Chronic stages of paracoccidioidomycosis (PCM) are characterized by granulomatous lesions which promote the development of pulmonary fibrosis leading to the loss of respiratory function in 50% of patients; in addition, it has been observed that neutrophils predominate during these chronic stages of P. brasiliensis infection. The goal of this study was to evaluate the role of the neutrophil during the chronic stages of experimental pulmonary PCM and during the fibrosis development and tissue repair using a monoclonal specific to this phagocytic cell. Male BALB/c mice were inoculated intranasally with 1.5x10⁶ P. brasiliensis yeast cells. A monoclonal antibody specific to neutrophils was administered at 4 weeks post-inoculation followed by doses every 48h during two weeks. Mice were sacrificed at 8 and 12 weeks post-inoculation to assess cellularity, fungal load, cytokine/chemokine levels, histopathological analysis, collagen and expression of genes related to fibrosis development. Depletion of neutrophils was associated with a significant decrease in the number of eosinophils, dendritic cells, B cells, CD4-T cells, MDSCs and Treg cells, fungal load and levels of most of the pro-inflammatory cytokines/chemokines evaluated, including IL-17, TNF-α and TGF-β1. Recovery of lung architecture was also associated with reduced levels of collagen, high expression of TGF-β3, matrix metalloproteinase (MMP)-12 and -14, and decreased expression of tissue inhibitor metalloproteinase (TIMP)-2, and MMP-8. Depletion of neutrophils might attenuate lung fibrosis and inflammation through down-regulating TGF-β1, TNF-α, IL-17, MMP-8 and TIMP-2. These results suggest that neutrophil could be considered as a therapeutic target in pulmonary fibrosis induced by P. brasiliensis.

Several studies have shown the potential use of bone marrow mesenchymal stem cells (BM-MSCs) as a therapeutic approach to infectious diseases. Since BM-MSCs can exert antimicrobial properties and influence the immune response against pathogens, our aim was to study the antimicrobial therapeutic potential of BM-MSCs in an experimental model of paracoccidioidomycosis (PCM). BM-MSCs were isolated from BALB/c donor mice. Paracoccidioides brasiliensis–infected male BALB/c mice were injected with purified BM-MSCs at 8th week post-infection. Mice were sacrificed at 12th week post-infection. Homing of BM-MSCs was confirmed by cellular labeling with fluorescent lipophilic dye and detected by flow cytometry. We found that, in comparison with nontransplanted infected animals, BM-MSCs-treated and P. brasiliensis-infected mice showed a significant increase in (i) fungal burdens, (ii) neutrophils, eosinophils and M2 macrophages counts, and (iii) interleukin (IL)-6, IL-9, GM-CSF, CXCL1, CXCL9, and CCL5 levels, while presenting a decrease in M1 macrophages and Treg cells in lungs. In addition, the histopathological analysis of the lungs showed an increased inflammatory process. This is the first study to our knowledge that evaluates the effects of BM-MSCs treatment in PCM. Our results indicate that the immunoregulatory function of BM-MSCs may be triggered by the interaction with P. brasiliensis, which exacerbates chronic pulmonary inflammatory response.

Itraconazole (ITC) is the drug of choice for treating paracoccidioidomycosis (PCM); nonetheless, patients with the chronic form of this mycosis develop fibrosis, a residual pulmonary abnormality, even after treatment. Recently, we observed that the depletion of neutrophils with a specific monoclonal antibody (mAb-anti-Ly6G) during the chronic stages of PCM was associated with a decrease in the fungal burden, the inflammatory response and a reduction of fibrosis. Herein, we aimed to evaluate the effect of ITC in combination with the mAb-anti-Ly6G in an experimental model of pulmonary PCM. BALB/c male mice were challenged with Paracoccidioides brasiliensis yeasts and treated with the mAb-anti-Ly6G and/or ITC at 4th week post-infection (p.i.) and then sacrificed at 12th week p.i. to assess neutrophil subpopulations, fungal load, collagen, expression of fibrosis- and pro-inflammatory-related genes and histopathology. We observed that combination of ITC/mAb-anti-Ly6G favored the control of infection and diminished the inflammatory response. Of note, such therapeutic strategy reduced the expression of IL-1β, IL-6, IL-17, IL-10, TNF-α, TGF-β1, TGF-β3, GATA-3, RORc, Ahr, MMP-1α, MMP-8 MMP-15, TIMP-1, and TIMP-2 genes in an additive manner compared to those mice treated with the mAb or ITC alone. Interestingly, ITC induced an increase of type-II neutrophils even in those mice treated with the mAb-anti-Ly6G. These results indicate that combination ITC/mAb-anti-Ly6G reduced the infection and pulmonary fibrosis through down-regulation of inflammatory and pro-fibrotic genes. Additionally, we confirmed the immunomodulatory properties of this antifungal in vivo. This work emphasizes the importance of exploring new potential combination treatments to treat fungal infections.

Bone marrow-derived mesenchymal stem cells (BMMSCs) have been consider as a promising therapy in fibrotic diseases. Experimental models suggest that BMMSCs may be used as an alternative therapy to treat chemical- or physical-induced pulmonary fibrosis. We investigated the anti-fibrotic potential of BMMSCs in an experimental model of lung fibrosis by infection with Paracoccidioides brasiliensis. BMMSCs were isolated and purified from BALB/c mice using standardized methods. BALB/c male mice were inoculated by intranasal infection of 1.5x10⁶ P. brasiliensis yeasts. Then, 1x10⁶ BMMSCs were administered intra venous at 8^th week post-infection (p.i.). An additional group of mice was treated with itraconazole (ITC) two weeks before BMMSCs administration. Animals were sacrificed at 12^th week p.i. Histopathological examination, fibrocytes counts, soluble collagen and fibrosis-related genes expression in lungs were evaluated. Additionally, human fibroblasts were treated with homogenized lung supernatants (HLS) to determine induction of collagen expression. Histological analysis showed an increase of granulomatous inflammatory areas in BMMSCs-treated mice. A significant increase of fibrocytes count, soluble collagen and collagen-3α1, TGF-β3, MMP-8 and MMP-15 genes expression were also observed in those mice. Interestingly, when combined therapy BMMSCs/ITC was used there is a decrease of TIMP-1 and MMP-13 gene expression in infected mice. Finally, human fibroblasts stimulated with HLS from infected and BMMSCs-transplanted mice showed a higher expression of collagen I. In conclusion, our findings indicate that late infusion of BMMSCs into mice infected with P. brasiliensis does not have any anti-fibrotic effect; possibly because their interaction with the fungus promotes collagen expression and tissue remodeling. This is the first study that evaluates the effect of BMMSCs therapy for lung fibrosis induced by the fungal pathogen Paracoccidioides brasiliensis, the causative agent of paracoccidioidomycosis, one of the most important systemic endemic mycosis diagnosed in South America and Central America. Our findings showed an impaired anti-fibrotic effect of BMMSCs transplantation. This effect could be triggered by either the chronic inflammatory microenvironment induced by P. brasiliensis or by a direct interaction between BMMSCs and the fungus, resulting in an exacerbation of the pulmonary fibrosis. In fact, the pro-fibrotic effect exerted by BMMSCs was toned-down by the usage of the antifungal ITC.

Implementing precise techniques in routine diagnosis of chronic granulomatous disease (CGD), which expedite the screening of molecular defects, may be critical for a quick assumption of patient prognosis. This study compared the efficacy of single‐strand conformation polymorphism analysis (SSCP) and high‐performance liquid chromatography under partially denaturing conditions (dHPLC) for screening mutations in CGD patients. We selected 10 male CGD patients with a clinical history of severe recurrent infections and abnormal respiratory burst function. gDNA, mRNA and cDNA samples were prepared by standard methods. CYBB exons were amplified by PCR and screened by SSCP or dHPLC. Abnormal DNA fragments were sequenced to reveal the nature of the mutations. The SSCP and dHPLC methods showed DNA abnormalities, respectively, in 55% and 100% of the cases. Sequencing of the abnormal DNA samples confirmed mutations in all cases. Four novel mutations in CYBB were identified which were picked up only by the dHPLC screening (c.904 insC, c.141+5 g>t, c.553 T>C, and c.665 A>T). This work highlights the relevance of dHPLC, a sensitive, fast, reliable and cost‐effective method for screening mutations in CGD, which in combination with functional assays assessing the phagocyte respiratory burst will contribute to expedite the definitive diagnosis of X‐linked CGD, direct treatment, genetic counselling and to have a clear assumption of the prognosis. This strategy is especially suitable for developing countries.