Antiinflammatory Effects

Over the course of our multiyear experience with photomodulation, we have observed the reduction of erythema from a variety of causes. Reduction of erythema may be induced from wide-ranging skin injuries, including but not limited to thermal laser treatments, UV burns, radiation therapy, and blunt trauma. In addition, anectodal experience with a series

of Gentlewaves® LED photomodulation treatments for atopic eczema or to reduce bruising and/or second degree burns has been encouraging. Treatment of atopic eczema in patients withdrawn from all topical medications has led to a rapid resolution within three to four treatments over one to two weeks (Fig. 12.3).

Use of LED photomodulation in combination with other laser modalities results in more effective clinical results, as well as faster resolution of erythema. We believe that the faster resolution of erythema from numerous causes is a result of the antiinflammatory effects of LED photomodulation. The mechanism has not yet been elucidated, although down – regulation by photomodulation of a number of inflammatory mediators from cells such as lymphocytes or macrophages is suspected. Studies on human skin fibroblasts and clinical biopsies have shown reduction in IL-1B1 and IL-6 [23].

A recent study looked at whether LED photomodulation therapy could accelerate resolu­tion of post-intense pulsed light (IPL) erythema [24]. Fifteen subjects were randomized to receive LED treatment to one side of the face immediately following a single IPL treatment for photodamage. Results showed mean erythema scores on the first visit were statistically significantly lower on the LED-treated side. This led the authors to conclude that LED photomodulation treatment accelerates the resolution of erythema and reduces posttreat­ment discomfort following IPL treatment [24]. This study confirms our observations.

A landmark study on radiation dermatitis examined whether LED photomodulation can alter and improve the outcome of intensity-modulated radiation treatments (IMRT) on

(a) (b)

overlying breast skin. Nineteen patients with breast cancer were treated with Gentlewaves® LED photomodulation immediately after every session of radiation. Treatments were for post-lumpectomy patients who received a full course of IMRT [25]. Skin reactions were monitored weekly, using National Cancer Institute (NCI) criteria for grading. Age-matched controls (n = 28) received IMRT without LED photomodulation. The results of this study showed that LED-treatment had a significantly positive effect. Of LED patients, 18 (94.7%) had Grade 0 or 1 reaction and only (5.3%) had Grade 2 reaction. Among controls, 4 (14.3%) had a Grade 1 reaction and 24 (85.7%) had a Grade 2 or Grade 3 reaction. On the non-LED treated group, 67.9% had to interrupt treatment due to side effects of skin breakdown with moist reactions, but only 5% of the LED-treated group had interrupted treatment. The authors concluded that not only did Gentlewaves® LED photomodulation treatments deliv­ered immediately after each IMRT reduce the incidence of adverse NCI criteria skin reac­tions, but also allowed the full course of treatment and resulted in a final smoother skin texture with improved skin elasticity postradiation treatment.

Additional data indicates an antiinflammatory effect for LED photomodulation follow­ing UV-induced erythema. Using a solar simulator, findings indicate a photoprotective effect when delivered after UV radiation [23]. This concept is a rescue from UV damage, even after inadvertant UV radiation has occurred. We have observed a noticeable reduction in UV erythema when LED photomodulation is supplied within hours after UV exposure. The use of 590 nm/870 nm Gentlewaves® LED photomodulation produced significant down-regulation of dermal matrix degrading enzymes which were stimulated by the UV exposure [23]. In addition, a pilot study with precise CO2 laser epidermal destruction has shown promise by using this device for accelerated wound healing.

Parallel to wound healing, the use of photomodulation has been extended to a protective or preventative effect following several types of toxic injury. Experiments using LED light to protect the retina against the toxic actions of methanol-derived formic acid in a rodent model of methanol toxicity have been successful. In a recent study, LED treatment pro­tected the retina from the histopathologic changes induced by methanol LILT on mitochon­drial oxidative metabolism in vitro, and retinal protection in vivo [26]. They also suggest that photomodulation may enhance recovery from retinal injury and other ocular diseases, in which mitochondrial dysfunction is postulated to play a role.

Our group has earlier reported on the treatment of human retinal pigment epithelial (RPE) cells in vitro using Gentlewaves® LED photomodulation produced by acute injury from blue light wavelengths [27 ] . The results showed reduction of cell death from 94% down to between 10-20% (as measured at 24 h). Another in vitro test on human RPE cells showed a 7-fold reduction in VEGF expression at 24 h post-LED exposure using LED photomodula­tion at 590 nm/870 nm delivered at 0.1 J/cm2 [27]. Incidentally, several cases of retinal degeneration have been improved by treatments with Gentlewaves® photomodulation (per­sonal communication, David Vasily, MD). Further clinical studies on wound healing, cell rescue from injury, and antiinflammatory applications are actively continuing.