Effect of low intensity helium-neon (HeNe) laser irradiation on experimental paracoccidioidomycotic wound healing dynamics.

The effect of HeNe laser on the extracellular matrix deposition, chemokine expression and angiogenesis in experimental paracoccidioidomycotic lesions was investigated. At days 7, 8 and 9 postinfection the wound of each animal was treated with a 632.8 nm HeNe laser at a dose of 3 J cm(-2). At day 10 postinfection, the wounds were examined by using histologic and immunohistochemical methods. Results revealed that laser-treated lesions were lesser extensive than untreated ones, and composed mainly by macrophages and lymphocytes. High IL-1beta expression was shown in the untreated group whereas in laser-treated animals the expression was scarce. On the other hand, the expression of CXCL-10 was found to be reduced in untreated animals and quite intensive and well distributed in the laser-treated ones. Also, untreated lesions presented vascular endothelial growth factor (VEGF) in a small area near the center of the lesion and high immunoreactivity for hypoxia-inducible factor-1 (HIF-1), whereas laser-treated lesions expressed VEGF surrounding blood vessels and little immunoreactivity for HIF-1. Laser-treated lesions presented much more reticular fibers and collagen deposition when compared with the untreated lesion. Our results show that laser was efficient in minimizing the local effects observed in paracoccidioidomycosis and can be an efficient tool in the treatment of this infection, accelerating the healing process.

Effects of HeNe laser irradiation on experimental paracoccidioidomycotic lesions.

Paracoccidioidomycosis (PCM) is the most prevalent human mycosis in Latin America. The infection is thought to take place firstly in the lungs and then may disseminate to other organs and tissues. Treatment by currently available antifungals is lengthy, the drugs may have undesirable side effects, and some are costly. Occasional resistant strains of Paracoccidioides brasiliensis, the causative agent of PCM, have been reported. So, the search for more efficient treatments or adjuvant therapies has to be continued. In this work, we evaluated the effects of HeNe laser irradiation on cutaneous inflammatory lesions caused by the inoculation of 5 x 10(6)/0.1ml yeasts cells into the back footpad of Balb/c mice. HeNe irradiation (lambda=632.8nm, 3mW, incident energy of 3J/cm(2)) was applied at days 7, 8 and 9 post-infection and histological and immunohistochemical analysis were done. Unirradiated animals were used as controls. The results showed that laser-treated mice presented reduction of footpad edema, faster cutaneous wound healing, confluent granuloma, diffuse- and more loosely distributed immunolabeling for TNF-alpha, enhanced labeling of IFN-gamma and any P. brasiliensis form detected, whereas multiple viable fungi were seen in diffuse widespread granulomas obtained from non-treated mice foot-pad. Fungi that were harvested from laser-treated animals presented no capability of growth in vitro as compared to those obtained from non-treated mice. We conclude that HeNe laser irradiation was able to inhibit the progress of inflammatory local reaction produced by P. brasiliensis infection and influence local cytokines production. We suggest that this treatment modality can be a useful coadjuvant tool to be combined with antifungal agents in the treatment of PCM ulcerations. The mechanisms involved in laser therapy of PCM lesions need further investigation.

Avaliacao histologica de pulmao e timo de camundongos inoculados com Paracoccidioides brasiliensis pela via intratraqueal / Histology avaliation of lung and thymus of mice inoculated with Paracoccidioides brasiliensis for the intratraqueal way

A Paracoccidoidomicose (PCM) e uma doenca granulomatosa cronica, causada pelo Paracoccidioides brasiliensis, que envolve primariamente os pulmoes e pode disseminar para outros orgaos e sistemas. Trabalhos realizados com camundongos tem demonstrado que o P. brasiliensis causa alteracoes histologicas no timo (orgao linfoide primario responsavel pela maturacao dos linfocitos T) quando inoculado pela via intraperitonial. Este trabalho teve por finalidade reproduzir o modelo de inoculacao intratraqueal e avaliar a ocorrencia de alteracoes histopatologicas no timo, visando contribuir para um melhor entendimento da dinamica fungo-hospedeiro-doenca. A analise histopatologica dos pulmoes revelou inicialmente a presenca de infiltrados ricos em polimorfonucleares (PMNs), que foram substituidos por granulomas composto por linfocitos, plasmocitos, celulas gigantes e fungos em proliferacao. Com relacao ao timo, os cortes histologicos revelaram uma atenuacao ou perda da delimitacao cortimedular, com rarefacao do cortex devido a apoptose. Observou-se ainda a presenca de infiltrados neutrofilicos na regiao subcapsular, assim como estruturas refringentes semelhantes a leveduras de P. brasiliensis cercados por neutrofilos.

Thymic atrophy in infectious diseases

The thymus is a primary lymphoid organ that plays an important role in the development of the immune system and in the differentiation and maturation of the vast majority of the T cell repertoire. During the normal life span, this organ undergoes involution in situations such as pregnancy, aging and in the presence of a wide variety of infectious diseases. This atrophy is characterized by intense structural and morphological alterations associated with an increased level of apoptosis, for which many direct and indirect mechanisms have been proposed. The fact that the thymus is a target for infectious diseases could make the host enviroment propitious for the maintenance or enhancement of infection.

Thymic atrophy and fungal virulence during experimental paracoccidioidomycosis

A imunossupressão observada em micoses sistêmicas pode estar relacionada a danos nos órgãos linfóides primários. Assim, nosso laboratório tem estudado uma possível ação do Paracoccidioides brasiliensis sobre o timo de camundongos. Neste estudo, analisamos o timo de camundongos susceptíveis e resistentes ao fungo utilizando cepas de alta e baixa virulência. Todos os grupos apresentaram atrofia tímica, perda de delimitação corticomedular e aumento da taxa de apoptose. Entretanto, as alterações foram mais precoces e pronunciadas em camundongos inoculados com a cepa virulenta do fungo, sugerindo que a virulência fúngica pode estar diretamente ligada à atrofia tímica e indução de imunossupressão.

Thymic atrophy and fungal virulence during experimental paracoccidioidomycosis

The immunosuppression observed in systemic mycosis can be related to primary lymphoid organs damage. Thus, our laboratory has studied the effects of the Paracoccidioides brasiliensis infection on the thymus of mice. Here, thymuses of susceptible and resistant mice were evaluated after inoculation with highly and slightly virulent isolates of the fungus. All groups presented thymic atrophy, loss of corticomedullary delimitation and increase of apoptotic index. However, mice inoculated with high virulent strain showed earlier and stronger alterations suggesting that thymic atrophy can be directly related to the fungal virulence and to the immunosuppression.

A imunossupressão observada em micoses sistêmicas pode estar relacionada a danos nos órgãos linfóides primários. Assim, nosso laboratório tem estudado uma possível ação do Paracoccidioides brasiliensis sobre o timo de camundongos. Neste estudo, analisamos o timo de camundongos susceptíveis e resistentes ao fungo utilizando cepas de alta e baixa virulência. Todos os grupos apresentaram atrofia tímica, perda de delimitação corticomedular e aumento da taxa de apoptose. Entretanto, as alterações foram mais precoces e pronunciadas em camundongos inoculados com a cepa virulenta do fungo, sugerindo que a virulência fúngica pode estar diretamente ligada à atrofia tímica e indução de imunossupressão.