The intestinal epithelium constitutes a first line of defense of the innate immune system. Epithelial dysfunction is a hallmark of intestinal disorders such as inflammatory bowel diseases (IBDs). The actin cytoskeleton controls epithelial barrier integrity but the function of actin regulators such as cortactin is poorly understood. Given that cortactin controls endothelial permeability, we hypothesized that cortactin is also important for epithelial barrier regulation. We found increased permeability in the colon of cortactin-KO mice that was accompanied by reduced levels of ZO-1, claudin-1, and E-cadherin. By contrast, claudin-2 was upregulated. Cortactin deficiency increased RhoA/ROCK1-dependent actomyosin contractility, and inhibition of ROCK1 rescued the barrier defect. Interestingly, cortactin deficiency caused increased epithelial proliferation without affecting apoptosis. KO mice did not develop spontaneous colitis, but were more susceptible to dextran sulfate sodium colitis and showed severe colon tissue damage and edema formation. KO mice with colitis displayed strong mucus deposition and goblet cell depletion. In healthy human colon tissues, cortactin co-localized with ZO-1 at epithelial cell contacts. In IBDs patients, we observed decreased cortactin levels and loss of co-localization with ZO-1. Thus, cortactin is a master regulator of intestinal epithelial barrier integrity in vivo and could serve as a suitable target for pharmacological intervention in IBDs.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), is a global health threat with the potential to cause severe disease manifestations in the lungs. Although COVID-19 has been extensively characterized clinically, the factors distinguishing SARS-CoV-2 from other respiratory viruses are unknown. Here, we compared the clinical, histopathological, and immunological characteristics of patients with COVID-19 and pandemic influenza A(H1N1). We observed a higher frequency of respiratory symptoms, increased tissue injury markers, and a histological pattern of alveolar pneumonia in pandemic influenza A(H1N1) patients. Conversely, dry cough, gastrointestinal symptoms and interstitial lung pathology were observed in COVID-19 cases. Pandemic influenza A(H1N1) was characterized by higher levels of IL-1RA, TNF-α, CCL3, G-CSF, APRIL, sTNF-R1, sTNF-R2, sCD30, and sCD163. Meanwhile, COVID-19 displayed an immune profile distinguished by increased Th1 (IL-12, IFN-γ) and Th2 (IL-4, IL-5, IL-10, IL-13) cytokine levels, along with IL-1β, IL-6, CCL11, VEGF, TWEAK, TSLP, MMP-1, and MMP-3. Our data suggest that SARS-CoV-2 induces a dysbalanced polyfunctional inflammatory response that is different from the immune response against pandemic influenza A(H1N1). Furthermore, we demonstrated the diagnostic potential of some clinical and immune factors to differentiate both diseases. These findings might be relevant for the ongoing and future influenza seasons in the Northern Hemisphere, which are historically unique due to their convergence with the COVID-19 pandemic.

Chordoid meningioma is a rare variant of meningioma with histological features resembling those of chordoma. This tumor has a great risk of recurrence and aggressive growth (WHO grade II). This study was done to document the clinical and pathological features of ten patients with chordoid meningioma who submitted to surgery at the National Institute of Neurology and Neurosurgery in Mexico City. Clinical, histological and immunohistochemical features were examined. The age range was from 30 to 67 years old (mean, 34.2 years). Seven patients were female and three male. The duration of symptoms varied from 3.5 months to 5 years (mean, 14.1 months). No systemic symptoms were noted. The tumor was localized in eight cases in the supratentorial compartments. Histologically, the tumors were characterized by strands and cords of meningothelial cells arranged in a mucinous stroma. Two of the ten tumors showed metaplasic changes, and seven showed brain invasion. Tumor cells demonstrated CK7, EMA and focal S-100 protein and Ep-CAM. Cytokeratin AE1/AE3, GFAP and synaptophysin were negative. The MIB-1 proliferative index was from 6 to 9% (mean 7.8). PCNA Li was 6 to 20% (mean, 14), and microvascular density was 6-16 (mean, 14.5). The mean rate of the MIB-1 labeling index in recurrences was 7.1% versus 6.33% for no tumor recurrence. Chordoid meningioma, World Health Organization grade II, is an uncommon variant of meningioma with a propensity for aggressive behavior and increased likelihood of recurrence. Chordoid meningiomas are predominantly tumors of young adults with a predilection for the supratentorial location. Intraventricular location and absence of systemic manifestations, despite the presence of abundant B-lymphocytes, mast cells and low MIB-1 LI, are some of the interesting findings in the present series that need further study. Hence, a larger number of cases with adequate follow-up data need to be studied further to establish the clinical relevance of this variant.

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Severe coronavirus disease 2019 (COVID‐19) is characterized by lung injury, cytokine storm, and increased neutrophil‐to‐lymphocyte ratio (NLR). Current therapies focus on reducing viral replication and inflammatory responses, but no specific treatment exists to prevent the development of severe COVID‐19 in infected individuals. Angiotensin‐converting enzyme‐2 (ACE2) is the receptor for SARS‐CoV‐2, the virus causing COVID‐19, but it is also critical for maintaining the correct functionality of lung epithelium and endothelium. Coronaviruses induce activation of a disintegrin and metalloprotease 17 (ADAM17) and shedding of ACE2 from the cell surface resulting in exacerbated inflammatory responses. Thus, we hypothesized that ADAM17 inhibition ameliorates COVID‐19‐related lung inflammation. We employed a preclinical mouse model using intratracheal instillation of a combination of polyinosinic:polycytidylic acid (poly(I:C)) and the receptor‐binding domain of the SARS‐CoV‐2 spike protein (RBD‐S) to mimic lung damage associated with COVID‐19. Histologic analysis of inflamed mice confirmed the expected signs of lung injury including edema, fibrosis, vascular congestion, and leukocyte infiltration. Moreover, inflamed mice also showed an increased NLR as observed in critically ill COVID‐19 patients. Administration of the ADAM17/MMP inhibitors apratastat and TMI‐1 significantly improved lung histology and prevented leukocyte infiltration. Reduced leukocyte recruitment could be explained by reduced production of proinflammatory cytokines and lower levels of the endothelial adhesion molecules ICAM‐1 and VCAM‐1. Additionally, the NLR was significantly reduced by ADAM17/MMP inhibition. Thus, we propose inhibition of ADAM17/MMP as a novel promising treatment strategy in SARS‐CoV‐2‐infected individuals to prevent the progression toward severe COVID‐19.

Background and Importance. Sellar tuberculomas are extremely rare lesions with nonspecific clinical manifestations. The tuberculous infection of the pituitary gland and sellar region is characterized by the presence of an acute or chronic inflammatory reaction and may occur in the absence of systemic tuberculosis. The diagnosis is difficult prior to the surgery. An adequate diagnostic and antituberculous drugs usually result in a good outcome. Clinical Presentation. We report four cases of sellar tuberculoma, 3/1 female/male, age range: 50–57 years. All patients had visual disturbances and low levels of cortisol. Conclusion. The clinical diagnosis of sellar tuberculoma is a challenge and should be suspected when a sellar lesion shows abnormal enhancement pattern and stalk involvement, and absence of signal suppression in FLAIR.

This study was developed in order to describe the early morphological events observed during the invasion of two pathogenic strains of Acanthamoeba (genotype T4); A. castellanii and A. culbertsoni, at the olfactory meatus and cerebral, pulmonary, renal, hepatic and splenic tissues levels, an in vivo invasion study. Histological and immunohistochemical description of the events at 24, 48, 72, and 96 h postintranasal inoculations of BALB/c mice was performed. A. castellanii showed a higher invasion rate than A. culbertsoni, which was only able to reach lung and brain tissue in the in vivo model. The current study supports previous evidence of lack of inflammatory response during the early stages of infection. Acanthamoeba invasion of the CNS and other organs is a slow and contact-dependent process. The early morphological events during the invasion of amoebae include the penetration of trophozoites into different epithelia: olfactory, respiratory, alveolar space, and renal tubule, which resemble the process of amoebae invasion described in corneal tissue. The data suggest that after reaching the nasal epithelium, trophozoites continued invasion, separating and lifting the most superficial cells, then migrating and penetrating between the cell junctions without causing a cytolytic effect on adjacent cells. These results reaffirm the idea that contact-dependent mechanisms are relevant for amoebae of Acanthamoeba genus regardless of the invasion site.

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