Innate Lymphoid Cells and Interferons Limit Neurologic and Articular Complications of Brucellosis

The effect of Brucella abortus on glial activation and cell death in adult male rat's hippocampus

A zoonotic disease called brucellosis can cause flu-like symptoms and heart inflammation. The bacteria responsible for this disease can also enter the brain, causing a condition called neurobrucellosis that can result in long-term neurological problems. In this study, researchers aimed to determine the changes in the hippocampal cells of rats infected with Brucella. For the study, 24 adult male albino rats were inoculated with 1 × 106 CFU Brucella abortus 544. The rats were then deeply anesthetized, and their hippocampus samples were taken for stereological, histological, and molecular studies. The results showed that the infected rats had increased microgliosis and astrogliosis. Furthermore, a high level of caspase-3 in their hippocampal tissue indicated their susceptibility to apoptosis. Additionally, there was a decrease in expression of Ki67, which further supported this. Sholl's analysis confirmed a significant failure in glial morphology. The study demonstrated that the pathogen has the ability to destroy the hippocampus and potentially affect its normal physiology. However, more research is needed to clarify various aspects of neurobrucellosis.

Contrasting roles for IgM and B-cell MHCII expression in Brucella abortus S19 vaccine-mediated efficacy against B. melitensis infection

Brucellosis, caused by the bacterium Brucella, poses a significant global threat to both animal and human health. Although commercial live Brucella vaccines including S19, RB51, and Rev1 are available for animals, their unsuitability for human use and incomplete efficacy in animals necessitate the further study of vaccine-mediated immunity to Brucella. In this study, we employed in vivo B-cell depletion, as well as immunodeficient and transgenic mouse models, to comprehensively investigate the roles of B cells, antigen uptake and presentation, antibody production, and class switching in the context of S19-mediated immunity against brucellosis. We found that antibody production, and in particular secretory IgM plays a protective role in S19-mediated immunity against virulent Brucella melitensis early after the challenge in a manner associated with complement activation. While T follicular helper cell deficiency dampened IgG production and vaccine efficacy at later stages of the challenge, this effect appeared to be independent of antibody production and rather was associated with altered T-cell function. By contrast, B-cell MHCII expression negatively impacted vaccine efficacy at later timepoints after the challenge. In addition, B-cell depletion after vaccination, but before the challenge, enhanced S19-mediated protection against brucellosis, suggesting a deleterious role of B cells during the challenge phase. Collectively, our findings indicate antibody production is protective, while B-cell MHCII expression is deleterious, to live vaccine-mediated immunity against brucellosis.

IMPORTANCE

Brucella is a neglected zoonotic pathogen with a worldwide distribution. Our study delves into B-cell effector functions in live vaccine-mediated immunity against brucellosis. Notably, we found antibody production, particularly secretory IgM, confers protection against virulent Brucella melitensis in vaccinated mice, which was associated with complement activation. By contrast, B-cell MHCII expression negatively impacted vaccine efficacy. In addition, B-cell depletion after vaccination, but before the B. melitensis challenge, enhanced protection against infection, suggesting a detrimental B-cell role during the challenge phase. Interestingly, deficiency of T follicular helper cells, which are crucial for aiding germinal center B cells, dampened vaccine efficacy at later stages of challenge independent of antibody production. This study underscores contrasting and phase-dependent roles of B-cell effector functions in vaccine-mediated immunity against Brucella.

The challenge of managing ischemic stroke in brucellosis: a case report

A 64-year-old woman was admitted to the hospital for sudden weakness in one of her left limbs. The patient was diagnosed with acute ischemic stroke (IS) of undetermined cause and received intravenous thrombolysis. Following thrombolysis, the patient's left limb weakness improved, but she subsequently developed recurrent high fever and delirium. Further diagnostic tests revealed that she had been infected with Brucella melitensis. The patient showed significant improvement during anti-infection treatment for Brucellosis and secondary prevention treatment for IS. However, her condition unexpectedly worsened on the 44th day after admission due to a hemorrhagic stroke (HS), which required an urgent craniotomy. Immunohistochemical analysis of the hematoma sample collected during the operation showed the presence of CD4+ and CD8+ T lymphocytes surrounding the blood vessels. This case highlights the unique challenge of managing IS in brucellosis and sheds light on the potential role of T lymphocytes in the immune response related to stroke.