Hepatitis C virus-associated pruritus: Etiopathogenesis and therapeutic strategies

Understanding the role of Ca2+ via transient receptor potential (TRP) channel in viral infection: Implications in developing future antiviral strategies

Transient receptor potential (TRP) channels are a superfamily of cation-specific permeable channels primarily conducting Ca2+ions across various membranes of the cell. The perturbation of the Ca2+ homeostasis is the hallmark of viral infection. Viruses hijack the host cell Ca2+ signaling, employing tailored Ca2+ requirements via TRP channels to meet their own cellular demands. This review summarizes the importance of Ca2+ across diverse viruses based on the Baltimore classification and focuses on the associated role of Ca2+-conducting TRP channels in viral pathophysiology. More emphasis has been given to the role of the TRP channel in viral life-cycle events such as viral fusion, viral entry, viral replication, virion maturation, and egress. Additionally, this review highlights the TRP channel as a store-operated channel which has been discussed vividly. The TRP channels form an essential aspect of host-virus interaction by virtue of its Ca2+ permeability. These channels are directly involved in regulating the viral calcium dynamics in host cells and thereby affect the viral infection. Considering its immense potential in regulating viral infection, the TRP channels may act as a target for antiviral therapeutics.

Pruritus: A Sensory Symptom Generated in Cutaneous Immuno-Neuronal Crosstalk

Pruritus or itch generated in the skin is one of the most widespread symptoms associated with various dermatological and systemic (immunological) conditions. Although many details about the molecular mechanisms of the development of both acute and chronic itch were uncovered in the last 2 decades, our understanding is still incomplete and the clinical management of pruritic conditions is one of the biggest challenges in daily dermatological practice. Recent research revealed molecular interactions between pruriceptive sensory neurons and surrounding cutaneous cell types including keratinocytes, as well as resident and transient cells of innate and adaptive immunity. Especially in inflammatory conditions, these cutaneous cells can produce various mediators, which can contribute to the excitation of pruriceptive sensory fibers resulting in itch sensation. There also exists significant communication in the opposite direction: sensory neurons can release mediators that maintain an inflamed, pruritic tissue-environment. In this review, we summarize the current knowledge about the sensory transduction of pruritus detailing the local intercellular interactions that generate itch. We especially emphasize the role of various pruritic mediators in the bidirectional crosstalk between cutaneous non-neuronal cells and sensory fibers. We also list various dermatoses and immunological conditions associated with itch, and discuss the potential immune-neuronal interactions promoting the development of pruritus in the particular diseases. These data may unveil putative new targets for antipruritic pharmacological interventions.

Transient Receptor Potential Vanilloid Subtype 1: Potential Role in Infection, Susceptibility, Symptoms and Treatment of COVID-19

The battle against the new coronavirus that continues to kill millions of people will be still long. Novel strategies are demanded to control infection, mitigate symptoms and treatment of COVID-19. This is even more imperative given the long sequels that the disease has on the health of the infected. The discovery that S protein includes two ankyrin binding motifs (S-ARBMs) and that the transient receptor potential vanilloid subtype 1 (TRPV-1) cation channels contain these ankyrin repeat domains (TRPs-ARDs) suggest that TRPV-1, the most studied member of the TRPV channel family, can play a role in binding SARS-CoV-2. This hypothesis is strengthened by studies showing that other respiratory viruses bind the TRPV-1 on sensory nerves and epithelial cells in the airways. Furthermore, the pathophysiology in COVID-19 patients is similar to the effects generated by TRPV-1 stimulation. Lastly, treatment with agonists that down-regulate or inactivate TRPV-1 can have a beneficial action on impaired lung functions and clearance of infection. In this review, we explore the role of the TRPV-1 channel in the infection, susceptibility, pathogenesis, and treatment of COVID-19, with the aim of looking at novel strategies to control infection and mitigate symptoms, and trying to translate this knowledge into new preventive and therapeutic interventions.

Clinical and Laboratory Characteristics of Elderly Patients with Pruritus

Introduction

For elderly, pruritus is considered the most common complaint in outpatient clinic. Pruritus occurs in association with primary skin disorders and can also be caused by many diseases and drugs. The aim of the work was to study clinical and laboratory characteristics of elderly patients with pruritus in Sohag, Egypt.

Patients and Methods

A cross-sectional study was conducted on 225 patients aged ≥60 years of both sexes complaining of pruritus and 160 age- and sex-matched patient group complaining of non-pruritic dermatological diseases. CBC, ESR, renal function tests, serology for HBV and HCV and blood glucose levels were done routinely in all patients (both groups). Skin biopsy was done in some selected cases.

Results

The mean duration of pruritus was 4.23 ± 4.9 months and was generalized in 73.8% of cases with moderate severity in 35.1% with winter exacerbation in 20%. Dermatological causes of pruritus were detected in 54.2%, followed by systemic causes in 29.8%. Eczema was the most common skin cause of senile itching in 33.7%, while renal diseases were the most common systemic cause in 46.2%.

Conclusion

Senile pruritus is a common problem in elderly. Early and proper management is mandatory to improve their quality of life.

Chronic Kidney Disease-Associated Itch (CKD-aI) in Children-A Narrative Review

Chronic kidney disease (CKD) is a condition of widespread epidemiology and serious consequences affecting all organs of the organism and associated with significant mortality. The knowledge on CKD is rapidly evolving, especially concerning adults. Recently, more data is also appearing regarding CKD in children. Chronic itch (CI) is a common symptom appearing due to various underlying dermatological and systemic conditions. CI may also appear in association with CKD and is termed chronic kidney disease-associated itch (CKD-aI). CKD-aI is relatively well-described in the literature concerning adults, yet it also affects children. Unfortunately, the data on paediatric CKD-aI is particularly scarce. This narrative review aims to describe various aspects of CKD-aI with an emphasis on children, based on the available data in this population and the data extrapolated from adults. Its pathogenesis is described in details, focusing on the growing role of uraemic toxins (UTs), as well as immune dysfunction, altered opioid transmission, infectious agents, xerosis, neuropathy and dialysis-associated aspects. Moreover, epidemiological and clinical aspects are reviewed based on the few data on CKD-aI in children, whereas treatment recommendations are proposed as well, based on the literature on CKD-aI in adults and own experience in managing CI in children.

Pathophysiology, diagnosis, and pharmacological treatment of prurigo nodularis

Introduction: Prurigo nodularis (PN) is a chronic inflammatory skin disease characterized by intensely pruritic, hyperkeratotic nodules distributed on the trunk and extensor surfaces of the extremities. PN has a profoundly negative impact on sleep and quality of life in patients with PN. There are currently no U.S. Food and Drug Administration-approved agents and patients are often recalcitrant to current therapies, highlighting the importance of further research into this severely debilitating condition. Areas covered: A PubMed search was conducted to find available literature on the pathophysiology and clinical management of PN. In this review article, we discuss the current understanding of the pathophysiology, recommended diagnostic approach, and treatment options available for PN. Expert opinion/commentary: PN is an extremely difficult condition to treat, because there is a lack of effective therapies available due to our limited understanding of its pathophysiology. Currently, available treatment options are often multimodal due to the intersection of neuroimmune etiologic factors in the pathogenesis of PN. Fortunately, as our knowledge of PN expands, novel treatments targeting specific molecular biomarkers of PN are emerging, providing hope to this long-suffering patient population.

Inhibition of transient receptor potential vanilloid 1 (TRPV1) channel regulates chikungunya virus infection in macrophages

Chikungunya virus (CHIKV), a virus that induces pathogenic inflammatory host immune responses, is re-emerging worldwide, and there are currently no established antiviral control measures. Transient receptor potential vanilloid 1 (TRPV1), a non-selective Ca²⁺-permeable ion channel, has been found to regulate various host inflammatory responses including several viral infections. Immune responses to CHIKV infection in host macrophages have been reported recently. However, the possible involvement of TRPV1 during CHIKV infection in host macrophages has not been studied. Here, we investigated the possible role of TRPV1 in CHIKV infection of the macrophage cell line RAW 264.7. It was found that CHIKV infection upregulates TRPV1 expression in macrophages. To confirm this observation, the TRPV1-specific modulators 5'-iodoresiniferatoxin (5'-IRTX, a TRPV1 antagonist) and resiniferatoxin (RTX, a TRPV1 agonist) were used. Our results indicated that TRPV1 inhibition leads to a reduction in CHIKV infection, whereas TRPV1 activation significantly enhances CHIKV infection. Using a plaque assay and a time-of-addition assay, it was observed that functional modulation of TRPV1 affects the early stages of the viral lifecycle in RAW 264.7 cells. Moreover, CHIKV infection was found to induce of pNF-κB (p65) expression and nuclear localization. However, both activation and inhibition of TRPV1 were found to enhance the expression and nuclear localization of pNF-κB (p65) and production of pro-inflammatory TNF and IL-6 during CHIKV infection. In addition, it was demonstrated by Ca²⁺ imaging that TRPV1 regulates Ca²⁺ influx during CHIKV infection. Hence, the current findings highlight a potentially important regulatory role of TRPV1 during CHIKV infection in macrophages. This study might also have broad implications in the context of other viral infections as well.

Factors associated with the severity of pruritus in patients with terminal chronic kidney disease undergoing hemodialysis in Lima, Peru

The objective of the study is to analyze the factors associated with the severity of pruritus in patients with terminal chronic kidney disease undergoing hemodialysis. The methodology used is based on a cross-sectional study in patients receiving hemodialysis at the Centro Nacional de Salud Renal. Severe pruritus was defined as a score on the visual analogue scale greater than or equal to 7, and the strength of association with the possible risk factors was assessed by calculating prevalence ratios. Regarding the results, 264 patients were included, 59.9% were male, with a mean time on hemodialysis of 10.26 ± 7.14 years. 75% experienced pruritus, of this group, 1 in 3 presented severe pruritus. Hyperphosphatemia and the use of antihistamines were associated with a higher prevalence of severe pruritus (RP 1.71, 95% CI 1.09-267 and RP 2.39, 95% CI 1.51-3.75, respectively). The positive serology for Hepatitis C Virus was described as a protective factor for presenting severe pruritus (RP 0.55, 95% CI 0.33-0.89). In conclusion, severe uremic pruritus is a frequent problem in patients with chronic terminal kidney disease who have hyperphosphatemia and treatment with antihistamines independently of the time they have been on hemodialysis.

Infectious differential diagnosis of chronic generalized pruritus without primary cutaneous lesions: a review of the literature

Pruritus is one of the most common complaints among patients referred to a dermatology clinic. "Chronic generalized pruritus" is described as the sensation of itching on the entire body surface, which lasts at least 6 or more weeks. This symptom can be a disabling phenomenon for patients and may sometimes interfere with daily activities such as sleep. If specific dermatological findings are observed, the physician easily comes to a diagnosis and treats the condition, whereas, when primary lesions are not detected, the diagnosis can become challenging, and some patients have to undergo extensive evaluations. The association between some systemic disorders and chronic generalized pruritus is widely known and confirmed. Many infections have been associated with pruritus, but few are considered to cause chronic generalized pruritus without any characteristic skin lesions. We aimed to gather all the available data on infectious causes of chronic generalized pruritus with no diagnostic cutaneous lesions to assist fellow physicians in the process of evaluation of these challenging cases.

Ethnic differences and comorbidities of 909 prurigo nodularis patients

BACKGROUND

Prurigo nodularis (PN) is a poorly understood, understudied pruritic dermatosis that reduces quality of life.

OBJECTIVE

To characterize the demographics and comorbidities associated with PN.

METHODS

Cross-sectional study of patients 18 years and older who were seen at the Johns Hopkins Health System between December 6, 2012, and December 6, 2017.

RESULTS

Over the past 5 years, 909 patients with PN were seen at Johns Hopkins Health System. African American patients were 3.4 times more likely to have PN than white patients were (odds ratio [OR], 3.4; 95% confidence interval [CI], 2.9-3.9; P < .001). A comparison of the study patients and race-matched controls revealed that PN was significantly associated with a variety of systemic, cardiovascular, and psychiatric comorbidities, including chronic kidney disease, chronic hepatitis C, chronic obstructive pulmonary disease, congestive heart failure, depression, and atopic dermatitis. Black patients with PN were 10.5 times more likely (OR, 10.5; 95% CI, 7.9-13.9; P < .001) to have HIV than were race-matched controls with atopic dermatitis, and 8 times more likely (OR, 8.0; 95% CI, 5.7-11.1; P < .001) to have HIV than were African American patients with psoriasis.

LIMITATIONS

Our data describe patients seen by 1 hospital system. Our data identify associated conditions and comorbidities but are unable to support a causal relationship.

CONCLUSION

PN disproportionately affects African Americans and is associated with several systemic conditions, including HIV, chronic kidney disease, and diabetes.

Effect of nalfurafine hydrochloride in patients with chronic liver disease with refractory pruritus on sleep disorders: a study protocol for single-arm, prospective, interventional study

Introduction

Chronic liver disease (CLD)-related pruritus manifests as cholestasis symptoms, which can cause severe itches in the whole body and significantly decrease quality of daily activities and sleep. The actigram, which documents movement by means of an accelerometer, has been demonstrated to be useful for assessing sleep quality. Nalfurafine hydrochloride, which is a selective κ-opioid receptor agonist, exerts its antipruritic efficacies through a novel mechanism. We aimed to prospectively examine the effect of nalfurafine hydrochloride on sleep quality for patients with CLD with pruritus utilising actigram.

Methods and analysis

This study will be a single-centre, prospective, interventional, single-arm study. Our study participants are subjects whose pruritus was confirmed to be uncontrollable by antihistamines or antiallergics within 6 months before informed consent (IC). Evaluation time points using actigram will be (1) before administration of testing drug; (2) after 1 week; (3) after 4 weeks (primary endpoint); and (4) every 4 weeks thereafter. The follow-up period will be 6 months. We will prospectively assess and compare changes in sleep quality in patients with CLD with pruritus undergoing nalfurafine hydrochloride therapy using actigram. Quantitative variables will be compared by paired t-test.

Ethics and dissemination

This study has received approval from the Institutional Review Board at Hyogo College of Medicine (approval no 2325). The study protocol, IC form and other documents were reviewed and approved. Final data will be publicly disseminated regardless of the results. A report releasing study results will be submitted in an appropriate journal.

Trial registration number

UMIN000028161; Pre-results.