Daily low dose intravesical cidofovir for the treatment of BK virus associated hemorrhagic cystitis after allogeneic stem cell transplantation

IntroductionBK virus associated hemorrhagic cystitis(BKV-AHC) is a serious complication observed after allogeneic stem cell transplantation and the current therapeutic options are scarce with substantial renal side effects. Although the guidelines recommend intravenous cidofovir application with caution to nephrotoxicity, there are few studies which investigated intravesical administration and reported similar therapeutic results with less renal side effects. Methods: We administered low dose, daily and consecutive (75 mg/day, for 5 days) intravesical cidofovir to 25 patients with BKV-AHC that developed after (ASCT). Results: The response rate in our cohort was 92% and relapse was not encountered in 84% of the patient population during one year of follow-up. The median BK urine viral load significantly decreased from 260,000,000 IU/mL to 53,000,000 IU/mL after a week of treatment (p = 0.0001). Rise in serum creatinine was observed in 5 patients during treatment and post-treatment nephrotoxicity was seen in only 1 patient. Conclusions: Daily low dose intravesical cidofovir might be an effective treatment option for BKV-AHC after ASCT with favorable less systemic side effects.     

Intravesicular cidofovir for the treatment of polyomavirus-associated hemorrhagic cystitis

OBJECTIVE : To review the literature regarding the use of intravesicular cidofovir in the treatment of polyomavirus-associated hemorrhagic cystitis. DATA SOURCES : Searches of PubMed were conducted, with key search terms including intravesicular cidofovir, polyomavirus, BK virus, JC virus, and hemorrhagic cystitis. Limits were set to include human subjects. STUDY SELECTION AND DATA EXTRACTION : All articles identified were evaluated, and one was excluded due to being published only in the German language. All case studies/case series were included if patients received at least 1 dose of intravesicular cidofovir for treatment of cystitis. DATA SYNTHESIS : Polyomavirus-associated hemorrhagic cystitis is more common in immunocompromised patients, particularly those who have undergone stem cell transplantation. Early-onset cystitis is often due to chemotherapy agents, while cystitis that develops 10-14 days into therapy is often associated with infection with polyomavirus, such as BK virus. There is no standard of therapy for polyomavirus-associated cystitis other than hyperhydration and continuous bladder irrigation, and many different therapeutic agents have been used in this setting, with mixed results. One such agent, intravenous cidofovir, provides clinical improvement but carries a risk of renal failure. Intravesicular cidofovir has been reported in case reports/series to provide positive symptomatic improvement; however, it has not been universally found to decrease urine viral load. CONCLUSIONS : At this time, it appears that intravesicular cidofovir may be used as an option to provide symptomatic relief in patients with polyomavirus-associated hemorrhagic cystitis. However, it is not definitively known whether its use significantly decreases urine virus load in these patients. Larger clinical trials need to be conducted to fully understand the role of intravesicular cidofovir in this setting.     

Comparative effects of cidofovir and cyclic HPMPC on lethal cowpox and vaccinia virus respiratory infections in mice

BACKGROUND: Cidofovir is approved for the treatment of cytomegalovirus retinitis in humans. Although highly effective, the drug can cause renal toxicity in patients. There is much interest in cidofovir as a potential treatment for smallpox, monkeypox and other orthopoxvirus infections. A cyclic phosphonate form of cidofovir, 1-[((S)-2-hydroxy-2-oxo-1,4,2-dioxaphosphorinan-5-yl)methyl]cytosine (cyclic HPMPC), was reported to be less nephrotoxic than cidofovir in animals. Thus, it was deemed important to directly compare the activities of cidofovir and cyclic HPMPC against poxvirus infections in mouse models. METHODS: The compounds were evaluated by intraperitoneal and intranasal infection routes using multiple doses of each agent, with single doses of compound given 24 h after virus challenge. RESULTS: By intraperitoneal route, cidofovir protected mice from mortality at 40, 80 and 160 mg/kg, whereas cyclic HPMPC was similarly protective only at 160 mg/kg. By intranasal route, cidofovir was active down to 5 mg/kg, compared to cyclic HPMPC efficacy at 20 and 40 mg/kg. Intraperitoneal doses of 40, 80 and 160 mg/kg cidofovir significantly reduced mortality from vaccinia virus infections, compared to doses of 80 and 160 mg/kg cyclic HPMPC. Intranasal treatment with cidofovir at 5-40 mg/kg was comparably effective to cyclic HPMPC doses of 20 and 40 mg/kg in vaccinia virus infections. Active doses significantly reduced lung virus titers and lung consolidation. Overall, the potency of cyclic HPMPC was about 4 times less than that of cidofovir. CONCLUSIONS: Although cyclic HPMPC is reported to exhibit reduced nephrotoxicity in vivo, it is also less potent than cidofovir against orthopoxvirus infections. For this reason, cyclic HPMPC may not offer any advantage over cidofovir in treating these infections in humans.     

Use of cidofovir in progressive multifocal leukoencephalopathy.

BACKGROUND: Progressive multifocal leukoencephalopathy (PML) is a subacute demyelinating illness caused by the JC virus, a polyomavirus that occurs in 4-5% of HIV-positive patients. Mortality is high, and no useful therapy has been identified. Highly active antiretroviral therapy (HAART) has been reported to be effective in halting progression of the disease in some, but not all, patients. Cidofovir has been shown to be active against polyomaviruses. OBJECTIVE: To review data on the use of cidofovir to treat PML. DATA SOURCES: English-language case reports and clinical studies were located through a literature search (MEDLINE and AIDSLINE, 1995-July 2000). STUDY SELECTION AND DATA EXTRACTION: Relevant case reports and studies describing the use of cidofovir for PML were reviewed. DATA SYNTHESIS: Most case reports describing the use of cidofovir have shown that the drug is effective in the treatment of PML. Some patients were also receiving HAART concurrently; therefore, it is not clear which treatment modality had a greater impact on PML. However, cidofovir may be effective in patients whose disease has progressed despite HAART or who are-unable to tolerate these regimens. A pilot study of cidofovir for treating PML has completed enrollment, but preliminary results showed no benefit. CONCLUSIONS: Cidofovir may be the most reasonable treatment option for PML in HIV-infected individuals who fail to improve with HAART or who are unable to tolerate these regimens. Patients who receive cidofovir should be monitored for renal and ocular toxicity.     

Alpha interferon augments cidofovir's antiviral and antiproliferative activities

The antiviral and antiproliferative activities of alpha 2a interferon (IFN-alpha 2a) and cidofovir in human papillomavirus type 16 (HPV-16)-transformed keratinocytes were evaluated. The compounds in combination were more effective than comparable levels of either drug alone. Evaluation of effective drug ratios revealed a synergistic cooperation between IFN-alpha 2a and cidofovir in inhibiting the proliferation of HPV-infected cells.     

Antivirals for the treatment of polyomavirus BK replication

Antiviral drugs with specific activity against polyomavirus replication have not been developed in the past. This deficiency has become fully apparent with the emergence of polyomavirus-associated nephropathy in kidney-transplant recipients, with a prevalence rate of up to 10%. In most cases, high BK virus replication in tubular epithelial cells causes significant cytopathology, leading to permanently impaired renal allograft function and return to hemodialysis within 6-60 months. In 5-10% of allogenic bone marrow/hematopoietic stem cell transplant recipients, high-level BK virus replication in the ureter/bladder mucosa has been associated with postengraftment hemorrhagic cystitis, which appears to involve significant immunopathology. Thus, in view of the increasing clinical need, a number of drugs have been studied in small case series. We review the antiviral strategies explored to date and specifically discuss available in vivo and in vitro data on cidofovir, leflunomide, fluoroquinolones and intravenous immunoglobulins, regarding mechanism, administration, dosing and outcome and provide a perspective on future therapy options.     

Aerosolized cidofovir is retained in the respiratory tract and protects mice against intranasal cowpox virus challenge

We employed a murine model to test the concept of using an aerosolized, long-acting antiviral drug to protect humans against smallpox. We previously showed that a low dose of aerosolized cidofovir (HPMPC [Vistide]) was highly protective against subsequent aerosolized cowpox virus challenge and was more effective than a much larger dose of drug given by injection, suggesting that aerosolized cidofovir is retained in the lung. Because the nephrotoxicity of cidofovir is a major concern in therapy, delivering the drug directly to the respiratory tract might be an effective prophylactic strategy that maximizes the tissue concentration at the site of initial viral replication, while minimizing its accumulation in the kidneys. In the present study, we found that treating mice with aerosolized (14)C-labeled cidofovir ((14)C-cidofovir) resulted in the prolonged retention of radiolabeled drug in the lungs at levels greatly exceeding those in the kidneys. In contrast, subcutaneous injection produced much higher concentrations of (14)C-cidofovir in the kidneys than in the lungs over the 96-h time course of the study. As further evidence of the protective efficacy of aerosolized cidofovir, we found that aerosol treatment before or after infection was highly protective in mice challenged intranasally with cowpox virus. All or nearly all mice that were treated once by aerosol, from 2 days before to 2 days after challenge, survived intranasal infection, whereas all placebo-treated animals died.     

In Vitro Efficacy of Brincidofovir against Variola Virus

Brincidofovir (CMX001), a lipid conjugate of the acyclic nucleotide phosphonate cidofovir, is under development for smallpox treatment using “the Animal Rule,” established by the FDA in 2002. Brincidofovir reduces mortality caused by orthopoxvirus infection in animal models. Compared to cidofovir, brincidofovir has increased potency, is administered orally, and shows no evidence of nephrotoxicity. Here we report that the brincidofovir half-maximal effective concentration (EC₅₀) against five variola virus strains in vitro averaged 0.11 μM and that brincidofovir was therefore nearly 100-fold more potent than cidofovir.     

Pharmacodynamics of cidofovir for vaccinia virus infection in an in vitro hollow-fiber infection model system

Variola major virus remains a potent weapon of bioterror. There is currently an investigational-new-drug application for cidofovir for the therapy of variola major virus infections. Stittelaar and colleagues compared the levels of effectiveness of postexposure smallpox vaccination (Elstree-RIVM) and antiviral treatment with cidofovir or an acyclic nucleoside phosphonate analogue {6-[2-(phosphonomethoxy)alkoxy]-2,4-diaminopyrimidine (HPMPO-DAPy)} after lethal intratracheal infection of cynomolgus monkeys with monkeypox virus, a variola virus surrogate. Their results demonstrated that either compound was more effective than vaccination with the Ellstree vaccine (K. J. Stittelaar et al., Nature 439:745-748, 2006). An unanswered question is how to translate this information into therapy for poxvirus infections in people. In a proof-of-principle study, we used a novel in vitro hollow-fiber infection model system to determine the pharmacodynamics of vaccinia virus infection of HeLa-S3 cells treated with cidofovir. Our results demonstrate that the currently licensed dose of cidofovir of 5 mg/kg of body weight weekly with probenecid (which ameliorates nephrotoxicity) is unlikely to provide protection for patients intentionally exposed to Variola major virus. We further demonstrate that the antiviral effect is independent of the schedule of drug administration. Exposures (area under the concentration-time curve) to cidofovir that will have a robust protective effect will require doses that are 5 to 10 times that currently administered to humans. Such doses may cause nephrotoxicity, and therefore, approaches that include probenecid administration as well as schedules of administration that will help ameliorate the uptake of cidofovir into renal tubular epithelial cells need to be considered when addressing such treatment for people.     

Development of CMX001 (Brincidofovir) for the treatment of serious diseases or conditions caused by dsDNA viruses

CMX001 (hexadecyloxypropyl-cidofovir, Brincidofovir) is a broad spectrum, lipid conjugate of cidofovir that is converted intracellularly into the active antiviral, cidofovir diphosphate. The lipid conjugation results in oral bioavailability, higher intracellular concentrations of active drug, lower plasma concentrations of cidofovir and increased antiviral potency against dsDNA viruses.     

Update on treatment of CMV retinitis

Recent developments in the treatment of CMV retinitis are highlighted, including new methods of administering ganciclovir, and use of a new parenteral agent, cidofovir (also called HPMPC). An intraocular ganciclovir sustained-release device has been developed and tested in two different trials. This implant releases 6 mg of ganciclovir over 33 to 39 weeks. In a study randomizing eyes of thirty patients with CMV retinitis, time to disease progression was 226 days for the immediate treatment group compared to 15 days in the deferred group; adverse effects are summarized. In a second study, comparing intraocular to intravenous ganciclovir in CMV retinitis patients, implant patients had a significantly longer time to retinitis progression. Significant risks to vision were noted, however, in the implant group. In another immediate vs. deferred retinitis trial, immediate intravenous cidofovir was shown to be effective, with a six-fold increase in time to progression over those who first received therapy after evidence of first progression. The primary adverse effect of intravenous cidofovir was nephrotoxicity, which was ameliorated by hydration and probenecid. Intravitreal cidofovir was studied, also resulting in delayed progression of retinitis. Finally, the use of oral ganciclovir to prevent CMV end-organ disease resulted in a decrease of CMV infections by about fifty percent, but much controversy remains due to the involvement of multiple individual factors.     

Tubular cell apoptosis and cidofovir-induced acute renal failure

Cidofovir is an antiviral drug with activity against a wide array of DNA viruses including poxvirus. The therapeutic use of cidofovir is marred by a dose-limiting side effect, nephrotoxicity, leading to proximal tubular cell injury and acute renal failure. Treatment with cidofovir requires the routine use of prophylactic measures. A correct knowledge of the cellular and molecular mechanisms of cidofovir toxicity may lead to the development of alternative prophylactic strategies. We recently cared for a patient with irreversible acute renal failure due to cidofovir. Renal biopsy showed tubular cell apoptosis. Cidofovir induced apoptosis in primary cultures of human proximal tubular cells in a temporal (peak apoptosis at 7 days) and concentration (10-40 microg/ml) pattern consistent with that of clinical toxicity. Apoptosis was identified by the presence of hypodiploid cells, by the exposure of annexin V binding sites and by morphological features and was associated with the appearance of active caspase-3 fragments. Cell death was specific as it was also present in a human proximal tubular epithelial cell line (HK-2), but not in a human kidney fibroblast cell line, and was prevented by probenecid. An inhibitor of caspase-3 (DEVD) prevented cidofovir apoptosis. The survival factors present in serum, insulin-like growth factor-1 and hepatocyte growth factor, were also protective. The present data suggest that apoptosis induction is a mechanism contributing to cidofovir nephrotoxicity. The prophylactic administration of factors with survival activity for tubular epithelium should be further explored in cidofovir renal injury.     

Anti-BK virus activity of nucleoside analogs

Polyomavirus BK is an important pathogen in transplant recipients with no effective therapy. This study demonstrates that alkoxyalkyl esters of (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine and fatty acid derivatives of 9-[2-(phosphonomethyoxy)ethyl]adenine (P393 and P405) are potent and selective inhibitors of BK virus replication in vitro, with a 50% effective concentration in the micromolar-to-nanomolar range.     

Iritis associated with intravenous cidofovir

OBJECTIVE: To report two patients with AIDS and cytomegalovirus retinitis who developed iritis after receiving intravenous cidofovir. Both experienced recurrent symptoms upon rechallenge. CASE SUMMARIES: Two HIV-positive patients with cytomegalovirus retinitis infections previously controlled with intravenous ganciclovir or foscarnet were treated with intravenous cidofovir. Symptoms of iritis developed after the second or third dose of cidofovir. One patient experienced symptoms unilaterally, while the other patient had bilateral symptoms. In both patients, the iritis resolved with topical ophthalmic therapy, but recurred following subsequent infusions of cidofovir. Therapy with cidofovir was discontinued, and no further recurrences of iritis were noted. One patient had post-inflammatory fixed dilated pupils. CONCLUSIONS: Iritis can uncommonly occur in patients receiving intravenous cidofovir and oral probenecid. With prompt drug discontinuation and administration of topical corticosteroids and/or mydriatic agents, symptoms are usually reversible.     

Clinical pharmacokinetics of cidofovir in human immunodeficiency virus-infected patients.

The pharmacokinetics of cidofovir (HPMPC; (S)-1-[3-hydroxy-2-(phosphonylmethoxy)propyl]cytosine) were examined at five dose levels in three phase I/II studies in a total of 42 human immunodeficiency virus-infected patients (with or without asymptomatic cytomegalovirus infection). Levels of cidofovir in serum following intravenous infusion were dose proportional over the dose range of 1.0 to 10.0 mg/kg of body weight and declined biexponentially with an overall mean +/- standard deviation terminal half-life of 2.6 +/- 1.2 h (n = 25). Approximately 90% of the intravenous dose was recovered unchanged in the urine in 24 h. The overall mean +/- standard deviation total clearance of the drug from serum (148 +/- 25 ml/h/kg; n = 25) approximated renal clearance (129 +/- 42 ml/h/kg; n = 25), which was significantly higher (P < 0.001) than the baseline creatinine clearance in the same patients (83 +/- 21 ml/h/kg; n = 12). These data indicate that active tubular secretion played a significant role in the clearance of cidofovir. The steady-state volume of distribution of cidofovir was approximately 500 ml/kg, suggesting that the drug was distributed in total body water. Repeated dosing with cidofovir at 3.0 and 10.0 mg/kg/week did not alter the pharmacokinetics of the drug. Concomitant administration of intravenous cidofovir and oral probenecid to hydrated patients had no significant effect on the pharmacokinetics of cidofovir at a 3.0-mg/kg dose. At higher cidofovir doses, probenecid appeared to block tubular secretion of cidofovir and reduce its renal clearance to a level approaching glomerular filtration.     

Antiviral prophylaxis of smallpox

Proof-of-concept studies suggest that current defences against smallpox could be strengthened by supplementing vaccination with antiviral drug prophylaxis, based on aerosolized or orally available forms of the long-acting medication cidofovir. Delivery of aerosolized cidofovir to mice results in its prolonged retention in respiratory tissues and protection against lethal intranasal or aerosol poxviral challenge. Although cidofovir itself is not orally available, the addition of an alkoxyalkanol ether side-chain allows it to be absorbed from the gastrointestinal tract. This also markedly increases its antiviral activity and lengthens its intracellular half-life from roughly 3 to 8-10 days. Oral treatment also protected mice against lethal poxviral challenge. These results suggest that a single aerosol dose of cidofovir (or an alkoxyalkanol-ether derivative) could provide prolonged protection against initiation of smallpox infection, whereas oral treatment could prevent both initiation of infection and internal dissemination of virus. Both approaches may avoid the nephrotoxicity that occasionally results from intravenous cidofovir therapy.     

肾移植术后BK病毒相关性肾病的研究现状

学术背景：肾移植术后并发并发BK病毒感染可以影响移植受者的预后．国外已经对该疾病有了较多的研究。 目的：总结肾移植术后BK病毒相关性肾病的诊断和治疗现状。检索策略：由该论文的研究人员应用计算机检索2000-01/2007-01 Pubmed数据库与肾移植术后BK病毒相关性肾病相关文献．检索词“Renal transplantation：BK virus”，限定文章语言种类为English。共检索到206篇文献，对资料进行初审，纳入标准：与肾移植术后患者并发BK病毒感染有关的文献。排除标准：重复性研究。 文献评价：文献的来源主要是Pubmed数据库，文献类型主要是论著及综述。 资料综合：30％-40％的成人肾移植患者尿中可以发现BK病毒。尽管在肾移植患者中BK病毒有较高的再激活率．但最终仅有较少的一部分患者发展到BK病毒相关性肾病的组织学表现。BK病毒相关性肾病的预后较差，30％-50％的患者最终发展为肾功能衰竭，移植物丢失。由BK病毒引起的移植肾疾病必需依据组织学诊断，由BK病毒引起的移植肾疾病必需依据组织学诊断，除了确定患者感染病毒外，血清学捡验作用不大。评估移植肾活检应该包括电镜检查，特别是肾功能衰竭原因不明确时，电镜能发现细胞核内、胞质内和细胞外的病毒颗粒。BK病毒尿症也能通过对尿样本的核酸杂交法、免疫荧光或ELISA检测病毒抗原。西多福韦是目前较有效的药物，主要缺点是其潜在的肾毒性，其合适的剂量、药代动力学、安全性和耐受性、抗BK病毒活性等这些问题都未得到正式评价，仍需进一步研究。 结论：BK病毒相关性肾病的预后较差，诊断需依据组织学检查。目前BK病毒相关性肾病的治疗主要包括对症支持治疗。减少免疫抑制剂用量。     

A Multicenter Phase I/II Dose Escalation Study of Single-Dose Cidofovir Gel for Treatment of Recurrent Genital Herpes

A randomized, double-blind, clinic-initiated, sequential dose-escalation pilot study was performed to compare the safety and efficacy of single applications of 1, 3, and 5% cidofovir gel with placebo in the treatment of early, lesional, recurrent genital herpes at five Canadian outpatient sites. Ninety-six patients began treatment within 12 h of lesion appearance and were evaluated twice daily until healing of the lesion occurred. Cidofovir gel at all strengths significantly decreased the median time to negative virus culture in a dose-dependent fashion (3.0 days in the placebo group versus 2.2, 1.3, and 1.1 days in the 1, 3, and 5% cidofovir gel treatment groups, respectively; P = 0.02, 0.0001, and 0.0003, respectively). A trend toward a reduction in the median time to complete healing in association with treatment was present, but the differences were not statistically significant (5.0 days in the placebo group versus 4.3, 4.1, and 4.6 days in the 1, 3, and 5% cidofovir gel treatment groups, respectively). Application site reactions occurred in 3, 5, 19, and 22% of the patients in these four groups, respectively. Treatment-associated lesion recrudescence with delayed healing, which is suggestive of local toxicity, was observed in three patients treated with 5% cidofovir gel and one patient treated with 3% cidofovir gel. In summary, single-dose application of cidofovir gel confers a significant antiviral effect on lesions of recurrent genital herpes. Additional studies are warranted to further identify the optimal efficacious dose of cidofovir in association with the maximum gel strength that can be tolerated.     

Carbon monoxide-mediated activation of large-conductance calcium-activated potassium channels contributes to mesenteric vasodilatation in cirrhotic rats

Large-conductance calcium-activated potassium channels (BK(Ca)s) are important regulators of arterial tone and represent a mediator of the endogenous vasodilator carbon monoxide (CO). Because an up-regulation of the heme oxygenase (HO)/CO system has been associated with mesenteric vasodilatation of cirrhosis, we analyzed the interactions of BK(Ca) and of HO/CO in the endothelium-dependent dilatation of mesenteric arteries in ascitic cirrhotic rats. In pressurized mesenteric arteries (diameter, 170-350 microm) of ascitic cirrhotic rats, we evaluated the effect of inhibition of BK(Ca), HO, and guanylyl-cyclase on dilatation induced by acetylcholine and by exogenous CO; and HO-1 and BK(Ca) subunit protein expression. Inhibition of HO and of BK(Ca) reduced acetylcholine-induced vasodilatation more in cirrhotic rats than in control rats, whereas inhibition of guanylyl-cyclase had a similar effect in the two groups. CO was more effective in cirrhotic rats than in control rats, and the effect was hindered by BK(Ca) inhibition. The expression of HO-1 and of BK(Ca) alpha-subunit was higher in mesenteric arteries of cirrhotic rats compared with that of control animals, whereas the expression of the BK(Ca) beta1-subunit was lower. In conclusion, an overexpression of BK(Ca) alpha-subunits, possibly due to HO up-regulation with increased CO production, participates in the endothelium-dependent alterations and mesenteric arterial vasodilatation of ascitic cirrhotic rats.     

Characterisation and mechanisms of bradykinin-evoked pain in man using iontophoresis

Bradykinin (BK) is an inflammatory mediator that can evoke oedema and vasodilatation, and is a potent algogen signalling via the B1 and B2 G-protein coupled receptors. In naïve skin, BK is effective via constitutively expressed B2 receptors (B2R), while B1 receptors (B1R) are purported to be upregulated by inflammation. The aim of this investigation was to optimise BK delivery to investigate the algesic effects of BK and how these are modulated by inflammation. BK iontophoresis evoked dose- and temperature-dependent pain and neurogenic erythema, as well as thermal and mechanical hyperalgesia (P < 0.001 vs saline control). To differentiate the direct effects of BK from indirect effects mediated by histamine released from mast cells (MCs), skin was pretreated with compound 4880 to degranulate the MCs prior to BK challenge. The early phase of BK-evoked pain was reduced in degranulated skin (P < 0.001), while thermal and mechanical sensitisation, wheal, and flare were still evident. In contrast to BK, the B1R selective agonist des-Arg9-BK failed to induce pain or sensitise naïve skin. However, following skin inflammation induced by ultraviolet B irradiation, this compound produced a robust pain response. We have optimised a versatile experimental model by which BK and its analogues can be administered to human skin. We have found that there is an early phase of BK-induced pain which partly depends on the release of inflammatory mediators by MCs; however, subsequent hyperalgesia is not dependent on MC degranulation. In naïve skin, B2R signaling predominates, however, cutaneous inflammation results in enhanced B1R responses.