Pituitary Abscess Causing Panhypopituitarism in a Patient With Neurobrucellosis: Case Report.

Background/Objective: Pituitary abscess is an uncommon life-threatening disease that could lead to panhypopituitarism. It is important to suspect its prevalence in regions with endemic infectious diseases. Case Report: A 55-year-old man, a farmer, with a background of consumption of unpasteurized dairy products, presented with headache, impaired consciousness, and fever that started in February 2023. Initial test results were consistent with neuroinfection. Brain MRI showed ventriculitis; the pituitary gland was heterogeneous with the presence of an 8 × 8 mm abscess. The pituitary hormone axis was evaluated, and it showed results compatible with the results of panhypopituitarism with central hypothyroidism, central hypocortisolism, central hypogonadism, and growth hormone deficiency. Hormone replacement treatment with hydrocortisone and levothyroxine was started. The Rose Bengal test for Brucella spp. and 2-mercaptoethanol Brucella agglutination test showed positive results. After neurobrucellosis (NB) was diagnosed, antibiotic treatment was commenced. The patient was discharged 6 weeks later and treatment with prednisone, levothyroxine, recombinant somatropin, testosterone, as well as doxycycline, and rifampin was continued for another 4 months. Discussion: NB and pituitary abscess are rare manifestations of brucellosis and are challenging to diagnose due to their nonspecific clinical presentation and cerebrospinal fluid (CSF) findings. NB diagnosis relies on neurologic symptoms and serological evidence of Brucella infection. Magnetic resonance imaging is the preferred diagnostic tool for pituitary abscesses. Medical management may be sufficient, while transsphenoidal drainage is not always necessary. Hormonal deficits typically remain permanent. Conclusion: Pituitary abscess could be suspected in patients presenting with symptoms of neuroinfection, panhypopituitarism, and heterogenous image in the magnetic resonance imaging differential diagnosis. Opportune management can lead to reduced mortality and improved recovery of the pituitary hormone function.

Bystander activation of microglia by Brucella abortus-infected astrocytes induces neuronal death via IL-6 trans-signaling.

Inflammation plays a key role in the pathogenesis of neurobrucellosis where glial cell interactions are at the root of this pathological condition. In this study, we present evidence indicating that soluble factors secreted by Brucella abortus-infected astrocytes activate microglia to induce neuronal death. Culture supernatants (SN) from B. abortus-infected astrocytes induce the release of pro-inflammatory mediators and the increase of the microglial phagocytic capacity, which are two key features in the execution of live neurons by primary phagocytosis, a recently described mechanism whereby B. abortus-activated microglia kills neurons by phagocytosing them. IL-6 neutralization completely abrogates neuronal loss. IL-6 is solely involved in increasing the phagocytic capacity of activated microglia as induced by SN from B. abortus-infected astrocytes and does not participate in their inflammatory activation. Both autocrine microglia-derived and paracrine astrocyte-secreted IL-6 endow microglial cells with up-regulated phagocytic capacity that allows them to phagocytose neurons. Blocking of IL-6 signaling by soluble gp130 abrogates microglial phagocytosis and concomitant neuronal death, indicating that IL-6 activates microglia via trans-signaling. Altogether, these results demonstrate that soluble factors secreted by B. abortus-infected astrocytes activate microglia to induce, via IL-6 trans-signaling, the death of neurons. IL-6 signaling inhibition may thus be considered a strategy to control inflammation and CNS damage in neurobrucellosis.

Subacute transverse myelitis as a clinical presentation of neurobrucellosis.

Brucella melitensis is the main cause of human brucellosis worldwide and is considered the most virulent and neurotropic species. In Mexico, this species is considered endemic, being reported since the first decade of the 20th century. Here we present a case of subacute transverse myelitis with the isolation and identification of B. melitensis as the causative agent of Neurobrucellosis in a female patient from the coastal state of Guerrero, Mexico.

Brucella abortus-Stimulated Platelets Activate Brain Microvascular Endothelial Cells Increasing Cell Transmigration through the Erk1/2 Pathway.

Central nervous system invasion by bacteria of the genus Brucella results in an inflammatory disorder called neurobrucellosis. A common feature associated with this pathology is blood-brain barrier (BBB) activation. However, the underlying mechanisms involved with such BBB activation remain unknown. The aim of this work was to investigate the role of Brucella abortus-stimulated platelets on human brain microvascular endothelial cell (HBMEC) activation. Platelets enhanced HBMEC activation in response to B. abortus infection. Furthermore, supernatants from B. abortus-stimulated platelets also activated brain endothelial cells, inducing increased secretion of IL-6, IL-8, CCL-2 as well as ICAM-1 and CD40 upregulation on HBMEC compared with supernatants from unstimulated platelets. Outer membrane protein 19, a B. abortus lipoprotein, recapitulated B. abortus-mediated activation of HBMECs by platelets. In addition, supernatants from B. abortus-activated platelets promoted transendothelial migration of neutrophils and monocytes. Finally, using a pharmacological inhibitor, we demonstrated that the Erk1/2 pathway is involved in the endothelial activation induced by B. abortus-stimulated platelets and also in transendothelial migration of neutrophils. These results describe a mechanism whereby B. abortus-stimulated platelets induce endothelial cell activation, promoting neutrophils and monocytes to traverse the BBB probably contributing to the inflammatory pathology of neurobrucellosis.

Immune Mediators of Pathology in Neurobrucellosis: From Blood to Central Nervous System.

Neurobrucellosis, which is the most morbid form of brucellosis disease, presents with inflammatory signs and symptoms. Recent experimental evidence clearly indicates that deregulation of astrocytes and microglia caused by Brucella infection creates a microenvironment in the central nervous system (CNS) in which secretion of pro-inflammatory mediators lead to destabilization of the glial structure, the damage of the blood brain barrier (BBB) and neuronal demise. This review of Brucella interactions with cells of the CNS and the BBB is intended to present recent immunological findings that can explain, at least in part, the basis for the inflammatory pathogenesis of the nervous system that takes place upon Brucella infection.

Neurobrucelosis evaluada por reibergrama. Presentación de un caso / Neurobrucellosis evaluated by reibergram. A case report

Introducción: La brucelosis es una enfermedad zoonótica y endémica en muchas partes del mundo. La causa principal de la infección se produce por la ingestión de leche no pasteurizada o por el contacto con animales infectados. La neurobrucelosis incluye afecciones en el sistema nervioso central y periférico. Las principales manifestaciones clínicas son la meningitis, la encefalitis, la neuritis óptica y la periférica. Objetivo: Evaluar, mediante reibergrama, la dinámica intratecal de las clases mayores de inmunoglobulinas y el estado de la barrera sangre/LCR de un paciente con neurobrucelosis. Presentación del caso: Los niveles de IgA, IgM. IgG y albúmina en suero y líquido cefalorraquídeo fueron cuantificados por inmunodifusión. Los resultados fueron colocados en el reibergrama correspondiente. El paciente mostró síntesis intratecal de las tres clases mayores de inmunoglobulinas, sin disfunción de la barrera sangre/LCR. Conclusión: El estudio neuroinmunológico del líquido cefalorraquídeo puede indicar el curso activo de la respuesta inmune intratecal contra el patógeno, donde la síntesis intratecal de inmunoglobulinas y el funcionamiento de la barrera sangre/líquido cefalorraquídeo constituyeron los principales marcadores en el diagnóstico de la neuroinflamación(AU)

Introduction: Brucellosis is a zoonotic and an endemic disease in many areas around the world. The main cause of infection is the intake of unpasteurized milk or the contact with infected animals. Neurobrucellosis includes pathologic conditions in the central and peripheral nervous systems. The main clinical manifestations are meningitis, encephalitis, optical neuritis, and peripheral neuritis. Objective: To evaluate, through reibergram, the intrathecal dynamics of the major immunoglobulin classes and the blood-CSF barrier function in one patient with neurobrucellosis. Case report: IgA, IgM, IgG and albumin levels in serum and cerebrospinal fluid were quantified by using a radial immunodiffusion technique. Results were placed in the corresponding reibergram. The patient showed evidences of intrathecal synthesis of the three major immunoglobulins without blood-CSF barrier dysfunction. Conclusion: The neuroimmunological study of cerebrospinal fluid can indicate the active course of the intrathecal immune response against this pathogen, where the intrathecal synthesis of immunoglobulins and blood-cerebrospinal fluid barrier function constitute the main markers in the diagnosis of neuroinflammation(AU)

Brucella abortus Traverses Brain Microvascular Endothelial Cells Using Infected Monocytes as a Trojan Horse.

Neurobrucellosis is an inflammatory disease caused by the invasion of Brucella spp. to the central nervous system (CNS). The pathogenesis of the disease is not well characterized; however, for Brucella to gain access to the brain parenchyma, traversing of the blood-brain barrier (BBB) must take place. To understand the CNS determinants of the pathogenesis of B. abortus, we have used the in vitro BBB model of human brain microvascular endothelial cells (HBMEC) to study the interactions between B. abortus and brain endothelial cells. In this study, we showed that B. abortus is able to adhere and invade HBMEC which was dependent on microtubules, microfilaments, endosome acidification and de novo protein synthesis. After infection, B. abortus rapidly escapes the endosomal compartment of HBMEC and forms a replicative Brucella-containing vacuole that involves interactions with the endoplasmic reticulum. Despite the ability of B. abortus to invade and replicate in HBMEC, the bacterium was unable by itself to traverse HBMEC, but could traverse polarized HBMEC monolayers within infected monocytes. Importantly, infected monocytes that traversed the HBMEC monolayer were a bacterial source for de novo infection of glial cells. This is the first demonstration of the mechanism whereby B. abortus is able to traverse the BBB and infect cells of the CNS. These results may have important implications in our understanding of the pathogenesis of neurobrucellosis.

Brucellosis caused by the wood rat pathogen Brucella neotomae: two case reports.

BACKGROUND: Brucellosis is a chronic bacterial disease caused by members of the genus Brucella. Among the classical species stands Brucella neotomae, until now, a pathogen limited to wood rats. However, we have identified two brucellosis human cases caused by B. neotomae, demonstrating that this species has zoonotic potential. CASES PRESENTATION: Within almost 4 years of each other, a 64-year-old Costa Rican white Hispanic man and a 51-year-old Costa Rican white Hispanic man required medical care at public hospitals of Costa Rica. Their hematological and biochemical parameters were within normal limits. No adenopathies or visceral abnormalities were found. Both patients showed intermittent fever, disorientation, and general malaise and a positive Rose Bengal test compatible with Brucella infection. Blood and cerebrospinal fluid cultures rendered Gram-negative coccobacilli identified by genomic analysis as B. neotomae. After antibiotic treatment, the patients recovered with normal mental activities. CONCLUSIONS: This is the first report describing in detail the clinical disease caused by B. neotomae in two unrelated patients. In spite of previous claims, this bacterium keeps zoonotic potential. Proposals to generate vaccines by using B. neotomae as an immunogen must be reexamined and countries housing the natural reservoir must consider the zoonotic risk.

Brucella neotomae Infection in Humans, Costa Rica.

Several species of Brucella are known to be zoonotic, but B. neotomae infection has been thought to be limited to wood rats. In 2008 and 2011, however, B. neotomae was isolated from cerebrospinal fluid of 2 men with neurobrucellosis. The nonzoonotic status of B. neotomae should be reassessed.

Brucella abortus-activated microglia induce neuronal death through primary phagocytosis.

Inflammation has long been implicated as a contributor to pathogenesis in neurobrucellosis. Many of the associated neurocognitive symptoms of neurobrucellosis may be the result of neuronal dysfunction resulting from the inflammatory response induced by Brucella abortus infection in the central nervous system. In this manuscript, we describe an immune mechanism for inflammatory activation of microglia that leads to neuronal death upon B. abortus infection. B. abortus was unable to infect or harm primary cultures of mouse neurons. However, when neurons were co-cultured with microglia and infected with B. abortus significant neuronal loss occurred. This phenomenon was dependent on TLR2 activation by Brucella lipoproteins. Neuronal death was not due to apoptosis, but it was dependent on the microglial release of nitric oxide (NO). B. abortus infection stimulated microglial proliferation, phagocytic activity and engulfment of neurons. NO secreted by B. abortus-activated microglia induced neuronal exposure of the "eat-me" signal phosphatidylserine (PS). Blocking of PS-binding to protein milk fat globule epidermal growth factor-8 (MFG-E8) or microglial vitronectin receptor-MFG-E8 interaction was sufficient to prevent neuronal loss by inhibiting microglial phagocytosis without affecting their activation. Taken together, our results indicate that B. abortus is not directly toxic to neurons; rather, these cells become distressed and are killed by phagocytosis in the inflammatory surroundings generated by infected microglia. Neuronal loss induced by B. abortus-activated microglia may explain, in part, the neurological deficits observed during neurobrucellosis.

The role of NLRP3 and AIM2 in inflammasome activation during Brucella abortus infection.

The innate immune system is essential for the detection and elimination of bacterial pathogens. Upon inflammasome activation, caspase-1 cleaves pro-IL-1ß and pro-IL-18 to their mature forms IL-1ß and IL-18, respectively, and the cell undergoes inflammatory death termed pyroptosis. Here, we reviewed recent findings demonstrating that Brucella abortus ligands activate NLRP3 and AIM2 inflammasomes which lead to control of infection. This protective effect is due to the inflammatory response caused by IL-1ß and IL-18 rather than cell death. Brucella DNA is sensed by AIM2 and bacteria-induced mitochondrial reactive oxygen species is detected by NLRP3. However, deregulation of pro-inflammatory cytokine production can lead to immunopathology. Nervous system invasion by bacteria of the genus Brucella results in an inflammatory disorder termed neurobrucellosis. Herein, we discuss the mechanism of caspase-1 activation and IL-1ß secretion in glial cells infected with B. abortus. Our results demonstrate that the ASC inflammasome is indispensable for inducing the activation of caspase-1 and secretion of IL-1ß upon infection of astrocytes and microglia with Brucella. Moreover, our results demonstrate that secretion of IL-1ß by Brucella-infected glial cells depends on NLRP3 and AIM2 and leads to neurobrucellosis. Further, the inhibition of the host cell inflammasome as an immune evasion strategy has been described for bacterial pathogens. We discuss here that the bacterial type IV secretion system VirB is required for inflammasome activation in host cells during infection. Taken together, our results indicate that Brucella is sensed by ASC inflammasomes mainly NLRP3 and AIM2 that collectively orchestrate a robust caspase-1 activation and pro-inflammatory response.

Treatment of a subdural empyema complicated by intracerebral abscess due to Brucella infection

A 55-year-old male presented with fever, stupor, aphasia, and left hemiparesis. A history of head trauma 3 months before was also reported. Cranial magnetic resonance imaging revealed slight contrast enhancement of lesions under the right frontal skull plate and right frontal lobe. Because of deterioration in nutritional status and intracranial hypertension, the patient was prepared for burr hole surgery. A subdural empyema (SDE) recurred after simple drainage. After detection of Brucella species in SDE, craniotomy combined with antibiotic treatment was undertaken. The patient received antibiotic therapy for 6 months (two doses of 2 g ceftriaxone, two doses of 100 mg doxycycline, and 700 mg rifapentine for 6 months) that resulted in complete cure of the infection. Thus, it was speculated that the preexisting subdural hematoma was formed after head trauma, which was followed by a hematogenous infection caused by Brucella species.

Neurobrucellosis: clinical, diagnostic, therapeutic features and outcome. Unusual clinical presentations in an endemic region

Brucellosis is a zoonotic infection and has endemic characteristics. Neurobrucellosis is an uncommon complication of this infection. The aim of this study was to present unusual clinical manifestations and to discuss the management and outcome of a series of 18 neurobrucellosis cases. Initial clinical manifestations consist of pseudotumor cerebri in one case, white matter lesions and demyelinating syndrome in three cases, intracranial granuloma in one case, transverse myelitis in two cases, sagittal sinus thrombosis in one case, spinal arachnoiditis in one case, intracranial vasculitis in one case, in addition to meningitis in all cases. Eleven patients were male and seven were female. The most prevalent symptoms were headache (83 percent) and fever (44 percent). All patients were treated with rifampicin, doxycycline plus trimethoprim-sulfamethoxazole or ceftriaxone. Duration of treatment (varied 3-12 months) was determined on basis of the CSF response. In four patients presented with left mild sequelae including aphasia, hearing loss, hemiparesis. In conclusion, although mortality is rare in neurobrucellosis, its sequelae are significant. In neurobrucellosis various clinical and neuroradiologic signs and symptoms can be confused with other neurologic diseases. In inhabitants or visitors of endemic areas, neurobrucellosis should be kept in mind in cases that have unusual neurological manifestations.