Interferon-induced anosmia in a patient with chronic hepatitis C

Signs and symptoms of Covid‐19 in patients with multiple sclerosis

Background and purpose

Clinical outcomes of multiple sclerosis (MS) patients affected by coronavirus disease 2019 (COVID‐19) have been thoroughly investigated, but a further analysis on main signs and symptoms and their risk factors still needs attention. The objective of this study was to group together and describe based on similarity the most common signs and symptoms of COVID‐19 in MS patients and identify all factors associated with their manifestation.

Method

Logistic and linear regression models were run to recognize factors associated with each pooled group of symptoms and their total number.

Results

From March 2020 to November 2021, data were collected from 1354 MS patients with confirmed infection of COVID‐19. Ageusia and anosmia was less frequent in older people (odds ratio [OR] 0.98; p = 0.005) and more in smoker patients (OR 1.39; p = 0.049). Smoke was also associated with an incremental number of symptoms (OR 1.24; p = 0.031), substance abuse (drugs or alcohol), conjunctivitis and rash (OR 5.20; p = 0.042) and the presence of at least one comorbidity with shortness of breath, tachycardia or chest pain (OR 1.24; p = 0.008). Some disease‐modifying therapies were associated with greater frequencies of certain COVID‐19 symptoms (association between anti‐CD20 therapies and increment in the number of concomitant symptoms: OR 1.29; p = 0.05). Differences in frequencies between the three waves were found for flu‐like symptoms (G1, p = 0.024), joint or muscle pain (G2, p = 0.013) and ageusia and anosmia (G5, p < 0.001). All cases should be referred to variants up to Delta.

Conclusion

Several factors along with the choice of specific therapeutic approaches might have a different impact on the occurrence of some COVID‐19 symptoms.

Modulation of olfactory signal detection in the olfactory epithelium: focus on the internal and external environment, and the emerging role of the immune system

Detection and discrimination of odorants by the olfactory system plays a pivotal role in animal survival. Olfactory-based behaviors must be adapted to an ever-changing environment. Part of these adaptations includes changes of odorant detection by olfactory sensory neurons localized in the olfactory epithelium. It is now well established that internal signals such as hormones, neurotransmitters, or paracrine signals directly affect the electric activity of olfactory neurons. Furthermore, recent data have shown that activity-dependent survival of olfactory neurons is important in the olfactory epithelium. Finally, as olfactory neurons are directly exposed to environmental toxicants and pathogens, the olfactory epithelium also interacts closely with the immune system leading to neuroimmune modulations. Here, we review how detection of odorants can be modulated in the vertebrate olfactory epithelium. We choose to focus on three cellular types of the olfactory epithelium (the olfactory sensory neuron, the sustentacular and microvillar cells) to present the diversity of modulation of the detection of odorant in the olfactory epithelium. We also present some of the growing literature on the importance of immune cells in the functioning of the olfactory epithelium, although their impact on odorant detection is only just beginning to be unravelled.

Systemic diseases and disorders

Alterations in the ability to smell or taste are of considerable consequence, impacting quality of life, safety, nutrition, and dietary activities. These primary senses are influenced by a wide range of systemic diseases and disorders that commonly involve the entire body. These include viral, bacterial, fungal, protozoal, cestode, and nematode infections that can spread throughout the gastric, lymphatic, neural, or circulatory systems as well as classic autoimmune disorders, collagen diseases, diabetes, and hypertension, and others. Although a considerable literature has evolved in which the function of both taste and smell has been assessed in a number of such disorders, quantitative chemosensory testing is still relatively rare with many disorders not receiving empirical assessment. Incongruent findings are not uncommon. This chapter reviews what is known about the influences of a wide spectrum of systemic diseases and disorders on the abilities to taste and smell.

Loss of smell (anosmia) and taste (ageusia) in a patient treated with pegylated interferon alfa and ribavirin

INTRODUCTION

Anosmia, the loss of the sense of smell, is a rare adverse event associated with interferon alpha (INF-α). Millions of patients with hepatitis B and hepatitis C virus (HCV) infection are currently treated with INF-alfa-2a daily. Only 5 cases of anosmia have been reported in the literature, and none was associated with pegylated INF-alfa.

CASE SUMMARY

A 55-year-old Arab male (height, 5'1″; weight, 81 kg) with chronic HCV developed anosmia and ageusia (loss of the sense of taste) after 36 weeks of treatment for HCV with subcutaneous pegylated INF-alfa-2a 180 μg and ribavirin 1200 mg. Treatment was continued for 12 additional weeks before being discontinued. Twenty-four weeks after treatment was discontinued, HCV-RNA was undetectable and, during the same visit, the patient reported that he had regained his sense of smell a few weeks previously. The Naranjo algorithm score was 7, representing a probable association of anosmia with INF-alfa-2a treatment. Other etiologies for loss of smell and taste were ruled out.

CONCLUSIONS

We report a case of anosmia and ageusia in a patient treated with pegylated INF-alfa-2b and ribavirin for HCV infection. The patient regained his sense of smell and taste within 24 weeks of stopping treatment.

Interferon gamma causes olfactory dysfunction without concomitant neuroepithelial damage

BACKGROUND

Olfactory loss is a debilitating symptom of chronic rhinosinusitis (CRS). The pathophysiology of inflammatory olfactory dysfunction likely involves both conductive and sensorineural components. To study the interaction of CRS-associated inflammatory cytokines with the olfactory epithelium (OE), a transgenic mouse model was developed that allows temporally-controlled local gene expression. Interferon-gamma (IFN-γ) is a prototypical T helper 1 (Th1) cytokine linked to nonpolypoid CRS (CRSsNP), as well as sinonasal viral and bacterial infections. In this study, the effects of chronic IFN-γ expression on olfactory histology and function were investigated.

METHODS

IFN-γ secretion by olfactory sustentacular cells was induced in the transgenic mouse. Viability and gross behavior were unaffected. Mice were euthanized after 6 weeks of IFN-γ expression, and olfactory tissue was studied by histology, immunohistochemistry, and electro-olfactography (EOG). Findings were compared with uninduced littermates.

RESULTS

IFN-γ expression did not result in alteration of the normal histologic architecture of the neuroepithelium or lamina propria. However, EOG recordings demonstrated a significant decrease in odorant responses after IFN-γ expression. In addition, a marked increase in submucosal CD45-positive cells was observed, the majority of which were CD3-positive and CD4-positive lymphocytes.

CONCLUSION

Chronic IFN-γ expression in the mouse OE results in diminished odorant responsiveness, despite the absence of inflammatory tissue damage. This suggests a direct effect of IFN-γ on olfactory neuron function that may underlie olfactory loss in CRSsNP or viral infections. The infiltration of submucosal lymphocytes raises the possibility that other downstream cytokines also contribute to olfactory dysfunction.

Interferon-alpha2b may impair myelinization of rat optic nerve

This story investigated the effects of interferon-alpha-2b (IFN-alpha2b) on the optic nerves of 17 adult male Wistar albino rats. Animals were divided into 3 groups: 6 rats (group 1) received 7.5 units (5 mIU/m2) IFN-alpha2b-a normal treatment dose, and 6 (groups 2) received 30.0 units (20 mIU/m2)-a high dose; 5 rats (control group) received 0.5 mL saline. Test substances were delivered by intraperitoneal injection 3 times a week for 3 weeks with animals under inhalation anesthesia. After the rats were sacrificed, their optic nerves were dissected, sectioned, and examined under an electron microscope. The mean thicknesses of the basal membranes of blood vessels were 86.354 nm in the control group, 104.297 nm in group 1, and 140.181 nm in group 2. Basal membrane changes in IFN groups were dose dependent. Mitochondrial swelling, degeneration, increased diameter of vacuoles, and vacuolization in the cytoplasm of oligodendrocytes and astrocytes were also observed. IFN-alpha2b has histopathologic effects on blood vessels and cells of the optic nerve.

Striking complete remission after interferon-? for secondary recurrent non-Hodgkin?s lymphoma but rare interferon-induced side effects

Interferon (IFN) treatment is a therapeutic option in the treatment of non-Hodgkin's lymphoma (NHL). Although randomized trials have failed to show significant differences in progression-free and overall survival (OS) with IFN compared to placebo after peripheral blood stem cell transplantation (PBSCT) as well as standard therapy for NHL, anecdotal case reports have documented impressive results in selected patients. With this case report, we demonstrate an astounding success of IFN therapy given in the treatment of a young man with second relapse after two consecutive autologous PBSCTs and abdominal irradiation. With occurrence of multiple lymph node enlargements despite this intensive treatment, he received IFN and obtained a well-documented complete remission (CR). Yet, treatment with IFN always has to be considered in the context of its significant side effect profile, which can have considerable impact on the patient's quality of life as illustrated in this case report.

The effect of recombinant interferon alpha treatment on hearing thresholds in patients with chronic viral hepatitis B

OBJECTIVES

To investigate the possible ototoxic effects of recombinant interferon alpha (IFN alpha) on patients with hepatitis B.

PATIENTS AND METHOD

Twenty-seven adult patients (14 male, 13 female) with chronic hepatitis B who were administered recombinant IFN alpha treatment were selected for this study. These patients were treated with a dose of 10 MU three times per week during 8-12 months (average follow-up period was 11.2 month). The mean hearing thresholds at seven frequencies (250-8000 Hz) were determined the day before therapy, after 1st, 7th and 21st day, and 1 month after termination of treatment.

RESULTS

Hearing loss was detected in nine of 27 patients on the 7th day and the degree of hearing loss increased until 21st day of treatment. It was not exceeded 20 dB for any frequency with continued IFN therapy. The hearing loss completely recovered 1 month after the cessation of the IFN alpha. When hearing thresholds values of the day before therapy, 1st day and 1 month after termination of treatment were compared with values of 7th and 21st days, a statistically significant difference was detected (P<0.001). But there was no significant difference between the hearing thresholds values of the day before therapy, 1st day and 1 month after termination of the treatment (P>0.05).

CONCLUSION

IFN alpha administration in patients with hepatitis B may cause mild reversible sensorineural hearing loss.

[Olfactory disorders due to medications: analysis and review of the literature]

INTRODUCTION

Olfactory disorders caused by medicinal drug intake are an uncommon occurrence. However, such an etiology should be systematically taken into account and investigated, as olfactory loss may be reversible once the particular treatment has been stopped.

CURRENT KNOWLEDGE AND KEY POINTS

An analysis of the literature shows that of the large number of drugs that are apparently responsible for olfactory disorders, this adverse side effect has in fact only been observed in animal study populations, and no clinical case report has been made on the subject. The real toxicity to man is therefore only hypothetical. Of the 150,000 cases recorded in the pharmacovigilance centers in France, only 68 have reported olfactory complications (0.05% of cases), and only 22% of the medical files on this disorder reach a satisfactory level of plausibility. Cardiovascular drugs are mainly implicated in the development of olfactory disorders. Of these, certain drugs in particular should be mentioned: conversion enzyme (ACE) inhibitors which are responsible for taste disorders, some betablockers, and a calcium antagonist (a dihydropyridine derivative). Olfactory disorders have also been reported following administration of drugs used in anesthesia, in cancerology, endocrinology (carbimazole), in immunology (interferon), in the treatment of infectious diseases (ciprofloxacine, dioxycycline, terbinafine), and in rheumatology (D-penicillamine).

FUTURE PROSPECTS AND PROJECTS

It is frequently difficult to establish a direct relationship between drug exposure and an olfactory disorder, and it is often not easy to determine with any certainty the causative role of the drug in the development of this disorder.

[Olfactory disorders and general pathology. Analysis and review of the literature]

INTRODUCTION

Disturbances of the sense of smell have been documented in many general pathologies. The actual etiology of such impairments is often difficult to determine. The aim of the authors is to review the literature on olfactory disorders in general diseases.

CURRENT KNOWLEDGE AND KEY POINTS

Acute and chronic liver disorders are frequently associated with hyposmia, which can be improved by vitamin A intake. Renal insufficiency could induce hyposmia according to the severity of the renal disease. Olfactory disorders seem to regress after transplantation but not after dialysis. Patients with AIDS--especially neurological forms--often present with taste and smell impairments. Smell alteration can also be noted in hypothyroidism and pseudohypoparathyroidism. In addition, taste and smell impairments have been described in patients with adrenal insufficiency or Cushing's disease. Subsequent to glucocorticoid therapy, adrenal insufficiency can induce regressive olfactory hypersensitivity. Olfactory impairments in diabetic patients can be associated with diabetic macrovascular manifestations due to ischemic alterations in the olfactory neuroepithelium. Impairment of the sense of smell has been described in many systemic diseases such as Horton's arteritis and Sjögren's syndrome.

FUTURE PROSPECTS AND PROJECTS

Olfactory disorders should be investigated in patients presenting one of the above-mentioned diseases.