Light-emitting diodes at 940 nm attenuate colitis-induced inflammatory process in mice

Preclinical Study of Dual-Wavelength Light-Emitting Diode Therapy in an Osteoarthritis Rat Model

OBJECTIVE

To evaluate the efficacy of light-emitting diode (LED) and their dual-wavelengths as a treatment strategy for osteoarthritis.

METHODS

We induced osteoarthritis in male Sprague-Dawley rats by intra-articular injection of sodium iodoacetate into the right rear knee joint. The animals with lesions were divided into an untreated group and an LED-treated group (n=7 each). In the LED-treated group, the lesioned knee was irradiated with lasers (850 and 940 nm) and dose (3.15 J/cm2) for 20 minutes per session, twice a week for 4 weeks. Knee joint tissues were stained and scanned using an in vivo micro-computed tomography (CT) scanner. Serum interleukin (IL)-6 and IL-18 levels were determined using enzyme-linked immuno-sorbent assay. Several functional tests (lines crossed, rotational movement, rearing, and latency to remain rotating rod) were performed 24 hours before LED treatment and at 7, 14, 21, and 28 days after treatment.

RESULTS

LED-treated rats showed improved locomotor function and suppressed matrix-degrading cytokines. Micro-CT images indicated that LED therapy had a preserving effect on cartilage and cortical bone.

CONCLUSION

LED treatment using wavelengths of 850 and 940 nm resulted in significant functional, anatomical, and histologic improvements without adverse events in a rat model. Further research is required to determine the optimal wavelength, duration, and combination method, which will maximize treatment effectiveness.

Effects of photobiomodulation in the experimental acetic acid-induced colitis: comparison between male and female

Ulcerative colitis (UC) is an important chronic and multifactorial disease, which alters the colon mucosal with a significant impact on life quality affecting both men and women. The difference between genders causes changes in the inflammatory processes, modulating the development of several diseases. The available drugs to treat UC exhibit limited outcomes and side effects; thus, new therapies are needed. Photobiomodulation (PBM) emerges as potential treatment by modulating the inflammatory process without side effects and low costs. The aim of this study was to evaluate the effects of PBM in acetic acid-induced UC comparing the responses between male and females. For this purpose, male and female Wistar rats (36) were submitted to induction of UC by rectal administration of 10% acetic acid (colitis group) and treated or not with PBM (colitis-PBM group) (LED, 660 nm, 100 mW, 150 s) in three points: right side and left of the ventral surface and in the external anal region. Non-manipulated rats were used as control (basal group). We investigated the disease activity index (DAI score), myeloperoxidase enzyme activity (MPO) and release of cytokines in the intestine homogenates, and histological analysis. PBM reduces DAI score, MPO activity, and mast cell degranulation while increased mucous production in both females and males. Moreover, PBM reduced histopathological score as well as the levels of IL-6 and IL-4 in the bowel only in males. We also showed reduced levels of IL-1beta and TNF-alpha after PBM in both males and females, while the levels of IL-10 and IFN-gamma were increased. In conclusion, despite our study has shown some differences between males and females, PBM attenuated the biomarkers of UC in both genders constituting a potential combined treatment that is non-invasive and low cost.

Antioxidant and anti-inflammatory effects of hesperidin methyl chalcone in experimental ulcerative colitis

Neutrophil infiltration, pro-inflammatory cytokines, and reactive oxygen species (ROS) production have been implicated in development and progression of ulcerative colitis (UC), an inflammatory bowel disease (IBD) characterized by ulcerating inflammation of the mucosal layer generally restricted to the colon. The side effects, safety and human intolerance are limitations of the currently approved treatments for UC. Hesperidin methyl chalcone (HMC) is a flavonoid used to treat chronic venous disease, which shows anti-inflammatory, analgesic, and antioxidant properties in pre-clinical studies, however, its effects on colitis have never been described. Therefore, we aimed to evaluate the protective effects of HMC in a mouse model of acetic acid-induced colitis. Treatment with HMC significantly reduced neutrophil infiltration, edema, colon shortening, macro and microscopic damages induced by intracolonic administration of acetic acid. The improvement of colitis after HMC treatment is related to the increase in colon antioxidant status, and the inhibition of pro-inflammatory cytokines TNF-α, IL-6, IL-1β, and IL-33 in the colon. We observed, moreover, that HMC inhibited NF-κB activation in the colon, which might explain the reduction of the cytokines we observed. Finally, these results demonstrate a novel applicability of HMC to increase antioxidant response and reduce inflammation during acetic acid-induced colitis suggesting it as a promising therapeutic approach for the treatment of ulcerative colitis.

Intraperitoneal Phototherapy Suppresses Inflammatory Reactions in a Surgical Model of Peritonitis

BACKGROUND

Standard treatment for diffuse peritonitis due to colorectal perforation may be insufficient to suppress inflammatory reaction in sepsis. Thus, developing new treatments is important. This study aimed to examine whether intraperitoneal irradiation by artificial sunlight suppresses inflammatory reaction in a lipopolysaccharide (LPS)-induced peritonitis model after surgical treatments.

MATERIALS AND METHODS

Mice were divided into naive, nontreatment (NT), and phototherapy (PT) groups. In the latter two groups, LPS was intraperitoneally administered to induce peritonitis and removed by intraperitoneal lavage after laparotomy. The PT group was irradiated with artificial sunlight intraperitoneally. We evaluated the local and systemic inflammatory reactions. Murine macrophages were irradiated with artificial sunlight after stimulation by LPS, and cell viability and expression of tumor necrotizing factor-α (TNF-α) were evaluated.

RESULTS

As a local inflammatory reaction, the whole cell count, the expression of interleukin-6 and TNF-α in the intra-abdominal fluid, and the peritoneal thickness were significantly lower in the PT group than in the NT group. As a systematic inflammatory reaction, the expression of serum TNF-α, granulocyte macrophage colony-stimulating factor, monocyte chemotactic protein-1, macrophage inflammatory protein (MIP)-1α, and MIP-1β were significantly lower in the PT group than in the NT group. Irradiation by artificial sunlight suppressed the expression of TNF-α in murine macrophages without affecting cell viability.

CONCLUSIONS

Intraperitoneal irradiation by artificial sunlight could suppress local and systemic inflammatory reactions in the LPS-induced peritonitis murine model. These effects may be associated with macrophage immune responses.

Modulation of exercise-induced muscular damage and hyperalgesia by different 630 nm doses of light-emitting diode therapy (LEDT) in rats

We compared the acute effects of different doses of 630 nm light-emitting diode therapy (LEDT) on skeletal muscle inflammation and hyperalgesia in rats submitted to exercise-induced muscle damage (EIMD). Wistar rats were divided into five experimental groups (n = 5-8/group): sedentary control (CON); exercise + passive recovery (PR); and exercise + LEDT (1.2 J/cm², 1.8 J; 4.2 J/cm², 6.3 J; 10.0 J/cm², 15 J). After 100 min of swimming, the rats in the LEDT groups were exposed to phototherapy on the triceps surae muscle. For mechanical hyperalgesia evaluation, paw withdrawal threshold was assessed before and 24 h after swimming. Immediately after hyperalgesia tests, blood samples were collected to analyze creatine kinase (CK) activity and the soleus muscle was removed for histological and tumor necrosis factor (TNF)-α immunohistological analyses. In all LEDT groups, plasma CK activity was reduced to levels similar to those measured in the CON group. Paw withdrawal threshold decreased in the PR group (- 11.9 ± 1.9 g) when compared to the CON group (2.2 ± 1.5 g; p < 0.01) and it was attenuated in the group LEDT 4.2 J/cm² (- 3.3 ± 2.4 g, p < 0.05). Less leukocyte infiltration and edema and fewer necrotic areas were found in histological sections of soleus muscle in LEDT (4.2 J/cm²) and LEDT (10.0 J/cm²) groups compared to the PR group. Also, LEDT (4.2 J/cm²) and LEDT (10.0 J/cm²) groups showed less immunostaining for TNF-α in macrophages or areas with necrosis of muscle fibers compared to the PR group. LEDT (4.2 J/cm², 6.3 J)-reduced muscle inflammation and nociception in animals submitted to EIMD.

Protective effect of carvacrol on acetic acid-induced colitis

The pharmacological therapy for inflammatory bowel diseases continues to be problematic, and requires new alternative options. In this study, we tested the hypothesis that carvacrol (CAR), a phenolic monoterpene with anti-inflammatory and antioxidant activities, can treat experimental colitis in mice. C57BL/6 mice (n=8/group) were subjected to intrarectal administration of acetic acid (5%) to induce colitis. Mice were pretreated with CAR (25, 50 or 100mg/kg, p.o.) every 12h for three days prior to the induction. Abdominal hyperalgesia, macroscopic and microscopic colon damage, myeloperoxidase (MPO) activity, tumor necrosis factor (TNF)-α and interleukin (IL)-1β levels, oxidative stress markers, and antioxidant enzyme activities were evaluated. Pretreatment with all doses of CAR significantly decreased abdominal hyperalgesia and colon MPO activity and TNF-α and IL-1β levels. A reduction in macroscopic and microscopic damage (p<0.05) was observed at doses of 50 and 100mg/kg CAR. Pretreatment with CAR significantly reduced lipid peroxidation (for all doses) and increased sulfhydryl groups (at 100mg/kg). This effect was accompanied by a significant increase in catalase, superoxide dismutase, and glutathione peroxidase activities. These findings indicate that CAR protected mice from acetic acid-induced colitis by reducing inflammatory, nociceptive, and oxidative damages.