Compartmentalized ocular lymphatic system mediates eye-brain immunity.

The eye, an anatomical extension of the central nervous system (CNS), exhibits many molecular and cellular parallels to the brain. Emerging research demonstrates that changes in the brain are often reflected in the eye, particularly in the retina1. Still, the possibility of an immunological nexus between the posterior eye and the rest of the CNS tissues remains unexplored. Here, studying immune responses to herpes simplex virus in the brain, we observed that intravitreal immunization protects mice against intracranial viral challenge. This protection extended to bacteria and even tumours, allowing therapeutic immune responses against glioblastoma through intravitreal immunization. We further show that the anterior and posterior compartments of the eye have distinct lymphatic drainage systems, with the latter draining to the deep cervical lymph nodes through lymphatic vasculature in the optic nerve sheath. This posterior lymphatic drainage, like that of meningeal lymphatics, could be modulated by the lymphatic stimulator VEGFC. Conversely, we show that inhibition of lymphatic signalling on the optic nerve could overcome a major limitation in gene therapy by diminishing the immune response to adeno-associated virus and ensuring continued efficacy after multiple doses. These results reveal a shared lymphatic circuit able to mount a unified immune response between the posterior eye and the brain, highlighting an understudied immunological feature of the eye and opening up the potential for new therapeutic strategies in ocular and CNS diseases.

Chronic GCPII (glutamate-carboxypeptidase-II) inhibition reduces pT217Tau levels in the entorhinal and dorsolateral prefrontal cortices of aged macaques.

Introduction: Current approaches for treating sporadic Alzheimer's disease (sAD) focus on removal of amyloid beta 1-42 (Aß1-42) or phosphorylated tau, but additional strategies are needed to reduce neuropathology at earlier stages prior to neuronal damage. Longstanding data show that calcium dysregulation is a key etiological factor in sAD, and the cortical neurons most vulnerable to tau pathology show magnified calcium signaling, for example in dorsolateral prefrontal cortex (dlPFC) and entorhinal cortex (ERC). In primate dlPFC and ERC, type 3 metabotropic glutamate receptors (mGluR3s) are predominately post-synaptic, on spines, where they regulate cAMP-calcium signaling, a process eroded by inflammatory glutamate carboxypeptidase II (GCPII) actions. The current study tested whether enhancing mGluR3 regulation of calcium via chronic inhibition of GCPII would reduce tau hyperphosphorylation in aged macaques with naturally-occurring tau pathology. Methods: Aged rhesus macaques were treated daily with the GCPII inhibitor, 2-MPPA (2-3-mercaptopropyl-penanedioic acid (2-MPPA)),Aged rhesus macaques were treated daily with the GCPII inhibitor, 2-MPPA (2-3-mercaptopropyl-penanedioic acid (2-MPPA)). Results: Aged macaques that received 2-MPPA had significantly lower pT217Tau levels in dlPFC and ERC, and had lowered plasma pT217Tau levels from baseline. pT217Tau levels correlated significantly with GCPII activity in dlPFC. Both 2-MPPA- and vehicle-treated monkeys showed cognitive improvement; 2-MPPA had no apparent side effects. Exploratory CSF analyses indicated reduced pS202Tau with 2-MPPA administration, confirmed in dlPFC samples. Discussion: These data provide proof-of-concept support that GCPII inhibition can reduce tau hyperphosphorylation in the primate cortices most vulnerable in sAD. GCPII inhibition may be particularly helpful in reducing the risk of sAD caused by inflammation. These data in nonhuman primates should encourage future research on this promising mechanism. Highlights: Inflammation is a key driver of sporadic Alzheimer's disease.GCPII inflammatory signaling in brain decreases mGluR3 regulation of calcium.Chronic inhibition of GCPII inflammatory signaling reduced pT217Tau in aged monkeys.GCPII inhibition is a novel strategy to help prevent tau pathology at early stages.

Fungal polymerase chain reaction testing in equine ulcerative keratitis.

OBJECTIVE: To assess the diagnostic utility of fungal polymerase chain reaction (PCR) in forty-three horses with naturally acquired corneal ulcers presenting to a private practice. METHODS: Routine evaluation of cytologic, histologic, and microbiologic samples was performed. Two PCR approaches were compared - generic and specific fungal nested PCR followed by sequencing and quantitative PCR (qPCR). PCRs were applied to pure control fungal cultures, corneal tissue from ulcerated eyes and in a subset of 9 horses, to swabs from contralateral normal eyes. RESULTS: The expected fungus was identified by nested PCR and qPCR in all control fungal cultures. In all fungal culture-positive affected eyes (10/43), one or more fungi were identified by nested PCR and 4/10 were positive by qPCR. In 6/10 animals, the same fungus was identified by nested PCR and culture. Of these 6, only three were positive by qPCR. Fungal agents were identified by morphology in 8/10 horses. Diagnosis of fungal keratitis was reserved for only those cases in which the same fungus could be identified by PCR, culture, and morphology (5 horses). In 33/43 culture-negative affected eyes and in 6/9 unaffected eyes, one or more fungi were identified by nested PCR in 26 samples and by qPCR in 2 samples. Apart from Aspergillus spp, similar fungi were identified in affected and control eyes. Most eyes harbored mixed bacterial and fungal agents. CONCLUSIONS: Nested PCR results confirmed all cytologically positive cases of fungal keratitis. Nested PCR identified a greater spectrum of agents than either culture or qPCR.

Iatrogenic tension pneumothorax in a rabbit (Oryctolagus cuniculus).

The following case report describes a complication after accidental overinflation of the lungs in an anesthetized rabbit. After anesthetic induction, endotracheal intubation, and preparation for surgery, the rabbit's arterial oxygen saturation dropped. Positive-pressure ventilation was administered using manual compression on the reservoir bag. The rabbit's condition rapidly deteriorated, and emergency treatment including oxygen, anesthetic reversal, and thoracocentesis was initiated. The rabbit failed to respond to therapy. A focal, acute, alveolar, vascular, and pleural rupture of the right caudal medial lung lobe with secondary pulmonary tension pneumothorax and atelectasis was identified postmortem. The etiology and pathophysiology of the clinical signs are reviewed. Pulmonary pressure overload after manual or assisted ventilation and subsequent stress failure occurs when pulmonary pressures approach 40 mm Hg. Close attention to the animal's size, tidal volume, and potentially altered pulmonary elasticity from pre-existing lung disease may help reduce the incidence of failure. Successful therapy of iatrogenic pneumothorax may necessitate both medical and surgical intervention.

Inducible, reversible hair loss in transgenic mice.

Telogen effluvium is a common type of hair loss. Although the morphological changes associated with telogen effluvium have been well characterized, the underlying molecular mechanisms remain unknown, and no animal models have been developed. We report here that inducible transgenic mice expressing high levels of the transcription factor, tTA (tetracycline transactivator), plus a reporter luciferase gene, show a reversible hair loss phenotype. Skin of these mice exhibits an increase in the number of hair follicles at the telogen phase, but a decreased number of follicles at the anagen phase. These changes resemble skin pathology seen in patients with telogen effluvium, which suggests that the inducible transgenic mice may be useful as a model for this disorder. Moreover, since overexpression of several other transgenes failed to cause skin pathology, the present findings also indicate types of molecular abnormalities that may cause reversible hair loss.