Infections in the monogenic autoimmune syndrome APECED.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is caused by mutations in the Autoimmune Regulator (AIRE) gene, which impair the thymic negative selection of self-reactive T-cells and underlie the development of autoimmunity that targets multiple endocrine and non-endocrine tissues. Beyond autoimmunity, APECED features heightened susceptibility to certain specific infections, which is mediated by anti-cytokine autoantibodies and/or T-cell driven autoimmune tissue injury. These include the 'signature' APECED infection chronic mucocutaneous candidiasis (CMC), but also life-threatening coronavirus disease 2019 (COVID-19) pneumonia, bronchiectasis-associated bacterial pneumonia, and sepsis by encapsulated bacteria. Here we discuss the expanding understanding of the immunological mechanisms that contribute to infection susceptibility in this prototypic syndrome of impaired central tolerance, which provide the foundation for devising improved diagnostic and therapeutic strategies for affected patients.

MPEG1/Perforin-2 Haploinsufficiency Associated Polymicrobial Skin Infections and Considerations for Interferon-γ Therapy.

Introduction: Macrophage expressed gene 1 (MPEG1) is highly expressed in macrophages and other phagocytes. The gene encodes a bactericidal pore-forming protein, dubbed Perforin-2. Structural-, animal-, and cell-based studies have established that perforin-2 facilitates the destruction of phagocytosed microbes upon its activation within acidic phagosomes. Relative to wild-type controls, Mpeg1 knockout mice suffer significantly higher mortality rates when challenged with gram-negative or -positive pathogens. Only four variants of MPEG1 have been functionally characterized, each in association with pulmonary infections. Here we report a new MPEG1 non-sense variant in a patient with the a newly described association with persistent polymicrobial infections of the skin and soft tissue. Case Description: A young adult female patient was evaluated for recurrent abscesses and cellulitis of the breast and demonstrated a heterozygous, rare variant in MPEG1 p.Tyr430*. Multiple courses of broad-spectrum antimicrobials and surgical incision and drainage failed to resolve the infection. Functional studies revealed that the truncation variant resulted in significantly reduced capacity of the patient's phagocytes to kill intracellular bacteria. Patient-derived macrophages responded to interferon gamma (IFN-γ) by significantly increasing the expression of MPEG1. IFN-γ treatment supported perforin-2 dependent bactericidal activity and wound healing. Conclusions: This case expands the phenotype of MPEG1 deficiency to include severe skin and soft tissue infection. We showed that haploinsufficiency of perforin-2 reduced the bactericidal capacity of human phagocytes. Interferon-gamma therapy increases expression of perforin-2, which may compensate for such variants. Thus, treatment with IFN-γ could help prevent infections.

A luciferase reporter for gene expression studies and dynamic imaging of superficial Candida albicans infections.

Real-time imaging of fungal infections is becoming integral to the study of host-pathogen interactions, as it allows monitoring of the spatial and temporal progression of pathogen growth or of the host response in a single animal as well as reducing the number of animals used to obtain significant data. We present different applications of a novel luciferase reporter gene constructed from the coding sequences of the Candida albicans PGA59 gene, encoding a GPI-linked cell wall protein, and the Gaussia princeps luciferase gene. Upon addition of the coelenterazine substrate, light produced by the surface-exposed luciferase can be used to quantify gene expression from a variety of C. albicans promoters as well as monitoring cutaneous, subcutaneous, and vaginal infections.

The biological significance of TLR3 variant, L412F, in conferring susceptibility to cutaneous candidiasis, CMV and autoimmunity.

OBJECTIVE: Toll-like receptors, a major component of the innate immune system, play an important role in the initial response against pathogens. Genetic abnormalities in some receptors like TLR2, TLR3 and TLR4 have been associated with susceptibility to fungal and viral infections while other aberrations in TLR genes such as TLR3, TLR7 and TLR9 may predispose to autoimmunity. Recently we have shown an association of a TLR3 receptor variant, L412F, to susceptibility to chronic candidiasis, recurrent viral and bacterial infections and autoimmunity. We investigated here the biological implications of this TLR3 mutant. METHODS: To study the functional impact of the L412F variant of TLR3 we tested patients' peripheral blood mononuclear cells (PBMCs) as well as fibroblasts for secretion of cytokines in response to TLR3 ligand, candida or cytomegalovirus (CMV). In addition, the P2.1 cell line was used as a model for the TLR3 WT and L412F variant receptors function. RESULTS: Patient's cells carrying the L412F variant showed reduced IFNγ as well as TNFα secretion in response to stimulation with the TLR3 ligand, CMV or Candida albicans. Fibroblasts with the L412F variant showed decreased secretion of IFNλ in response to stimulation with both polyinosine ploycytidylic acid (Poly I:C) and CMV and P2.1 cells transfected with the L412F variant showed reduced secretion of IFN-ß in comparison to cells transfected with the wild type receptor. CONCLUSION: We have shown here aberrant biological responses mediated by the TLR3 variant receptor, L412F, which may explain in part susceptibility of patients to chronic candidiasis, viral infections and autoimmunity.

Genital candidosis in heterosexual couples.

BACKGROUND: Evidence suggests that Candida can be sexually transmitted; however, the contribution of sexual transmission to the pathogenesis of genital candidosis needs further elucidation. OBJECTIVE: The aim was to evaluate genital candidosis and its transmissibility in heterosexual couples. METHODS: Heterosexual couples were recruited among attendees of an Sexually Transmitted Diseases clinic. Specimens for yeast culture were collected from the glans penis and inner preputial layer using direct impression on CHROMagar Candida medium; vaginal exudates were collected using a cotton swab with subsequent inoculation on CHROMagar Candida medium. Mitochondrial DNA restriction analysis was performed to compare Candida isolates from both partners. RESULTS: A total of 64 couples were enrolled in the study. Frequency of sexual intercourse was significantly higher in couples where both partners yielded positive cultures and with at least one having genital candidosis (Odds ratios: 6.844; 95% CI 1.408-33.266). The same Candida species was found in both partners in 25% (16/64) of all couples but only 17.2% (11/64) were genetically similar. In total 12 of the 34 women suffering from vulvovaginal candidosis (VVC) had recurrent VVC (RVVC); two sexual partners of RVVC women (16.7%) had candida positive cultures, compared with 15 (68.2%) sexual partners of non RVVC women (Odds ratios: 0.093; 95% CI 0.016-0.544). CONCLUSIONS: Only in a few heterosexual couples a genetic similarity of Candida species recovered from both partners was found. RVVC women were more likely to have an asymptomatic candida negative sexual partner. This study suggests that male genitalia do not represent a relevant reservoir for RVVC; thus, the relevance of sexual transmission should not be emphasized.

Apolipoprotein E gene polymorphism and serum lipids in patients with superficial fungal disease.

Superficial mycosis, including dermatophytic infections, tinea versicolor, and cutaneous candidiasis is mostly limited to the outer layers of the skin, nails, and mucous membranes. In this study, Apolipoprotein E (ApoE) polymorphism and lipoprotein cholesterol concentrations were compared between 42 patients with superficial fungal disease and 27 control subjects. Both the patients and controls were found to be normolipemic. The patients with superficial fungal disease had significantly higher concentrations of high-density cholesterol (HDL) compared to the control group (p=0.0462). However, there was no difference in the serum triglyceride, low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL) cholesterol concentrations. A significantly higher incidence of heterozygosity E2/3 was found in the patients (p=0.0228), and significantly lower incidence of homozygosity E3/3 in all patients, and those with candidiasis and dermatophytosis (p=0.0139, 0.0194 and 0.0337, respectively) compared to the control group. The E3/4 genotype differences between patients and controls were not statistically significant. There were slight differences in the allele frequencies between the two groups, but these did not reach statistically significant levels. It was concluded that the presence of apoE2/3 genotype, high HDL-cholesterol levels and the absence of apoE3/3 genotype can be regarded as risk factors for superficial fungal disease, especially dermatophytosis.

Chronic mucocutaneous candidiasis. Immunologic studies of three generations of a single family.

A family consisting of eight members in three generations (age 10 months to 53 years) affected with chronic mucocutaneous candidiasis was studied along with three unaffected relatives. Dermatophytosis, loss of teeth and recurrent viral infections were present in some members. Results of tests for endocrinologic, muscle or liver disease, thymoma, iron deficiency, antitissue antibodies and malabsorption were normal in all patients. Antibody function and levels, B cell counts, serum complement, leukocyte enzymes, chemotaxis, phagocytosis and adherence were normal in all members. Plasma inhibitors to lymphocyte transformation and leukocyte inhibitory factor were not found. No unique HLA haplotype or antigen segregated in this family. Evaluation of cell-mediated immunity revealed total cutaneous anergy in three of eight whereas four of the other five had negative lymphocyte transformation and skin tests to Candida but responded normally to other antigens. Leukocyte inhibitory factor was not produced to Candida antigen in all four patients tested. T cell counts were within normal limits in all. Extensive evaluation of all limbs of the immune system in this family revealed a defect in cell-mediated immunity to Candida that appeared to be inherited as a dominant characteristic.

[In vitro investigations of microphages function in patients with chronic mucocutaneous candidosis (author's transl)]. / In-vitro-Untersuchungen der Mikrophagenfunktion bei Patienten mit chronischer mucocutaner Candidose.

In five patients with either familial or non-familial type of chronic mucocutaneous candidosis some properties of phagocytic function of the polymorphonuclear leucocytes (PMNL) have been studied in vitro. In each of the patients there were found: a) a decreased chemotactic activity of PMNL, b) a weakness of intake and of intracellular destruction of Candida albicans cells by PMNL, c) an impairment of phagocytosis and intracellular killing of Candida albicans as well of Staphylococcus aureus by PMNL. The rate of phagocytosis of heat-inactivated Candida albicans cells by PMNL was normal in each case. In the serum of two patients a phagocytosis inhibiting factor is supposed to exist. In PMNL of 3 patients a defective activity of NADH-dependent oxidase was found. The occurrence of hereditary CMCC in a father and his two daughters points to an autosomal dominant trait, whereas in most cases of familiar CMCC hitherto described an autosomal recessive mode of transmission was found.

Evidence for defective immunoregulation in the syndrome of familial candidiasis endocrinopathy.

We studied three children with candidiasis endocrinopathy syndrome, together with their parents and five siblings, to explore the possibility that defective immunoregulation allows autoimmune phenomena to be involved in the pathogenesis of this syndrome. Inheritance of the syndrome appeared to be autosomal recessive. Immunologic abnormalities in this family included hypergammaglobulinemia, selective IgA deficiency, anergy, autoimmune endocrinopathies and active chronic hepatitis. Defective suppressor T-cell function was noted in the two surviving children with clinically apparent disease and in a clinically normal sibling. Analysis of the immunologic abnormalities in the family suggests that defective immunoregulation rather than disordered effector mechanisms may explain the large number of immunologic defects noted. These defects, in turn, may result in the clinical manifestation of the syndrome.

Impairment of chemotactic activity of microphages in chronic mucocutaneous candidosis.

The chemotactic microphage function in combating and eliminating microorganisms is one of the most important features of the cellular immune system. Using a modified Boyden method we studied in vitro the chemotactic activity of the granulocytes in 5 patients suffering from chronic muco-cutaneous candidosis (CMCC), 3 of the familial and 2 of the non-familial type. To obtain quantitative results comparable to those of a control group, we investigated the granulocytes of 55 clinically and immunologically healthy persons by the same way. So we found, in comparison with the results of the controls, a striking reduction of the chemotactic granulocyte activity in all CMCC patients. This impairment of chemotaxis is apparently due to an inborn defect of the microphages. It is pointed out, however, that a non-specific stimulation of the immune system might be a promising way in the treatment of patients affected by CMCC.

[Disorders of phagocytic and fungicide function of granulocytes in chronic muco-cutaneous candidiasis]. / Störungen der phagozytären und fungiziden Granulozytenfunktion bei chronischer muco-cutaner Candidose.

The granulocytes which are distributed by blood circulation close to the extern and intern body surfaces as well as in all organs protect the organism from microbial perils by phagocytosis and intracellular killing of bacteria and fungi so constituting a very important component of the granulocytic functions seriously impairs the host resistance and may entail a state of persisting infectious disease. As chronic mucocutaneous candidosis (CMCC) represents such a persistent generalized infection, we studied in vitro several functional activities of the granulocytes of 5 patients suffering from CMCC. 2 of them presented a non-familiar type of CMCC, the remaining 3 patients (father and 2 daughters) were subject to the hereditary type of CMCC. For comparison, by the same way we investigated the granulocytic functions of 51 clinically and immunologically healthy adult persons. Each of our 5 patients exhibited a reduced ability of the granulocytes to phagocytize and kill Candida albicans. In the CMCC family, the father had a marked deficiency of the oxidase activity of the granulocytes whereas in his daughters, the oxidase deficiency proved to be of a minor grade. In the sera of both daughters a phagocytosis inhibiting factor could be assumed to exist in addition to the granulocytic abnormalities. When heat-inactivated Candida albicans cells, however, were used for experiments, the granulocytes of each patient were able to phagocytize the germs at the same rate as did the granulocytes taken from the controls. With regard to alterations of the T cell function previously reported in CMCC, in all patients we also could demonstrate various symptoms of a T cell-dependent immunodeficiency. The results of the present in vitro-experiments furnish good evidence of a state of fundamental deficiency of the microphages in patients with CMCC, which may be the dominating cellular factor in the aetiopathogenesis of CMCC.