Low level laser therapy reduces acute lung inflammation without impairing lung function.

Acute lung injury is a condition characterized by exacerbate inflammatory reaction in distal airways and lung dysfunction. Here we investigate the treatment of acute lung injury (ALI) by low level laser therapy (LLLT), an effective therapy used for the treatment of patients with inflammatory disorders or traumatic injuries, due to its ability to reduce inflammation and promote tissue regeneration. However, studies in internal viscera remains unclear. C57BL/6 mice were treated with intratracheal lipopolysaccharide (LPS) (5 mg/kg) or phosphate buffer saline (PBS). Six hours after instillation, two groups were irradiated with laser at 660 nm and radiant exposure of 10 J/cm2 . Intratracheal LPS inoculation induced a marked increase in the number of inflammatory cells in perivascular and alveolar spaces. There was also an increase in the expression and secretion of cytokines (TNF-α, IL-1ß, IL-6,) and chemokine (MCP-1). The LLLT application induced a significant decrease in both inflammatory cells influx and inflammatory mediators secretion. These effects did not affect lung mechanical properties, since no change was observed in tissue resistance or elastance. In conclusion LLLT is able to reduce inflammatory reaction in lungs exposed to LPS without affecting the pulmonary function and recovery.

Laser therapy, used in a specific dose, modulates pulmonary inflammatory processes in an experimental model of sepsis in rats / O uso da laserterapia em dose específica modula o processo inflamatório pulmonar em um modelo experimental de sepse em ratos / El uso de la láserterapia en dosis específica modula el proceso inflamatorio pulmonar en un modelo experimental de sepsis en ratones

ABSTRACT This study aimed to determine the effectiveness of LLLT in decreasing the lung inflammatory process in septic rats. A total of 32 male Wistar rats were divided into four groups (n=8): control group (CG), sepsis 24h (S24), sepsis and LLLT with 30 J/cm² (S24L30); sepsis and LLLT with 65 J/cm² (S24L65). The irradiation was performed immediately after surgery in the anterior region of the trachea and ventral regions of the chest, bilaterally, just below the ribs. Histological analysis of lung tissue was performed and the number of inflammatory cells was quantified. The S24 group showed an increase of inflammatory cells compared to the CG (p <0.01); S24L30 increased the number of inflammatory cells, while S24L65 decreased this number compared to S24 (both p<0.05); S24L65 had a lower number of inflammatory cells compared to S24L30 (p<0.01). In conclusion, LLLT at a specific energy dose (30J / cm²) was capable of decreasing the number of inflammatory cells in acute lung tissue inflammation due to sepsis.

RESUMO O objetivo do estudo foi determinar a eficácia da LLLT na diminuição do processo inflamatório pulmonar em ratos sépticos. Foram utilizados 32 ratos machos Wistar divididos em quatro grupos (n=8): controle (CG); sepse 24h (S24); sepse e tratamento com LLLT 30 J/cm² (S24L30); sepse e tratamento com LLLT 65 J/cm² (S24L65). A irradiação foi realizada imediatamente após a cirurgia na região anterior de traqueia e nas regiões ventrais do tórax, bilateralmente, logo abaixo das costelas. Foi realizada análise histológica do tecido pulmonar e o número de células inflamatórias foi quantificado. O grupo S24 apresentou um aumento de células inflamatórias comparado ao CG (p <0,05); S24L30 aumentou o número de células inflamatórias, enquanto S24L65 diminuiu este numero em relação ao S24 (ambos p <0,05); S24L65 diminui o numero de células inflamatórias comparado ao S24L30 (p<0.01). Concluiu-se que LLLT em dose específica de energia (30J/cm²) foi capaz de diminuir o número de células inflamatórias no tecido pulmonar em fase aguda da sepse.

RESUMEN El objetivo del estudio es determinar la eficacia de la LLLT en la disminución del proceso inflamatorio pulmonar en ratones sépticos. Se utilizaron 32 ratones machos Wistar divididos en cuatro grupos (n=8): control (CG); sepsis 24h (S24); sepsis y tratamiento con LLLT 30 J/cm2 (S24L30); sepsis y tratamiento con LLLT 65 J/cm2 (S24L65). Se realizó la irradiación inmediatamente después de la cirugía en la región anterior de la tráquea y en las regiones ventrales del tórax, bilateralmente, debajo de las costillas. Se realizó un análisis histológico del tejido pulmonar y se cuantificó el número de células inflamatorias. El grupo S24 presentó un aumento de células inflamatorias en comparación al CG (p <0,05); S24L30 aumentó el número de células inflamatorias, mientras S24L65 disminuyó este número en relación al S24 (ambos p <0,05); S24L65 disminuyó el número de células inflamatorias en comparación al S24L30 (p<0,01). Se concluye que la LLLT en dosis específica de energía (30J/cm2) ha sido capaz de disminuir el número de células inflamatorias en el tejido pulmonar en fase aguda de la sepsis.

Low level laser therapy increases angiogenesis in a model of ischemic skin flap in rats mediated by VEGF, HIF-1α and MMP-2.

It is known that low level laser therapy is able to improve skin flap viability by increasing angiogenesis. However, the mechanism for new blood vessel formation is not completely understood. Here, we investigated the effects of 660 nm and 780 nm lasers at fluences of 30 and 40 J/cm(2) on three important mediators activated during angiogenesis. Sixty male Wistar rats were used and randomly divided into five groups with twelve animals each. Groups were distributed as follows: skin flap surgery non-irradiated group as a control; skin flap surgery irradiated with 660 nm laser at a fluence of 30 or 40 J/cm(2) and skin flap surgery irradiated with 780 nm laser at a fluence of 30 or 40 J/cm(2). The random skin flap was performed measuring 10×4 cm, with a plastic sheet interposed between the flap and the donor site. Laser irradiation was performed on 24 points covering the flap and surrounding skin immediately after the surgery and for 7 consecutive days thereafter. Tissues were collected, and the number of vessels, angiogenesis markers (vascular endothelial growth factor, VEGF and hypoxia inducible factor, HIF-1α) and a tissue remodeling marker (matrix metalloproteinase, MMP-2) were analyzed. LLLT increased an angiogenesis, HIF-1α and VEGF expression and decrease MMP-2 activity. These phenomena were dependent on the fluences, and wavelengths used. In this study we showed that LLLT may improve the healing of skin flaps by enhancing the amount of new vessels formed in the tissue. Both 660 nm and 780 nm lasers were able to modulate VEGF secretion, MMP-2 activity and HIF-1α expression in a dose dependent manner.

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-1ß 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.

Low-level laser therapy (808 nm) reduces inflammatory response and oxidative stress in rat tibialis anterior muscle after cryolesion.

BACKGROUND AND OBJECTIVE: 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. MATERIAL AND METHODS: Sixty Wistar rats were randomly divided into three groups (n = 20): control (BC), injured TA muscle without LLLT (IC), injured TA muscle submitted to LLLT (IRI). The injured region was irradiated daily for 4 consecutive days, starting immediately after the lesion using a AlGaAs laser (continuous wave, 808 nm, tip area of 0.00785 cm(2) , power 30 mW, application time 47 seconds, fluence 180 J/cm(2) ; 3.8 mW/cm(2) ; and total energy 1.4 J). The animals were sacrificed on the fourth day after injury. RESULTS: LLLT reduced oxidative and nitrative stress in injured muscle, decreased lipid peroxidation, nitrotyrosine formation and NO production, probably due to reduction in iNOS protein expression. Moreover, LLLT increased SOD gene expression, and decreased the inflammatory response as measured by gene expression of NF-kß and COX-2 and by TNF-α and IL-1ß concentration. CONCLUSION: These results suggest that LLLT could be an effective therapeutic approach to modulate oxidative and nitrative stress and to reduce inflammation in injured muscle.

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 1ß (IL-1ß) 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-1ß 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.

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.