Low responsiveness of peripheral lymphocytes in extraparenchymal neurocysticercosis

Murine Extraparenchymal Neurocysticercosis: Appropriate Model for Evaluating Anthelminthic and Anti-Inflammatory Treatment Schedules

BACKGROUND

Experimental models of neurocysticercosis (NCC) are helpful for an improved understanding of the pathophysiological mechanisms of human diseases and for testing novel therapeutic approaches. Controlling inflammation without reducing the effectiveness of anthelmintics is an important challenge in treating neurocysticercosis. This study investigates the effects of currently used drugs (Albendazole and Dexamethasone) in treating murine extraparenchymal NCC.

METHODS

Twenty-two rats were inoculated with Taenia crassiceps in the subarachnoid space. The animals underwent magnetic resonance imaging to ascertain the success of infection 3 months after inoculation. The infected animals were randomly assigned to one of the three groups (five rats each): control (no treatment), Albendazole (ABZ), or Albendazole + Dexamethasone (ABZ + DXM) for 14 days. The animals were subsequently euthanised for morphological assessment 2 weeks after the end of treatment.

RESULTS

Macroscopically integrated cysts were found in all animals. The ABZ + DXM animals demonstrated lower ventricular sizes, lymphocyte infiltration rates, and immunopositivity for IL-6, with statistical differences in lymphocytes within the arachnoid region.

CONCLUSIONS

This experimental model, which has previously shown similarities to human infections, is also helpful in reproducing the morphological changes upon treatment with Albendazole and Dexamethasone.

Neurocysticercosis: The duration of its preclinical phase relies on the parasite location

OBJECTIVES

Neurocysticercosis (NC) is a heterogeneous disease particularly in terms of response to treatment and prognosis. Parasite localization is one of the main factors involved in this heterogeneity. In this study we aim to determine whether differences in the duration of the preclinical phase associated with parasite location, could contribute to said heterogeneity.

METHODS

Ninety-nine patients were included, 24 with parasites in the parenchyma (PAR), 56 in the subarachnoid (SA) space and 19 in the ventricular system (IV). A questionnaire designed to assess exposure to classic NC risk factors 5, 10, 15, 20 and more than 20 years prior to diagnosis was applied. The results were compared between the three groups. Also, asymptomatic relatives of patients who had shared their living conditions in childhood or more recently were included and underwent brain scan and blood testing for specific antibodies.

RESULTS

Over the course of their lives, exposure to risk factors decreased significantly for all patients, although the decrease was more evident in patients with parasites in the SA space (p < 0.001) compared to patients with PAR (p = 0.011) or IV cysts (p = 0.020). Five years prior to diagnosis, exposure to risk factors was significantly higher in patients with PAR or IV NC than in patients with SA NC (p = 0.04). Furthermore, individuals in close contact with PAR or IV patients in the years preceding diagnosis were more likely to have asymptomatic NC, specific antibodies in sera, particularly IgM, compared to individuals in close contact with SA patients during the same period.

CONCLUSIONS

All these findings are highly suggestive of the possibility of a more recent infection of patients affected by parenchymal and ventricular NC than of patients with subarachnoid NC. Consequently, subarachnoid disease could be considered a chronic disease, which, probably contributes to the severity of the disease as well as the minimal response to medical treatment.

Can sPD-1 and sPD-L1 Plasma Concentrations Predict Treatment Response among Patients with Extraparenchymal Neurocysticercosis?

Extraparenchymal neurocysticercosis (EP-NC) is a chronic, potentially life-threatening disease that responds poorly to initial anthelmintic drug therapy. A depressed specific reactivity of peripheral lymphocytes and an increased level of specific Tregs accompanies EP-NC. The immune checkpoint pathway PD-1 and its ligand PD-L1 downregulates effector T cells, causing specific immune suppression in chronic diseases. This study explored whether their soluble forms, sPD-1/sPD-L1, are present in plasma among patients with EP-NC and if their levels could be associated with treatment response. A total of 21 patients with vesicular EP-NC and 22 healthy controls were included. Patients received standard treatment and were followed for six months to assess treatment response by assessing changes in cyst volume determined with 3D MRI. The presence of both sPD-1 and sPD-L1 was more frequently detected among patients with EP-NC than in healthy controls and had higher concentrations. Among patients, higher pre-treatment levels of both markers were associated with a poor treatment response, and the sensitivity and specificity of the sPD-1/sPD-L1 ratio for predicting any response to treatment were high. Our results are consistent with the presence of lymphocyte exhaustion and open new research perspectives to improve the prognosis of patients with this severe disease.