Hepatitis C may enhance key amplifiers of psoriasis

BACKGROUND

Multiple studies have noted an association between hepatitis C and psoriasis, but it is not known whether psoriasis is a result of treatment modalities for hepatitis C or a result of hepatitis C alone.

OBJECTIVE

To examine the relationship between psoriasis and hepatitis C by measuring the expression of cathelicidin, TLR9 and IFNγ in psoriatic lesional and non-lesional skin in HCV-positive and negative psoriatic patients.

METHODS

Two 2 mm punch biopsies of lesional and non-lesional skin in 10 patients who were HCV-negative psoriatics and seven HCV-positive psoriatics were used to measure cathelicidin, TLR9 and IFNγ mRNA expression by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR).

RESULTS

The mRNA levels of cathelicidin, TLR9 and IFNγ were significantly higher in both non-lesional and lesional skin of HCV-positive patients with psoriasis as compared to HCV-negative psoriatic patients. Additionally, the IFNγ level in lesional skin of HCV-positive psoriatic patients was higher than the IFNγ level seen in non-lesional skin of those same patients.

CONCLUSION

These findings suggest that HCV infection upregulates these inflammatory cytokines, possibly increasing susceptibility to developing psoriasis.

Cathelicidin, kallikrein 5, and serine protease activity is inhibited during treatment of rosacea with azelaic acid 15% gel

BACKGROUND

Excess cathelicidin and kallikrein 5 (KLK5) have been hypothesized to play a role in the pathophysiology of rosacea.

OBJECTIVE

We sought to evaluate the effects of azelaic acid (AzA) on these elements of the innate immune system.

METHODS

Gene expression and protease activity were measured in laboratory models and patients with rosacea during a 16-week multicenter, prospective, open-label study of 15% AzA gel.

RESULTS

AzA directly inhibited KLK5 in cultured keratinocytes and gene expression of KLK5, Toll-like receptor-2, and cathelicidin in mouse skin. Patients with rosacea showed reduction in cathelicidin and KLK5 messenger RNA after treatment with AzA gel. Subjects without rosacea had lower serine protease activity (SPA) than patients with rosacea. Distinct subsets of patients with rosacea who had high and low baseline SPA were identified, and patients with high baseline exhibited a statistically significant reduction of SPA with 15% AzA gel treatment.

LIMITATIONS

Study size was insufficient to predict clinical efficacy based on the innate immune response to AzA.

CONCLUSIONS

These results show that cathelicidin and KLK5 decrease in association with AZA exposure. Our observations suggest a new mechanism of action for AzA and that SPA may be a useful biomarker for disease activity.

A randomized controlled double-blind investigation of the effects of vitamin D dietary supplementation in subjects with atopic dermatitis

BACKGROUND

Subjects with atopic dermatitis (AD) have defects in antimicrobial peptide (AMP) production possibly contributing to an increased risk of infections. In laboratory models, vitamin D can alter innate immunity by increasing AMP production.

OBJECTIVE

To determine if AD severity correlates with baseline vitamin D levels, and to test whether supplementation with oral vitamin D alters AMP production in AD skin.

METHODS

This was a multi-centre, placebo-controlled, double-blind study in 30 subjects with AD, 30 non-atopic subjects, and 16 subjects with psoriasis. Subjects were randomized to receive either 4000 IU of cholecalciferol or placebo for 21 days. At baseline and day 21, levels of 25-hydroxyvitamin D (25OHD), cathelicidin, HBD-3, IL-13, and Eczema Area and Severity Index (EASI) and Rajka-Langeland scores were obtained.

RESULTS

At baseline, 20% of AD subjects had serum 25OHD below 20 ng/mL. Low serum 25OHD correlated with increased Fitzpatrick Skin Type and elevated BMI, but not AD severity. After 21 days of oral cholecalciferol, mean serum 25OHD increased, but there was no significant change in skin cathelicidin, HBD-3, IL-13 or EASI scores.

CONCLUSIONS

This study illustrated that darker skin types and elevated BMI are important risk factors for vitamin D deficiency in subjects with AD, and highlighted the possibility that seasonality and locale may be potent contributors to cathelicidin induction through their effect on steady state 25OHD levels. Given the molecular links between vitamin D and immune function, further study of vitamin D supplementation in subjects with AD is warranted.

NLRP3/cryopyrin is necessary for interleukin-1beta (IL-1beta) release in response to hyaluronan, an endogenous trigger of inflammation in response to injury

Inflammation under sterile conditions is a key event in autoimmunity and following trauma. Hyaluronan, a glycosaminoglycan released from the extracellular matrix after injury, acts as an endogenous signal of trauma and can trigger chemokine release in injured tissue. Here, we investigated whether NLRP3/cryopyrin, a component of the inflammasome, participates in the inflammatory response to injury or the cytokine response to hyaluronan. Mice with a targeted deletion in cryopyrin showed a normal increase in Cxcl2 in response to sterile injuries but had decreased inflammation and release of interleukin-1beta (IL-1beta). Similarly, the addition of hyaluronan to macrophages derived from cryopyrin-deficient mice increased release of Cxcl2 but did not increase IL-1beta release. To define the mechanism of hyaluronan-mediated activation of cryopyrin, elements of the hyaluronan recognition process were studied in detail. IL-1beta release was inhibited in peritoneal macrophages derived from CD44-deficient mice, in an MH-S macrophage cell line treated with antibodies to CD44, or by inhibitors of lysosome function. The requirement for CD44 binding and hyaluronan internalization could be bypassed by intracellular administration of hyaluronan oligosaccharides (10-18-mer) in lipopolysaccharide-primed macrophages. Therefore, the action of CD44 and subsequent hyaluronan catabolism trigger the intracellular cryopyrin --> IL-1beta pathway. These findings support the hypothesis that hyaluronan works through IL-1beta and the cryopyrin system to signal sterile inflammation.