Antinociceptive and anti-inflammatory effects of Aloe saponaria Haw on thermal injury in rats

ETHNOPHARMACOLOGICAL RELEVANCE

In Brazil, the plant Aloe saponaria Haw, popularly known as "babosa pintadinha", has been empirically used for its potential effect on thermal injury. Because there are no scientific data confirming its popular use, the aim of the present study was to investigate the effects of Aloe saponaria on nociceptive and inflammatory parameters in a rat model of thermal injury.

MATERIALS AND METHODS

Adult male Wistar rats were subjected to a thermal injury or sham procedure (immersion in water at 70 or 37°C, respectively, for 5 or 8s). Burned animals were topically treated with vehicle (base cream), sulfadiazine 1% (positive control) or Aloe saponaria cream (0.3%-30%) once a day for 2 or 6 days. Each day, 30min before the treatment, we measured nociceptive (static and dynamic mechanical allodynia, thermal allodynia and spontaneous pain) and inflammatory (paw edema) parameters. Moreover, enzymatic indicators of leukocyte infiltration into burned tissue were also determined 2 or 6 days after the thermal injury.

RESULTS

The thermal injury (fist and second-degree) procedure, but not the sham procedure, induced nociception and inflammation from 1 to 6 days after the injury. The topical treatment with Aloe saponaria cream (10%) reduced nociceptive behaviors from day 1 to 6 (peak at day 2), edema at days 5 and 6 (peak at day 6) and myeloperoxidase, N-acetyl-glucosaminidase and eosinoperoxidase activities at day 6. The antinociceptive and anti-inflammatory effects of Aloe saponaria were obtained with doses of 3%-30%, with maximal inhibition obtained with a dose of 10% (reductions of 39±9%, 41±9%, 31±7%, 83±7% and 23±2% for static and dynamic mechanical allodynia, thermal allodynia, spontaneous pain and paw edema, respectively).

CONCLUSION

Our results demonstrate that topically applied Aloe saponaria presented antinociceptive and anti-inflammatory effects in rats subjected to a thermal injury, which supports its traditional use for burn injuries.

Role of nocturnal rostral fluid shift in the pathogenesis of obstructive and central sleep apnoea

Obstructive sleep apnoea (OSA) is common in the general population and increases the risk of motor vehicle accidents due to hypersomnolence from sleep disruption, and risk of cardiovascular diseases owing to repetitive hypoxia, sympathetic nervous system activation, and systemic inflammation. In contrast, central sleep apnoea (CSA) is rare in the general population. Although their pathogenesis is multifactorial, the prevalence of both OSA and CSA is increased in patients with fluid retaining states, especially heart failure, where they are associated with increased mortality risk. This observation suggests that fluid retention may contribute to the pathogenesis of both OSA and CSA. According to this hypothesis, during the day fluid accumulates in the intravascular and interstitial spaces of the legs due to gravity, and upon lying down at night redistributes rostrally, again owing to gravity. Some of this fluid may accumulate in the neck, increasing tissue pressure and causing the upper airway to narrow, thereby increasing its collapsibility and predisposing to OSA. In heart failure patients, with increased rostral fluid shift, fluid may additionally accumulate in the lungs, provoking hyperventilation and hypocapnia, driving below the apnoea threshold, leading to CSA. This review article will explore mechanisms by which overnight rostral fluid shift, and its prevention, can contribute to the pathogenesis and therapy of sleep apnoea.

A possible correlation between oxytocin-induced and angiotensin IV-induced anti-hyperalgesia at the spinal level in rats

In our previous study, we showed that intrathecal (i.t.) administration of angiotensin IV (Ang IV), an insulin-regulated aminopeptidase (IRAP) inhibitor, attenuated inflammatory hyperalgesia in rats. Using the plantar test in rats with carrageenan-induced paw inflammation, we investigated the possible mechanism(s) of this effect. Because i.t. oxytocin was reported to produce a dose-dependent anti-hyperalgesia in rats with inflammation, we speculate that there is a possible correlation between oxytocin-induced and Ang IV-induced anti-hyperalgesia. Using i.t. co-administered atosiban (oxytocin receptor antagonist), the anti-hyperalgesia by Ang IV was completely abolished. This indicated that oxytocin could be the major IRAP substrate responsible for the anti-hyperalgesia by Ang IV. When Ang IV was co-administered with a low dose of oxytocin, there was a significant enhancing effect of Ang IV on oxytocin-induced anti-hyperalgesia. In recent reports, electrical stimulation on the paraventricular hypothalamic nucleus (PVN) was proved to increase oxytocin release at the spinal cord. Our results also showed that Ang IV could prolong the anti-hyperalgesia induced by PVN stimulation. This suggests a possible protective effect of Ang IV on endogenous oxytocin degradation/dysfunctioning. Moreover, we examined the local effect of intraplantarly injected Ang IV in the same model. Our results showed no effect of local Ang IV on hyperalgesia and paw edema, indicating that Ang IV may not regulate the peripheral inflammatory process. Overall, our study suggests that Ang IV may act through the inhibition of the activity of IRAP to reduce the degradation of oxytocin at the spinal cord, thereby leading to anti-hyperalgesia in rats with inflammation.

[Dependency syndrome]

The most common causes of lower limb edema include cardiac insufficiency, venous insufficiency, insufficiency of lymph flow, and side effects of drugs. It can also be due to dependency syndrome, in which the edema and skin changes can only be explained by a passive calf muscle pump and the resulting venous hypertension. Underlying the drop foot is always immobilization for one reason or other. The patient must be given an explanation about the situation, activated to move if possible, and in any case guided to the use of support stockings and postural therapy.

[Edemas in chronic lower extremity venous insufficiency: clinical manifestations, medical and surgical treatments]

The review presents data on the causes and pathogenesis of lower extremity (LE) edemas with special emphasis on the edemas occurring in chronic LE venous insufficiency. It discusses the possibilities of noninvasive and surgical treatments for LE edemas in venous insufficiency. Particular attention is given to the possibilities of phlebotonic therapy.

[Syndrome of abdominal compartment in trauma]

BACKGROUND

the intra-abdominal hypertension is defined as an increase in intra-abdominal pressure more or equal as ≥ 12 mmHg and it is called as abdominal compartment syndrome when associates with any organ dysfunction. Its development in the patient with multiple trauma is the result of the mechanism of injury, aggressive resuscitation and/or surgical treatment. The goal of this investigation is to describe the monitoring and all decisions made based on the measurement of intra-abdominal pressure in a patient with multiple injuries that developed abdominal compartment syndrome.

CLINICAL CASE

21 years old male with multiple trauma who underwent damage control surgery with splenectomy, repair of liver injury and packaging. Intra-abdominal pressure monitoring showed progressive increase that was associated with cardiopulmonary dysfunction resistant to medical treatment so we decided to unpack, which reduced the intra-abdominal pressure and improved cardiopulmonary fitness.

CONCLUSIONS

intra-abdominal hypertension / abdominal compartment syndrome significantly increases morbidity and mortality therefore the measurement of intra-abdominal pressure is a fundamental tool for early detection and timely management of this condition and its complications.

Compression stockings have a synergistic effect with walking in the late afternoon to reduce edema of the lower limbs

AIM

The aim of this study was to evaluate whether an association of elastic stockings and walking for a short period in the late afternoon reduces leg edema.

METHODS

Volume changes of the legs of sixteen patients (32 limbs), who walked on a treadmill for 30 minutes using elastic compression stockings, were analyzed in a quantitative, cross-over randomized (in order of arrival at the clinic) study. They were submitted to volumetry using the water displacement technique and subsequently required to put on 20/30 made-to-measure compression stockings (Sigvaris). The patients walked on a treadmill for 30 minutes and after removing the stockings volumetry of the legs was again performed. Legs were assessed using the CEAP classification and divided into groups. Analysis of variance was used for statistical analysis with an alpha error of 5% being considered acceptable.

RESULTS

When participants walked wearing compression stockings, there was a reduction in leg volume. When the CEAP classification was evaluated, it was noted that there was a statistically significant difference for the CEAP C0, C1 and C2 categories of legs using stockings compared to those that did not use.

CONCLUSION

Compression stockings have a synergistic effect with walking in the late afternoon thus reducing edema of the lower limbs.

Radiology case of the month. Nausea, vomiting, and diarrhea in a patient with hepatitis C and acquired immunodeficiency syndrome (AIDS). Diffuse, severe gastric-wall thickening, consistent with edema

The patient is a 42-year-old male with a past medical history of HIV/AIDS (his most recent CD4 count, four months before admission, was 19) and hepatitis C who presented to the Emergency Department complaining of one week of persistent nausea, vomiting, and diarrhea. His admit labs were as follows: hemoglobin of 11.8, hematocrit of 35, total protein of 6.0, albumin of 1.6, total bilirubin of 2.3, aspartate aminotransferase (AST) of 141, alkaline phosphatase (ALP) of 146, and alanine aminotransferase (ALT) of 31. Computed tomography (CT) images of the abdomen and pelvis with contrast were obtained (Figures 1 - 4).

Chronic edema of the lower extremities: international consensus recommendations for compression therapy clinical research trials

Chronic edema is a multifactorial condition affecting patients with various diseases. Although the pathophysiology of edema varies, compression therapy is a basic tenant of treatment, vital to reducing swelling. Clinical trials are disparate or lacking regarding specific protocols and application recommendations for compression materials and methodology to enable optimal efficacy. Compression therapy is a basic treatment modality for chronic leg edema; however, the evidence base for the optimal application, duration and intensity of compression therapy is lacking. The aim of this document was to present the proceedings of a day-long international expert consensus group meeting that examined the current state of the science for the use of compression therapy in chronic edema. An expert consensus group met in Brighton, UK, in March 2010 to examine the current state of the science for compression therapy in chronic edema of the lower extremities. Panel discussions and open space discussions examined the current literature, clinical practice patterns, common materials and emerging technologies for the management of chronic edema. This document outlines a proposed clinical research agenda focusing on compression therapy in chronic edema. Future trials comparing different compression devices, materials, pressures and parameters for application are needed to enhance the evidence base for optimal chronic oedema management. Important outcomes measures and methods of pressure and oedema quantification are outlined. Future trials are encouraged to optimize compression therapy in chronic edema of the lower extremities.

The association between skin blood flow and edema on epidermal thickness in the diabetic foot

BACKGROUND

Skin blood flow plays an important role in maintaining the health of the skin. The development of interstitial edema may impede oxygen diffusion to the skin. The aim of this study was to evaluate the association of skin blood flow and edema and epidermal thickness in the feet of people with and without diabetic neuropathy compared with a healthy control group.

SUBJECTS AND METHODS

Eighty-seven subjects (19 people with diabetic neuropathy and foot ulceration, 35 people with diabetes but without neuropathy, and 33 healthy controls without diabetes) participated in the study. High-frequency ultrasonography was used to measure the epidermal thickness and edema in papillary skin at the big toe as reflected by the thickness of the subepidermal low echogenic band (SLEB). The capillary nutritive blood flow was measured by the use of video capillaroscopy, and skin blood flux was monitored by laser Doppler flowmetry.

RESULTS

There was a 7.2% increase in epidermal thickness in those with diabetes but without neuropathy and a 16.5% decrease in people with diabetic neuropathy and foot ulceration compared with the healthy controls (all P<0.05). The SLEB thickness increased in all subjects with diabetes to a greater degree in those with neuropathy and ulceration than in those without (64.7% vs. 11.8%, P<0.001). Skin blood flux was shown to be higher in the diabetes groups than in the controls (all P<0.05), but no significant differences were found in the resting nutritive capillary blood flow (P>0.05). A significant negative correlation (P=0.002, r=-0.366) was demonstrated between the SLEB and epidermal thickness at the pulp of the big toe, whereas no significant correlation was demonstrated between skin blood flow and epidermal thickness (all P>0.05).

CONCLUSIONS

An increase in subepidermal edema was demonstrated in people with diabetic neuropathy and ulceration, which may partly contribute to reduced epidermal thickness at the pulp of the big toe. This may subsequently lead to the breaking down of skin in the diabetic foot.

[Lipedema: a misdiagnosed entity]

Lipedema is a clinical entity frequently misdiagnosed or confound with primary lymphedema. Lipedema is a disorder of adipose tissue that occurs almost exclusively in obese women. It is characterized by bilateral enlargement from hip to ankle due to abnormal depositions of subcutaneous fat associated with often mild edema, usually sparing the feet. Disease onset is usually at or soon after puberty. Lipedema results in considerable frustration and distress resulting from the cosmetic appearance. Patients may complain of pain, tenderness, easy bruising of the affected areas with moderate to severe sensitivity to digital pressure or pinching. Imaging studies using computed tomography, magnetic resonance imaging, ultrasound, lymphoscintigraphy are not indicated, except if the diagnosis is atypic or doubtful. Long-term evolution may alter lymphatic system and lead to a lipo-lymphedema with specific complications such as cellulitis. Lipedema management is not codified and included weight loss (poorly improving leg appearance or discomfort), psychological counselling and compression therapy. Liposuction, especially using tumescent local anaesthesia, may reduce edema, spontaneous pain, sensitivity to pressure, bruising and improve appearance resulting in a important increase in quality of life.

Lipedema is associated with increased aortic stiffness

Lipedema is a disproportional obesity due to unknown pathomechanism. Its major hallmark is frequent hematoma formation related to increased capillary fragility and reduced venoarterial reflex. Beyond microangiopathy, both venous and lymphatic dysfunction have also been documented. However, arterial circulation in lipedema has not been examined, and therefore we explored aortic elastic properties by echocardiography. Fourteen women with and 14 without lipedema were included in the study. Each subject consented to blood pressure measurement, physical examination, and transthoracic echocardiography. Aortic stiffness index (beta), distensibility, and strain were evaluated from aortic diameter and blood pressure data. Mean systolic (30.0 +/- 3.2 vs. 25.5 +/- 3.6, P < 0.05) and diastolic (27.8 +/- 3.3 vs. 22.3 +/- 3.1) aortic diameters (in mm) and aortic stiffness index (9.05 +/- 7.45 vs. 3.76 +/- 1.22, P < 0.05) were significantly higher, while aortic strain (0.082 +/- 0.04 vs. 0.143 +/- 0.038, P < 0.05) and distensibility (2.24 +/- 1.07 vs. 4.38 +/- 1.61, P < 0.05) were significantly lower in lipedematous patients compared to controls. Thus, lipedema is characterized with increased aortic stiffness.

Safety and efficacy of mild compression (18-25 mm Hg) therapy in patients with diabetes and lower extremity edema

BACKGROUND

Patients with diabetes often present with lower extremity (LE) edema; however, because of concomitant peripheral arterial disease, compression therapy is generally avoided by providers in fear of compromising arterial circulation. This pilot study sought to assess whether diabetic socks with mild compression (18-25 mm Hg) can reduce LE edema in patients with diabetes without negatively impacting vascularity.

METHODS

Eighteen subjects (9 males, 9 females) aged 61 ± 11 years with diabetes, LE edema, and a mean ankle-brachial index (ABI) of 1.10 ± 0.21 successfully completed this uncontrolled study. At baseline, subjects were fitted and instructed to wear the socks during all waking hours. Follow-up visits occurred weekly for four consecutive weeks. Edema was quantified through midfoot, ankle, and calf circumferences and cutaneous fluid measurements. Vascular status was tracked via ABI.

RESULTS

Repeated measures analysis of variance and least significant difference post hoc analyses were used for data analyses. Calf circumferences showed a statistically significant (p < .05) decrease of 1.3 ± 0.28 cm after just one week and remained significantly smaller than baseline throughout the study. Foot circumferences were significantly reduced at week 2 (-0.98 ± 0.35 cm) and remained significantly below baseline for the remainder of the study. The ankle also demonstrated a trend of circumference reduction but was not statistically significant. Cutaneous edema significantly reduced by week 3 (-3.1 ± 1.3 U) and remained so at week 4. Ankle-brachial index significantly increased (0.14 ± 0.049) at week 2 but was not significantly higher at weeks 3 or 4. No adverse events occurred during the study.

CONCLUSIONS

Mild compression therapy (18-25 mm Hg) decreased swelling in diabetes patients with LE edema without compromising vascularity.

Antinociceptive and anti-inflammatory effects of olive oil (Olea europeae L.) in mice

CONTEXT

Olive [Olea europaea L. (Oleaceae)] is a long-lived evergreen tree that is widespread in different parts of the world.

OBJECTIVE

Olive oil has been reported to relieve pain; however, there is still insufficient data in the literature on the subject. Thus, it is considered worthwhile investigating the antinociceptive and anti-inflammatory effects of olive oil in adult male Balb/C mice.

MATERIALS AND METHODS

The antinociceptive effects were studied using formalin, hot plate and writhing tests. The acute anti-inflammatory effects of olive oil in mice were studied using xylene ear edema test. Olive oil (1, 5 and 10 ml/kg body wt.) was injected intraperitoneally. Intact animals served as controls.

RESULTS

Our results showed that the olive oil only decreased the second phase of formalin-induced pain. In the hot plate test, olive oil did not raise the pain threshold over the 60 min duration of the test. Olive oil exhibited antinociceptive activity against writhing-induced pain by acetic acid. In the xylene ear edema test, olive oil showed significant anti-inflammatory activity in the mice.

DISCUSSION AND CONCLUSION

The present data indicated that olive oil has antinociceptive and anti-inflammatory effects in mice but further investigation of these effects is required to elucidate the mechanism(s) involved in analgesic and anti-inflammatory effects of Olea europaea oil.

Complex regional pain syndrome type-I after rubella vaccine

Complex regional pain syndrome type I (CRPS-I) is a complex disorder characterised by pain, autonomic dysfunction, and decreased range of motion. The syndrome was believed as a well-recognized disorder in adults but, less commonly recognized in children. CRPS-I after vaccination has been rarely reported. We reported an 11-year-old young girl with CRPS-I due to rubella vaccine.

[Three elderly patients in which systemic edema developed with subsequent large amounts of exudate excretion from the whole body]

AIM

Systemic edema is often observed at the terminal stages of cardiac or renal failure, with some cases showing a large amount of exudate excretion from the whole body. We investigated 3 such cases by comparison with those excreting less exudate.

METHODS

We examined the data of 3 male inpatients (age, 81, 89 and 97 years) with cardiac or renal failure who had systemic edema, with excretions of a large amount of exudate (more than 3,000 ml/day) and who subsequently died of malnutrition, oliguria or anuria. We used a control group (20 inpatients, 10 men and 10 women, mean age, 82) with excretions of less than 1,000 ml/day of exudate for comparison. Blood test values and the number of remaining days of life after the onset of oliguria/anuria were compared between the 2 groups. Moreover, the laboratory test findings of exudade and serum were compared within the subject group.

RESULTS

The subject group had a higher mean serum BUN level than the control group (138 mg/dl vs. 81 mg/dl). There were no significant differences in any other blood test values between the 2 groups. Remarkably, the number of remaining days of life after the onset of oliguria or anuria in the subject group was greater than that in the control group (mean, 14 days vs. 7 days). The laboratory data of the subject group showed that total protein, lipids, AST, ALT, γ-GTP, Ca and CRP levels were lower in the exudate than in the serum, whereas BUN, creatinine, UA, K and Cl levels showed no significant differences.

CONCLUSIONS

It is suggested that a production of large amount of exudate is caused by a complex of various factors which increase vascular permeability. However, in the present study, BUN, UA and K levels in the exudate of patients were similar to those in the serum of the subject group. The longer survival observed after oliguria or anuria in the subject group may be explained by an increased excretion of K which occurs with a large amount of exudate. Further investigation is necessary for elucidation of the etiology of large amounts of exudate.

Beta-blockers and weight change in patients with chronic heart failure

BACKGROUND

There is an inverse association between body mass and mortality in patients with chronic heart failure (CHF). Beta-blockers have been associated with weight gain. We wanted to examine the relation between beta-blocker use and weight in a population of patients with CHF.

METHODS AND RESULTS

We weighed 276 patients presenting with CHF (mean age 71.3 ± 9.5 years, 72.8% male). None were taking a beta-blocker at presentation, but all had started by 4 months' follow-up. The patients were reweighed after 1 year. There was an increase in weight (0.9 ± 7.0 kg; P = .03) and body mass index (0.2 ± 2.4 kg/m(2); P = .02). Patients in New York Heart Association (NYHA) functional class III or IV had no significant weight change, whereas those in class I or II had an increase of 1.62 kg (P < .0001). In patients who had no peripheral edema at baseline or 1 year, there was a greater increase in weight (1.3 ± 6.9 kg; P = .01).

CONCLUSIONS

Beta-blocker use and intensification of heart failure treatment is associated with weight gain in CHF. The increase is greater in those who are nonedematous and tends to occur in patients with NYHA functional class I and II symptoms.

Lymphedema treatment decreases pain intensity in lipedema

Lipedema is a disproportional obesity featuring light pressure-induced or spontaneous pain. On the basis of our clinical observations, lymphedema therapy, as practiced in our clinic, reduces the perception of pain beyond leg volume reduction. We therefore aimed to measure pain intensity prior and subsequent to treatment. 38 women with lipedema were enrolled in the study with 19 patients undergoing treatment and 19 serving as the control group using exclusively moisturizers. Treatment consisted of once daily manual lymph drainage (MLD), intermittent pneumatic compression (IPC), and multilayered short-stretch bandaging performed throughout a 5-day-course. Pain was evaluated with a 10-item questionnaire, a pain rating scale (PRS), and the Wong-Baker Faces scale. Treatment resulted in a significant reduction of pain with a decrease in mean scores of all three measures. In the control group, only PRS showed significant decrease. Our study results indicate that this treatment regimen not only reduces leg volume and capillary fragility, but also improves pain intensity in patients with lipedema.

Electromuscular stimulation with VEINOPLUS® for the treatment of chronic venous edema

AIM

Electromuscular stimulation (EMS) with VEINOPLUS® has recently emerged as a new technique to activate the calf muscle pump, improving the symptoms of venous disease. The aim of the study was to evaluate efficacy of EMS and its impact on evening edema, venous pain, venous outflow and patients quality of life.

METHODS

Thirty patients (32 legs) aged 19-50 (mean 45.2±1.3) classified CEAP C3 with chronic evening venous edema took part in the study (22 limbs: C3, S, Ep, Asp, Pr and 10 limbs: C3, S, Es, Aspd, Pr). All patients were treated with CE-registered VEINOPLUS® neuromuscular stimulator for 30 days. 3 sessions per day (each session lasted for 20 minutes) for the first 10 days, the next 10 days 2 sessions per day and one session per day for the last 10 days. The main evaluated criteria for venous edema was the circumference of the supramaleoal shin segment, measured twice with a tape measure; in the evening the day before and then 5 days after the treatment. All measurements were taken during the interval between 6 and 8 o'clock P.M. All the patients were asked to evaluate venous pain using the Visual Analog Scale, and to fill in a CIVIQ questionnaire (validated for Russian patients) for the Quality Of Life (QOL) measurement. Also venous refilling time (RT) was measured by digital PPG. That was also made twice - before the treatment and in 35 days after the treatment. No other treatments were used.

RESULTS

The EMS treatment was well tolerated by patients. There were no drop outs and patients had no need to change their lifestyles. After the treatment, total or partial reduction of evening edema was shown in 93.8% of limbs, the circumference of the lower leg diminished by 20.3mm (P<0.001), the number of painful legs reduced from 28 to 12 and the severity score of venous pain was cut from 8.3 ±1.1 to 3.8 points ±0.9 (P<0.001), QOL improved significantly as the score dropped from 34.5 ±7.8 to 17.2 points ±4.6 (P<0.001) and RT increased from 17.3 ±0.9 to 21.5 seconds ±1.1 (P<0.001). Three months after VEINOPLUS® treatment, total remission of symptoms was observed in 50% of legs, despite there being no other treatments.

CONCLUSION

VEINOPLUS® stimulation is an effective and well-tolerated therapeutic method for the treatment of chronic venous disease. The introduced scheme of EMS application was shown to be useful for treatment of chronic edema, for reducing pain and improving quality of life. It can be used as an additional mean in treatment and to prevent symptoms of CVI. This study also reveals that stimulation of calf muscles with VEINOPLUS® can improve venous outflow and symptoms of CVI. This finding should be investigated and confirmed in further studies.

Apelin attenuates UVB-induced edema and inflammation by promoting vessel function

Apelin, the ligand of the G protein-coupled receptor APJ, is involved in the regulation of cardiovascular functions, fluid homeostasis, and vessel formation. Recent reports indicate that apelin secreted from endothelial cells mediates APJ regulation of blood vessel caliber size; however, the function of apelin in lymphatic vessels is unclear. Here we report that APJ was expressed by human lymphatic endothelial cells and that apelin induced migration and cord formation of lymphatic endothelial cells dose-dependently in vitro. Furthermore, permeability assays demonstrated that apelin stabilizes lymphatic endothelial cells. In vivo, transgenic mice harboring apelin under the control of keratin 14 (K14-apelin) exhibited attenuated UVB-induced edema and a decreased number of CD11b-positive macrophages. Moreover, activation of apelin/APJ signaling inhibited UVB-induced enlargement of lymphatic and blood vessels. Finally, K14-apelin mice blocked the hyperpermeability of lymphatic vessels in inflamed skin. These results indicate that apelin plays a functional role in the stabilization of lymphatic vessels in inflamed tissues and that apelin might be a suitable target for prevention of UVB-induced inflammation.

Nav1.9 channel contributes to mechanical and heat pain hypersensitivity induced by subacute and chronic inflammation

Inflammation is known to be responsible for the sensitization of peripheral sensory neurons, leading to spontaneous pain and invalidating pain hypersensitivity. Given its role in regulating neuronal excitability, the voltage-gated Nav1.9 channel is a potential target for the treatment of pathological pain, but its implication in inflammatory pain is yet not fully described. In the present study, we examined the role of the Nav1.9 channel in acute, subacute and chronic inflammatory pain using Nav1.9-null mice and Nav1.9 knock-down rats. In mice we found that, although the Nav1.9 channel does not contribute to basal pain thresholds, it plays an important role in heat pain hypersensitivity induced by subacute paw inflammation (intraplantar carrageenan) and chronic ankle inflammation (complete Freund's adjuvant-induced monoarthritis). We showed for the first time that Nav1.9 also contributes to mechanical hypersensitivity in both models, as assessed using von Frey and dynamic weight bearing tests. Consistently, antisense-based Nav1.9 gene silencing in rats reduced carrageenan-induced heat and mechanical pain hypersensitivity. While no changes in Nav1.9 mRNA levels were detected in dorsal root ganglia (DRGs) during subacute and chronic inflammation, a significant increase in Nav1.9 immunoreactivity was observed in ipsilateral DRGs 24 hours following carrageenan injection. This was correlated with an increase in Nav1.9 immunolabeling in nerve fibers surrounding the inflamed area. No change in Nav1.9 current density could be detected in the soma of retrolabeled DRG neurons innervating inflamed tissues, suggesting that newly produced channels may be non-functional at this level and rather contribute to the observed increase in axonal transport. Our results provide evidence that Nav1.9 plays a crucial role in the generation of heat and mechanical pain hypersensitivity, both in subacute and chronic inflammatory pain models, and bring new elements for the understanding of its regulation in those models.