Hemophagocytic lymphohistiocytosis-like hyperinflammation due to a de novo mutation in DPP9.

BACKGROUND: Genetic defects in components of inflammasomes can cause autoinflammation. Biallelic loss-of-function mutations in dipeptidyl peptidase 9 (DPP9), a negative regulator of the NLRP1 and CARD8 inflammasomes, have recently been shown to cause an inborn error of immunity characterized by pancytopenia, skin manifestations, and increased susceptibility to infections. OBJECTIVE: We sought to study the molecular basis of autoinflammation in a patient with severe infancy-onset hyperinflammation associated with signs of fulminant hemophagocytic lymphohistiocytosis. METHODS: Using heterologous cell models as well as patient cells, we performed genetic, immunologic, and molecular investigations to identify the genetic cause and to assess the impact of the identified mutation on inflammasome activation. RESULTS: The patient exhibited pancytopenia with decreased neutrophils and T, B, and natural killer cells, and markedly elevated levels of lactate dehydrogenase, ferritin, soluble IL-2 receptor, and triglycerides. In addition, serum levels of IL-1ß and IL-18 were massively increased, consistent with inflammasome activation. Genetic analysis revealed a previously undescribed de novo mutation in DPP9 (c.755G>C, p.Arg252Pro) affecting a highly conserved amino acid residue. The mutation led to destabilization of the DPP9 protein as shown in transiently transfected HEK293T cells and in patient-derived induced pluripotent stem cells. Using functional inflammasome assays in HEK293T cells, we demonstrated that mutant DPP9 failed to restrain the NLRP1 and CARD8 inflammasomes, resulting in constitutive inflammasome activation. These findings suggest that the Arg252Pro DPP9 mutation acts in a dominant-negative manner. CONCLUSIONS: A de novo mutation in DPP9 leads to severe infancy-onset autoinflammation because of unleashed inflammasome activation.

Bacterial pathogens in pediatric appendicitis: a comprehensive retrospective study.

Background: Appendicitis is a frequent condition, with peak incidences in the second decade of life. Its pathogenesis is under debate, but bacterial infections are crucial, and antibiotic treatment remains essential. Rare bacteria are accused of causing complications, and various calculated antibiotics are propagated, yet there is no comprehensive microbiological analysis of pediatric appendicitis. Here we review different pre-analytic pathways, identify rare and common bacterial pathogens and their antibiotic resistances, correlate clinical courses, and evaluate standard calculated antibiotics in a large pediatric cohort. Method: We reviewed 579 patient records and microbiological results of intraoperative swabs in standard Amies agar media or fluid samples after appendectomies for appendicitis between May 2011 and April 2019. Bacteria were cultured and identified via VITEK 2 or MALDI-TOF MS. Minimal inhibitory concentrations were reevaluated according to EUCAST 2022. Results were correlated to clinical courses. Results: Of 579 analyzed patients, in 372 patients we got 1330 bacterial growths with resistograms. 1259 times, bacteria could be identified to species level. 102 different bacteria could be cultivated. 49% of catarrhal and 52% of phlegmonous appendices resulted in bacterial growth. In gangrenous appendicitis, only 38% remained sterile, while this number reduced to 4% after perforation. Many fluid samples remained sterile even when unsterile swabs had been taken simultaneously. 40 common enteral genera were responsible for 76.5% of bacterial identifications in 96.8% of patients. However, 69 rare bacteria were found in 187 patients without specifically elevated risk for complications. Conclusion: Amies agar gel swabs performed superior to fluid samples and should be a standard in appendectomies. Even catarrhal appendices were only sterile in 51%, which is interesting in view of a possible viral cause. According to our resistograms, the best in vitro antibiotic was imipenem with 88.4% susceptible strains, followed by piperacillin-tazobactam, cefuroxime with metronidazole, and ampicillin-sulbactam to which only 21.6% of bacteria were susceptible. Bacterial growths and higher resistances correlate to an elevated risk of complications. Rare bacteria are found in many patients, but there is no specific consequence regarding antibiotic susceptibility, clinical course, or complications. Prospective, comprehensive studies are needed to further elicit pediatric appendicitis microbiology and antibiotic treatment.

Semi-occlusive management of fingertip injuries with finger caps: A randomized controlled trial in children and adults.

BACKGROUND: Human fingertips can regenerate functionally and cosmetically excellent skin and soft tissues. Physiological conditions suppress scar formation and are thus a prerequisite for regenerative healing. Self-adhesive film dressings can provide such favorable conditions. The semi-occlusive treatment is superior to surgery. However, standard dressings leak malodorous wound fluid eventually until the wound is dry. Therefore, we developed and tested a silicone finger cap that forms a mechanically protected, wet chamber around the injury. Its puncturable reservoir allows access to the wound fluid for diagnostic and research purposes and the delivery of pro-regenerative drugs in the future. METHODS: Patients >2 years with full-thickness fingertip injuries unsuitable for simple primary closure were randomized to start treatment with either the film dressing or the silicone finger cap. After 2 weeks, we changed to the other treatment. Patients' choice on the preferred treatment after 4 weeks was the primary outcome parameter. Additionally, we monitored adverse events, unplanned visits, tissue gain, functionality, cosmetic outcome, and quality of life. RESULTS: We randomized 11 patients 2 to 72 years to each group. Eighteen to 20 (90%, intention-to-treat) patients preferred the finger cap. All patients were satisfied with the cosmetic outcome, 88.9% had no disturbing sensibility changes, and 73.7% could report no distortion in the finger's daily use. Epithelialization took between 5 weeks for Allen II and up to 9 weeks in Allen IV injuries. There were 19 device-related adverse events under film dressing and 13 under the finger cap. There were neither severe adverse device effects nor unexpected severe adverse device effects. CONCLUSION: Employing the summative or synthetic primary endpoint "patient decision for one or the other procedure," our pseudocross-over-designed RCT succeeded in statistically significantly demonstrating the superiority of the silicone finger cap over conventional film therapy. The finger cap was safe and effective, reaching excellent results on all treated injuries without any need for disinfection, antibiotics, shortening of protruding bones, or treatment of hypergranulations. Distal to the tendon insertions, we did not see any limitations regarding injury mechanism, amputation plane, or patients' age.

Diagnostics and Treatment of Volkmann Ischemic Contracture in a Seven-Year-Old Child.

A 7-year-old boy presented 6 weeks after open reduction and crossed Kirschner wire (K-wire) fixation of a supracondylar humerus fracture. Previous treatments had restored skeletal anatomy without documented complications. However, the patient would not move the entire arm, including his forearm and hand. Any passive movement led to anxious adverse reactions, and there was partial numbness of all fingers. After intensive physio- and occupational therapy supported by nerve stimulation and psychological counseling, anxiety-related functional deficits of the shoulder and elbow resolved to reveal the severe Volkmann contracture of the right hand developed fully. Electroneurography, X-ray, magnetic resonance imaging of the forearm, and ultrasonography showed nonfunctional ulnar and a partially disturbed radial motor nerve distal to the elbow along with damaged flexor muscles of the forearm after compartment syndrome. In addition, damage to the median nerve at the elbow level was diagnosed. After intense conservative therapy, we partially resected fibrotic fascia of the superficial flexor compartment, freed ulnar and median nerves, and performed staircase-like releases of tendons and tenotomies. We achieved a full range of motion of all fingers and markedly improved the range of motion of the wrist. The Disabilities of the Arm, Shoulder and Hand scores for function improved from 80 to 16 at the 2-year follow-up postoperatively, but some impairments of fine motor function persisted. Subtle symptoms of a developing compartment syndrome need to be recognized. Overlooked and untreated, a consecutive Volkmann contracture can turn the extremity nonfunctional. Intensive physical, psychological, and surgical therapy in a specialized center can restore function but requires endurance and perseverance throughout the lengthy recovery.

Duplex ultrasound for assessing vascular impairment after supracondylar humerus fractures.

BACKGROUND: Supracondylar humerus fractures (SHF) are the second most common fracture in children and the most common fracture in children under seven years. Subtle neurovascular lesions in displaced SHF may be underdiagnosed clinically, but their sequelae can mean life-long symptoms. Here we show that color-coded duplex ultrasound (DUS) could help to identify these patients. METHODS: We reviewed records of 229 children who had recovered from SHF. Ninety patients were available for detailed questionnaires, in-depth neurovascular examinations, and DUS. RESULTS: In 90 examined patients, only two had been known to have suffered from vascular complications before our study. Only one still complained spontaneously about perfusion-induced symptoms. Qualitative changes in blood flow in duplex-sonography were detectable in both. Another two patients showed similar changes in blood flow at the fracture site. Both reported load-induced pain and paresthesia on detailed inquisition when no vascular impairments had been known before. Thus, duplex-sonography identified two patients with vascular affections that had not been noticed before in routine clinical examinations. CONCLUSION: DUS can be a sensitive tool in diagnosing vascular impairments in patients with SHF. It could reduce diagnostic insecurity, especially in anesthetized or otherwise hard to examine children, and thus help avoid the therapeutic delay that otherwise might foster life-long sequelae for the patients. More studies are needed to establish age-adjusted reference values for duplex-sonography of children's arms. Level of Evidence: Level III, Study of nonconsecutive patients (without consistently applied reference).

Distribution of RET proto-oncogene variants in children with appendicitis.

BACKGROUND: In addition to patient-related systemic factors directing the immune response, the pathomechanisms of appendicitis (AP) might also include insufficient drainage leading to inflammation caused by decreased peristalsis. Genetic predisposition accounts for 30%-50% of AP. M. Hirschsprung (HSCR), also characterized by disturbed peristalsis, is associated with variants in the RET proto-oncogene. We thus hypothesized that RET variants contribute to the etiology of AP. METHODS: DNA from paraffin-embedded appendices and clinical data of 264 children were analyzed for the RET c.135A>G variant (rs1800858, NC_000010.11:g.43100520A>G). In 46 patients with gangrenous or perforated AP (GAP), peripheral blood DNA was used for RET sequencing. RESULTS: Germline mutations were found in 13% of GAP, whereas no RET mutations were found in controls besides the benign variant p.Tyr791Phe (NC_000010.11:g.43118460A>T). In GAP, the polymorphic G-allele in rs2435352 (NC_000010.11:g.43105241A>G) in intron 4 was underrepresented (p = 0.0317). CONCLUSION: Our results suggest an impact of the RET proto-oncogene in the etiology of AP. Mutations were similar to patients with HSCR but no clinical features of HSCR were observed. The pathological phenotypes in both populations might thus represent a multigenic etiology including RET germline mutations with phenotypic heterogeneity and incomplete penetrance.

Conservative treatment of fingertip injuries in children - first experiences with a novel silicone finger cap that enables woundfluid analysis.

Introduction: Human fingertips are able to regenerate soft tissue and skin after amputation injuries with excellent cosmetic and functional results when treated with semiocclusive dressings. Despite bacterial colonizations, proceeding infections are not reported with this management. The underlying mechanisms for this form of regenerative healing as well as for the resilience to infections are not known. Due to the lack of mechanical protection, the leakage of maloderous woundfluid and the sometimes challenging application, conventional film dressings have their problems, especially in treating young children. We therefore treated selected patients with a novel silicone finger cap with an integrated wound fluid reservoir that enables atraumatic routine wound fluid aspiration. Methods: We report on 34 patients in between 1 and 13 years with traumatic fingertip amputations primarily treated with occlusive dressings. 12 patients were treated with a novel silicone finger cap. We summarized clinical data for each patient. This included photographs and microbiological results from wound fluid analyses, whenever available. Results: The results of both, conventional film dressing and silicone finger cap treatment, were excellent with no hypersensitivity and no restrictions in sensibility and motility. Even larger pulp defects were rearranged in a round shape and good soft tissue coverage of the distal phalanx was achieved. Nail deformities were not observed. We detected a wide spectrum of both aerobic and anaerobic bacteria in the wound fluids but infections were not observed. Epithelialization times did not differ significantly and no severe complications were seen in all primarily conservatively treated patients. Conclusion: This study provides preliminary data demonstrating that the treatment with the silicone finger cap leads to excellent clinical results in wound healing. Interestingly, the wounds were colonized with a wide range of bacteria including species that may cause wound infections. However, we saw no proceeding inflammation and the regeneration was undisturbed. In the future, the efficacy of this new management should be evaluated in randomized, controlled clinical trials to confirm the results under standard conditions and get more insight into the role of the wound microbiome as well as other factors that may promote regeneration. The aspirable Reservoir of the finger cap will enable easy atraumatic sampling of wound fluids both for diagnostic and for research purposes as well as possibly allowing direct administration of pro-regenerative drugs in the future.

Study protocol for a randomized controlled pilot-trial on the semiocclusive treatment of fingertip amputation injuries using a novel finger cap.

INTRODUCTION: Fingertip amputation injuries are common in all ages. Conservatively treated fingertips can regenerate skin and soft tissues to form a functionally and cosmetically excellent new fingertip. Little is known about this ability that, in humans, is confined to the fingertips. Even less is known about the role of the bacteria that regularly colonize these wounds without negative impact on regeneration and healing.As an alternative to surgery, self-adhesive film dressings are commonly used to establish a wet chamber around the injury. These dressings leak malodorous wound fluid eventually until the wound is dry. Having that into consideration, we have therefore developed a silicone finger cap that forms a mechanically protected, wet chamber around the injury for optimal regeneration conditions. It contains a puncturable reservoir for excess wound fluid, which can be thus routinely analyzed for diagnostic and research purposes.This study protocol explains the first randomized controlled trial (RCT) on the semiocclusive treatment of fingertip amputations in both children and adults comparing traditional film dressings with the novel silicone finger cap. Being the first RCT using 2 medical devices not yet certified for this indication, it will gather valuable information for the understanding of fingertip regeneration and the design of future definitive studies. METHODS AND ANALYSIS: By employing an innovative pseudo-cross-over-design with a dichotomous primary endpoint based on patients preference, this pilot study will gain statistically significant data with a very limited sample size. Our RCT will investigate acceptance, safety, effectiveness, and efficacy of this novel medical device while gathering information on the clinical course and outcome of conservatively treated fingertip injuries. A total of 22 patients older than 2 years will be randomly assigned to start the conservative treatment with either the traditional film-dressing or the novel finger cap. The treatment will be changed to the other alternative for another 2 weeks before the patient or the guardian is confronted with the decision of which method they would prefer for the rest of the treatment (if required). ETHICS AND DISSEMINATION: Ethical approval (EK 148042015) of the study protocol has been obtained from Institutional Review Board at the TU Dresden. The trial is registered at the European Database on Medical Devices (EUDAMED-No.: CIV-15-03-013246) and at ClinicalTrials.gov (NCT03089060).

Actinobacillus equuli ssp. haemolyticus in a semi-occlusively treated horse bite wound in a 2-year-old girl.

We report on the isolation of Actinobacillus equuli ssp. haemolyticus from wound smears of a 2-year-old girl who was admitted to the hospital due to partial amputation of the distal phalanx of her right middle finger caused by a horse bite. A. equuli typically causes diseases in horses and only very few reports describing human infections (mostly associated with wounds) are available in the literature. Interestingly, although the bacteria could be found in consecutive samples taken at different points in time, there were no signs of advancing infection or inflammation. Moreover, the fingertip regenerated after 74 days under semi-occlusive dressings with very pleasant results. For strain identification two automated systems were employed producing discrepant results: VITEK 2 described the pathogens as Pasteurella pneumotropica while MALDI-TOF MS analysis revealed A. equuli. Sequence analysis of 16S rDNA gene finally confirmed A. equuli ssp. haemolyticus as the isolated strain. The antimicrobial susceptibility testing was performed according to the CLSI criteria for Pasteurella spp. Additionally we conducted a test according to the EUCAST criteria.