Urticarial vasculitis in northern Spain: clinical study of 21 cases

Urticarial vasculitis (UV) is a subset of cutaneous vasculitis (CV), characterized clinically by urticarial skin lesions of more than 24 hours' duration and histologically by leukocytoclastic vasculitis. We assessed the frequency, clinical features, treatment, and outcome of a series of patients with UV. We conducted a retrospective study of patients with UV included in a large series of unselected patients with CV from a university hospital. Of 766 patients with CV, UV was diagnosed in 21 (2.7%; 9 male and 12 female patients; median age, 35 yr; range, 1-78 yr; interquartile range, 5-54 yr). Eight of the 21 cases were aged younger than 20 years old. Potential precipitating factors were upper respiratory tract infections and drugs (penicillin) (n = 4; in all cases in patients aged <20 yr), human immunodeficiency virus (HIV) infection (n = 1), and malignancy (n = 1). Besides urticarial lesions, other features such as palpable purpura (n = 7), arthralgia and/or arthritis (n = 13), abdominal pain (n = 2), nephropathy (n = 2), and peripheral neuropathy (n = 1) were observed. Hypocomplementemia (low C4) with low C1q was disclosed in 2 patients. Other abnormal laboratory findings were leukocytosis (n = 7), increased erythrocyte sedimentation rate (n = 6), anemia (n = 4), and antinuclear antibody positivity (n = 2). Treatment included corticosteroids (n = 12), antihistaminic drugs (n = 6), chloroquine (n = 4), nonsteroidal antiinflammatory drugs (n = 3), colchicine (n = 2), and azathioprine (n = 1). After a median follow-up of 10 months (interquartile range, 2-38 mo) recurrences were observed in 4 patients. Apart from 1 patient who died because of an underlying malignancy, the outcome was good with full recovery in the remaining patients. In conclusion, our results indicate that UV is rare but not exceptional. In children UV is often preceded by an upper respiratory tract infection. Urticarial lesions and joint manifestations are the most frequent clinical manifestation. Low complement serum levels are observed in a minority of cases. The prognosis is generally good, but depends on the underlying disease

Osteopenia Due to Enhanced Cathepsin K Release by BK Channel Ablation in Osteoclasts

BACKGROUND: The process of bone resorption by osteoclasts is regulated by Cathepsin K, the lysosomal collagenase responsible for the degradation of the organic bone matrix during bone remodeling. Recently, Cathepsin K was regarded as a potential target for therapeutic intervention of osteoporosis. However, mechanisms leading to osteopenia, which is much more common in young female population and often appears to be the clinical pre-stage of idiopathic osteoporosis, still remain to be elucidated, and molecular targets need to be identified. METHODOLOGY/PRINCIPAL FINDINGS: We found, that in juvenile bone the large conductance, voltage and Ca(2+)-activated (BK) K(+) channel, which links membrane depolarization and local increases in cytosolic calcium to hyperpolarizing K(+) outward currents, is exclusively expressed in osteoclasts. In juvenile BK-deficient (BK(-/-)) female mice, plasma Cathepsin K levels were elevated two-fold when compared to wild-type littermates. This increase was linked to an osteopenic phenotype with reduced bone mineral density in long bones and enhanced porosity of trabecular meshwork in BK(-/-) vertebrae as demonstrated by high-resolution flat-panel volume computed tomography and micro-CT. However, plasma levels of sRANKL, osteoprotegerin, estrogene, Ca(2+) and triiodthyronine as well as osteoclastogenesis were not altered in BK(-/-) females. CONCLUSION/SIGNIFICANCE: Our findings suggest that the BK channel controls resorptive osteoclast activity by regulating Cathepsin K release. Targeted deletion of BK channel in mice resulted in an osteoclast-autonomous osteopenia, becoming apparent in juvenile females. Thus, the BK(-/-) mouse-line represents a new model for juvenile osteopenia, and revealed the BK channel as putative new target for therapeutic controlling of osteoclast activity

A generic strategy for pharmacological caging of growth factors for tissue engineering

The caging of small molecules has revolutionized biological research by providing a means to regulate a wide range of processes. Here we report on a generic pharmacological method to cage proteins in a similar fashion. The present approach is of value in both fundamental and applied research, e.g. in tissue engineering