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.

TRAF1 suppresses antifungal immunity through CXCL1-mediated neutrophil recruitment during Candida albicans intradermal infection.

BACKGROUND: Candida albicans is the most common opportunistic human fungal pathogen. The chemokine ligand CXCL1 plays a protective role in fungal infection through the recruitment of neutrophils. TRAF1 (tumor necrosis factor-associated factor 1) can be highly induced by proinflammatory stimuli such as LPS and TNF and has been implicated in septic shock. However, the role of TRAF1 in infection, especially fungal infection, remains elusive. Herein, we reveal that TRAF1 suppresses the antifungal immune response to Candida albicans intradermal infection through the regulation of CXCL1 induction and neutrophil recruitment. METHODS: A mouse model of C. albicans intradermal infection was established. The Traf1-/- mice and Traf1-/- immortalized human keratinocytes were generated. The p65 inhibitor triptolide, STAT1 inhibitor fludarabine, neutrophil-depletion antibody Ly6G, and neutralizing antibody for CXCL1 were utilized. The expression of proinflammatory cytokines and chemokines was assessed by real-time PCR and ELISA, and the activation of signaling molecules was analyzed by Western blotting. Hematoxylin and eosin staining and periodic acid Schiff staining were used for histology or fungal detection, respectively. The immunofluorescence and flow cytometry analyses were employed in the assessment of immune cell infiltration. Bone marrow transplantation and adoptive transfer experiments were conducted to establish a role for TRAF1 in the macrophage compartment in fungal skin infection. RESULTS: TRAF1-deficient mice demonstrated improved control of Candida albicans intradermal infection, and concomitant increase in neutrophil recruitment and reduction in fungal burden. The chemokine CXCL1 was upregulated in the TRAF1-deficient macrophages treated with heat-killed C. albicans. Mechanistically, TRAF1-deficient macrophages showed increased activation of transcription factor NFκB p65. The human CXCL8 was also highly induced in the TRAF1-deficient human keratinocytes upon TNF stimulation through decreasing the activation of transcription factor STAT1. TRAF1-deficient macrophages played a critical role in containing the C. albicans skin infection in vivo. CONCLUSION: TRAF1-deficient mice can better control fungal infection in the skin, a process attributable to the CXCL-neutrophil axis. Mechanistically, TRAF1 likely regulates CXCL1 expression in both macrophages and keratinocytes through the transcriptional factor NFκB and STAT1, respectively. Our finding offers new insight into the understanding of the immune regulatory mechanisms in host defense against C. albicans infection.

Infection and tissue repair of experimental cutaneous candidiasis in diabetic mice.

PURPOSE: Diabetic patients seem to be predisposed to cutaneous candidiasis. In this study, we evaluated the interference of diabetic conditions in alloxan-induced diabetic mice in relation to the development of C. albicans infection, density of M1 and M2 macrophages, distribution of collagen type I and III and anti-inflamamatory cytokines involved in tissue repair. METHODOLOGY: The mice were treated with intravenous alloxan, and all animals with blood glucose levels >250 mg dl-1 were inoculate with C. albicans intradermally in the hind paw and were studied for up to 21 days. Control groups without alloxan were used. The fungal burden was evaluated by periodic acid-Schiff (PAS) and by counting the colony forming units. Total population of macrophages were targeted with antibody to F4/80 antigen and M2 macrophages with anti-arginase antibody. Anti-inflammatory cytokines from popliteal lymph nodes were determined by capture ELISA procedures. Picrosirius red staining allowed qunantification of collagen types I and III in the infected skin by using a polarized light microscope.Results/Key findings. Diabetic mice, versus non-diabetic mice, showed a significant lower density of F4/80 and M2 macrophages, higher fungal burden, deficiency in interleukin (IL)-4 production, and delayed IL-13 responses. The later clearance of C. albicans enhanced tissue injury, leading to a decrease in collagen type I. Moreover, collagen type III was increased by interference of IL-13 and transforming growth factor-ß cytokines. CONCLUSION: These findings highlight some important changes in diabetic animal responses to C. albicans infection that may be important to the pathophysiological processes underpinning cutaneous candidiasis in diabetic patients.

In situ photoimmunotherapy for cutaneous granuloma caused by itraconazole-resistant Candida guilliermondii.

Cutaneous granulomas caused by Candida guilliermondii are difficult to cure. In situ photoimmunotherapy (ISPI) is a novel method composed of local photothermal therapy and immunoadjuvant. In this study, ISPI was used the first time clinically for cutaneous granuloma caused by itraconazole-resistant C.guilliermondii. A 10-week cycle of ISPI was composed of (1) 5% imiquimod applied topically every other day and (2) irradiation of lesions with an 808-nm diode laser at Days 14, 28, 42, and 56. Here we report our first case. A patient was treated with ISPI for four cycles. After the treatment, the lesions were eliminated without recurrence during a 12-month follow-up. Our results demonstrate that ISPI can be used as an effective treatment modality for cutaneous fungal granuloma.

Folliculocentric cutaneous presentation of disseminated Candida krusei infection in a patient with acute myeloid leukemia.

Candida krusei (C. krusei) is a multidrug-resistant opportunistic fungal pathogen that may cause disseminated infections in immunocompromised hosts. However, its clinical and histologic features are not well-characterized. We present a unique case to contribute to the growing knowledge base associated with this organism. During hospitalization for neutropenic fever, a 19-year-old man with acute myeloid leukemia, who underwent hematopoietic stem cell transplantation, developed a generalized folliculocentric eruption following initiation of antifungal therapy for newly diagnosed C. krusei fungemia. Despite adequate antifungal coverage and negative blood cultures, the follicular-based erythematous papules persisted. Biopsies demonstrated yeast within ruptured follicles, without angiotropism or involvement of the interfollicular dermis, subcutaneous tissue, or stratum corneum. Concurrent skin tissue cultures confirmed C. krusei. The patient remained febrile despite aggressive antifungal therapy, with relapse of leukemia and subsequent death. Our case is unusual given the development of cutaneous lesions following clearance of fungemia, with yeast limited to ruptured follicular lumina, possibly indicating a primary cutaneous source or early transfollicular/transepidermal elimination. Given the limited available descriptions of cutaneous histopathology for C. krusei, we seek to add to the understanding of its pathophysiology and aid in the diagnosis and treatment of this often fatal infection.

IL-22 and TNF-α represent a key cytokine combination for epidermal integrity during infection with Candida albicans.

T cells exercise their full impact on target cells through a combination of secreted cytokines. The recently described T helper cell subset Th22 is characterized by a combinatorial secretion of IL-22 and TNF-α. Here, we demonstrate that IL-22 increases the TNF-α-dependent induction and secretion of several immune-modulatory molecules such as initial complement factors C1r and C1s, antimicrobial peptides S100A7 and HBD-2 (human ß defensin 2), and antimicrobial chemokines CXCL-9/-10/-11 in primary human keratinocytes. The synergism of IL-22 and TNF-α is transmitted intracellularly by MAP kinases and downstream by transcription factors of the AP-1 family. The induction of innate immunity is relevant in an in vitro infection model, where keratinocytes stimulated with Th22 supernatants or recombinant IL-22 plus TNF-α effectively inhibit the growth of Candida albicans and maintain survival of epithelia. Accordingly, the combinatorial stimulation of keratinocytes with IL-22 and TNF-α most efficiently conserves the integrity of the epidermal barrier in a three-dimensional skin infection model as compared with IFN-γ, IL-17, IL-22 or TNF-α alone. In summary, we demonstrate that IL-22 and TNF-α represent a potent, synergistic cytokine combination for cutaneous immunity.

Candida krusei fungemia in an immunocompromised patient.

Candida krusei is an emerging fungal pathogen found primarily in immunocompromised patients. Intrinsic resistance to fluconazole and decreasing susceptibility to other anti-fungal agents are problematic. When colonization occurs, dissemination may follow rapidly. We present a case of a patient with acute lymphoblastic leukemia who, despite being treated prophylactically with fluconazole, developed disseminated C. krusei.

Cytokine expression induced by Candida albicans in a model of cutaneous candidosis based on reconstituted human epidermis.

Skin equivalents based on reconstituted human epidermis have been used recently to establish models for allergic/irritant contact dermatitis and cutaneous candidosis. In the present study the cytokine expression pattern and the morphological alterations in experimental cutaneous candidosis were investigated by RT-PCR and histological analysis. In experimental cutaneous C albicans infection the mRNA expression levels of interleukin (IL)-1a, IL-1beta, IL-8, GM-CSF, Exodus-2, tumour necrosis factor-alpha and PSL (P-selectin ligand) were upregulated. Cytokine profile and histological features of infected skin (separation of keratinocytes, oedema, vacuolisation) were comparable to that seen in experimental contact dermatitis. These immunomodulatory and morphological similarities might reflect a common pathogenesis factor in both diseases.

Fungal infections inducing HLA-DR but not HLA-DQ transplantation antigens on keratinocytes.

The phenotypes of infiltrating cells and class II transplantation antigens on keratinocytes in candida and dermatophyte lesions from 15 patients were analysed in situ with an immunohistochemical double staining technique combined with periodic acid-Schiff staining. In five out of ten biopsies from candida lesions and in one of five biopsies from dermatophyte lesions the keratinocytes expressed HLA-DR but not HLA-DQ antigens. The HLA-DR expression was patchy in all and most pronounced in two candida biopsies which also contained large infiltrates of anti-Leu 3a reactive T lymphocytes. The induction of detectable amounts of different class II antigens on keratinocytes might depend on the type of antigen, the magnitude and duration of the response elicited and/or the immunological state of the patient.

Pathological observations in experimental candida infection of sensitized guinea pigs.

Guinea pigs immunized intramuscularly with heat-killed or viable Candida albicans were infected intracutaneously with C. albicans. Animals with negative delayed hypersensitivity against C. albicans antigen showed similar lesions with non-immunized controls. Delayed hypersensitivity-positive guinea pigs, which were detected in the animals immunized with heat-killed C. albicans in CFA and IFA, demonstrated a delay of the resolution of the inflammatory tissue reaction and, in the animals immunized with C. albicans in CFA, developed a granuloma. These results suggest that both humoral and cell-mediated immunities do not play a significant role for protection against candidiasis and at a late stage of infection, cell-mediated immunity may play a secondary role of the enhancement of resistance to candida infection associated with granuloma formation.

Anti-ovarian and anti-lymphocyte antibodies in patients with chronic vaginal candidiasis.

Seventeen of 30 patients with chronic vaginal candidiasis (CVC) of at least 5 years duration had varying degrees of menstrual problems and defective T lymphocyte function; 8 developed amenorrhea. In a group of 40 CVC patients, titers of autoantibodies to ovary, thymocytes, a T-cell line (CCRF-CEM), and a B-cell line (RN114) were significantly higher than those in 45 normal females (69 +/- 3 vs. 5 +/- 2, 70 +/- 27 vs. 4 +/- 2, l7 +/- 6, vs. 4 +/ 2, and 73 +/- 24 vs. 8 +/- 5, respectively, mean +/- S.E.). Antibody titers to sperm, T-cell line HSB-2, and B-cell lines RAJI and BALL-1 were within the normal range. Significant correlations were found between anti-Candida, anti-ovarian, and anti-thymocyte antibody titers. Similar results were found for 6 patients with chronic mucocutaneous candidiasis (CMCC) and in serial samples obtained over a one-year period from a representative patient with both CVC and CMCC. The anti-T-lymphocyte antibodies in these patients were directed primarily against non-suppressor (predominately helper) T cells. Absorption of the sera with either Candida cells, ovarian follicle cells, or thymocytes reduced all three antibody titers; absorption with sperm or B-cell lines did not alter the titers. These results suggest the presence of one or more cross-reactive antigens on ovarian follicle, T lymphocytes (especially the helper cell subpopulation), and Candida.

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.

Widely disseminated cutaneous candidosis in adults.

Of 9 adults, 5 males, 4 females, with wide dissemination of Candida albicans skin lesions, the eruption started in the groin, from which it spread to other areas in most cases. In 5 cases the disseminated lesions were papulo-pustular; the rest were erythematous-squamous. Hyphae and yeast cells of C. albicans were found on direct microscopy. Diabetes was present in 5 patients, lymphoma in 1, and bullous pemphigoid in another. Onychia and paronychia were found in 7 patients, intertriginous lesions of the fingers in 4 and oral thrush in 2. Intradermal skin tests were negative. The percentage and absolute numbers of T-lymphocytes were normal in 6 of 7 patients, whereas their functional activity was imparied in 4 of 6 patients, as evidenced by the negative Graft-versus host reaction. The role of concurrent disease in the pathogenesis of the candidosis is discussed.

Mucocutaneous candidiasis and thymoma.

The clinical, pathologic and immunologic features of 27 patients with chronic mucocutaneous candidiasis and thymic tumors are reviewed. This form of chronic candidiasis is unique in that the infections do not occur until after the third decade and, in contrast to patients in whom candidiasis develops during infancy or childhood, it is not accompanied by failure of endocrine organs. Instead, the patients have the disorders that often accompany thymoma, such as myasthenia gravis, hypogammaglobulinemia, and abnormalities of the bone marrow and circulating blood elements. Evidence of impaired cell-mediated immunity was found in 16 of the 21 patients in whom studies were made. The pathogenesis of the immunodeficiency in these patients is unknown. Immunosuppressive activities in the plasma of four patients were found, but none of the five patients in whom the appropriate studies were made was found to have suppressor cells. The features of this disorder are unique enough that it should be considered a syndrome, and patients in whom candidiasis develops during their adult years should be studied for the presence of thymoma.

Immunologic features of chronic granulomatous mucocutaneous candidiasis before and after treatment with transfer factor.

We report the acquisition of skin test sensitivity to Candida albicans antigen and the ability to produce leukocyte migration inhibition factor (MIF) by a Candida-negative patient with chronic granulomatous mucocutaneous candidiasis after treatment with dialyzable transfer factor (TFd). The TFd was acquired from Candida-positive healthy donors. Three of seven attempts to transfer Candida skin test sensitivity were successful, and the acquired skin reactivity lasted for 12 to 21 days. The acquisition of cellular immunity to Candida was demonstrated in vitro by production of leukocyte MIF. No Candida-induced lymphocyte transformation was observed before or after TFd injection. The TFd did not cause Candida-induced blast transformation when added directly to cultures of lymphocytes from the patient. Pain, tenderness, redness, and edema were observed around the Candida granulomas on each occasion when the skin test to Candida became positive. Two weeks after TDd injection, the proliferative response of peripheral blood lymphocytes increased, as measured by incorporation of tritiated thymidine into lymphocytes within the first hour of in vitro incubation.