Background: Among the common malignancies, pancreatic cancer has the shortest long-term survival. The aggressive, rapid, and infiltrative growth pattern of pancreatic cancer, together with the lack of specific symptoms, often leads to late diagnosis. Metastases are frequently found at the time of diagnosis, which prevents curative surgical treatment. Good tumor markers would enable early detection, thus improving the prognosis. Unfortunately, no such markers are available in the clinic. The tumor stroma is defined as the non-malignant cells and the extracellular matrix (ECM) of a cancer. Pancreatic cancer is characterized by an abundant tumor stroma, rich in ECM proteins such as collagens, which have been shown to play important roles in tumor progression. Furthermore, pancreatic cancer cells produce large quantities of ECM proteins, especially the basement membrane (BM) protein type IV collagen. All epithelial cells are anchored to a BM, which must be degraded in order for an in situ cancer to become invasive. Matrix metalloproteinases (MMPs) are enzymes involved in BM degradation. In this thesis, the tumor stroma of pancreatic cancer is studied, focusing on the BM proteins type IV and type XVIII collagen, with the aim to clarify if the stroma could be a source of novel tumor markers for this form of cancer. Additionally, the role of type IV collagen produced by the cancer cells is studied. Methods: Expression patterns of type IV and type XVIII collagen, MMPs involved in collagen degradation, and collagen receptors (integrins) were studied by immunoflourescence in both normal and pancreatic cancer tissue, and in pancreatic cancer cell lines. Circulating plasma levels of type IV and type XVIII collagen and conventional tumor markers (TPS, Ca 19-9, CEA and Ca 125) were measured in controls and pancreatic cancer patients at the time of diagnosis and after treatment. The role of cancer cell produced type IV collagen was studied in human pancreatic cancer cell lines by functional blocking of integrin receptors (integrin a1, a2 and b1) and integrin-binding sites on type IV collagen, and by siRNA-induced down-regulation of type IV collagen synthesis. Proliferation was analyzed by a luminescence based cell viability assay, migration by time-lapse microscopy, and apoptosis by M30-neoepitope detection. Results: MMPs involved in BM degradation were upregulated in pancreatic cancer tissue. The expression of type XVIII collagen shifted from a general BM expression pattern in normal tissue, to mainly being found in the tumor vasculature in pancreatic cancer. Type IV collagen, on the other hand, remained highly expressed in the vicinity of the cancer cells. The a1, a2, and b1 integrin receptors were highly expressed at the cancer cell surface. Both down-regulation of type IV collagen synthesis and blocking the integrin/type IV collagen interaction decreased cell proliferation and migration. The proliferative capacity was rescued by the addition of exogenous type IV collagen. Furthermore, the circulating levels of both type IV and type XVIII collagen were increased in pancreatic cancer patients at the time of diagnosis compared to controls. After treatment, the levels were normalized for type XVIII collagen, whereas the levels of type IV collagen remained high after surgery. High postoperative levels of type IV collagen were associated with short overall survival. A similar association to short survival was found for preoperative type XVIII collagen levels. No such associations to survival could be detected for the conventional markers.   Conclusion: The results of this thesis show that type IV and type XVIII collagens can serve as tumor markers for pancreatic cancer with advantages compared to conventionally used markers. Additionally, evidence is provided of an autocrine loop, involving type IV collagen and its integrin receptors, with importance for retaining a proliferative and migratory phenotype in pancreatic cancer cells.

Ligament/tendon tissue engineering has the potential to provide therapies that overcome the limitations of incomplete natural healing responses and inadequate graft materials. While ligament/tendon fibroblasts are an obvious choice of cell type for these applications, difficulties associated with finding a suitable cell source have limited their utility. Mesenchymal stem cells/marrow stromal cells (MSCs) are seen as a viable alternative since they can be harvested through routine medical procedures and can be differentiated toward a ligament/tendon fibroblast lineage. Further study is needed to create an optimal biomaterial/biomechanical environment for ligament/tendon fibroblastic differentiation of MSCs. The overall goal of this dissertation was to improve the understanding of the role that biomechanical stimulation and the biomaterial environment play, both independently and combined, on human MSC (hMSC) differentiation toward a ligament/tendon fibroblast phenotype. Specifically, the effects of cyclic tensile stimuli were studied in a biomaterial environment that provided controlled presentation of biological moieties. The influence of an enzymatically-degradable biomaterial environment on hMSC differentiation was investigated by creating biomaterials containing enzymatically-cleavable moieties. The role that preculture may play in tensile responses of hMSCs was also explored. Together, these studies provided insights into the contributions of the biomaterial and biomechanical environment to hMSC differentiation toward a ligament/tendon fibroblast phenotype.

Cartilage regeneration is one of the most widely studied areas in tissue-engineering. Despite significant progress, most efforts to date have only focused on generating homogenous tissues whose bulk properties are similar to articular cartilage. However, anatomically and functionally, articular cartilage consists of four spatially distinct regions: the superficial, transitional, deep, and calcified zones. Each zone is characterized by unique extra-cellular matrix (ECM) compositions, mechanical properties, and cellular organization. The ECM is primarily composed of type II collagen and glycosaminoglycans (GAGs), whose relative concentrations vary between zones and therefore lead to distinctive mechanical properties. One of the major unsolved challenges in engineering cartilage has been the inability to regenerate tissue that mimics the zonal architecture of articular cartilage. Recent studies have attempted to imitate this spatial organization using zone-specific chondrocytes isolated from donor animal cartilage. Directed differentiation of a single stem population into zonally organized native-like articular cartilage has not yet been reported. This dissertation reports that hydrogels, incorporating both synthetic and natural polymers as well as cell-induced degradability, are suitable for generating zone-specific chondrogenic phenotypes from a single MSC population. Specifically, cues provided from the unique combinations of chondroitin sulfate (CS), hyaluronic acid (HA), and MMP-sensitive peptide (MMP-pep) within a PEG-based hydrogel, direct the chondrogenic differentiation of MSCs. The findings of this dissertation demonstrate the capability of creating native-like and mechanically relevant articular cartilage consisting of zone specific layers. This ability provides a new direction in cartilage tissue engineering and could be invaluable for cartilage repair if incorporated with current minimally invasive surgical techniques. / text

Thymoquinone (TQ), a volatile oil component of black seed oil (derived from Nigella sativa), has been shown to have various biological effects including disease treatment and prevention. TQ is believed to share similar properties to the benzoquinones already in use as therapeutic drugs. Based on previous reports on the anti-inflammatory properties of black seed oil and TQ, it was originally hypothesized that TQ would inhibit lipopolysaccharide (LPS)-induced cellular sialidase activity in an anti-inflammatory manner. Sialidase activity was tested on live mouse bone marrow derived primary macrophage cells, BMC-2 macrophage cells, human embryonic kidney epithelial (HEK293) cells and human fibroblast cells using an assay that measures the cleavage of the sialidase specific fluorescent substrate 2’-(4-methylumbelliferyl)-α-DN-acetylneuraminic acid (4-MUNANA). The cleavage of 4-MUNANA causes the release of free 4-methylumbelliferone, which fluoresces at 450nm (blue) after excitation at 365nm. Unexpectedly, TQ induced sialidase activation in all three cell lines and wild type primary macrophage cells. TQ was unable to induce sialidase activity in primary macrophage cells isolated from Neu4 knockout mice suggesting that the TQ activates Neu4 sialidase enzyme. TQ-induced sialidase activity in these live cells was found to occur through intermediate GPCR-associated guanine nucleotide Gαi subunit and matrix metalloproteinase 9 (MMP9) by using specific inhibitors. In addition, TQ was found to induce sialidase activity in Toll-like receptor-deficient HEK293 cells. These latter data suggested that TQ may be activating GPCR Gαi and MMP9 signaling associated with Neu4 sialidase independent of TLRs. It is proposed that TQ-induced sialidase activity may activate Toll-like receptors in macrophage cells and the subsequent production of pro-inflammatory cytokines in the absence of LPS. Immunocytochemical staining of BMC-2 cells shows that TQ induced NFκB activation. NFκB activation was confirmed with electrophoretic mobility shift assay (EMSA) and western immunoblotting techniques. Cytokine arrays were used to test the pro-inflammatory cytokine response induced in mice by 5 hour treatment of TQ, compared to LPS. Mice treated with TQ exhibited an increase in IL-1β, IL-6 and TNF-α production, similar to LPS treatment. Taken together, the findings in these studies suggest that TQ is a novel ligand for Neu4 sialidase activation which consequently induces pro-inflammatory cytokine responses. / Thesis (Master, Microbiology & Immunology) -- Queen's University, 2009-04-21 17:38:10.413

Systemic inflammation is associated with impaired lung function. Inflammation is part of asthma and chronic obstructive pulmonary disease (COPD), but the local and systemic inflammatory pattern differs. The overall aim was to evaluate systemic inflammatory markers in obstructive lung diseases and more specifically: To determine if CRP is related to respiratory symptoms, asthma, atopy and bronchial responsiveness (paper I), in a population sample from three countries (paper I and II); to evaluate if CRP is related to COPD, lung function and rate of lung function decline (paper II); to investigate the association of serum MMP-9 and TIMP-1 with lung function in a cross-sectional population based study (paper III); and finally, to study possible gender differences in the longitudinal association between CRP and lung function in a prospective population based study (paper IV). In the first study we reported that CRP was related to non-allergic asthma but not allergic asthma, and that CRP was related to respiratory symptoms such as wheeze, nocturnal cough and breathlessness after effort, but not associated with atopy or bronchial responsiveness. In the second study we found that COPD was more common in subjects in the highest CRP quartiles and higher CRP levels were associated with lower FEV1 values in both men and women, but the negative association between CRP and FEV1 was larger in men than women. The FEV1 decline was larger in men with high CRP levels, whereas no such association was found for women. In the third study we reported that lower FEV1 was associated with higher levels of MMP-9, TIMP-1 and their ratio MMP-9/TIMP-1. After stratification for gender this association was significant in men but not women. In the fourth study we found that CRP levels were associated with change in both FEV1 and FVC in men but not women. This association was found for both baseline CRP and change in CRP, confirming a stronger association between systemic inflammation and lung function decline in men than women. In conclusion, systemic inflammation is associated with non-allergic asthma but not allergic asthma. Our findings of a stronger association between the systemic inflammation and lung function impairment in men, but not women, may indicate a gender difference in the mechanisms of lung function decline.

Thesis (Ph. D.)--University of Oklahoma. / Bibliography: leaves 164-207.

Orientador: Sergio Roberto Peres Line / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-10T16:39:26Z (GMT). No. of bitstreams: 1 EspiritoSanto_AlexandreRibeirodo_D.pdf: 9422040 bytes, checksum: 9034465ff462c933a4d9d5ab9721b610 (MD5) Previous issue date: 2008 / Resumo: O esmalte envolve a porção coronária dos dentes e constitui a estrutura mais mineralizada do corpo vertebrado. Seu desenvolvimento tem início com secreção, processamento proteolítico e auto-agregação de uma complexa mistura de proteínas. O estabelecimento de uma matriz orgânica ordenada parece ser fundamental para a formação adequada da fase mineral do esmalte. Microscopia de luz polarizada mostra que a matriz orgânica do esmalte secretório (MOES) apresenta-se fortemente birrefringente em cortes não corados de 5 µm de espessura. Esta propriedade reflete alto grau de organização em nível molecular com possível relevância funcional. Alterações no brilho de birrefringência da MOES podem indicar desordens moleculares e estar associadas a alterações na formação da fase mineral. Atraso no processo de fixação da MOES pode levar a uma rápida perda de sua birrefringência, comprometendo o seu estudo por meio de microscopia de luz polarizada. No presente trabalho, analisaram-se os efeitos do nocauteamento dos genes Amelx e Mmp20 (experimento 1), dos bisfosfonatos (experimento 2) e de inibidores de serina proteinases e metaloproteinases (experimento 3) sobre a birrefringência da MOES. O experimento 1 mostrou quecamundongos fêmeas Amelx+/- apresentam redução significativa no brilho debirrefringência quando comparados aos animais Amelx+/+ do mesmo gênero (p=0,0029). A MOES dos camundongos fêmeas Amelx-/- não exibiu birrefringência. Os camundongos Mmp20-/- mostraram uma expressiva diminuição nos valores de retardo ótico em comparação aos camundongos Mmp20+/+ e Mmp20+/- (p=0,0000). Os animais Mmp20+/+ e Mmp20+/- apresentaram birrefringência semelhante (p=1,0000). O experimento 2 mostrou que ratos tratados com alendronato de sódio não apresentam alterações morfológicas na MOES, mas exibem diminuiçãoexpressiva no brilho de birrefringência quando comparados a ratos controles (p<0,01). Interessantemente, os ratos tratados com etidronato dissódico apresentaram alterações morfológicas severas na MOES, mas mostraram brilho de birrefringência na matriz secretada semelhante ao dos ratos controles (p>0,05). O experimento 3 mostrou que a fenantrolina (inibidora de metaloproteinases, como a Mmp20) e o fenilmetilsulfonil fluoreto (inibidor de serina proteinases, como a Klk- 4) preservam a birrefringência da MOES ex vivo. Os resultados aqui apresentados sugerem que: 1) a birrefringência da MOES depende da organização supramolecular das amelogeninas e é influenciada pela atividade proteolítica da Mmp20; 2) o alendronato de sódio pode induzir alterações quantitativas na organização supramolecular da MOES; 3) o etidronato dissódico não altera a ordem molecular da matriz orgânica do esmalte secretada e pode induzir defeitos no esmalte maduro através de interferência direta sobre a atividade secretora dos ameloblastos; 4) a rápida perda de birrefringência da MOES em amostras não imediatamente fixadas é resultante da atividade de proteinases do esmalte. Palavras-chave: Esmalte dentário, Birrefringência, Bisfosfonatos, Fenantrolina, Fenilmetilsulfonil fluoreto / Abstract: Enamel covers dental crown and is the most mineralized structure in the vertebrate body. Its development begins with the secretion, processing and selfassembly of a complex mixture of proteins. The establishment of an ordered organic matrix seems to be a crucial step for the proper formation of enamel mineral phase. Polarizing microscopy shows that the secretory-stage enamel organic matrix (SEOM) is strongly birefringent in non-stained 5 µm-thick sections. This property indicates high level of molecular organization, which may be physiologically important. Changes in SEOM birefringence brightness may reflect molecular disorders and may be associated with alterations in the forming enamel mineral phase. Delay in fixation of SEOM may lead to rapid loss of birefringence, impairing analysis of that tissue with polarized light microscopy. In the present work, we analyzed the effects of Amelx and Mmp20 knocking out (experiment 1), bisphosphonates (experiment 2) and metallo and serine proteinases¿ inhibitors (experiment 3) on SEOM birefringence. Experiment 1 showed that Amelx+/- female mice exhibit a significant reduction in the birefringence brightness when compared to Amelx+/+ female animals. (p=0.0029). The SEOM from Amelx-/- female mice did not show birefringence. Mmp20-/- mice presented an expressive reduction in the optical retardation values in comparison to Mmp20+/+ and Mmp20+/- animals (p=0.0000). Mmp20+/+ and Mmp20+/- mice presented similar birefringence (p=1.0000). Experiment 2 showed that rats treated with sodium alendronate do not present morphological alterations in the SEOM, but exhibit significant decrease in the birefringence brightness when compared to control rats (p<0.01). Interestingly, bisodic etidronate rats showed severe morphological alterations in the SEOM, but exhibited SEOM birefringence brightness similar to that observed in control rats (p>0.05). Experiment 3 evidenced that 1,10-phenanthroline (metalloproteinase inhibitor) and phenylmethylsulphonyl fluoride (serine proteinase inhibitor) preserve SEOM birefringence brightness ex vivo. The results presented here support the following conclusions: 1) SEOM birefringence results from amelogenin supramolecular organization and is influenced by proteolytic activity of Mmp20; 2) sodium alendronate can induce quantitative changes in the supramolecular organization of the SEOM; 3) bisodic etidronate does not disturb molecular order of the secreted enamel organic matrix and may induce changes in mature enamel by affecting directly secretory activity of ameloblasts; 4) rapid loss of birefringence in no immediately fixed SEOM is caused by the activity of enamel proteinases. Key Words: Dental enamel, Birefringence, Bisphosphonates, Phenanthroline, Phenylmethylsulphonyl Fluoride / Doutorado / Histologia e Embriologia / Doutor em Biologia Buco-Dental

Introdução: Poucos estudos têm sido direcionados às mudanças histopatológicas nas pequenas vias áreas e seu possível papel no processo de remodelamento, nas pneumonias intersticiais idiopáticas. Objetivos: Estudar aspectos morfológicos, morfométricos e de imunohistoquímica das pequenas via aéreas na Fibrose Pulmonar Idiopática/ Pneumonia Intersticial Usual (FPI/ UIP) e Pneumonia Intersticial Não-específica (NSIP). Métodos: Foram estudadas as pequenas vias aéreas em biópsias pulmonares de 29 pacientes com FPI/ UIP e 08 com NSIP. As biópsias foram comparadas com 13 pacientes com Bronquiolite Constritiva Crônica (BC) - como controle positivo - e 10 pulmões controles normais de autópsia. Foram analisados semi e quantitativamente aspectos arquiteturais, inflamatórios, estruturais das vias aéreas, além da expressão de TGF-&#946;, MMP -2, -7, -9, e seus inibidores (TIMP-1, -2). Resultados: Comparados com os controles, pacientes com FPI/ UIP, NSIP e BC apresentaram inflamação bronquiolar, inflamação e fibrose peribronquiolar aumentadas e áreas luminais diminuídas. Pacientes com FPI/ UIP tiveram paredes das vias aéreas mais espessadas, devido ao aumento de todos os compartimentos. Pacientes com NSIP apresentaram área do epitélio aumentada, enquanto pacientes com BC tiveram maior lâmina própria. Todos os grupos estudados demonstraram expressão epitelial bronquiolar aumentada de MMP-7 e -9 comparados ao controle. Conclusão: As pequenas vias aéreas são patologicamente alteradas e podem fazer parte do processo de remodelamento nas pneumonias intersticiais idiopáticas. / Background: Few studies have addressed small airway (SA) histopathological changes, and their possible role in the remodeling process, in idiopathic interstitial pneumonias. Objectives: To study morphological, morphometrical and immunohistochemical features of SA in Idiopathic Pulmonary Fibrosis (Usual Interstitial Pneumonia - UIP) and Non-Specific Interstitial Pneumonia (NSIP). Methods: We analyzed SA pathology in lung biopsies of 29 patients with UIP and of 8 with NSIP. Biopsies were compared with lung tissue of 13 patients with Constrictive Bronchiolitis (CB) - as a positive control - and 10 normal autopsied control lungs. We analyzed, semi-quantitatively, SA structure, inflammation, architectural features and the bronchiolar epithelial immunohistochemical expression of TGF-&#946;, MMP -2, -7, -9, and their tissue inhibitors (TIMP-1, -2). Results: Compared to controls, patients with UIP, NSIP and CB presented increased bronchiolar inflammation, peribronchiolar inflammation and fibrosis and decreased luminal areas. UIP patients had thicker walls, due to an increase in most airway compartments. NSIP patients presented increased epithelial areas, whereas patients with CB had larger inner wall areas. All of the groups studied presented increased bronchiolar expression of MMP-7 and MMP-9, compared to the controls. Conclusion: We conclude that SA are pathologically altered and may take part in the lung remodeling process in idiopathic interstitial pneumonias.

A endometriose é uma doença de origem multifatorial, caracterizada por presença de tecido endometrial fora da cavidade uterina, responsável por sintomas álgicos com grande impacto na qualidade de vida da paciente, além de ser um dos principais fatores de infertilidade. Muitos estudos já foram realizados no intuito de explicar a etiopatogenia da endometriose, assim como muito tem sido estudado para encontrar novas estratégias de tratamento. Várias linhas de medicamentos têm sido estudadas com este intuito, agindo em diferentes pontos da etiopatogênese da doença, uma delas na inibição de metaloproteinases da matriz extracelular, que tem papel no remodelamento do mesotélio do peritônio e angiogênese. O objetivo deste estudo foi avaliar a influência de uma droga (doxiciclina) de baixo custo, com ação conhecida na inibição das metaloproteinases, em endometriose peritoneal induzida em ratas. Para isso, foram usadas 30 ratas adultas Wistar com lesão induzida de endometriose, divididas em três grupos, um grupo controle (C, n=10) sem tratamento, um grupo onde foi administrado doxiciclina em baixa dose (BD, n=10) e um grupo onde foi realizado doxiciclina em alta dose (AD, n=10). Foi realizada avaliação da área das lesões de cada rata e estudo imunohistoquímico para positividade de anticorpo primário de metaloproteinase de matriz 9 (MMP9) e de inibidor de metaloproteinase de matriz 2 (TIMP2). A doxiciclina atuou reduzindo a área das lesões nos grupos BD e AD (p=0,0052) em relação ao grupo C e reduzindo a expressão do TIMP2 no grupo AD (p=0,0009) em relação aos grupos BD e C. Não houve resultado significativo na expressão da MMP9. / Endometriosis is a multifactorial origin disease, characterized by the presence of endometrial tissue outside the uterine cavity, responsible for painful symptoms with important impact on the life quality of the patient, besides being one of the main factors of infertility. Many studies have already been carried out to explain the etiopathogenesis of endometriosis, and much has been studied to find new treatment strategies. Several lines of drugs have been studied for this purpose, acting at different points in the etiopathogenesis of the disease, one of them in the inhibition of extracellular matrix metalloproteinases, which plays a role in the remodeling of the peritoneum mesothelium and angiogenesis. The purpose of this study was to evaluate the influence of a low-cost drug (doxycycline), with known action on the inhibition of metalloproteinases, in induced peritoneal endometriosis in rats. Thirty adult Wistar rats with endometriosis-induced lesions were divided into three groups: one untreated control group (C, n = 10), one group receiving low dose doxycycline (BD, n = 10) and a group where high dose doxycycline (AD, n = 10) was performed. An evaluation of the lesion area of each rat and immunohistochemical study for primary antibody to matrix metalloproteinase 9 (MMP9) and matrix metalloproteinase inhibitor 2 (TIMP2) was performed. Doxycycline worked by reducing the area of lesions in the BD and AD groups (p = 0.0052) in relation to the C group and reducing the expression of TIMP2 in the AD group (p = 0.0009) in relation to the BD and C groups. There was no significant effect on MMP9 expression in the present study.

Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-10-10T10:45:14Z No. of bitstreams: 0 / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-10-16T13:33:10Z (GMT) No. of bitstreams: 0 / Made available in DSpace on 2018-10-16T13:33:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-06-29 / A Artrite Reumatóide (AR) é uma doença inflamatória crônica, caracterizada por inflamação das articulações e associada à incapacidade motora e laboral dos pacientes. Tendo em vista que as estratégias atuais para o tratamento da AR podem apresentar sérios efeitos colaterais e nem sempre resultam em melhora clínica, a terapia com laser de baixa potência (LLLT) surgiu como alternativa para o tratamento da artrite, devido às suas propriedades anti-inflamatórias e de regeneração tecidual. Entretanto, os mecanismos anti-inflamatórios da LLLT nos tecidos biológicos ainda não são completamente conhecidos. Assim, o presente estudo teve por objetivo avaliar os mecanismos imunológicos e a participação das metaloproteinases de matriz (MMP) e seu inibidor (TIMP2), na resolução do processo inflamatório articular após o tratamento com LLLT. Para isso, um processo inflamatório foi induzido nas articulações talocrural e subtalar dos membros posteriores de camundongos C57BL/6, através da administração de zymosan na região periarticular. Os animais foram divididos em 4 grupos (n = 8): (ZY) artrite induzida por zymosan e não tratado, (ZY + 3Jcm-2) artrite induzida por zymosan + LLLT em 3Jcm-2, (ZY + 30Jcm-2) artrite induzida por zymosan + LLLT em 30Jcm-2 e (ZY + DEXA) artrite induzida por zymosan e tratado com dexametasona. As condições da LLLT foram: 830nm, 10mW e densidades energéticas de 3Jcm-2 e 30Jcm-2, no modo contínuo de emissão. A irradiação foi realizada durante 4 dias consecutivos, iniciando 5 horas após a indução da inflamação. Os animais foram eutanasiados 24h após a última aplicação da LLLT e as seguintes análises foram realizadas no tornozelo: morfológica, níveis relativos de mRNA de quimiocinas, citocinas, MMPs e TIMP2 por RT-qPCR, quantificação de citocinas por ELISA e quantificação da expressão tecidual de MMP13 e TIMP2 por imunohistoquímica. No linfonodo poplíteo foi realizada análise de citometria de fluxo para identificação e quantificação das populações de leucócitos. As análises morfológicas revelaram a presença de infiltrado celular no tecido conjuntivo adjacente à região periarticular, após a administração de zymosan. Foi observada diminuição dos níveis teciduais de citocinas após LLLT e alteração nos níveis de mRNA de citocinas e quimiocinas com importância na fisiopatologia da AR, diferentemente, dependendo da densidade de energia utilizada. O grupo ZY + 3Jcm-2 demonstrou aumento na maioria das populações de leucócitos analisadas, bem como na expressão de proteínas co-estimulatórias em macrófagos e células dendríticas do linfonodo proximal à inflamação. Adicionalmente, foi observado maior população de células Treg nos grupos LLLT, e no grupo ZY + 30Jcm-2, mais células Treg CD8+ expressando níveis elevados de CD25. Embora LLLT tenha diminuído os níveis de mRNA da maioria das MMPs analisadas e aumentado de TIMP2, foi observado aumento da expressão tecidual de MMP13 e TIMP2 na região inflamatória do grupo ZY + 3Jcm-2. Tendo em vista a totalidade dos resultados, o LLLT em ambas as densidades de energia, apresentou efeitos anti-inflamatórios positivos para o tratamento da AR, uma vez que diminuiu os níveis da maioria das citocinas, quimiocinas e MMPs nos tecidos inflamados, além de modificar o quantitativo e o fenótipo dos leucócitos linfonodais, especialmente de células Treg. / Rheumatoid Arthritis (AR) is a chronic inflammatory disease, characterized by joint inflammation and associated with motor and labor incapacity. Since treatment strategies could present a serious side effects and not always achieved clinic improvement, the Low Level Laser Therapy (LLLT) have being considered as an alternative to arthritis treatment, due to its anti-inflammatory and healing abilities. However, LLLT anti-inflammatory mechanisms in biological tissues is not completely understood. Then, this study aimed to evaluate immunological mechanisms and contribution of matrix metaloproteinases (MMPs) and its inhibitor (TIMP) on inflammation resolution process induced by LLLT. Arthritis was induced in C57BL/6 mice by zymosan injection into periarticular region. Experimental animals were divided in 4 groups (n=8): (ZY) arthritis induced by zymosan and untreated; (ZY + 3Jcm-2) arthritis induced by zymosan and treated with LLLT at 3Jcm-2; (ZY + 30Jcm-2) arthritis induced by zymosan and treated with LLLT at 30Jcm-2; (ZY + DEXA) arthritis induced by zymosan and treated with dexamethasone. LLLT parameters were: 830nm, 10mW energy densities at 3 Jcm-2 e 30 Jcm-2, in continuous wave emission mode. Irradiation sections and dexamethasone treatment were carried out 4 days consecutively, starting 5 hours after arthritis induction. Animals were euthanized 24h after the last treatment section and the following analysis were procedure at ankle: morphological, cytokine mRNA relative levels, chemokines, MMPs and TIMP2 by RT-qPCR, quantification of cytokines tissue expression by ELISA and MMP13 and TIMP2 by imunohistochemistry. In popliteal lymph node, leukocytes populations were identificated and quantificated by flow cytometry. Morphological analysis showed inflammatory infiltration at adjacent connective tissue of joints, after zymosan injection. After LLLT, it was observed cytokines tissue expression decrease and mRNA levels alteration of important cytokines and chemokines in pathophisiology of AR, depending of energy density used. The ZY + 3Jcm-2 group showed an increase leukocytes populations, as well as, higher expression of costimulatory proteins in macrophages and dendritic cells of popliteal lymph node. Additionally, it was observed higher Treg population in LLLT groups than ZY group. More, ZY + 30Jcm-2 showed higher Treg CD8+ population presenting CD25high. LLLT decreased mRNA levels of almost MMPs analyzed and increased of TIMP2, except for ZY + 3Jcm-2 group in which was observed MMP13 and TIMP2 tissue expression increase. Taken togheter, all results showed that LLLT, at both energy densities used, presente positive anti-inflammatory effects for RA treatment, since it decreases the levels of cytokines, chemokines and MMPs at inflammed tissues. LLLT could also alter number and phenotype leukocytes in lymph node, especially Treg cells.