Potentiation of amyloid beta phagocytosis and amelioration of synaptic dysfunction upon FAAH deletion in a mouse model of Alzheimer's disease.

BACKGROUND: The complex pathophysiology of Alzheimer's disease (AD) hampers the development of effective treatments. Attempts to prevent neurodegeneration in AD have failed so far, highlighting the need for further clarification of the underlying cellular and molecular mechanisms. Neuroinflammation seems to play a crucial role in disease progression, although its specific contribution to AD pathogenesis remains elusive. We have previously shown that the modulation of the endocannabinoid system (ECS) renders beneficial effects in a context of amyloidosis, which triggers neuroinflammation. In the 5xFAD model, the genetic inactivation of the enzyme that degrades anandamide (AEA), the fatty acid amide hydrolase (FAAH), was associated with a significant amelioration of the memory deficit. METHODS: In this work, we use electrophysiology, flow cytometry and molecular analysis to evaluate the cellular and molecular mechanisms underlying the improvement associated to the increased endocannabinoid tone in the 5xFAD mouse- model. RESULTS: We demonstrate that the chronic enhancement of the endocannabinoid tone rescues hippocampal synaptic plasticity in the 5xFAD mouse model. At the CA3-CA1 synapse, both basal synaptic transmission and long-term potentiation (LTP) of synaptic transmission are normalized upon FAAH genetic inactivation, in a CB1 receptor (CB1R)- and TRPV1 receptor-independent manner. Dendritic spine density in CA1 pyramidal neurons, which is notably decreased in 6-month-old 5xFAD animals, is also restored. Importantly, we reveal that the expression of microglial factors linked to phagocytic activity, such as TREM2 and CTSD, and other factors related to amyloid beta clearance and involved in neuron-glia crosstalk, such as complement component C3 and complement receptor C3AR, are specifically upregulated in 5xFAD/FAAH-/- animals. CONCLUSION: In summary, our findings support the therapeutic potential of modulating, rather than suppressing, neuroinflammation in Alzheimer's disease. In our model, the long-term enhancement of the endocannabinoid tone triggered augmented microglial activation and amyloid beta phagocytosis, and a consequent reversal in the neuronal phenotype associated to the disease.

Role of interleukin 1-beta in the inflammatory response in a fatty acid amide hydrolase-knockout mouse model of Alzheimer's disease.

The search for novel therapies for the treatment of Alzheimer's disease is an urgent need, due to the current paucity of available pharmacological tools and the recent failures obtained in clinical trials. Among other strategies, the modulation of amyloid-triggered neuroinflammation by the endocannabinoid system seems of relevance. Previous data indicate that the enhancement of the endocannabinoid tone through the inhibition of the enzymes responsible for the degradation of their main endogenous ligands may render beneficial effects. Based on previously reported data, in which we described a paradoxical effect of the genetic deletion of the fatty acid amide hydrolase, we here aimed to expand our knowledge on the role of the endocannabinoid system in the context of Alzheimer's disease. To that end, we inhibited the production of interleukin-1ß, one of the main inflammatory cytokines involved in the neuroinflammation triggered by amyloid peptides, in a transgenic mouse model of this disease by using minocycline, a drug known to impair the synthesis of this cytokine. Our data suggest that interleukin-1ß may be instrumental in order to achieve the beneficial effects derived of fatty acid amide hydrolase genetic inactivation. This could be appreciated at the molecular (cytokine expression, amyloid production, plaque deposition) as well as behavioral levels (memory impairment). We here describe a previously unknown link between the endocannabinoid system and interleukin-1ß in the context of Alzheimer's disease that open new possibilities for the development of novel therapeutics.

Cannabinoid CB2 receptors in the mouse brain: relevance for Alzheimer's disease.

BACKGROUND: Because of their low levels of expression and the inadequacy of current research tools, CB2 cannabinoid receptors (CB2R) have been difficult to study, particularly in the brain. This receptor is especially relevant in the context of neuroinflammation, so novel tools are needed to unveil its pathophysiological role(s). METHODS: We have generated a transgenic mouse model in which the expression of enhanced green fluorescent protein (EGFP) is under the control of the cnr2 gene promoter through the insertion of an Internal Ribosomal Entry Site followed by the EGFP coding region immediately 3' of the cnr2 gene and crossed these mice with mice expressing five familial Alzheimer's disease (AD) mutations (5xFAD). RESULTS: Expression of EGFP in control mice was below the level of detection in all regions of the central nervous system (CNS) that we examined. CB2R-dependent-EGFP expression was detected in the CNS of 3-month-old AD mice in areas of intense inflammation and amyloid deposition; expression was coincident with the appearance of plaques in the cortex, hippocampus, brain stem, and thalamus. The expression of EGFP increased as a function of plaque formation and subsequent microgliosis and was restricted to microglial cells located in close proximity to neuritic plaques. AD mice with CB2R deletion exhibited decreased neuritic plaques with no changes in IL1ß expression. CONCLUSIONS: Using a novel reporter mouse line, we found no evidence for CB2R expression in the healthy CNS but clear up-regulation in the context of amyloid-triggered neuroinflammation. Data from CB2R null mice indicate that they play a complex role in the response to plaque formation.

Myeloid cell deficiency of p38γ/p38δ protects against candidiasis and regulates antifungal immunity.

Candida albicans is a frequent aetiologic agent of sepsis associated with high mortality in immunocompromised patients. Developing new antifungal therapies is a medical need due to the low efficiency and resistance to current antifungal drugs. Here, we show that p38γ and p38δ regulate the innate immune response to C. albicans We describe a new TAK1-TPL2-MKK1-ERK1/2 pathway in macrophages, which is activated by Dectin-1 engagement and positively regulated by p38γ/p38δ. In mice, p38γ/p38δ deficiency protects against C. albicans infection by increasing ROS and iNOS production and thus the antifungal capacity of neutrophils and macrophages, and by decreasing the hyper-inflammation that leads to severe host damage. Leucocyte recruitment to infected kidneys and production of inflammatory mediators are decreased in p38γ/δ-null mice, reducing septic shock. p38γ/p38δ in myeloid cells are critical for this effect. Moreover, pharmacological inhibition of p38γ/p38δ in mice reduces fungal burden, revealing that these p38MAPKs may be therapeutic targets for treating C. albicans infection in humans.

Massive haemolysis, gas-forming liver abscess and sepsis due to Clostridium perfringens bacteraemia.

Clostridial soft tissue infections are infrequent, but can be life-threatening when associated with certain underlying conditions, such as immunosuppression or malignancy. When bacteraemia occurs, it can be accompanied by haemolysis. Only surgical removal of the focus of infection and early onset of antibiotic therapy can prevent a very poor outcome. We describe the case of a man aged 65 years who presented with sepsis, haemolysis and rapid worsening. The identification of a gas-forming liver abscess, the early percutaneous drainage and the prompt initiation of antibiotic treatment were the key factors in the outcome of this patient.

Neurogenic fever in a patient with a chordoid glioma.

Chordoid gliomas are rare tumours. Despite being considered low-grade neoplasms, recent reviews have reported generally poor prognosis due to complications involving severe hypothalamic symptoms. We report a patient aged 30 years with chordoid glioma. What makes this case report interesting is the presence of neurogenic fever, which was already present before the final diagnosis of the brain tumour and also several months after the surgical removal. Since the patient underwent a subtotal resection of the tumour, it remains unclear whether the fever was due to hypothalamic dysfunction or remnants of the tumour. We also performed temperature logging with a continuous-monitoring recording device.

Eosinophilia and multiple lymphadenopathy: Kimura disease, a rare, but benign condition.

Kimura disease is a benign rare chronic inflammatory disorder of unknown aetiology. This disease is mainly endemic in Asia, although cases have also been reported in Europe and America. We describe a case in a 34-year-old Chinese man presenting with severe eosinophilia and multiple lymphadenopathy. Since our initial aim was to rule out the diagnosis of lymphoma, and given the limitations of our laboratory, we decided to perform an excision of one of the cervical lymph nodes. The histological diagnosis was consistent with Kimura disease. We review the epidemiology, the aetiology and clinical features of this entity.

Dysphagia and aspiration as the only manifestations of a stroke.

A 56-year-old patient was admitted to our hospital, presenting with dysphagia as the only symptom. He was very concerned about this difficulty in swallowing. Diseases of the upper digestive tract were suspected, but further investigations revealed a neurological disorder. He had suffered a brain stem stroke and, as a consequence, developed an aspiration pneumonia. What seemed a digestive disorder was indeed a brain stem stroke, therefore we had to deal with the diverse impacts of this condition.

Primary bone metastasis as first manifestation of an unknown primary tumour.

Unknown primary tumour refers to a group of cancers for which the anatomical site of origin remains occult after detailed investigations. Thanks to sophisticated imaging, immunohistochemical testing and molecular-profiling tools, there is a more accurate approach to unknown primary cancer. Metastasis to bone is not a rare phenomenon, because any tumour can metastasise to bone, so it is a common clinical scenario. The role of clinical history, physical examination, laboratory tests, radiographic studies and immunohistochemistry is critical for a successful diagnostic strategy. Subsets of unknown primary cancers can be identified primarily on the basis of histopathological findings, the pattern of spread and serum markers. New immunohistochemical markers and tissue-of-origin profiles may establish presumable primary sites to unknown primary cancer on the basis of immunohistochemical and molecular patterns. We present a case of a 57-year-old woman without a cancer history, who had primary bone metastasis as the first manifestation of an occult primary tumour.

Combined deletion of p38γ and p38δ reduces skin inflammation and protects from carcinogenesis.

The contribution of chronic skin inflammation to the development of squamous cell carcinoma (SCC) is poorly understood. While the mitogen-activated protein kinase p38α regulates inflammatory responses and tumour development, little is known about the role of p38γ and p38δ in these processes. Here we show that combined p38γ and p38δ (p38γ/δ) deletion blocked skin tumour development in a chemically induced carcinogenesis model. p38γ/δ deletion reduced TPA-induced epidermal hyperproliferation and inflammation; it inhibited expression of proinflammatory cytokines and chemokines in keratinocytes in vitro and in whole skin in vivo, resulting in decreased neutrophil recruitment to skin. Our data indicate that p38γ/δ in keratinocytes promote carcinogenesis by enabling formation of a proinflammatory microenvironment that fosters epidermal hyperproliferation and tumourigenesis. These findings provide genetic evidence that p38γ and p38δ have essential roles in skin tumour development, and suggest that targeting inflammation through p38γ/δ offers a therapeutic strategy for SCC treatment and prevention.

Pro-oncogenic role of alternative p38 mitogen-activated protein kinases p38γ and p38δ, linking inflammation and cancer in colitis-associated colon cancer.

p38 MAPK signaling has been implicated in the regulation of processes leading to cancer development and progression. Chronic inflammation is a known risk factor for tumorigenesis, yet the precise mechanism of this association remains largely unknown. The related p38αMAPK (MAPK14) proteins p38γ (MAPK12) and p38δ (MAPK13) were recently shown to modulate the immune response, although their role in tumorigenesis remains controversial and their function in inflammation-associated cancer has not been studied. We analyzed the role of p38γ and p38δ in colon cancer associated to colitis using the azoxymethane/dextran sodium sulphate (AOM/DSS) colitis-associated colon cancer model in wild-type (WT), p38γ-, p38δ-, and p38γ/δ-deficient (p38γ/δ(-/-)) mice. We found that p38γ/δ deficiency significantly decreased tumor formation, in parallel with a decrease in proinflammatory cytokine and chemokine production. Analysis of leukocyte populations in p38γ/δ(-/-) mouse colon showed less macrophage and neutrophil recruitment than in WT mice. Furthermore, WT chimeric mice with transplanted p38γ/δ(-/-) bone marrow had less tumors than WT mice transplanted with WT bone marrow, whereas tumor number was significantly increased in p38γ/δ(-/-) chimeric mice with WT bone marrow compared with p38γ/δ(-/-) mice transplanted with p38γ/δ(-/-) bone marrow. Together, our results establish that p38γ and p38δ are central to colitis-associated colon cancer formation through regulation of hematopoietic cell response to injury, and validate p38γ and p38δ as potential targets for cancer therapy.