The interaction between the immune system and the peripheral sensory nerves in pruritus

How to train your myeloid cells: a way forward for helminth vaccines?

Soil-transmitted helminths affect approximately 1.5 billion people worldwide. However, as no vaccine is currently available for humans, the current strategy for elimination as a public health problem relies on preventive chemotherapy. Despite more than 20 years of intense research effort, the development of human helminth vaccines (HHVs) has not yet come to fruition. Current vaccine development focuses on peptide antigens that trigger strong humoral immunity, with the goal of generating neutralizing antibodies against key parasite molecules. Notably, this approach aims to reduce the pathology of infection, not worm burden, with only partial protection observed in laboratory models. In addition to the typical translational hurdles that vaccines struggle to overcome, HHVs face several challenges (1): helminth infections have been associated with poor vaccine responses in endemic countries, probably due to the strong immunomodulation caused by these parasites, and (2) the target population displays pre-existing type 2 immune responses to helminth products, increasing the likelihood of adverse events such as allergy or anaphylaxis. We argue that such traditional vaccines are unlikely to be successful on their own and that, based on laboratory models, mucosal and cellular-based vaccines could be a way to move forward in the fight against helminth infection. Here, we review the evidence for the role of innate immune cells, specifically the myeloid compartment, in controlling helminth infections. We explore how the parasite may reprogram myeloid cells to avoid killing, notably using excretory/secretory (ES) proteins and extracellular vesicles (EVs). Finally, learning from the field of tuberculosis, we will discuss how anti-helminth innate memory could be harnessed in a mucosal-trained immunity-based vaccine.

The association between pruritic dermatoses and inflammatory factors on sleep disorders: a cross-sectional study of the National Health and Nutrition Examination Survey (NHANES)

Pruritic dermatoses and sleep disorders have significant impacts on the health and quality of life of patients. Inflammatory conditions may lead to the sensation of itching. This study was to evaluate the association between pruritic dermatoses and inflammatory factors on sleep disorders. Data in the cross-sectional study were extracted from the National Health and Nutrition Examination Survey. The study population was divided into participants with and without sleep disorders. Pruritic dermatoses were assessed by the participant's self-report. Inflammatory factors included white blood cell count (WBC), lymphocyte count (LYM) and prognostic nutritional index (PNI). Logistic regression models were used with odds ratios and confidence intervals. The attributable proportion of interaction (AP) was utilized to assess the interaction between pruritic dermatoses and inflammatory factors on sleep disorders. Totally, 3,520 participants were included and 214 (6.08%) had sleep disorders. Pruritic dermatoses were associated with sleep disorders after adjusting for gender, age, race, marital status, body mass index, drinking, smoking, asthma, hay fever, allergy, depression and caffeine. LYM was associated with sleep disorders when inflammatory factors were divided by median. The interaction between participants without pruritic dermatoses and PNI < median on sleep disorders was observed compared to participants without pruritic dermatoses and PNI > median. Pruritic dermatoses were significantly associated with sleep disorders. We also found that a high level of PNI had an enhanced effect on the relationship between pruritic dermatoses and sleep disorders. Clinicians should focus on the potential sleep-related risks and changes in inflammatory factors in patients with pruritic dermatoses and intervene in time.

Nerve growth factor mediates activation of transient receptor potential vanilloid 1 in neurogenic pruritus of psoriasis

Pruritus is a common and painful symptom in psoriasis with profoundly negative impacts on quality of life. The underlying mechanisms of pruritus are complex and multifactorial, and accumulating evidence suggests that pruritus induced by neurogenic inflammation predominates in psoriasis. Nerve growth factor (NGF) -mediated transient receptor potential vanilloid receptor 1(TRPV1) pathway has emerged as a crucial node in the regulation of neurogenic pruritus. TRPV1 appears coupled to most pruritus-specific molecules via the neuro-immune axis. While the modes of regulation differ for each axis, TRPV1 is involved in substantial biochemical crosstalk-causing feedback loops with significant effects on neurogenic pruritus. Therefore, TRPV1 has emerged as a target molecular in drug development for pruritus in psoriasis. However, no significant clinical progress occurred in the development of systemic TRPV1 antagonists due to elevated core temperature. Thus, topical application of TRPV1 antagonists and interference with mediators linked to the TRPV1 activation pathway may be promising therapeutic options to ameliorate pruritus. This Review focuses on recent advances in complicated regulation of NGF-mediated TRPV1 pathway in psoriatic neurogenic pruritus, as well as the therapeutic options that arise from the dissection of the pathway.

Chronic Nodular Prurigo: An Update on the Pathogenesis and Treatment

Chronic nodular prurigo (CNPG) is a recalcitrant chronic itchy disorder that affects the quality of life. It can be triggered by multiple etiologies, such as atopic dermatitis, diabetes, and chronic renal diseases. The mechanisms of CNPG are complicated and involved the interaction of the cutaneous, immune, and nervous systems. Diverse immune cells, including eosinophils, neutrophils, T cells, macrophages, and mast cells infiltrated the lesional skin of CNPG, which initiated the inflammatory cytokines and pruritogens release. In addition, the interaction between the immune cells and activated peripheral sensory nerve fibers by neurotransmitters caused neuroinflammation in the skin and intractable itch. This itch-scratch vicious cycle of CNPG results in disease exacerbation. CNPG is difficult to treat with traditional therapies. Recently, great advances have been made in the pathophysiology of both inflammation and pruritus transmission in CNPG. In this review, we summarize the updated mechanisms and novel therapies for CNPG.