nine (57%) patients required surgery. CONCLUSIONS: Pyomyositis is a challenging diagnosis that requires a high level of awareness. Blood and/or tissue cultures revealed S. aureus and S. pyogenes as the predominant causative agents.

Cohort profile: the Swiss Mother and Child HIV Cohort Study (MoCHiV).

PURPOSE: Prospective, multicentric observational cohort study in Switzerland investigating measures to prevent mother-to-child transmission in pregnant women with HIV (WWH) and assessing health and development of their exposed children as well as of children with HIV (CWH) in general. PARTICIPANTS: Between January 1986 and December 2022, a total of 1446 mother-child pairs were enrolled. During the same period, the study also registered 187 CWH and 521 HIV-exposed but uninfected children (HEU), for whom detailed maternal information was not available. Consequently, the cohort comprises a total of 2154 children. FINDINGS TO DATE: During these 37 years, research by the Swiss Mother and Child HIV Cohort Study (MoCHiV) and its international collaborators has strongly influenced the prevention of vertical transmission of HIV (eg, introduction and discontinuation of elective caesarean section, neonatal postexposure prophylaxis and breastfeeding). Contributions have also been made to the management of diagnostics (eg, p24 antigen assay) and the effects of antiretroviral treatment (eg, prematurity, growth) in HEU and CWH. FUTURE PLANS: Most children present within the cohort are now HEU, highlighting the need to investigate other vertically transmitted pathogens such as hepatitis B and C viruses, cytomegalovirus or Treponema pallidum. In addition, analyses are planned on the longitudinal health status of CWH (eg, resistance and prolonged exposure to antiretroviral therapy), on social aspects including stigma in CWH and HEU, and on interventions to further optimise antenatal and postpartum care in WWH.

Impact of the availability of an influenza virus rapid antigen test on diagnostic decision making in a pediatric emergency department.

OBJECTIVES: Fever is one of the most commonly seen symptoms in the pediatric emergency department. The objective of this study was to observe how the rapid testing for influenza virus impacts on the management of children with fever. METHODS: We performed a review of our pediatric emergency department records during the 2008/2009 annual influenza season. The BinaxNow Influenza A+B test was performed on patients with the following criteria: age 1.0 to 16.0 years, fever greater than 38.5 °C, fever of less than 96 hours' duration after the onset of clinical illness, clinical signs compatible with acute influenza, and nontoxic appearance. Additional laboratory tests were performed at the treating physician's discretion. RESULTS: The influenza rapid antigen test was performed in 192 children. One hundred nine (57%) were influenza positive, with the largest fraction (101 patients) positive for influenza A. The age distribution did not differ between children with negative and positive test results (mean, 5.3 vs. 5.1 years, not statistically significant). A larger number of diagnostic tests were performed in the group of influenza-negative patients. Twice as many complete blood counts, C-reactive protein determinations, lumbar punctures, and urinalyses were ordered in the latter group. CONCLUSIONS: Rapid diagnosis of influenza in the pediatric emergency department affects the management of febrile children as the confirmation of influenza virus infection decreases additional diagnostic tests ordered.

[Fever without a localizing source in infants]. / Fieber ohne Fokus beim Kleinkind.

In this chapter we will give an overview over the most frequent etiologies of fever in infants in Switzerland, propose an algorithm to evaluate this children, and we will end up with a discussion on the value of additional laboratory parameters. Fever in infants and small children is a leading cause for parents to seek medical attention. The vast majority has a self limiting viral infection, but all the same, all infants need to be thoroughly evaluated. After this process, the treating physician has to decide, which child needs to be specifically treated or cared for, either to avoid overtreatment nor overlooking a serious infection. Because of a broader immunization coverage against bacterial infections, the epidemiology of invasive bacterial disease is changing. Additional laboratory work up is sometimes necessary, but has it's limitations. The interpretation of lab values must taken into account the changing prevalence of serious bacterial infections. Newer parameters (e. g. Procalcitonin) are upcoming, of which the importance is still debatable. Fever causes in this age other than infectious diseases will be alluded.

Successful implementation of new Swiss recommendations on breastfeeding of infants born to women living with HIV.

INTRODUCTION: Swiss national recommendations advise, since end of 2018, supporting women with HIV who wish to breastfeed. Our objective is to describe the motivational factors and the outcome of these women and of their infants. METHODS: mothers included in MoCHiV with a delivery between January 2019 and February 2021 who fulfilled the criteria of the "optimal scenario" (adherence to cART, regular clinical care, and suppressed HIV plasma viral load (pVL) of <50 RNA copies/ml) and who decided to breastfeed after a shared decision-making process, were approached to participate in this nested study and asked to fill-in a questionnaire exploring the main motivating factors for breastfeeding. RESULTS: Between January 9, 2019 and February 7, 2021, 41 women gave birth, and 25 decided to breastfeed of which 20 accepted to participate in the nested study. The three main motivational factors of these women were bonding, neonatal and maternal health benefits. They breastfed for a median duration of 6.3 months (range 0.7-25.7, IQR 2.5-11.1). None of the breastfed neonates received HIV post-exposure prophylaxis. There was no HIV transmission: 24 infants tested negative for HIV at least 3 months after weaning; one mother was still breastfeeding when we analyzed the data. CONCLUSIONS: As a result of a shared decision-making process, a high proportion of mothers expressed a desire to breastfeed. No breastfed infant acquired HIV. The surveillance of breastfeeding mother-infant pairs in high resource settings should be continued to help update guidelines and recommendations.

Viral suppression and retention in HIV care during the postpartum period among women living with HIV: a longitudinal multicenter cohort study.

Background: Low rates of postnatal retention in HIV care and viral suppression have been reported in women living with HIV (WLWH) despite viral suppression at delivery. At the same time, postpartum follow-up is of crucial importance in light of the increasing support offered in many resource-rich countries including Switzerland to WLWH choosing to breastfeed their infant, if optimal scenario criteria are met. Methods: We longitudinally investigated retention in HIV care, viral suppression, and infant follow-up in a prospective multicentre HIV cohort study of WLWH in the optimal scenario who had a live birth between January 2000 and December 2018. Risk factors for adverse outcomes in the first year postpartum were assessed using logistic and proportional hazard models. Findings: Overall, WLWH were retained in HIV care for at least six months after 94.2% of the deliveries (694/737). Late start of combination antiretroviral therapy (cART) during the third trimester was found to be the main risk factor for failure of retention in HIV care (crude odds ratio [OR] 3.91; 95% confidence interval [CI], 1.50-10.22; p = 0.005). Among mothers on cART until at least one year after delivery, 4.4% (26/591) experienced viral failure, with illicit drugs use being the most important risk factor (hazard ratio [HR], 13.2; 95% CI, 2.35-73.6; p = 0.003). The main risk factors for not following the recommendations regarding infant follow-up was maternal depression (OR, 3.52; 95% CI, 1.18-10.52; p = 0.024). Interpretation: Although the results are reassuring, several modifiable risk factors for adverse postpartum outcome, such as late treatment initiation and depression, were identified. These factors should be addressed in HIV care of all WLWH, especially those opting to breastfeed in resource-rich countries. Funding: This study has been financed within the framework of the Swiss HIV Cohort Study, supported by the Swiss National Science Foundation (grant #201369), by SHCS project 850 and by the SHCS research foundation.

Gene therapy for immunodeficiency due to adenosine deaminase deficiency.

BACKGROUND: We investigated the long-term outcome of gene therapy for severe combined immunodeficiency (SCID) due to the lack of adenosine deaminase (ADA), a fatal disorder of purine metabolism and immunodeficiency. METHODS: We infused autologous CD34+ bone marrow cells transduced with a retroviral vector containing the ADA gene into 10 children with SCID due to ADA deficiency who lacked an HLA-identical sibling donor, after nonmyeloablative conditioning with busulfan. Enzyme-replacement therapy was not given after infusion of the cells. RESULTS: All patients are alive after a median follow-up of 4.0 years (range, 1.8 to 8.0). Transduced hematopoietic stem cells have stably engrafted and differentiated into myeloid cells containing ADA (mean range at 1 year in bone marrow lineages, 3.5 to 8.9%) and lymphoid cells (mean range in peripheral blood, 52.4 to 88.0%). Eight patients do not require enzyme-replacement therapy, their blood cells continue to express ADA, and they have no signs of defective detoxification of purine metabolites. Nine patients had immune reconstitution with increases in T-cell counts (median count at 3 years, 1.07x10(9) per liter) and normalization of T-cell function. In the five patients in whom intravenous immune globulin replacement was discontinued, antigen-specific antibody responses were elicited after exposure to vaccines or viral antigens. Effective protection against infections and improvement in physical development made a normal lifestyle possible. Serious adverse events included prolonged neutropenia (in two patients), hypertension (in one), central-venous-catheter-related infections (in two), Epstein-Barr virus reactivation (in one), and autoimmune hepatitis (in one). CONCLUSIONS: Gene therapy, combined with reduced-intensity conditioning, is a safe and effective treatment for SCID in patients with ADA deficiency. (ClinicalTrials.gov numbers, NCT00598481 and NCT00599781.)

Pediatric Tularemia-A Case Series From a Single Center in Switzerland.

Background: The incidence of tularemia has recently increased throughout Europe. Pediatric tularemia typically presents with ulceroglandular or glandular disease and requires antimicrobial therapy not used in the empirical management of childhood acute lymphadenitis. We describe the clinical presentation and course in a case series comprising 20 patients. Methods: This is a retrospective analysis of a single-center case series of microbiologically confirmed tularemia in patients <16 years of age diagnosed between 2010 and 2021. Results: Nineteen patients (95%) presented with ulceroglandular (n = 14) or glandular disease (n = 5), respectively. A characteristic entry site lesion (eschar) was present in 14 (74%). Fever was present at illness onset in 15 patients (75%) and disappeared in all patients before targeted therapy was initiated. The diagnosis was confirmed by serology in 18 patients (90%). While immunochromatography was positive as early as on day 7, a microagglutination test titer 1:≥160 was found no earlier than on day 13. Sixteen patients (80%) were initially treated with an antimicrobial agent ineffective against F. tularensis. The median delay (range) from illness onset to initiation of targeted therapy was 12 (6-40) days. Surgical incision and drainage were ultimately performed in 12 patients (60%). Conclusions: Pediatric tularemia in Switzerland usually presents with early, self-limiting fever and a characteristic entry site lesion with regional lymphadenopathy draining the scalp or legs. Particularly in association with a tick exposure history, this presentation may allow early first-line therapy with an agent specifically targeting F. tularensis, potentially obviating the need for surgical therapy.

Striking Decrease of Enteroviral Meningitis in Children During the COVID-19 Pandemic.

We report the unprecedented complete absence of pediatric enteroviral meningitis in 2020 in the area of Bern, Switzerland. Presumably an unintended effect of coronavirus disease 2019 public health measures, this finding highlights the potential of community-wide nonpharmaceutical interventions for controlling the circulation of a major pediatric pathogen, which is mainly transmitted by the fecal-oral route.

Recurrent Mycobacterium chelonae Skin Infection Unmasked as Factitious Disorder Using Bacterial Whole Genome Sequence Analysis.

Mycobacterium chelonae infections usually resolve with adequate therapy. We report the case of an adolescent with a chronic and progressive M chelonae infection refractory to combined antimicrobial and surgical therapy. Whole genome sequence analysis of consecutive isolates distinguished reinfection from recurrence and contributed to the diagnosis of a factitious disorder.

Treatment of intestinal and hepatic mucormycosis in an immunocompromized child.

During ALL chemotherapy, a 4-year-old patient presented with febrile neutropenia and abdominal pain. Ultrasound examinations were repeatedly normal. Computerized tomography on day 7 demonstrated appendicitis and multiple hepatic foci identified as mucormycosis (Absidia corymbifera). Successful outcome was achieved by aggressive re-surgery, long-term antifungal therapy with serum level-monitored posaconazole, and recovery of neutrophil counts. Considering the interference of posaconazole with CYP3A4, vincristine was administered during 72 hr posaconazole windows. Pediatric intestinal mucormycosis, still associated with a >70% case-fatality rate, calls for early imaging and surgery to establish the diagnosis, reduce the fungal mass, and provide a rationale for using posaconazole.

High Levels of IL-18 and IFN-γ in Chronically Inflamed Tissue in Chronic Granulomatous Disease.

Background: Chronic granulomatous disease (CGD) is caused by a malfunctioning nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex in phagocytes, leading to impaired bacterial and fungal killing and hyperinflammation. Objective: To characterize macrophage subsets and cytokine/chemokine signaling loops involved in CGD tissue hyperinflammation. Methods: Cytokine/chemokine production and surface marker expression were analyzed in inflamed tissue of four CGD patients and compared to cytokine/chemokine released by CGD macrophages upon priming to different macrophage subpopulations. Furthermore, the re-priming capacity of CGD pro-inflammatory M1 to M2a anti-inflammatory macrophages was evaluated. Results: In human CGD inflammatory tissue, IL-18 and IFN-γ were detected in significant quantity. Immunofluorescence analysis identified macrophages as one source of IL-18 in inflamed tissue. In vitro, CGD macrophages could be primed and re-primed into all inflammatory/anti-inflammatory macrophage subpopulations. IL-18 was also released by M1 CGD and control macrophages. Conclusion: CGD pro-inflammatory M1 macrophages remain M1 primed in vivo. As CGD M1 macrophages can be re-primed to anti-inflammatory M2a phenotype in vitro, macrophages are kept in M1 state in vivo by a persistent pro-inflammatory environment. Our results suggest a paracrine signaling loop between M1 macrophage derived IL-18 and non-macrophage derived IFN-γ maintaining macrophage pro-inflammatory activity in CGD tissue.

ROS and glutathionylation balance cytoskeletal dynamics in neutrophil extracellular trap formation.

The antimicrobial defense activity of neutrophils partly depends on their ability to form neutrophil extracellular traps (NETs), but the underlying mechanism controlling NET formation remains unclear. We demonstrate that inhibiting cytoskeletal dynamics with pharmacological agents or by genetic manipulation prevents the degranulation of neutrophils and mitochondrial DNA release required for NET formation. Wiskott-Aldrich syndrome protein-deficient neutrophils are unable to polymerize actin and exhibit a block in both degranulation and DNA release. Similarly, neutrophils with a genetic defect in NADPH oxidase fail to induce either actin and tubulin polymerization or NET formation on activation. Moreover, neutrophils deficient in glutaredoxin 1 (Grx1), an enzyme required for deglutathionylation of actin and tubulin, are unable to polymerize either cytoskeletal network and fail to degranulate or release DNA. Collectively, cytoskeletal dynamics are achieved as a balance between reactive oxygen species-regulated effects on polymerization and glutathionylation on the one hand and the Grx1-mediated deglutathionylation that is required for NET formation on the other.