Case study-based time-course analysis of symptoms of respiratory syncytial virus infections followed by acute sinusitis in otherwise-healthy adults

Molecular mimicry-driven autoimmunity in chronic rhinosinusitis with nasal polyps

BACKGROUND

The pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP) remains a subject of discussion. Although both microbial infection and autoimmunity have been proposed as potential contributors to CRSwNP pathobiology, their respective roles and intricate interactions in disease progression remain unclear owing to the limited knowledge regarding dysregulated humoral immunity in CRSwNP.

OBJECTIVE

To deepen understanding of CRSwNP, we sought to identify the precise humoral antigens targeted by dominant B-cell clones within the disease environments.

METHODS

Immunoglobulin repertoire sequencing was performed to identify dominant B-cell clones in CRSwNP tissues. These immunoglobulin clones were reconstructed as antibodies, which were then used in immunoprecipitation and antigen array experiments for hypothesis-free global antigen profiling of autogenous and exogenous antigens.

RESULTS

From analysis of 13 patients with CRSwNP, 31 antibodies were reconstructed from dominant B-cell clones identified in 9 patients. Seven novel protein autoantigens were identified, 5 of which were nucleic acid-binding proteins, and all were associated with autoimmune diseases. Additionally, 9 microbial antigens, including various viruses, bacteria, and fungi, were discovered. Notably, 2 antibodies demonstrated dual reactivity, simultaneously recognizing both microbial and human proteins. For example, 1 antibody targeted cytomegalovirus, Clostridium tetani, and human PLEC, whereas another recognized Aspergillus niger and human DLAT, through molecular mimicry of shared amino acid homologies.

CONCLUSION

Our data indicate the possibility that the pathobiology of CRSwNP involves autoreactive humoral immunity, with a subset of cases potentially exhibiting molecular mimicry-driven autoimmune features triggered by microbial infections. Nevertheless, this hypothesis requires further investigation.

A case report on parainfluenza virus type 4a infection in a 1-year-old boy with biphasic fever

A 1-year-old boy was infected with parainfluenza virus type 4a (PIV4a) during an influenza epidemic in January 2016. His body temperature was 38.2 °C on day 1 of the illness followed by an intermittent phase of 36.5 °C on days 2 and 3, and it rose again on day 3 and peaked at 39.6 °C on day 4, of which the fever pattern was reminiscent of an influenza case with biphasic fever. However, results of rapid influenza virus (IFV) antigen tests performed at the first clinical visit and during the second fever phase on day 4 were both negative. The PIV4a was isolated from all the nasal aspirate specimens on days 1, 4, and 7. Other common respiratory viruses were negative in all the specimens in the viral isolation trials using the multiplex cell culture system and RT-PCR tests. The fever disappeared within 5 days after the onset without any antibiotic treatment, which strongly suggested the PIV4a as the causative agent of the patient's illness. On the basis of the incubation period required for the appearance of the cytopathic effect (CPE) in the infected cells, from specimen inoculation to the cells, the viral load in the nasal cavity was speculated to be greatest on day 4. His cough started on day 1 and persisted until day 9, and the viral isolation indicated that the shedding of the active virus continued with the coughing even after the termination of fever.