Bell's palsy and HSV-1 infection

The Alterations and Significance of Intercellular Adhesion Molecule-1 in Mouse Brainstem During Herpes Simplex Virus Type 1-Induced Facial Palsy

Herpes simplex virus type 1 (HSV-1) results in the development of Bell's pals but still, the pathophysiology of the facial nerve paralysis is still not fully studied. The main objective is to establish an animal model of type 1 herpes simplex virus (HSV-1)-induced face paralysis in the mouse and to investigate the pattern of changes in intercellular adhesion molecule -1(ICAM-1) expression in the facial nucleus of the brain stem in mice with facial paralysis as well as the effects of glucocorticoids on intercellular adhesion molecule -1(ICAM-1) expression. A total of 170 4-week-old Balb/c male mice were randomly divided into the virus inoculation group (n = 135), saline control group (n = 26), and blank control group (n = 9). Mice in the virus inoculation group that showed facial paralysis were divided into A, B, and C subgroups. The A group did not receive any treatments, the B group received methylprednisolone sodium succinate (MPSS) intervention, and the C group received MPSS + RU486 treatment. The mouse model of facial paralysis was established by inoculating HSV-1 to the skin at the back of the ears. The facial nerve function of mice was assessed, and real-time PCR and western blot were used to assess ICAM-1 expression in the facial nucleus of the brain stem in mice with facial paralysis after drug intervention. In the virus inoculation group, 95 mice (55.88%) showed varying degrees of facial paralysis symptoms within 2-5 days after inoculation. The ICAM-1 gene and protein expression levels remained at low levels in the facial nucleus of the brain stem of mice in the saline group, which showed no significant difference compared to the normal control group (P > 0.05). However, for mice of the virus inoculation group, ICAM-1 expression increased at 6 h after the occurrence of facial paralysis and peaked after 2 days, differing significantly from the blank control group (P < 0.01). ICAM-1 expression subsequently decreased gradually. In the HSV-1 + MPSS group, ICAM-1 protein expression decreased significantly on the 2^nd day after facial paralysis. In the HSV-1 + MPSS + RU486 group, MPSS inhibition of ICAM-1 protein expression was reduced. The results suggested that ICAM-1 is involved in the pathological processes by which HSV-1 induces facial paralysis in mice, and the treatment effects of MPSS for Bell's palsy can be achieved by the inhibition of MCP-1.

The expression of IL-2 and IL-4 in CD4(+) T cells from mouse lymph nodes and spleen during HSV-1-induced facial palsy

OBJECTIVE

Herpes simplex virus 1 (HSV-1) is regarded as an important underlying cause of Bell's palsy, but the immunologic mechanism remains unknown. Here, we employed a mouse facial paralysis model to investigate the expressions of CD4(+) T lymphocytes and interleukin (IL)-2 and -4 in the left draining cervical lymph nodes (LCLN) and spleen, as well as the inhibitory effects of glucocorticoids (GCs).

METHODS

HSV-1 was inoculated into the surface of the posterior auricle to generate the facial paralysis model. The paralyzed mice were divided into three groups; in one group without any treatment, mice were killed at different time points, and those in the other two groups were injected with methylprednisolone sodium succinate (MPSS) or with a combination of MPSS and GC receptor blocker (RU486). The expression levels of CD4(+) T lymphocytes and CD4(+)-IL-2(+) and CD4(+)-IL-4(+) cells in the LCLN and spleen were detected by fluorescence-activated cell sorting.

RESULTS

Expression levels of CD4(+), IL-2, and IL-4 first increased then decreased in LCLN and spleen and peaked 5 and 7 days, respectively, after the manifestation of facial paralysis. All the data at the peak points were significantly different compared with control (p < 0.05), and these effects were inhibited by MPSS.

CONCLUSION

Our results suggest that CD4(+), IL-2, and IL-4 participate in the HSV-1-induced facial paralysis immune response. MPSS can effectively attenuate HSV-1-mediated nervous system damage, which is associated with its inhibitory effect on expression of these inflammatory markers.

Cranial and peripheral neuropathies

An acute polyneuropathy developing over days to several weeks is most likely to be Guillain-Barré syndrome or a toxic neuropathy, although vasculitis can also present acutely. This presentation should be referred immediately for further investigation. A subacute to chronic (ie, developing over months) neuropathy with significant proximal weakness and prominent loss of reflexes is highly suggestive of chronic inflammatory demyelinating polyradiculoneuropathy. If there is a clear stepwise onset of symptoms, suggestive of multiple mononeuropathies, or significant asymmetry, vasculitic neuropathy should be considered, even in the absence of systemic vasculitis. Idiopathic chronic axonal neuropathy is an indolent, predominantly sensory neuropathy that typically occurs in older patients. Neuropathies occurring in young or middle age or with more subacute onset always warrant further investigation.