Vivian Cury

Low-Level Laser Therapy (808 nm) Reduces Inflammatory Response and Oxidative Stress in Rat Tibialis Anterior Muscle After Cryolesion

Muscle regeneration is a complex phenomenon, involving coordinated activation of several cellular responses. During this process, oxidative stress and consequent tissue damage occur with a severity that may depend on the intensity and duration of the inflammatory response. Among the therapeutic approaches to attenuate inflammation and increase tissue repair, low‐level laser therapy (LLLT) may be a safe and effective clinical procedure. The aim of this study was to evaluate the effects of LLLT on oxidative/nitrative stress and inflammatory mediators produced during a cryolesion of the tibialis anterior (TA) muscle in rats.

The effects of 660 nm and 780 nm laser irradiation on viability of random skin flap in rats.

BACKGROUND AND OBJECTIVE Some studies have shown that laser phototherapy is able to increase skin flap viability by decreasing the necrotic area and increasing neoangiogenesis. However, the mechanism by which laser acts on cells is not fully understood. The present study investigated the effects of two different laser wavelengths at 30 and 40 J/cm(2) on the viability of skin flap in rats. MATERIAL AND METHODS Sixty male animals were used in this study. They were distributed into the following groups (n = 12 each group): control group, group irradiated with 660 nm at 30 J/cm(2); group irradiated with 780 nm, at 30 J/cm(2), group irradiated with 660 nm at 40 J/cm(2); and group irradiated with 780 nm at 40 J/cm(2). The skin flap was performed on the back of all animals studied, with a plastic sheet interposed between the flap and the donor site. Laser irradiation was done immediately after the surgery and on days 1, 2, 3, and 4 post-surgery. The percentage of the necrotic area of the flap was calculated at day 7 post-surgery. RESULTS Control group showed a necrotic area of 62.83%. Interestingly, no statistically significant differences were found among the treated groups and the control group. CONCLUSION This present study showed that 660 nm and 780 nm lasers at doses of 30 and 40 J/cm(2) were not effective for decreasing the necrotic area of the skin flaps in rats.

Nitric oxide modulates metalloproteinase-2, collagen deposition and adhesion rate after polypropylene mesh implantation in the intra-abdominal wall.

Prosthetic meshes are commonly used to correct abdominal wall defects. However, the inflammatory reaction induced by these devices in the peritoneum is not completely understood. We hypothesized that nitric oxide (NO), produced by nitric oxide synthase 2 (NOS2) may modulate the response induced by mesh implants in the abdominal wall and, consequently, affect the outcome of the surgical procedure. Polypropylene meshes were implanted in the peritoneal side of the abdominal wall in wild-type and NOS2-deficient (NOS2(-/-)) mice. After 15 days tissues around the mesh implant were collected, and inflammatory markers (the cytokine interleukin 1β (IL-1β) and NO) and tissue remodeling (collagen and metalloproteinases (MMP) 2 and 9) were analyzed. The lack of NOS2-derived NO induced a higher incidence of visceral adhesions at the mesh implantation site compared with wild-type mice that underwent the same procedure (P<0.05). Additionally, higher levels of IL-1β were present in the mesh-implanted NOS2(-/-) animals compared with control and wild-type mice. Mesh implantation induced collagen I and III deposition, but in smaller amounts in NOS2(-/-) mice. MMP-9 activity after the surgical procedure was similarly increased in both groups. Conversely, MMP-2 activity was unchanged in mesh-implanted wild-type mice, but was significantly increased in NOS2(-/-) mice (P<0.01), due to decreased S-nitrosylation of the enzyme in these animals. We conclude that NOS2-derived NO is crucial for an adequate response to and integration of polypropylene mesh implants in the peritoneum. NO deficiency results in a prolonged inflammatory reaction to the mesh implant, and reduced collagen deposition may contribute to an increased incidence of visceral adhesions.

Inducible nitric oxide synthase inhibition increases MMP-2 activity leading to imbalance between extracellular matrix deposition and degradation after polypropylene mesh implant †

Prosthetic mesh implants are commonly used to correct abdominal wall defects. However, success of the procedure is conditioned by an adequate inflammatory response to the device. We hypothesized that nitric oxide produced by nitric oxide synthase 2 (NOS2) and MMP-2 and -9 participate in response induced by mesh implants in the abdominal wall and, consequently, affect the outcome of the surgical procedure. In the first step, temporal inflammatory markers profile was evaluated. Polypropylene meshes were implanted in the peritoneal side of the abdominal wall of C57Black mice. After 2, 4, 7, 15, and 30 days, tissues around the mesh implant were collected and inflammatory markers were analyzed. In the second step, NOS2 activity was inhibited with nitro-L-arginine methyl ester (L-NAME). Samples were collected after 15 days (when inflammation was reduced), and the inflammatory and tissue remodeling markers were investigated. Polypropylene mesh implant induced a pro-inflammatory environment mediated by intense MMP-2 and -9 activities, NO release, and interleukin-1β production peaking in 7 days and gradually decreasing after 15 days. NOS2 inhibition increased MMP-2 activity and resulted in a higher visceral adhesion incidence at the mesh implantation site when compared with non-treated animals that underwent the same procedure. We conclude that NOS2-derived NO is crucial for adequate response to polypropylene mesh implant integration in the peritoneum. NO deficiency results in an imbalance between extracellular matrix deposition/degradation contributing to visceral adhesions incidence.

PGC-1β regulates HER2-overexpressing breast cancer cells proliferation by metabolic and redox pathways.

Breast cancer is a prevalent neoplastic disease among women worldwide which treatments still present several side effects and resistance. Considering that cancer cells present derangements in their energetic homeostasis, and that peroxisome proliferator-activated receptor- gamma coactivator 1 (PGC-1) is crucial for cellular metabolism and redox signaling, the main objective of this study was to investigate whether there is a relationship between PGC-1 expression, the proliferation of breast cancer cells and the mechanisms involved. We initially assessed PGC-1β expression in complementary DNA (cDNA) from breast tumor of patients bearing luminal A, luminal B, and HER2-overexpressed and triple negative tumors. Our data showed that PGC-1β expression is increased in patients bearing HER2-overexpressing tumors as compared to others subtypes. Using quantitative PCR and immunoblotting, we showed that breast cancer cells with HER2-amplification (SKBR-3) have greater expression of PGC-1β as compared to a non-tumorous breast cell (MCF-10A) and higher proliferation rate. PGC-1β expression was knocked down with short interfering RNA in HER2-overexpressing cells, and cells decreased proliferation. In these PGC-1β-inhibited cells, we found increased citrate synthase activity and no marked changes in mitochondrial respiration. Glycolytic pathway was decreased, characterized by lower intracellular lactate levels. In addition, after PGC-1β knockdown, SKBR-3 cells showed increased reactive oxygen species production, no changes in antioxidant activity, and decreased expression of ERRα, a modulator of metabolism. In conclusion, we show an association of HER2-overexpression and PGC-1β. PGC-1β knockdown impairs HER2-overexpressing cells proliferation acting on ERRα signaling, metabolism, and redox balance.

Low-level laser therapy enhances muscle regeneration through modulation of inflammatory markers

Abstract Objective: The purpose of this study was to evaluate the in vivo response of two different laser fluences (4 and 8 J/cm2) on molecular markers involved in muscle repair after a cryolesion of the tibialis anterior (TA) muscle. Study design: Forty-eight male Wistar rats were randomly distributed into six groups: control (C); normal/uninjured TA muscle treated with either 4 J/cm2 (L4J) or 8 J/cm2 (L8J) laser irradiation; injured TA muscle without treatment (IC); and injured TA muscle treated with either 4 J/cm2 (IL4J) or 8 J/cm2 (IL8J) laser irradiation. The injured region was irradiated daily for 5 consecutive days, starting immediately after the cryolesion was set using a GaAlAs laser (continuous wave; wavelength, 830 nm; tip area, 0.0028 cm2; power, 20 mW). The animals were euthanized on the sixth day after injury. The injured right TA muscles were removed for histological evaluation, zymography, and immunoblotting and biotin switch analyses. Nitrite and nitrate plasma levels were measured to evaluate the nitric oxide (NO) production. Results: After low-level laser therapy (LLLT), in both injured treatment groups (IL4J and IL8J) the injured area was reduced, the NO production decreased and the S-nitrosated COX-2 was lowered. Moreover, both laser fluences increased the activity and expression of MMP-2. Conclusion: These results suggest that LLLT, for both fluences, could be an efficient therapeutic approach to modulate molecules involved in injured muscle, accelerating regeneration process.