Matrix metalloproteinase-2 and -9 in the granulomatous fibrosis of rats infected with Angiostrongylus cantonensis

Gross, microscopic, radiologic, echocardiographic and haematological findings in rats experimentally infected with Angiostrongylus cantonensis

Although the gross and microscopic pathology in rats infected with Angiostrongylus cantonensis has been well described, corresponding changes detected using diagnostic imaging modalities have not been reported. This work describes the cardiopulmonary changes in mature Wistar rats chronically infected with moderate burdens of A. cantonensis using radiology, computed tomography (CT), CT angiography, echocardiography, necropsy and histological examinations. Haematology and coagulation studies were also performed. Thoracic radiography, CT and CT angiography showed moderately severe alveolar pulmonary patterns mainly affecting caudal portions of the caudal lung lobes and associated dilatation of the caudal lobar pulmonary arteries. Presumptive worm profiles could be detected using echocardiography, with worms seen in the right ventricular outflow tract or straddling either the pulmonary and/or the tricuspid valves. Extensive, multifocal, coalescing dark areas and multiple pale foci affecting the caudal lung lobes were observed at necropsy. Histologically, these were composed of numerous large, confluent granulomas and fibrotic nodules. Adult worms were found predominantly in the mid- to distal pulmonary arteries. An inflammatory leukogram, hyperproteinaemia and hyperfibrinogenaemia were found in most rats. These findings provide a comparative model for A. cantonensis in its accidental hosts, such as humans and dogs. In addition, the pathological and imaging changes are comparable to those seen in dogs infected with Angiostrongylus vasorum, suggesting rats infected with A. cantonensis could be a model for dogs with A. vasorum infection.

Matrix metalloproteinase-2 and matrix metalloproteinase-9 in mice with ocular toxocariasis

In ocular toxocariasis, Toxocara canis-induced inflammatory reaction can lead to eye destruction and granuloma, which is formed by immune cell infiltration and concurrent extensive remodeling tissue. Herein, the histomorphology of granuloma and proteinase production in the eye of T. canis-infected BALB/c mice were investigated. Pathological effects substantially increased after the infection culminated in a severe leukocyte infiltration and granuloma formation from days 4 to 56 post-inoculation. The matrix metalloproteinase (MMP)-2 and MMP-9 activities remarkably increased, compared with those of uninfected control, by gelatin zymography and Western blot analysis in ocular toxocariasis. Granuloma formation had a remarkably positive correlation with MMP-2 and MMP-9 levels. We suggested that T. canis larvae and leukocytes infiltrated from blood vessel both migrated into corpus adiposum orbitae. Activated leukocytes secreted MMP-2 and MMP-9, leading to fibronectin degradation. The imbalance of MMP-2/TIMP-2 and MMP-9/TIMP-1 may play a role in inflammatory cell infiltration and extracellular matrix degradation, forming granuloma, in ophthalmological pathogenesis of T. canis infection.

Evaluation of in situ expression of effector and regulatory cytokines, TLR, galectins and matrix metalloproteinases in oral manifestations of paracoccidioidomycosis

BACKGROUND

Although the pathophysiology of paracoccidioidomycosis (PCM) is not completely understood, the study of immune response against fungus has provided insight into understanding the natural course of the disease and its clinical manifestations, hence contributing to the development of preventive measures and treatment proposals. The aim of this study was to evaluate the histopathological and immunological aspects involved in the role of different effector and regulatory responses, as well as the correlation between the TLRs, Galectins, Matrix Metalloproteinases and cytoplasmic proteases of mast cells in this infection.

METHODS

Sixteen biopsy specimens with oral lesions of chronic PCM, as well as 13 sections of normal oral mucosa were analyzed. Histopathological and immunological aspects involved in the role of different effector and regulatory responses were evaluated. Indirect immunohistochemistry was performed for IL-17, IL-10, IL-4, TGF-β, FoxP3, Gal-1, Gal-3, Gal-9, TLR-2, TLR-4, MMP-3 and MMP-9, as well as for chymase and tryptase for mast cells identification. Fibrosis was quantified using Picrosirius.

RESULTS

There was a significant increase in the area of fibrosis and in the number of cells expressing IL-10, IL-4, IL-17, FoxP3, Gal-3, TLR-2, MMP3 and MMP9 in patients with PCM in comparison with patients in the group control. There was no difference in the expression of TGF-β, TLR-4, Gal-1 or Gal-9. Mast cells number was found to be significantly lower in oral chronic PCM when compared to control samples after quantification of mast cells and expression of chymase and tryptase. PCM granulomas were classified to the morphological aspects in organized ou non-organized. Expression of IL-4 in non-organized granulomas was significantly higher.

CONCLUSION

The proteins studied herein appear to play an important role in the development and maintenance of oral lesions of PCM, as well as in the processes of development and progression of lesions caused by the fungus and by the immune response associated with the infection.

Active matrix metalloprotease-9 is associated with the collagen capsule surrounding the Madurella mycetomatis grain in mycetoma

Madurella mycetomatis is the main causative organism of eumycetoma, a persistent, progressive granulomatous infection. After subcutaneous inoculation M. mycetomatis organizes itself in grains inside a granuloma with excessive collagen accumulation surrounding it. This could be contributing to treatment failure towards currently used antifungal agents. Due to their pivotal role in tissue remodelling, matrix metalloproteinases-2 (MMP-2) and 9 (MMP-9) or tissue inhibitor of metalloproteinases (TIMP) might be involved in this process. Local MMP-2 and MMP-9 expression was assessed by immunohistochemistry while absolute serum levels of these enzymes were determined in mycetoma patients and healthy controls by performing ELISAs. The presence of active MMP was determined by gelatin zymography. We found that both MMP-2 and MMP-9 are expressed in the mycetoma lesion, but the absolute MMP-2, -9, and TIMP-1 serum levels did not significantly differ between patients and controls. However, active MMP-9 was found in sera of 36% of M. mycetomatis infected subjects, whereas this active form was absent in sera of controls (P<0.0001). MMP-2, MMP-9, and TIMP-1 polymorphisms in mycetoma patients and healthy controls were determined through PCR-RFLP or sequencing. A higher T allele frequency in TIMP-1 (+372) SNP was observed in male M. mycetomatis mycetoma patients compared to controls. The presence of active MMP-9 in mycetoma patients suggest that MMP-9 is activated or synthesized by inflammatory cells upon M. mycetomatis infection. Inhibiting MMP-9 activity with doxycycline could prevent collagen accumulation in mycetoma, which in its turn might make the fungus more accessible to antifungal agents.

Eumycetoma, mainly caused by the fungus Madurella mycetomatis, is a chronic infection which, without treatment, results in deformation of the infected body part. Inside the body, the fungus organises itself in grains which are surrounded by collagen. This collagen could act as a natural barrier for antifungal agents. Since collagen modulation is regulated by matrix metalloproteinase-2 (MMP-2), MMP-9 and tissue inhibitors of metalloproteinases (TIMPs), these enzymes could play a role in the formation of the collagen capsule surrounding the fungal grain. Indeed, we demonstrated that MMPs were found surrounding the mycetoma grain and that measurable levels of both MMPs were found in serum of both mycetoma patients and healthy controls. Only in mycetoma patients the active form MMP-9 was found. The presence of active MMP-9 in the serum of mycetoma-patients was not the result of lower levels TIMP-1 but more likely from differences in allele frequencies in the TIMP-1 gene. In conclusion, our results showed an increased MMP-9 activity in mycetoma patients. We hypothesize that inhibition of MMP-9 activity by doxycycline will result in breakdown of the collagen capsule surrounding the grain, which in turn will make the entrance of antifungal drugs into the grain easier.

Matrix metalloproteinases with gelatinolytic activity induced by Paracoccidioides brasiliensis infection

Matrix metalloproteinases (MMPs) modulate extracellular matrix turnover, inflammation and immunity. We studied MMP-9 and MMP-2 in experimental paracoccidioidomycosis. At 15 and 120 days after infection (DAI) with virulent Paracoccidioides brasiliensis, MMP-9 was positive by immunohistochemistry in multinucleated giant cells, in mononuclear cells with macrophage and lymphocyte morphologies and also in fungal cells in the lesions of susceptible and resistant mice. Using gelatin zymography, pro- and active MMP-9 and active MMP-2 were detected in all infected mice, but not in controls. Gelatinolytic activity was not observed in P. brasiliensis extracts. Semiquantitative analysis of gelatinolytic activities revealed weak or absent MMP-2 and strong MMP-9 activity in both mouse strains at 15 DAI, declining at 120 DAI. Avirulent P. brasiliensis-infected mice had residual lesions with MMP-9-positive pseudoxantomatous macrophages, but no gelatinase activity at 120 DAI. Our findings demonstrate the induction of MMPs, particularly MMP-9, in experimental paracoccidioidomycosis, suggesting a possible influence in the pattern of granulomas and in fungal dissemination.

Effect of praziquantel treatment on the expression of matrix metalloproteinases in relation to tissue resorption during fibrosis in hamsters with acute and chronic Opisthorchis viverrini infection

Praziquantel has been used for the treatment of diseases caused by infection with various parasites. Praziquantel treatment in Opisthorchis viverrini-infected patients reduces the hepatobiliary fibrosis due to tissue resorption, however, some fibroses are irreversible. To clarify the effect of praziquantel treatment on hepatobiliary fibrosis, we examined the expression of matrix metalloproteinases (MMPs) in relation to fibrolysis on praziquantel-treated hamsters after O. viverrini acute infection (AI) for 21 days and chronic infection (CI) for 4 months. The reduction rate of hydroxyproline content in the livers of the AI group with 6-month praziquantel treatment (71%) was higher than that of corresponding praziquantel-treated CI group (13%), similar to the decrease in the thickness of peribiliary fibrosis. Hepatic mRNA levels of collagen I significantly decreased compared with untreated control after praziquantel treatment both in AI and CI groups. Expression of collagen III significantly decreased in the AI group but unchanged in the CI group. MMP-9 and MMP-13 (except 3 months in CI group) levels significantly decreased in both groups. Notably, expression of MMP-7 level increased at 1 and 6 months in both AI and CI groups, respectively. MMP-2 level did not change in both groups. Gelatinase activity of MMPs-2 and -9 was associated with their transcriptional levels. Tissue inhibitors of MMP (TIMP)-1 and TIMP-2 significantly decreased in the AI group, whereas TIMP-1 levels did not change and TIMP-2 level was significantly increased in CI group. Praziquantel treatment increased the expression of TNF-alpha in both groups, suggesting an association with MMP-7 expression. TGF-beta expression was significantly increased only in the CI group indicating its may involve in TIMPs expression. These results suggest that in animals with chronic O. viverrini infection, praziquantel treatment induces the expression of TGF-beta, and TIMPs and resultant inhibition of MMP activity, leading to slow resorption of hepatic fibrosis.

Matrix metalloproteinase-2, -9 and -13 are involved in fibronectin degradation of rat lung granulomatous fibrosis caused by Angiostrongylus cantonensis

Pulmonary granuloma formation and fibrosis were experimentally induced in Sprague-Dawley strain rats by Angiostrongylus cantonensis. Increased protein levels of matrix metalloproteinase (MMP)-2, -9, -13 and the imbalance between these enzymes and metalloproteinase inhibitors, tissue inhibitors of MMPs (TIMP-1 and -2), occur during granulomatous fibrosis. Activation of proteolytic enzymes (MMP-2, -9 and -13) and fibronectin degradation occur simultaneously. Furthermore, the present study demonstrated that fibronectin avidly binds MMP-2, -9 or -13. Immunohistochemical observations also showed the localization of MMP-13, TIMP-1 and -2 within the infiltrating leucocytes. These results suggest that MMP-2, -9 and -13 may participate in the fibronectin degradation of A. cantonensis-induced granulomatous fibrosis.

Angiostrongylus cantonensis: induction of urokinase-type PA and degradation of type IV collagen in rat lung granulomatous fibrosis

Granuloma formation and subsequent fibrosis around Angiostrongylus cantonensis larvae in the lungs were induced experimentally in Sprague-Dawley strain rats. Casein zymogram analysis demonstrated that urokinase-type plasminogen activator (uPA) activity was increased during lung inflammation and fibrosis. Granulomatous fibrosis, type IV collagen degradation and activation of uPA occur simultaneously. Furthermore, the present study demonstrated that collagen avidly binds uPA. Immunohistochemical observations showed localization of uPA within the infiltrating leucocytes. We propose that uPA may participate in A. cantonensis-induced granulomatous fibrosis.

Matrix metalloproteinases in lung: multiple, multifarious, and multifaceted

The matrix metalloproteinases (MMPs), a family of 25 secreted and cell surface-bound neutral proteinases, process a large array of extracellular and cell surface proteins under normal and pathological conditions. MMPs play critical roles in lung organogenesis, but their expression, for the most part, is downregulated after generation of the alveoli. Our knowledge about the resurgence of the MMPs that occurs in most inflammatory diseases of the lung is rapidly expanding. Although not all members of the MMP family are found within the lung tissue, many are upregulated during the acute and chronic phases of these diseases. Furthermore, potential MMP targets in the lung include all structural proteins in the extracellular matrix (ECM), cell adhesion molecules, growth factors, cytokines, and chemokines. However, what is less known is the role of MMP proteolysis in modulating the function of these substrates in vivo. Because of their multiplicity and substantial substrate overlap, MMPs are thought to have redundant functions. However, as we explore in this review, such redundancy most likely evolved as a necessary compensatory mechanism given the critical regulatory importance of MMPs. While inhibition of MMPs has been proposed as a therapeutic option in a variety of inflammatory lung conditions, a complete understanding of the biology of these complex enzymes is needed before we can reasonably consider them as therapeutic targets.

The paradox of matrix metalloproteinases in infectious disease

Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that perform multiple roles in the normal immune response to infection. MMPs facilitate leucocyte recruitment, cytokine and chemokine processing, defensin activation and matrix remodelling. However, excess MMP activity following infection may lead to immunopathology that causes host morbidity or mortality and favours pathogen dissemination or persistence. Here, we review the normal functions of MMPs in immunity and then discuss viral and bacterial infections where excess MMP activity has been implicated in pathology, specifically examining HIV, HTLV-1, hepatitis B, endotoxin shock, Helicobacter pylori and Mycobacterium tuberculosis. Tissue destruction may be exacerbated further by bacterial-derived enzymes which activate the host pro-MMPs. Finally, the potential for therapeutic targeting of excess MMP activity in infection is considered.