A young girl with severe cerebral fungal infection due to card 9 deficiency.

Pattern recognition receptors (PRRs), receptors of the innate immune system, are important in interaction with pathogens. Caspase Recruitment Domain-containing protein 9 (CARD9), a member of PRRs, is an intracellular adaptor protein important in fungal defense. CARD9 deficiency causes a rare primary immunodeficiency (PID) characterized by superficial and deep fungal infections. We report a 17year-old female with a homozygous nonsense mutation in CARD9, who presented with severe cerebral fungal infection of the central nervous system. She was also found to have an heterozygous NLRP12 mutation, which may have had add-on effect on the severity of the infection.

Dermatophytic disease with deficit in CARD9: A new case with a brain impairment.

INTRODUCTION: Dermatophytic disease individualized by Hadida and Schousboe in 1959 is a rare form of chronic dermatophyte infection; characterized by subcutaneous and visceral invasion and a therapeutic failure. We report a case of dermatophytic disease with brain abscess in an Algerian patient. OBSERVATIONS: The patient was 47-year-old, she was born parents first cousins. She had since the age of 10 years scaly scalp lesions that became secondarily papular and nodular. At the age of 17 years, the patient had a generalized skin involvement with multiple nodular lesions, diffuse disease of the nails (plurionyxis), poly lymphadenopathies affecting the cervical, axillary and inguinal areas. Mycological tests identified Trichophyton rubrum. Histopathological examinations showed caseiform necrosis with epithelioid and giant cells. PAS staining showed hyphae in necrosis. The rest of the blood and urine tests were normal. Sequencing CARD9 allowed to highlight a homozygous mutation Q289X. The evolution was marked by an appearance at the age of 47 of a right cerebral abscess fronto-temporo-parietal, cortico-subcortical detected by MRI. The patient was given itraconazole 200mg/day with good evolution after three months of decline. DISCUSSION: Dermatophytic disease is very rare. Fifty cases have been published, mostly from North Africa, a strong endogamy region. Signs and symptoms almost always start with a scalp ringworm with almost constant occurrence of complications: in our patient a cerebral localization with a good evolution with itraconazole. Immunologically it is characterized by an autosomal recessive deficiency CARD9. This observation is notable for the onset of the disease at an early age, the dermatophyte T. rubrum and the favourable outcome of the brain lesion with itraconazole. CONCLUSION: Dermatophytic disease is rare, often severe. Our case is original because of the occurrence of a cerebral localization with good response to itraconazole and its mechanism of action deserves to be elucidated.

Impaired RASGRF1/ERK-mediated GM-CSF response characterizes CARD9 deficiency in French-Canadians.

BACKGROUND: Caspase recruitment domain-containing protein 9 (CARD9) deficiency is an autosomal recessive primary immunodeficiency conferring human susceptibility to invasive fungal disease, including spontaneous central nervous system candidiasis (sCNSc). However, clinical characterization of sCNSc is variable, hindering its recognition. Furthermore, an in-depth understanding of the bases for this susceptibility has remained elusive. OBJECTIVES: We sought to comprehensively characterize sCNSc and to dissect the mechanisms by which a hypomorphic CARD9 mutation causes susceptibility to Candida species. METHODS: We describe the clinical and radiologic findings of sCNSc caused by CARD9 deficiency in a French-Canadian cohort. We performed genetic, cellular, and molecular analyses to further decipher its pathophysiology. RESULTS: In our French-Canadian series (n = 4) sCNSc had onset in adulthood (median, 38 years) and was often misinterpreted radiologically as brain malignancies; 1 patient had additional novel features (eg, endophthalmitis and osteomyelitis). CARD9 deficiency resulted from a hypomorphic p.Y91H mutation and allelic imbalance established in this population through founder effects. We demonstrate a consistent cellular phenotype of impaired GM-CSF responses. The ability of CARD9 to complex with B-cell CLL/lymphoma 10 (BCL10) and mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) is intact in our series, arguing against its involvement in susceptibility to fungi. Instead, we show that the p.Y91H mutation impairs the ability of CARD9 to complex with Ras protein-specific guanine nucleotide-releasing factor 1 (RASGRF1), leading to impaired activation of nuclear factor κB and extracellular signal-regulated kinase (ERK) in monocytes and subsequent GM-CSF responses. Successful treatment of a second patient with adjunctive GM-CSF bolsters the clinical relevance of these findings. CONCLUSIONS: Hypomorphic CARD9 deficiency caused by p.Y91H results in adult-onset disease with variable penetrance and expressivity. Our findings establish the CARD9/RASGRF1/ERK/GM-CSF axis as critical to the pathophysiology of sCNSc.

CARD9 deficiency and spontaneous central nervous system candidiasis: complete clinical remission with GM-CSF therapy.

We demonstrate autosomal-recessive Caspase Recruitment Domain-containing protein 9 (CARD9) deficiency in a patient with relapsing C. albicans meningoencephalitis. We identified a novel, hypomorphic mutation with intact Th17 responses, but impaired GM-CSF responses. We report complete clinical remission with adjunctive GM-CSF therapy, suggesting that a CARD9/GM-CSF axis contributes to susceptibility to candidiasis.

Mannose-binding lectin deficiency does not appear to predispose to cryptococcosis in non-immunocompromised patients.

While most patients with cryptococcosis have obvious cellular immune deficiency, a minority have no apparent predisposing factors. However, in the latter there may be subtle innate immune system deficiencies which go unrecognized. Mannose-binding lectin (MBL) deficiency is associated with increased susceptibility to infectious diseases and may predispose to cryptococcosis, particularly when it disseminates to the central nervous system (CNS) in apparently immunocompetent patients. MBL function and levels, as well as MBL2 genotype were determined in 36 HIV-negative cryptococcosis patients (25 with CNS involvement) using C4 deposition and mannan-binding ELISA. MBL deficiency was defined using C4 deposition level < 0.2 U/microl or mannan-binding level < 0.5 microg/ml. MBL results were compared between patients with cryptococcosis and healthy controls and among the cryptococcosis patients according to the site of their disease. There was no difference in MBL function, mannan-binding level or increase in the frequency of MBL deficiency or low producing MBL2 genotypes in any of these comparisons. Patients with CNS cryptococcosis were no more likely to be MBL deficient than those with non-CNS disease. It appears that MBL deficiency is not associated with cryptococcosis in non-immunocompromised hosts. Beta errors consequent on the small number of patients studied may account for the lack of association.