Stacey R. Rose

CARD9-Dependent Neutrophil Recruitment Protects against Fungal Invasion of the Central Nervous System.

Candida is the most common human fungal pathogen and causes systemic infections that require neutrophils for effective host defense. Humans deficient in the C-type lectin pathway adaptor protein CARD9 develop spontaneous fungal disease that targets the central nervous system (CNS). However, how CARD9 promotes protective antifungal immunity in the CNS remains unclear. Here, we show that a patient with CARD9 deficiency had impaired neutrophil accumulation and induction of neutrophil-recruiting CXC chemokines in the cerebrospinal fluid despite uncontrolled CNS Candida infection. We phenocopied the human susceptibility in Card9 -/- mice, which develop uncontrolled brain candidiasis with diminished neutrophil accumulation. The induction of neutrophil-recruiting CXC chemokines is significantly impaired in infected Card9 -/- brains, from both myeloid and resident glial cellular sources, whereas cell-intrinsic neutrophil chemotaxis is Card9-independent. Taken together, our data highlight the critical role of CARD9-dependent neutrophil trafficking into the CNS and provide novel insight into the CNS fungal susceptibility of CARD9-deficient humans.

The utility of bronchoalveolar lavage beta-D-glucan testing for the diagnosis of invasive fungal infections.

OBJECTIVES To investigate the utility of beta-D-glucan (BDG) testing in bronchoalveolar lavage (BAL) fluid for the diagnosis of invasive fungal infection (IFI), as compared to BAL galactomannan (GM). METHODS We retrospectively reviewed medical records of 132 consecutive patients at the National Institutes of Health (NIH) in whom BAL BDG testing was performed for diagnosis of pneumonia. Using the European Organization for Research and Treatment of Cancer/Mycoses Study Group guidelines, we determined which patients had proven or probable IFI, and assessed the diagnostic performance of BAL BDG testing, relative to BAL GM. We also determined the reproducibility of the BDG assay in BAL via repeat testing of patient samples. RESULTS Ten patients had Pneumocystis pneumonia, and 34 patients had proven/probable IFI, including 14 with invasive aspergillosis (IA). BAL BDG was 100% sensitive for Pneumocystis. Although BAL BDG had similar sensitivity to BAL GM for the diagnosis of IA and IFI, it exhibited inferior specificity. Repeat testing demonstrated poor reproducibility of the BDG assay in BAL but not in serum. CONCLUSIONS BDG testing exhibits poor specificity and reproducibility in BAL. Identification of the BAL-specific factors that may interfere with the performance of the assay could improve the clinical usefulness of BAL BDG testing.

Gastrointestinal basidiobolomycosis treated with posaconazole.

A 67 year-old Caucasian male from Arizona presented with indolent symptoms of intestinal obstruction and hydronephrosis, found at surgery to be caused by a mass involving the terminal ileum and cecum, extending into the posterior abdominal wall and obstructing the right ureter. Histopathology was diagnostic of basidiobolomycosis. PCR of tissue and sequencing identified the fungus as, Basidiobolus ranarum. During one year of posaconazole treatment, the residual mass shrank, hydronephrosis was relieved and peripheral eosinophilia resolved.

Fluid-containing emphysematous bullae: a spectrum of illness

Fluid-containing emphysematous bullae are an under-reported complication of chronic obstructive pulmonary disease. The roles of bronchoscopy in the work-up and of antibiotics in the treatment are undefined. This study reports the combined results from the analysis of 16 cases treated at the present authors’ institution and 36 previously reported cases. The median age at presentation was 58 yrs and the median duration of follow-up was 60 weeks. A third of the patients were asymptomatic, while two-thirds presented with symptoms, including 10% who had evidence of a severe lung infection. Methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa and Bacteroides melaninogenicus were cultured from the bullae fluid in three symptomatic patients. Sputum and blood cultures were uninformative. Bronchoscopy, performed in two-thirds of the cases, added no diagnostic information. Antibiotic treatment did not result in a more rapid resolution of the air fluid level. Percutaneous drainage was safe and effective in four patients. In conclusion, patients with fluid-containing bullae present with a spectrum of illness. Antibiotic treatment does not hasten radiographic resolution and bronchoscopy has no diagnostic or therapeutic role.

Etiology of thrombocytosis in a general medicine population: analysis of 801 cases with emphasis on infectious causes.

Background The clinical importance of an elevated platelet count is often overlooked, particularly as a diagnostic clue to the presence of an underlying infection. We sought to better describe the relationship between thrombocytosis and inflammatory conditions, with a focus on infectious causes. Methods We retrospectively reviewed 801 sequential cases of thrombocytosis (platelet count > 500 × 109/L) at a tertiary care hospital. Results Essential thrombocythemia was the most common cause of primary thrombocytosis, and these patients were more likely to have extreme (> 800 × 109/L) and prolonged (> 1 month) thrombocytosis. Secondary thrombocytosis was more common than primary, with infectious causes accounting for nearly half the cases. Demographic factors associated with an infectious etiology included inpatient status, quadriplegia/paraplegia, an indwelling prosthesis, dementia and diabetes. Clinical and laboratory characteristics associated with an infectious cause of thrombocytosis included fever, tachycardia, weight loss, hypoalbuminemia, neutrophilia, leukocytosis and anemia. Patients with thrombocytosis secondary to infection had a more rapid normalization of platelet count, but higher risk of dying, than those with secondary, non-infectious causes. Conclusions Infection is a common cause of thrombocytosis and should be considered in patients with comorbidities that increase risk of infection and when clinical and/or laboratory data support an infectious etiology. Thrombocytosis may have prognostic implications as a clinical parameter.

Novel signal transducer and activator of transcription 1 mutation disrupts small ubiquitin-related modifier conjugation causing gain of function

Background Sumoylation is a posttranslational reversible modification of cellular proteins through the conjugation of small ubiquitin‐related modifier (SUMO) and comprises an important regulator of protein function. Objective We sought to characterize the molecular mechanism of a novel mutation at the SUMO motif on signal transducer and activator of transcription 1 (STAT1). Methods STAT1 sequencing and functional characterization were performed in transfection experiments by using immunoblotting and immunoprecipitation in STAT1‐deficient cell lines. Transcriptional response and target gene activation were also investigated in PBMCs. Results We identified a novel STAT1 mutation (c.2114A>T, p.E705V) within the SUMO motif (702IKTE705) in a patient with disseminated Rhodococcus species infection, Norwegian scabies, chronic mucocutaneous candidiasis, hypothyroidism, and esophageal squamous cell carcinoma. The mutation is located in the tail segment and is predicted to disrupt STAT1 sumoylation. Immunoprecipitation experiments performed in transfected cells confirmed absent STAT1 sumoylation for E705V, whereas it was present in wild‐type (WT) STAT1 cells, as well as the loss‐of‐function mutants L706S and Y701C. Furthermore, stimulation with IFN‐&ggr; led to enhanced STAT1 phosphorylation, enhanced transcriptional activity, and target gene expression in the E705V‐transfected compared with WT‐transfected cells. Computer modeling of WT and mutant STAT1 molecules showed variations in the accessibility of the phosphorylation site Y701, which corresponded to the loss‐of‐function and gain‐of‐function variants. Conclusion This is the first report of a mutation in the STAT1 sumoylation motif associated with clinical disease. These data reinforce sumoylation as a key posttranslational regulatory modification of STAT1 and identify a novel mechanism for gain‐of‐function STAT1 disease in human subjects.