Thomas J. Cummings

Systemic CTLA-4 Blockade Ameliorates Glioma-Induced Changes to the CD4+ T Cell Compartment without Affecting Regulatory T-Cell Function

Purpose: Patients with malignant glioma suffer global compromise of their cellular immunity, characterized by dramatic reductions in CD4+ T cell numbers and function. We have previously shown that increased regulatory T cell (Treg) fractions in these patients explain T-cell functional deficits. Our murine glioma model recapitulates these findings. Here, we investigate the effects of systemic CTLA-4 blockade in this model. Experimental Design: A monoclonal antibody (9H10) to CTLA-4 was employed against well-established glioma. Survival and risks for experimental allergic encephalomyelitis were assessed, as were CD4+ T cell numbers and function in the peripheral blood, spleen, and cervical lymph nodes. The specific capacities for anti-CTLA-4 to modify the functions of regulatory versus CD4+CD25− responder T cells were evaluated. Results: CTLA-4 blockade confers long-term survival in 80% of treated mice, without eliciting experimental allergic encephalomyelitis. Changes to the CD4 compartment were reversed, as anti-CTLA-4 reestablishes normal CD4 counts and abrogates increases in CD4+CD25+Foxp3+GITR+ regulatory T cell fraction observed in tumor-bearing mice. CD4+ T-cell proliferative capacity is restored and the cervical lymph node antitumor response is enhanced. Treatment benefits are bestowed exclusively on the CD4+CD25− T cell population and not Tregs, as CD4+CD25− T cells from treated mice show improved proliferative responses and resistance to Treg-mediated suppression, whereas Tregs from the same mice remain anergic and exhibit no restriction of their suppressive capacity. Conclusions: CTLA-4 blockade is a rational means of reversing glioma-induced changes to the CD4 compartment and enhancing antitumor immunity. These benefits were attained through the conferment of resistance to Treg-mediated suppression, and not through direct effects on Tregs.

Systemic Anti-CD25 Monoclonal Antibody Administration Safely Enhances Immunity in Murine Glioma without Eliminating Regulatory T Cells

Purpose: Elevated proportions of regulatory T cells (Treg) are present in patients with a variety of cancers, including malignant glioma, yet recapitulative murine models are wanting. We therefore examined Tregs in mice bearing malignant glioma and evaluated anti-CD25 as an immunotherapeutic adjunct. Experimental Design: CD4+CD25+Foxp3+GITR+ Tregs were quantified in the peripheral blood, spleens, cervical lymph nodes, and bone marrow of mice bearing malignant glioma. The capacities for systemic anti-CD25 therapy to deplete Tregs, enhance lymphocyte function, and generate antiglioma CTL responses were assessed. Lastly, survival and experimental allergic encephalitis risks were evaluated when anti-CD25 was combined with a dendritic cell–based immunization targeting shared tumor and central nervous system antigens. Results: Similar to patients with malignant glioma, glioma-bearing mice show a CD4 lymphopenia. Additionally, CD4+CD25+Foxp3+GITR+ Tregs represent an increased fraction of the remaining peripheral blood CD4+ T cells, despite themselves being reduced in number. Similar trends are observed in cervical lymph node and spleen, but not in bone marrow. Systemic anti-CD25 administration hinders detection of CD25+ cells but fails to completely eliminate Tregs, reducing their number only moderately, yet eliminating their suppressive function. This elimination of Treg function permits enhanced lymphocyte proliferative and IFN-γ responses and up to 80% specific lysis of glioma cell targets in vitro. When combined with dendritic cell immunization, anti-CD25 elicits tumor rejection in 100% of challenged mice without precipitating experimental allergic encephalitis. Conclusions: Systemic anti-CD25 administration does not entirely eliminate Tregs but does prevent Treg function. This leads to safe enhancement of tumor immunity in a murine glioma model that recapitulates the tumor-induced changes to the CD4 and Treg compartments seen in patients with malignant glioma.

Gliomas of the optic nerve: histological, immunohistochemical (MIB-1 and p53), and MRI analysis

Abstract Gliomas of the optic nerve, although typically of pilocytic (WHO grade I) histology, can present within the spectrum of astrocytic neoplasia including glioblastoma (WHO grade IV). In certain cases, histologic features alone make the distinction between pilocytic and diffuse astrocytomas difficult. We reviewed 22 cases of optic nerve gliomas, 19 of which were pilocytic astrocytomas (PA), and 3 of which were diffuse, non-pilocytic astrocytomas. The cases were evaluated for their clinical course, radiographic appearance, histologic grade, and proliferation indices as detected by MIB-1 (Ki-67) and p53 antibodies. Of the 19 PA, 14 showed no tumor growth by magnetic resonance imaging, and had Ki-67 and p53 labeling indices (LI) of < 1%. The other 5 PA exhibited aggressive behavior manifest by marked diffuse infiltrative tumor growth causing death in 2 patients, 1 of whom was diagnosed with neurofibromatosis type 1 (immunoperoxidase and radiographs not available), and marked local growth with an average time to growth of 39.3 months, a Ki-67 LI of 2–3%, and a p53 LI of < 1% in three others. Three of the five aggressive PA histologically demonstrated a finely reticulated pattern, a pattern that appears as an exaggeration or expansion of the normal neuroglia of the optic nerve, and may simulate a diffuse low-grade astrocytoma. Two demonstrated the coarsely reticulated pattern, with the biphasic and microcystic pattern typical of PA. Three diffuse astrocytomas (2 anaplastic astrocytomas and 1 glioblastoma) originated clinically and radiographically from the optic nerve, and revealed a Ki-67 LI of 2–12%, a p53 LI of 2–8%, and an average time to growth of 8 months. We conclude that the majority of PA of the optic nerve are non-aggressive, stabilize radiographically, and have Ki-67 and p53 LI < 1%. However, a subpopulation of PA has a propensity for aggressive behavior, and are identified by a Ki-67 LI of 2–3% and a p53 LI of < 1%. Diffuse astrocytomas have both Ki-67 and p53 LI > 2%. Thus, in cases of aggressive optic nerve tumors in which the histologic review of biopsy material cannot confidently confirm the diagnosis of pilocytic or diffuse fibrillary glioma, a p53 LI of > 1% appears to favor the diagnosis of diffuse astrocytoma.

Recovery and expression of messenger RNA from postmortem human brain tissue

The Bryan Alzheimers Disease Research Center Rapid Autopsy Program at Duke University Medical Center obtains postmortem human brain tissue for experimental investigations. We evaluated 19 brains for RNA integrity and mRNA gene expression. Nine were from patients diagnosed with Alzheimers disease, and ten were from nondemented controls. In all cases, the following variables were recorded: postmortem procurement delay (range, 1 hour and 10 minutes to 14 hours), pH of cerebrospinal fluid, premortem fever or sepsis, provision of supplemental oxygen in the agonal period, and temporal relation to time of death (either sudden death or protracted illness). Total RNA was extracted, quantified, and evaluated by agarose gel electrophoresis and quantitative gene expression analysis of 18S rRNA and edg-1 using TaqMan technology. All samples appeared to yield intact RNA without significant degradation, and expression of the edg-1 gene was detected by the real time reverse transcriptase polymerase chain reaction in all cases. We conclude that intact RNA can be obtained from postmortem human brain tissue, even in patients with severe premortem illnesses and delayed postmortem tissue procurement intervals. However, we caution that the successful expression of certain genes from postmortem brain tissue may require enhanced procurement efforts to maximize RNA integrity.

CD34 and dural fibroblasts: the relationship to solitary fibrous tumor and meningioma

Abstract. Intracranial solitary fibrous tumors (SFTs) are typically dural-based, CD34-positive neoplasms of uncertain histogenesis. We examined ten cases of meninges obtained at autopsy from patients with no history of neurological illness, head trauma, or neurosurgical intervention, and ten cases of typical meningiomas with attached dural margins not involved by tumor. All cases were immunostained with CD34. CD34 reactivity was noted in the long, thin delicate processes of dural fibroblasts preferentially located in the meningeal portion of the dura rather than the periosteal portion. No CD34 reactivity was identified in the arachnoid or pia mater, except in some endothelial cells. One supratentorial dural-based fibrous nodule and one SFT within the confines of the fourth ventricle showed strong and diffuse reactivity to CD34, bcl-2, and vimentin, and were negative for epithelial membrane antigen (EMA), S-100 protein, glial fibrillary acidic protein, smooth muscle actin, and desmin. We also describe a meningothelial meningioma within which a well circumscribed SFT-like nodule was embedded. The SFT-like nodule was strongly CD34 positive and EMA negative, and the meningioma was strongly EMA positive and CD34 negative. Fibroblasts of the dural border cell layer are attached to the underlying arachnoid, and their inclusion with arachnoidal stromal elements and pial-based tela choroidea during formation of choroid plexus interstitium may account for intraventricular SFTs. Our results suggest that SFTs and dural-based fibrous nodules derive from CD34-positive dural-based fibroblasts, and that CD34 reactivity in meningiomas may result from inclusion of dural fibroblasts within the neoplasm.

Survival Risk Assessment for Primary Blast Exposures to the Head

Many soldiers returning from the current conflicts in Iraq and Afghanistan have had at least one exposure to an explosive event and a significant number have symptoms consistent with traumatic brain injury. Although blast injury risk functions have been determined and validated for pulmonary injury, there is little information on the blast levels necessary to cause blast brain injury. Anesthetized male New Zealand White rabbits were exposed to varying levels of shock tube blast exposure focused on the head, while their thoraces were protected. The specimens were euthanized and evaluated when the blast resulted in respiratory arrest that was non-responsive to resuscitation or at 4?h post-exposure. Injury was evaluated by gross examination and histological evaluation. The fatality data from brain injury were then analyzed using Fishers exact test to determine a brain fatality risk function. Greater blast intensity was associated with post-blast apnea and the need for mechanical ventilation. Gross examination revealed multifocal subdural hemorrhages, most often near the brainstem, at more intense levels of exposure. Histological evaluation revealed subdural and subarachnoid hemorrhages in the non-responsive respiratory-arrested specimens. A fatality risk function from blast exposure to the head was determined for the rabbit specimens with an LD(50) at a peak overpressure of 750?kPa. Scaling techniques were used to predict injury risk at other blast overpressure/duration combinations. The fatality risk function showed that the blast level needed to cause fatality from an overpressure wave exposure to the head was greater than the peak overpressure needed to cause fatality from pulmonary injury. This risk function can be used to guide future research for blast brain injury by providing a realistic fatality risk to guide the design of protection or to evaluate injury.

Effects of indocyanine green on the retina and retinal pigment epithelium in a porcine model of retinal hole.

Purpose: This study was designed to emulate human macular hole surgery and to test the effects of indocyanine green (ICG) on the retina and retinal pigment epithelium (RPE). Methods: Yorkshire Cross pigs (n = 23) underwent vitrectomy, separation of the posterior cortical vitreous, and creation of a single retinal hole. In three study groups (n = 6, each group), air–fluid exchange was performed, following which balanced salt solution (BSS), 1.0% ICG, or 0.5% ICG was applied over the retinal hole. In one additional group (n = 5), 0.5% ICG was injected into the fluid-filled eye. At 4 weeks, the eyes were examined clinically, and fundus photographs were obtained before enucleation and light microscopic examination. Results: Clinical evaluations documented a statistically significant difference between study groups (P = 0.036). There was a higher rate of moderate or severe RPE atrophy among animals where 1% or 0.5% ICG was applied in air-filled eyes (83% and 67%, respectively) compared with BSS controls (17%) and fluid-filled eyes receiving 0.5% ICG (40%). Histologic evaluation demonstrated a statistically significant difference between groups (P = 0.044), with extensive outer retinal degeneration observed in air-filled eyes receiving 1% or 0.5% ICG (66% and 60%, respectively) compared with BSS controls or fluid-filled eyes receiving 0.5% ICG (none of the eyes in either group). None of the study groups had any changes in the inner retina except at the retinal hole site. Conclusions: Retina exposed to ICG concentrations used in human vitreoretinal surgery had greater RPE atrophy and outer retinal degeneration than control eyes undergoing the same surgery without ICG. Eyes filled with infusion fluid during ICG injection had less damage to the RPE and outer retina than did air-filled eyes receiving ICG.

Ultrasonographic appearance of intraneural injections in the porcine model.

Background: Ultrasonographic (US) images of apparent intraneural injection of local anesthetic solutions have been reported. We aimed to define US signs of intraneural (ie, subepineural) injection using a histologic standard in an animal model and compare these signs with other potential markers of intraneural injection, including low nerve stimulation current thresholds and high injection pressures. Methods: In 6 anesthetized adult swine, bilateral brachial plexus and femoral nerves were contacted by needles and penetrated. India ink was injected intraneurally under US monitoring. The minimum current that elicited a motor response was recorded. Injection pressures were measured using a digital manometer. Nerves were then excised, processed, and subjected to histologic analysis. Results: Nerve expansion during injection was visualized under ultrasonography in all procedures. Electrical current intensity to elicit motor response to nerve stimulation varied between 0.2 and 3.3 mA with the needle tip positioned intraneurally. The mean injection pressure was 7.40 ± 8.07 psi (range, 0.07-31.5 psi), with 80% of injections between 0.61 and 15.0 psi. None of 24 intraneural injections resulted in histologic evidence of intrafascicular injection (95% confidence interval, 0.0%-16.3%). Conclusions: Ultrasonographic images compatible with nerve swelling during an injection are consistent with true intraneural injections as demonstrated by histologic analysis. Under the conditions studied, intensity of the stimulating current required to elicit motor response was not associated with intraneural needle placement. In the absence of fascicular injury, intraneural injections were associated with low injection pressure, although false-positive results can occur.

Dementia with Lewy bodies and Alzheimer's disease

Abstract.To investigate similarities and differences between Alzheimers disease (AD) and dementia with Lewy bodies (DLB), we undertook a demographic analysis of 277 patients from the Kathleen Price Bryan Brain Bank with an antemortem diagnosis of probable AD. Patients with additional, possibly confounding clinical and pathologic diagnoses such as infarcts, hematomas, neoplasms, and other neurodegenerative disorders, were excluded from the analysis. Neuropathologically, AD alone was present in 192 subjects (69%), and DLB was found in 85 subjects (31%). All of the DLB cases had neuropathologic evidence of AD sufficient to meet CERAD criteria for a diagnosis of definite AD plus nigral Lewy bodies. Gender, apolipoprotein E (APOE) genotype, brain weight, age at death, duration of disease and Braak stage were compared between the two groups. Statistical analyses were performed using Fishers exact test for comparisons of categorical data and Students t-test for comparison of means for continuous outcomes. The proportion of males and females was balanced in the combined AD and DLB populations. There was a highly statistically significant increased frequency of APOE 3/4 in males with DLB (P=0.007). We found higher brain weights in males with DLB versus males with AD (P=0.012). AD was more frequent in females and DLB was more frequent in males (P=0.019). Our findings with respect to age at death, duration of disease and Braak stage within diagnostic groups confirm previously reported findings. These data suggest that Lewy bodies are more common in males affected with dementia, especially those with the APOE 3/4 genotype.

Endodermal cyst of the oculomotor nerve

Endodermal cysts are rare congenital intracranial lesions. Although histologically benign, they can become symptomatic as a result of mass effect and cause neurological deficits. We report a 30-year-old woman who presented with paresis of her right oculomotor nerve. Magnetic resonance imaging showed a 13×8-mm cystic lesion originating from the right oculomotor nerve at its exit from the mesencephalon. She underwent craniotomy, biopsy, slit resection, and drainage of the cyst. To our knowledge, endodermal cysts have not been previously described in relation to the oculomotor nerve.