Neuroprotective Effects of a Serotonin Receptor Peptide Following Sham vs. Mild Traumatic Brain Injury in the Zucker Rat

Aims

Accelerated cognitive decline frequently complicates traumatic brain injury. Obesity and type 2 diabetes mellitus drive peripheral inflammation which may accelerate traumatic brain injury-associated neurodegeneration. The Zucker rat harbors G-protein coupled receptor agonist IgG autoantibodies and in vitro neurotoxicity caused by these autoantibodies was prevented by a novel synthetic fragment of the serotonin 2A receptor. The aim of the present study was to test whether genetic obesity manifested in Zucker diabetic fatty rat is associated with greater spatial memory impairment before and after mild traumatic brain injury compared to Zucker lean rats. Furthermore, we investigated whether these neurodegenerative complications can be lessened by administration of a novel putative neuroprotective peptide comprised of a fragment of the second extracellular loop of the serotonin 2A receptor.

Methods

Age-matched lean and fatty diabetic Zucker rats were tested in the Morris water maze (spatial memory) prior to receiving a sham-injury or lateral fluid percussion (LFP) mild traumatic brain injury. Behavioral testing was repeated at 1-week, 1-month, and 3-month intervals following injury. A synthetic peptide consisting of a portion of the 5-hydroxytryptamine (serotonin) 2A receptor (2 mg/kg) (vehicle, or an inactive scrambled version of the peptide (2 mg/kg)) was administered via intraperitoneal route every other day for 7 days after sham or LFP injury to lean rats or 7 days before and after sham or LFP injury to fatty rats.

Results

Mild traumatic brain injury impaired recall of spatial memory in fatty and lean rats. Zucker fatty rats subjected to sham-injury or mild TBI experienced a significantly greater longitudinal decline in recall of spatial memory compared to lean Zucker rats. A synthetic peptide fragment of the 5-hydroxytryptamine 2A receptor significantly enhanced acquisition of spatial learning and it appeared to strengthen recall of spatial learning (one-week) after sham injury in Zucker rats.

Conclusions

These data suggest that the Zucker diabetic fatty rat is a suitable animal model to investigate the role of metabolic factor(s) in accelerated cognitive decline. A novel synthetic peptide comprised of a fragment of the second extracellular loop of the human serotonin 2A receptor appeared to have neuroprotective effects on both acquisition and recall of spatial memory in subsets of Zucker rats, with relatively greater benefit in sham-injured, lean Zucker rats.

Repeated Traumatic Brain Injury is Associated with Neurotoxic Plasma Autoantibodies Directed against the Serotonin 2A and Alpha 1 Adrenergic Receptors

Objectives

Traumatic brain injury (TBI) was associated with increased plasma agonist autoantibodies targeting the serotonin 2A receptor. Repeated TBI exposure is associated with high risk for neurodegenerative and neuropsychiatric complications. Here we tested a hypothesis that repeated TBI is associated with plasma agonist autoantibodies targeting more than one kind of catecholamine G-protein coupled receptor.

Methods

Protein-A affinity chromatography was used to isolate the IgG fraction of plasma in forty-two middle-aged and older adults who had experienced one or more TBI exposures. The Ig (1/40th dilution=7.5 ug/mL) were tested for neurotoxicity in mouse neuroblastoma cells using an acute neurite retraction assay indicative of Gq11/IP3/Ca2+ and RhoA/Rho kinase signaling pathways' activation. Three different linear synthetic peptides corresponding to the second extracellular loop of the alpha 1A, alpha 2A or serotonin 2A receptors were used as target antigen in different enzyme-linked immunoassays. The second extracellular loop receptor peptides themselves (alpha 1A, alpha 2A) or a fragment (serotonin 2A) were tested for ability to prevent Ig-induced neurite retraction.

Results

Patients who had experienced either repeated TBI (N=10) or a single TBI with a co-morbid autoimmune disease (N=5) were significantly more likely to harbor neurotoxic plasma autoantibodies targeting both alpha 1 adrenergic and serotonin 2A receptors vs. patients having only a single TBI. Ig-induced neurotoxicity was significantly prevented by co-incubation with either 850 nM prazosin (alpha 1 adrenergic receptor) and/or 500 nM M100907 (serotonin 2A receptor) antagonists. Alpha 1 adrenergic receptor and serotonin 2A receptor Ig immunoreactive level and titer were significantly increased in repeated TBI and single TBI/autoimmune patients (N=7-8) compared to age-matched TBI patients without neurotoxic plasma Ig (N=4). SN.8, a linear synthetic peptide corresponding to a conserved region of the second extracellular loop (ECL) of the serotonin 2A receptor completely prevented neurite retraction induced by repeated TBI plasma Ig. A repeated TBI patient harboring alpha adrenergic receptor AAB alone experienced prospective steep decline in cognitive function over two years.

Conclusions

Repeated TBI and TBI with associated autoimmunity harbored more than one kind of neurotoxic catecholaminergic agonist GPCR autoantibody each associated with high risk for steep rate of cognitive decline. Specific immunoassays using the second extracellular receptor loop as target antigen are needed to detect each specific different GPCR autoantibody. A fragment of the second ECL of the serotonin 2A receptor (SN.8) neutralized Ig-induced neurotoxicity in repeated TBI or TBI with associated systemic autoimmunity.

Myristolated Serotonin 2A Receptor Peptide Promotes Long-Lasting Blood Pressure-Lowering and Reno protection in Hypertensive Rat Species

Aim

The aim of the present study was to test whether conjugation of a synthetic peptide corresponding to a fragment of the second extracellular domain of the human serotonin 2A receptor substantially alters the in vivo pharmacodynamic blood pressure-lowering profile of the peptide in different hypertensive rat strains.

Methods

Sertuercept (SCLLADDN) was synthesized and modified using pegylation or myristolation. The two different peptide conjugates were tested in male Zucker diabetic fatty rats for acute and long-lasting blood pressure-lowering effects following single intraperitoneal administration. The myristolated Sertuercept was administered intraperitoneally to female Zucker fatty and male spontaneously hypertensive rats (SHR) and blood pressure was monitored either using tail cuff measurement (female Zucker) or by telemetry (SHR) rats. Plasma immunoglobulin G obtained by Protein G affinity chromatography in 25-week-old female Zucker or male spontaneously hypertensive rats was tested for binding to a linear synthetic peptide corresponding to the second extracellular loop of the serotonin 2A receptor. A cohort of male Zucker diabetic fatty rats was randomized to seven weeks of once-weekly myristolated Sertuercept or scrambled peptide (injections) and the kidneys were examined histologically for differences in total kidney lesions or fibrosis.

Results

Pegylated Sertuercept promoted substantial blood pressure-lowering lasting approximately 30-48 hours in male Zucker diabetic fatty rats. Blood pressure-lowering following a single injection of Myristolated Sertuercept was much longer-lasting (6-11 days) and it was effective in male Zucker diabetic fatty rats, male spontaneously hypertensive rats and in a subset of hypertensive female Zucker fatty rats. Seven weeks' treatment with once-weekly Myristolated Sertuercept (2mg/kg) was associated with significantly fewer kidney lesions and less interstitial fibrosis compared to scrambled peptide in 25-week-old male Zucker diabetic fatty rats. Male spontaneously hypertensive rats (4 of 4 tested) harbored plasma IgG which bound significantly to serotonin 2A receptor peptide, and a subset of female Zucker fatty rats harboring IgG were responsive to blood pressure-lowering from the myristolated Sertuercept peptide.

Summary

Myristolated-Sertuercept, an epitope-specific peptide comprised of a portion of second extracellular loop of the human serotonin 2A receptor was safe, well-tolerated and effectively lowered blood pressure for one week or longer in two different strains of male hypertensive rats. These data provide proof-of-concept that once-weekly systemic drug administration is feasible to achieve not only long-lasting hypertension control, but also substantial renoprotection.

Plasma Serotonin 2A Receptor Autoantibodies Predict Rapid, Substantial Decline in Neurocognitive Performance in Older Adult Veterans with TBI

AIM

Traumatic brain injury (TBI) was associated with increased plasma serotonin 2A receptor (5-HT2AR) autoantibodies in adults who experienced neurodegenerative complications. We tested whether the baseline presence of plasma serotonin 2A receptor (5-HT2AR) autoantibodies was a significant predictor of the two-year rate of cognitive decline in middle-aged and older adult TBI.

METHODS

Plasma from thirty-five middle-aged and older adult veterans (mean 65 years old) who had suffered traumatic brain injury was subjected to protein-A affinity chromatography. One-fortieth dilution of the resulting immunoglobulin (Ig) G fraction was tested for binding (in ELISA) to a linear synthetic peptide corresponding to the second extracellular loop region of the human 5-HT2A receptor. All available patients completed baseline and two-year follow-up neurocognitive tests of memory (St Louis University Mental Status), processing speed (Digit Symbol Substitution Test) and executive function (Trails-making Test, Part B). Change in cognitive performance was computed as (two-year - baseline) raw test score.

RESULTS

Eighteen patients completed both baseline and two-year follow up neurocognitive tests. TBI patients harboring plasma 5-HT2AR autoantibodies at the baseline examination (n=13) did not differ significantly in their baseline clinical characteristics (age, education level) compared to TBI patients lacking baseline plasma autoantibodies (n=5). Plasma serotonin 2AR antibody-positive patients experienced a significantly greater post-baseline decline in performance on the St Louis University Mental Status test (P=0.0118) and in the Digit Symbol Substitution Test (P=0.011), but not in Trails-making Part B (P=0.129) compared to serotonin 2AR antibody-negative patients. In multivariable linear regression analyses that adjusted for age, baseline presence of plasma 5-HT2AR autoantibody was a significant predictor of the two-year rate of decline in memory, and processing speed. Binding of plasma autoantibody to the serotonin 2A receptor peptide in the enzyme linked immunosorbent assay was also significantly higher (at 1/160th titer of the protein-A eluate= 1 μg/mL IgG) in TBI patients harboring vs. those not harboring baseline plasma 5-HT2AR autoantibodies.

CONCLUSION

These data suggest that plasma 5-hydroxytryptamine 2A receptor autoantibodies which were increased in approximately two-thirds of middle-aged and older adults following traumatic brain injury predicts rapid and substantial declines in cognitive function (memory and processing speed), independent of age.

A Serotonin 2A-Receptor Decoy Peptide Potently Lowers Blood Pressure in Male Zucker Diabetic, Fatty, Hypertensive Rats

AIMS

To test whether a novel 5-hydroxytryptamine 2A decoy receptor peptide, SN..8 (Sertuercept), administered via intraperitoneal injection, acutely lowers arterial blood pressure in obese, hypertensive male Zucker diabetic rats (ZDF). To examine the safety, tolerability and possible reno-protective effects following chronic alternate daily administration of Sertuercept (for 10 weeks) in the male ZDF rat.

METHODS

Systolic and diastolic blood pressure were determined at baseline and regular intervals for up to 48 hours after a single IP administration of either Sertuercept (2 mg/kg), vehicle (saline) or an identical concentration of a scrambled sequence of the decoy receptor peptide, LN…8, in male ZDF and Zucker lean rats using tail cuff plethysmography. Plasma autoantibodies were obtained in thirteen male ZDF rats for determination of 5-hydroxytryptamine 2A receptor-mediated neurotoxicity using an acute neurite retraction assay in mouse neuroblastoma cells. Rats were sacrificed at 25-weeks of age, the kidneys were perfused, fixed and sections were stained using Masson's trichrome for semi-quantitative determination of glomerular and interstitial fibrosis.

RESULTS

Sertuercept (2 mg/kg IP) potently lowered systolic and diastolic blood pressure in both 11-week-old and 25-week-old male ZDF rats and in a subset of hypertensive Zucker lean rats. There was no significant blood pressure-lowering effect of vehicle (saline) or scrambled peptide sequence (LN.8). Blood pressure-lowering was rapid in onset (15-30 minutes following IP injection) and sustained for at least 24 hours. Alternate daily IP administration of 2 mg/kg dose of Sertuercept vs. scrambled peptide (for 10 weeks) was safe, well-tolerated and associated with a significant decrease in glomerulosclerosis in 25-week-old male ZDF rats. Plasma autoantibody-induced neurotoxicity correlated significantly with the global index of renal fibrosis severity in 25-week-old male ZDF rats.

CONCLUSIONS

These data indicate potent arterial blood pressure-lowering efficacy from a decoy receptor peptide comprised of a second extracellular loop region of the human 5-hydroxytryptamine receptor. Chronic administration of the decoy receptor peptide (10 weeks) was safe, well-tolerated and protected against renal glomerulosclerosis in the male ZDF rat.

Gene Expression Changes in a Model Neuron Cell Line Exposed to Autoantibodies from Patients with Traumatic Brain Injury and/or Type 2 Diabetes

Traumatic brain injury and adult type 2 diabetes mellitus are each associated with the late occurrence of accelerated cognitive decline and Parkinson’s disease through unknown mechanisms. Previously, we reported increased circulating agonist autoantibodies targeting the 5-hydroxytryptamine 2A receptor in plasma from subsets of Parkinson’s disease, dementia, and diabetic patients suffering with microvascular complications. Here, we use a model neuron, mouse neuroblastoma (N2A) cell line, to test messenger RNA expression changes following brief exposure to traumatic brain injury and/or type 2 diabetes mellitus plasma harboring agonist 5-hydroxytryptamine 2A receptor autoantibodies. We now report involvement of the mitochondrial dysfunction pathway and Parkinson’s disease pathways in autoantibody-induced gene expression changes occurring in neuroblastoma cells. Functional gene categories upregulated significantly included cell death, cytoskeleton-microtubule function, actin polymerization or depolymerization, regulation of cell oxidative stress, mitochondrial function, immune function, protein metabolism, and vesicle function. Gene categories significantly downregulated included microtubule function, cell adhesion, neurotransmitter release, dopamine metabolism synaptic plasticity, maintenance of neuronal differentiation, mitochondrial function, and cell signaling. Taken together, these results suggest that agonist 5-hydroxytryptamine receptor autoantibodies (which increase in Parkinson’s disease and other forms of neurodegeneration) mediate a coordinating program of gene expression changes in a model neuron which predispose to neuro-apoptosis and are linked to human neurodegenerative diseases pathways.

Severe COVID-19 Pneumonia is Associated with Increased Plasma Immunoglobulin G Agonist Autoantibodies Targeting the 5-Hydroxytryptamine 2A Receptor

Aims

To test whether plasma autoantibodies targeting the 5-hydroxytryptamine 2A receptor increase in COVID-19 infection; and to characterize the pharmacologic specificity, and signaling pathway activation occurring downstream of receptor binding in mouse neuroblastoma N2A cells and cell toxicity of the autoantibodies.

Methods

Plasma obtained from nineteen, older COVID-19 patients having mild or severe infection was subjected to protein-A affinity chromatography to obtain immunoglobulin G fraction. One-fortieth dilution of the protein-A eluate was tested for binding to a linear synthetic peptide QN.18 corresponding to the second extracellular loop of the human 5-hydroxytryptamine 2A receptor. Mouse neuroblastoma N2A cells were incubated with COVID-19 IgG autoantibodies in the presence or absence of selective inhibitors of G-protein coupled receptors, signaling pathway antagonists, or a novel decoy receptor peptide.

Results

5-hydroxytryptamine 2A receptor autoantibody binding occurred in 17 of 19 (89%) patients with acute COVID-19 infection and increased level was significantly correlated with increased severity of COVID-19 infection. The agonist autoantibodies mediated acute neurite retraction in mouse neuroblastoma cells by a mechanism involving Gq11/PLC/IP3R/Ca2+ activation and RhoA/Rho kinase pathway signaling occurring downstream of receptor binding which had pharmacologic specificity consistent with binding to the 5-HT2A receptor. A novel synthetic peptide 5-HT2AR fragment, SN..8, dose-dependently blocked autoantibody-induced neurotoxicity. The COVID-19 autoantibodies displayed acute toxicity in bovine pulmonary artery endothelial cells (stress fiber formation, contraction) and modulated proliferation in a manner consistent with known 'biased agonism' on the 5-HT2A receptor.

Conclusion

These data suggest that 5-HT2AR targeting autoantibodies are highly prevalent may contribute to pathophysiology in acute, severe COVID-19 infection.

Inverse Association between Serotonin 2A Receptor Antagonist Medication Use and Mortality in Severe COVID-19 Infection

Advanced age and medical co-morbidity are strong predictors of mortality in COVID-19 infection. Yet few studies (to date) have specifically addressed risk factors associated with COVID-19 mortality in a high-risk subgroup of older US adults having one or more chronic diseases. Our hypothesis is that medications having 'off-target' anti-inflammatory effects may play a role in modulating the immune response in COVID-19 infection. We analyzed baseline risk factors associated with respiratory failure or death in 55 older adult US military veterans hospitalized for COVID-19 infection during (March-June 2020) the peak of the pandemic in New Jersey. Fifty-three percent (29/55) of patients experienced respiratory failure and thirty-one percent (17/55) died. In adjusted logistic regression analysis, baseline neutrophil to lymphocyte ratio (NLR) (P=0.0035) and body mass index (P=0.03) were significant predictors of the risk for respiratory failure. Age (P=0.05) and non-use (vs. use) of psychotropic medications having serotonin 2A receptor antagonist properties (odds ratio 5.06; 95% confidence intervals 1.18-21.7; P= 0.029) was each a significant predictor of an increased risk of death. There was a significant interaction effect of age and non-use (vs.. use) of psychotropic serotonin 2A receptor antagonist medications on the odds ratio (OR) for death (P=0.011). In selected, ventilator-dependent COVID-19 pneumonia patients treated with psychotropic serotonin 2A receptor antagonist medications to control agitation and ICU delirium, there was an apparent positive association between medication use and significant rise in the absolute lymphocyte count and decrease in the neutrophil: lymphocyte ratio. Taken together, these data are the first to suggest that certain psychotropic medications used in the treatment of chronic psychiatric illness and/or for acute delirium are inversely associated with mortality in severe COVID-19 infection by unknown mechanism which may involve (in part) immunomodulatory effects.

Circulating Agonist Autoantibody to 5-Hydroxytryptamine 2A Receptor in Lean and Diabetic Fatty Zucker Rat Strains

AIMS

Circulating neurotoxic autoantibodies to the 5-hydroxytryptamine 2A receptor were increased in older adult type 2 diabetes in association with certain neurodegenerative complications. The male Zucker diabetic fatty (ZDF) rat is a model system for studies of obese, type 2 diabetes mellitus. The aim of the current study was to test for (and compare) circulating neurotoxic autoantibodies to the 5-hydroxytryptamine 2A receptor in the Zucker diabetic fatty rat and age-matched lean Zucker rat strains.

METHODS

Plasma from lean and Zucker diabetic fatty rat (obtained at different developmental stages) was subjected to protein G affinity chromatography. The resulting immunoglobulin G fraction was tested for neurotoxicity (acute neurite retraction, accelerated neuron loss) in N2A mouse neuroblastoma cells and for binding to a linear synthetic peptide corresponding to the second extracellular loop of the 5-hydroxytryptamine 2A receptor.

RESULTS

The male Zucker diabetic fatty rat (fa/fa) and two Zucker lean strains (+/?) and (fa/+) harbored autoantibodies to the 5-hydroxytryptamine 2A receptor which appeared spontaneously around 7-8.5 weeks of age. The circulating autoantibodies persisted until at least 25 weeks of age in the Zucker diabetic fatty rat and in the Zucker heterozygote (fa/+), but were no longer detectable in 25-week-old lean (+/?) Zucker rats. Autoantibody-induced acute neurite retraction and accelerated loss in mouse neuroblastoma N2A cells was dose-dependently prevented by selective antagonists of the 5-hydroxytryptamine 2A receptor. It was also substantially prevented by co-incubation with antagonists of RhoA/Rho kinase-mediated signaling (Y27632) or Gq11/phospholipase C/inositol triphosphate receptor-coupled signaling.

CONCLUSIONS

These data suggest that neurotoxic 5-hydroxytryptamine 2A receptor-targeting autoantibodies increase in the aging male Zucker diabetic fatty rat and in male Zucker lean rats harboring a heterozygous mutation, but not in age-matched, older Zucker lean rats lacking a known leptin receptor mutation. The Zucker genetic strain may be useful in studies of the role of humoral and/or innate immunity in late neurodegeneration.

Serotonin 2A Receptor Autoantibodies Increase in Adult Traumatic Brain Injury In Association with Neurodegeneration

OBJECTIVE

Traumatic brain injury (TBI) is associated with an increased risk of late neurodegenerative complications via unknown mechanisms. Circulating neurotoxic 5-hydroxytryptamine 2A receptor (5-HT2AR) autoantibodies were reported to increase in subsets of obese type 2 diabetes having microvascular complications. We tested whether 5-HT2AR autoantibodies increase in adults following traumatic brain injury in association with neurodegenerative complications.

METHODS

Plasma from thirty-five middle-aged and older adult veterans (mean 65 years old) who had suffered traumatic brain injury was subjected to protein-A affinity chromatography. The resulting immunoglobulin (Ig) G fraction was tested for neurotoxicity (acute neurite retraction, and accelerated cell death) in mouse N2A neuroblastoma cells or for binding to a linear synthetic peptide corresponding to the second extracellular loop region of the human 5-HT2A receptor.

RESULTS

Nearly two-thirds of traumatic brain injured-patients harbored 5-HT2AR autoantibodies in their circulation. Active TBI autoantibodies caused neurite retraction in mouse N2A neuroblastoma cells and accelerated N2A cell loss which was substantially prevented by co-incubation with a two hundred and fifty nanomolar concentration of M100907, a highly selective 5-HT2AR antagonist. Antagonists of RhoA/Rho kinase and Gq11/phospholipase C/inositol triphosphate receptor signaling pathways blocked TBI autoantibody-induced neurite retraction. Following traumatic brain injury, autoantibody binding to a 5-HT2A receptor peptide was significantly increased in patients having co-morbid Parkinson's disease (n=3), dementia (n=5), and painful neuropathy (n=8) compared to TBI subsets without neurologic or microvascular complication (n=20). Autoantibody titer was significantly elevated in TBI subsets experiencing multiple neurotraumatic exposures vs. single TBI. Plasma white blood cell, a marker of systemic inflammation, correlated significantly (correlation coefficient r =0.52; P < 0.01) with, 5-HT2A receptor peptide binding of the TBI-autoantibody.

CONCLUSION

These data suggest that circulating neurotoxic 5-hydroxytryptamine 2A receptor agonist autoantibodies increase in adults following traumatic brain injury in association with late neurodegenerative complications.

Schizophrenia Plasma Autoantibodies Promote 'Biased Agonism' at the 5-Hydroxytryptamine 2A Receptor: Neurotoxicity is Positively Modulated by Metabotropic Glutamate 2/3 Receptor Agonism

AIMS

To test whether neurite-inhibitory plasma autoantibodies in chronic schizophrenia activate Gq/11- and Gi- coupled signaling pathways downstream of 5-hydroxytryptamine 2A receptor activation; and for modulation of serotonergic signaling by the metabotropic 2/3 receptor agonist LY379268.

METHODS

Plasma from five older adults with chronic schizophrenia and eight age-matched patients having another neuropsychiatric, immune or metabolic disorder was subjected to Protein-A affinity chromatography to obtain IgG autoantibodies. Mean neurite retraction (5 minutes) or cell survival (24 hours) was determined in mouse N2A neuroblastoma cells incubated with autoantibodies in the presence or absence of specific antagonists of the Gq/11/PLC/IP3R signaling pathway, Gi-coupled, beta-arrestin2-directed pathways, or LY379268.

RESULTS

Chronic schizophrenia plasma autoantibodies- mediated dose- and time-dependent acute N2A neurite retraction was completely prevented by M100907, a selective 5-hydroxytryptamine 2A receptor antagonist. LY379268 promoted autoantibody-induced neurite retraction causing a shift-to-the-left in the dose-response curve. Antagonists of the RhoA/Rho kinase and Gq/11/PLC/IP3R signaling pathways blocked autoantibody-mediated neurite retraction. Chronic schizophrenia plasma autoantibodies mediated increased N2A cell survival which was blocked by LY379268, pertussis toxin, and antagonists of PI3-kinase- mediated survival signaling.

CONCLUSION

Schizophrenia plasma autoantibodies activate the 5-hydroxytryptamine 2A receptor positively coupled to Gq/11/PLC/IP3R pathway and RhoA/Rho kinase signaling activation in promoting acute N2A cell neurite retraction. Autoantibodies in a subset of patients experiencing hallucinations promoted increased N2A cell survival mediated (in part) via a pertussis-toxin sensitive, Gi-coupled, PI3-kinase-dependent mechanism. Positive modulation of 5-HT2AR-mediated neurite retraction by LY379268 suggests the autoantibodies may target (in part) the 5-HT2AR/mGlu2R heteromer.

Endothelial Cell Growth Promoting Activity in Graves' Disease Sera is Neutralized by Anti-Basic Fibroblast Growth Factor Antibodies in Patients with Fat Expansive but Not Infiltrative Orbitopathy

PURPOSE

To report a case of orbital fat expansion leading to globe prolapse in a Graves' disease patient undergoing high-dose glucocorticoid therapy. To evaluate the growth factor receptor specificities of plasma autoantibodies in Graves' disease patients who exhibited contrasting subtypes of thyroid-associated ophthalmopathy, i.e. orbital fat expansion-type vs. infiltrative.

METHODS

Sera from Graves' orbitopathy and control patients with or without Graves' disease were subjected to protein-A affinity chromatography to obtain immunoglobulin G. A (1/50th to 1/1600th) range in dilutions of the protein-A eluate fraction was incubated for four days at 37 degrees C with bovine pulmonary artery endothelial cells to test for endothelial cell inhibition or stimulation. Growth stimulatory autoantibodies were co-incubated with specific neutralizing anti-insulin like growth factor 1 receptor antibodies or anti-basic fibroblast growth factor antibodies to assess autoantibody specificity in contrasting Graves' orbitopathy subtypes.

RESULTS

We observed increased mean endothelial cell growth promoting activity in the protein-A eluates of serum from eighteen patients with active Graves' disease (117 ± 28%, n = 18) compared to mean endothelial cell activity (89 ± 10%, n = 13, P = 0.003) in thirteen adults without Graves' disease. The protein-A eluate fraction in acute infiltrative-type Graves' orbitopathy contained a high titer (> 1:1000) of endothelial cell stimulatory activity which was significantly neutralized by specific monoclonal anti-human insulin-like growth factor 1 receptor antibodies. The protein-A eluate fraction in fat expansion-type Graves' orbitopathy contained endothelial cell inhibitory activity (at low titers) and stimulatory activity (at high titers), and the latter stimulatory activity was completely neutralized by specific anti-basic fibroblast growth factor antibodies.

CONCLUSION

Graves' disease suffering globe prolapse secondary to marked orbital fat-expansion had coexisting plasma fibroblast growth factor-inhibitory and -stimulatory autoantibodies. The latter was completely neutralized by anti-basic fibroblast growth factor antibodies.

Type 2 Diabetes Predicts Increased Risk of Neurodegenerative Complications in Veterans Suffering Traumatic Brain Injury

AIMS

Obese type 2 diabetes and traumatic brain injury are associated with persistent peripheral and neuro-inflammation, respectively. We tested whether adult type 2 diabetes increased the hazard rate for neurodegeneration complications following traumatic brain injury.

METHODS

Retrospective chart review of patients treated at the Veterans Affairs New Jersey Healthcare System between 2016-2019 and having a diagnosis of prior traumatic brain injury was performed in adult veterans, age 50 years or older. Cox proportional hazards regression analysis was used to identify risk factors predictive of an increased risk of neurodegeneration, i.e. worsening major depression, dementia or Parkinson's disease following traumatic brain injury.

RESULTS

Type 2 diabetes predicted a nearly three-fold increased hazard ratio (HR = 2.95, 95% CI 1.15-7.56, P =0.02) for the occurrence of worsening major depression, dementia or Parkinson's disease in eighty adults age 50 years or older who had experienced prior traumatic brain injury. After adjusting for other covariates, hypertension (HR= 4.15, 95% CI 1.21-14.29, P =0.02) was significant and body mass index (HR=1.14, 95% CI 0.99-1.30; P=0.06) modestly significant predictors of the risk for the time to first occurrence of the composite neurodegenerative outcome.

CONCLUSION

Type 2 diabetes, hypertension and higher body mass index increase the hazard for the occurrence of worsening depression, Parkinson's disease and dementia following traumatic brain injury in middle-aged and older adults.

Thyroid Hormone Resistance in Identical Twin Sisters with Atrial Fibrillation: Case Report and Review of the Literature

AIM

To report identical twin sisters harboring the A317T mutation in the thyroid hormone beta receptor gene (TR β) who developed atrial fibrillation and refractory congestive heart failure in the sixth decade of life. To critically assess whether the A317T mutation may be responsible for increased cardiotoxicity compared to other thyroid hormone beta receptor gene mutations.

METHODS

A 59-year-old woman referred for evaluation of abnormal thyroid function tests had been experiencing frequent spells of tachycardia associated with dyspnea, and dizziness necessitating multiple hospitalizations. Elevation in free thyroxine (T4), total triiodothyronine (T3) and inappropriately normal thyroid stimulating hormone (TSH) was consistent with a clinical diagnosis of thyroid hormone resistance. Magnetic resonance imaging of the brain was negative for a TSH-secreting pituitary adenoma. A blood sample was sent for thyroid hormone receptor gene mutational analysis, but it would require eight weeks to complete processing.

RESULTS

A modified L-T3 suppression test was used to assess thyroid-pituitary axis feedback. After three weeks' of cytomel (L-T3) (25 micrograms daily) TSH decreased by 50%, and free T4 level decreased by 22% compared to baseline levels. Genetic testing revealed a heterozygous A317T mutation in the thyroid hormone beta receptor gene. Serial two-dimensional echocardiography demonstrated evolution to left atrial enlargement over a three-year period. Prior published literature suggests a less than 10% prevalence of atrial fibrillation in adults with thyroid hormone resistance harboring various TR-β gene mutations. Yet all five of five (100%) adults having the A317T mutation were reported to experience atrial fibrillation by age 50.

CONCLUSIONS

A new kindred with resistance to thyroid hormone harboring the A317T disease-causative mutation is described in which identical twin sisters had a mid-life onset of atrial fibrillation and refractory congestive heart failure.

Circulating Neurotoxic 5-HT2A Receptor Agonist Autoantibodies in Adult Type 2 Diabetes with Parkinson's Disease

AIMS

To test whether circulating neurotoxic autoantibodies increase in adult type 2 diabetes mellitus with Parkinson's disease (PD) or dementia. To identify the G-protein coupled receptor on neuroblastoma cells mediating neural inhibitory effects in diabetic Parkinson's disease plasma autoantibodies. To determine the mechanism of accelerated neuroblastoma cell death and acute neurite retraction induced by diabetic Parkinson's disease and dementia autoantibodies.

METHODS

Protein-A eluates from plasma of twelve older adult male diabetic patients having Parkinson's disease (n=10) or dementia (n=2), and eight age-matched control diabetic patients were tested for ability to cause accelerated N2A neuroblastoma cell death and acute neurite retraction. Specific antagonists of G protein coupled receptors belonging to the G alpha q subfamily of heterotrimetric G-proteins, the phospholipase C/inositol triphosphate/Ca2+ pathway, or the RhoA/Rho kinase pathway were tested for ability to block diabetic Parkinson's disease/dementia autoantibody-induced neurite retraction or N2A accelerated cell loss. Sequential Liposorber LA-15 dextran sulfate cellulose/protein-A affinity chromatography was used to obtain highly-purified fractions of diabetic Parkinson's disease autoantibodies.

RESULTS

Mean accelerated neuroblastoma cell loss induced by diabetic Parkinson's disease or dementia autoantibodies significantly exceeded (P = 0.001) the level of N2A cell loss induced by an identical concentration of the diabetic autoantibodies in control patients without these two co-morbid neurodegenerative disorders. Co-incubation of diabetic Parkinson's disease and dementia autoantibodies with two-hundred nanomolar concentrations of M100907, a highly selective 5-HT2AR antagonist, completely prevented autoantibody-induced accelerated N2A cell loss and neurite retraction. A higher concentration (500 nM-10μM) of alpha-1 adrenergic, angiotensin II type 1, or endothelin A receptor antagonists did not substantially inhibit autoantibody-induced neuroblastoma cell death or prevent neurite retraction. Antagonists of the inositol triphosphate receptor (2-APB, 50μM), the intracellular calcium chelator (BAPTA-AM, 30 μM) and Y27632 (10 μM), a selective RhoA/Rho kinase inhibitor, each completely blocked acute neurite retraction induced by sixty nanomolar concentrations of diabetic Parkinson's disease autoantibodies. Co-incubation with 2-APB (1-2 μM) for 8 hours' prevented autoantibody-induced N2A cell loss. The highly-purified fraction obtained after Liposorber LA/protein-A affinity chromatography in hypertriglyceridemic diabetic dementia and Parkinson's disease plasmas had apparent MWs > 30 kD, and displayed enhanced N2A toxicity requiring substantially higher concentrations of 5-HT2AR antagonists (M100907, ketanserin, spiperone) to effectively neutralize.

CONCLUSION

These data suggest increased autoantibodies in older adult diabetes with Parkinson's disease or dementia cause accelerated neuron loss via the 5-hydroxytryptamine 2 receptor coupled to inositol triphosphate receptor-mediated cytosolic Ca2+ release.

Diabetes Autoantibodies Mediate Neural- and Endothelial Cell- Inhibitory Effects Via 5-Hydroxytryptamine- 2 Receptor Coupled to Phospholipase C/Inositol Triphosphate/Ca2+ Pathway

AIMS

To identify the G-protein coupled receptor(s) on neuroblastoma and endothelial cells which mediate neural- and endothelial cell-inhibitory effects in plasma autoantibodies from a subset of older type 2 diabetes with neurologic and vascular co-morbidity. To determine the mechanism(s) of neurite retraction induced by diabetic pathologies' auto antibodies.

METHODS

Protein-A eluates from plasma of 11 diabetic patients having nephropathy, moderate-severe obesity and/or complications in which increased inflammation plays a role (depression, Parkinson's disease, atrial fibrillation, obstructive sleep apnea) were tested for neurite retraction and decreased survival in N2A neuroblastoma cells, and decreased survival in pulmonary artery endothelial cells. Specific antagonists of G protein coupled receptors belonging to the G alpha q subfamily of hetero trimetric G proteins or the phospholipase C/inositol triphosphate/Ca2+ pathway were tested for modulatory effects on diabetic pathologies' autoantibody-induced N2A neurite retraction, or cell survival.

RESULTS

Co-incubation with specific antagonists of the 5-hydroxytryptamine- 2A receptor significantly prevented acute N2A neurite retraction induced by 50-100 nM concentrations of diabetic pathologies' autoantibodies. Protection against neurite retraction (M100907> spiperone> ketanserin) closely paralleled the antagonists' potency order at the 5-HT2-AR. Neuroblastoma or endothelial cell death (after 24 hours incubation) with 50-100 nM autoantibodies was completely or nearly completely (91%) prevented by co-incubation with 200 nM M100907, a highly selective 5-HT2-AR antagonist. Alpha-1 adrenergic, angiotensin II, metabotropic glutamate 5, or endothelin A (100 nM-10µM) receptor antagonists did not substantially inhibit autoantibody-induced cell death. The intracellular calcium chelator (BAPTA-AM, 50 µM) and inhibitors of the inositol triphosphate (IP3) receptor (2-APB, 50µM), and phospholipase C-gamma (U73144, 1µM) each significantly protected against autoantibody-induced acute N2A neurite retraction.

CONCLUSION

These data suggest that neural- and endothelial- inhibitory effects in autoantibodies from older adult diabetes with nephropathy and obesity/inflammation-associated complications are mediated by agonist autoantibodies directed against the 5-hydroxytryptamine 2 receptor positively coupled to the phospholipase C/inositol triphosphate/ cytosolic Ca2+ release pathway.

Increased Neuronal Depolarization Evoked by Autoantibodies in Diabetic Obstructive Sleep Apnea: Role for Inflammatory Protease(s) in Generation of Neurotoxic Immunoglobulin Fragment

11 AIM

Obstructive sleep apnea increases in diabetes and morbid obesity. We tested a hypothesis that circulating autoantibodies in adult type 2 diabetes which increase in association with morbid obesity are capable of causing long-lasting neuronal depolarization and altered calcium release in mouse atrial cardiomyocytes.

12 METHODS

Protein-A eluates from plasma of 14 diabetic obstructive sleep apnea patients and 17 age-matched diabetic patients without sleep apnea were tested for effects on depolarization and neurite out growth in N2a mouse neuroblastoma cells. The mechanism of autoantibody-mediated neurite outgrowth inhibition was investigated in co-incubation experiments of diabetic obstructive sleep apnea autoantibodies with specific antagonists of G-protein coupled receptors or the RhoA/Rho kinase signaling pathway. Following long-term storage of the protein-A eluates (to allow spontaneous proteolysis and IgG subunit dissociation), plasma autoantibodies from diabetic obstructive sleep apnea, cancer or control patients were compared for enhancement of inhibitory effects on endothelial cell survival. Size exclusion chromatography performed (in the presence or absence of a specific membrane type 1-matrix metalloproteinase inhibitor) was used to characterize the IgG autoantibody subunit(s) or fragments associated with peak neurotoxicity in diabetic obstructive sleep apnea.

13 RESULTS

Diabetic obstructive sleep apnea (n = 14) autoantibodies caused a significant increase (P = 0.01) in membrane depolarization in N2a mouse neuroblastoma cells compared to control diabetic patients (n = 15) not suffering with obstructive sleep apnea. Process extension in N2A mouse neuroblastoma cells was significantly inhibited (P = 0.01) by diabetic obstructive sleep apnea (n = 9) autoantibodies compared to effects from identical 10 μg/mL concentrations of control diabetic autoantibodies in patients without obstructive sleep apnea. Ten micromolar concentrations of SCH-202676, a G-protein coupled receptor antagonist (n = 5) or ten micromolar concentration of Y27632, a selective Rho kinase inhibitor (n = 6), each significantly prevented (P < 0.001) neurite outgrowth inhibition by diabetic obstructive sleep apnea autoantibodies. Autoantibodies in representative patients with obstructive sleep apnea and either atrial fibrillation or left ventricular hypertrophy evoked acute large increases in intracellular Ca2+ in HL-1 mouse atrial cardiomyocytes. The magnitude of intracellular Ca2+ release was dose-dependently significantly correlated to the electrocardiographic Cornell voltage-duration product. Gel filtration of diabetic obstructive sleep apnea autoantibodies revealed peak neurotoxicity associated with MWs corresponding to IgG light chain dimer(s), monomers or half-light chains as well as a novel ∼ 5.5 kD putative light chain fragment.

14 CONCLUSIONS

These results suggest that diabetic obstructive sleep apnea autoantibodies may induce strong depolarization in neuronal cells and alter Ca2+ signaling in atrial cardiomyocytes consistent with a role in pathophysiology in subsets of diabetic obstructive sleep apnea having co-morbid atrial fibrillation or another clinically significant cardiac rhythm disturbance.

Toxic Immunoglobulin Light Chain Autoantibodies are Associated with a Cluster of Severe Complications in Older Adult Type 2 Diabetes

AIMS

To assess neuronal depolarization evoked by autoantibodies in diabetic depression compared to depolarization evoked by autoantibodies in control patients. To determine whether a subset of severe (late-onset) diabetic complications may be mediated in part by toxic immunoglobulin light chains that may increase in diabetic nephropathy.

METHODS

Protein-A eluates from plasma of 21 diabetic depression patients and 37 age-matched controls were tested for depolarization in hippocampal or immature neurons. Subsets of depolarizing or non-depolarizing autoantibodies were tested for neurite outgrowth inhibition in N2A neuroblastoma cells or the ability to modulate Ca2+ release in HL-1 atrial cardiomyocytes or in endothelial cells. The stability of depolarizing autoantibodies was investigated by heat treatment (56°C × 30 minutes) or following prolonged exposure to the pro-protein convertase, furin. Gel filtration of active depolarizing autoantibodies was performed to determine the apparent molecular mass of peak neurotoxicity associated with the autoantibodies.

RESULTS

Diabetic depression (n = 21) autoantibodies caused significantly greater mean depolarization in neuroblastoma cells (P < 0.01) compared to autoantibodies in diabetic (n = 15) or non-diabetic (n = 11) patients without depression. Depolarizing autoantibodies caused significantly more (P=0.011) inhibition of neurite outgrowth in neuroblastoma cells than non-depolarizing autoantibodies (n = 10) and they evoked sustained, global intracellular Ca2+ release in atrial cardiomyocytes or in endothelial cells. A subset of older diabetic patients suffering with a cluster of nephropathy, non-ischemic cardiomyopathy and/or depression demonstrated the presence of stable light chain dimers having apparent MW of 46 kD and associated with peak neurotoxicity in neuroblastoma cells.

CONCLUSION

These data suggest that autoantibodies in older adult diabetic depression cause long-lasting depolarization in hippocampal neurons including adult dentate gyrus neural progenitor cells. The autoantibodies may impair adult dentate gyrus neurogenesis associated with treatment-refractory depression via several mechanisms including suppression of neurite outgrowth, and alteration of membrane excitability. Stable, toxic light chain autoantibody components may contribute to a cluster of severe (late-onset) complications characterized by dysfunction in highly vascularized tissues.

Predictors of Cognitive Decline in Older Adult Type 2 Diabetes from the Veterans Affairs Diabetes Trial

AIMS

Cognitive decline disproportionately affects older adult type 2 diabetes. We tested whether randomized intensive (INT) glucose-lowering reduces the rate(s) of cognitive decline in adults with advanced type 2 diabetes (mean: age, 60 years; diabetes duration, 11 years) from the Veterans Affairs Diabetes Trial.

METHODS

A battery of neuropsychological tests [digit span, digit symbol substitution (DSym), and Trails-making Test-Part B (TMT-B)] was administered at baseline in ~1700 participants and repeated at year 5. Thirty-seven risk factors were evaluated as predictors of cognitive decline in multivariable regression analyses.

RESULTS

The mean age-adjusted DSym or TMT-B declined significantly in all study participants (P < 0.001). Randomized INT glucose-lowering did not significantly alter the rate of cognitive decline. The final model of risk factors associated with 5-year decline in age-adjusted TMT-B included as significant predictors: longer baseline diabetes duration (beta = -0.028; P = 0.0057), lower baseline diastolic blood pressure (BP; beta = 0.028; P = 0.002), and baseline calcium channel blocker medication use (beta = -0.639; P < 0.001). Higher baseline pulse pressure was significantly associated with decline in age-adjusted TMT-B suggesting a role for both higher systolic and lower diastolic BPs. Baseline thiazide diuretic use (beta = -0.549; P = 0.015) was an additional significant predictor of 5-year decline in age-adjusted digit symbol score. Post-baseline systolic BP-lowering was significantly associated (P < 0.001) with decline in TMT-B performance. There was a significant inverse association between post-baseline plasma triglyceride-lowering (P = 0.045) and decline in digit symbol substitution task performance.

CONCLUSION

A 5-year period of randomized INT glucose-lowering did not significantly reduce the rate of cognitive decline in older-aged adults with type 2 diabetes. Systolic and diastolic BPs as well as plasma triglycerides appeared as modifiable risk factors of the rate of cognitive decline in older adult type 2 diabetes.

Autoantibodies in Human Diabetic Depression Inhibit Adult Neural Progenitor Cells In vitro and Induce Depressive-Like Behavior in Rodents

AIM

Diabetic depression increases in association with microvascular complications. We tested a hypothesis that circulating autoantibodies having anti-endothelial and anti-neuronal properties increase in subsets of diabetes with co-morbid depression.

METHODS

Protein-A eluates from plasma of 20 diabetic depression patients and 30 age-matched controls were tested for effects on endothelial cell survival, neurite outgrowth in rat pheochromocytoma (PC12) cells, or process extension and survival in adult rat dentate gyrus neural progenitor cells. The protein-A eluates from depressed or non-depressed, diabetic patients were injected (via intracerebroventricular route) into mice and 7-10 days later behavioral tests (sucrose preference, and tail suspension tests) were conducted to determine whether the autoantibodies induced anhedonia or despair.

RESULTS

Diabetic depression (n=20) autoantibodies caused a significant inhibition of PC12 cell neurite outgrowth (P<0.001) or endothelial cell proliferation compared to autoantibodies in control, diabetic (n=20) or non-diabetic (n=10) patients without depression. Process extension and survival in adult rat dentate gyrus neural progenitor cells was significantly reduced (P<0.001) by diabetic depression autoantibodies (n= 11) compared to the effects from similar concentrations (5-7 μg/mL) of autoantibodies in diabetic (n=12) or non-diabetic patients without depression (n=7). Ten micromolar concentrations of Y27632, a selective Rho-Associated Protein Kinase (ROCK) inhibitor, significantly prevented (P<0.0001) neural progenitor cell process retraction induced by diabetes depression autoantibodies (n=5). Mice treated with diabetic depression autoantibodies (n=16 from two different patients' autoantibodies) exhibited significantly reduced (P=0.027) sucrose preference (anhedonia) compared to mice treated with diabetic control autoantibodies (n=16 from two different patients' autoantibodies).

CONCLUSION

These data suggest that autoantibodies in a subset of older adult diabetic depression inhibit endothelial cell survival, and impair process extension and survival in adult dentate gyrus neural progenitor cells in vitro.

Endothelial cell autoantibodies in predicting declining renal function, end-stage renal disease, or death in adult type 2 diabetic nephropathy

Albuminuria is a strong predictor of diabetic nephropathy chronic kidney disease outcomes. Yet, therapeutic albuminuria-lowering has not consistently translated into a reduction in clinical events suggesting the involvement of additional pathogenic factors. Our hypothesis is that anti-endothelial cell autoantibodies play a role in development and progression in diabetic nephropathy. We determined anti-endothelial cell antibody (AECA) bioactivity in protein A-elutes of baseline plasma in 305 participants in the VA NEPHRON-D study, a randomized trial of angiotensin receptor blocker (ARB) or dual ARB plus angiotensin-converting enzyme inhibitor therapy in type 2 diabetes with proteinuric nephropathy. Thirty-eight percent (117/305) of participants had significantly reduced endothelial cell survival ( ≤80%) in the IgG fraction of plasma. A VA NEPHRON-D primary endpoint [end-stage renal disease (ESRD), significant reduction in estimated glomerular filtration rate, or death] was experienced by 58 individuals. In adjusted Cox regression analysis, there was a significant interaction effect of baseline anti-endothelial cell-mediated cell survival and albuminuria on the hazard rate (HR) for primary composite endpoint (P = 0.017). Participants lacking strongly inhibitory antibodies with albuminuria ≥1 g/g creatinine had a significantly increased primary event hazard ratio, 3.41 - 95% confidence intervals (CI 1.84-6.33; P < 0.001) compared to those lacking strongly inhibitory antibodies with lower baseline albuminuria ( <1 g/g creatinine). These results suggest that anti-endothelial cell antibodies interact significantly with albuminuria in predicting the composite endpoint of death, ESRD, or substantial decline in renal function in older, adult type 2 diabetic nephropathy.

Anti-neurotrophic effects from autoantibodies in adult diabetes having primary open angle glaucoma or dementia

AIM

To test for anti-endothelial and anti-neurotrophic effects from autoantibodies in subsets of diabetes having open-angle glaucoma, dementia, or control subjects.

METHODS

Protein-A eluates from plasma of 20 diabetic subjects having glaucoma or suspects and 34 age-matched controls were tested for effects on neurite outgrowth in rat pheochromocytoma PC12 cells or endothelial cell survival. The mechanism of the diabetic glaucoma autoantibodies' neurite-inhibitory effect was investigated in co-incubations with the selective Rho kinase inhibitor Y27632 or the sulfated proteoglycan synthesis inhibitor sodium chlorate. Stored protein-A eluates from certain diabetic glaucoma or dementia subjects which contained long-lasting, highly stable cell inhibitory substances were characterized using mass spectrometry and amino acid sequencing.

RESULTS

Diabetic primary open angle glaucoma (POAG) or suspects (n = 20) or diabetic dementia (n = 3) autoantibodies caused significantly greater mean inhibition of neurite outgrowth in PC12 cells (p < 0.0001) compared to autoantibodies in control diabetic (n = 24) or non-diabetic (n = 10) subjects without glaucoma (p < 0.01). Neurite inhibition by the diabetic glaucoma autoantibodies was completely abolished by 10 μM concentrations of Y27632 (n = 4). It was substantially reduced by 30 mM concentrations of sodium chlorate (n = 4). Peak, long-lasting activity survived storage ×5 years at 0-4°C and was associated with a restricted subtype of Ig kappa light chain. Diabetic glaucoma or dementia autoantibodies (n = 5) caused contraction and process retraction in quiescent cerebral cortical astrocytes effects which were blocked by 5 μM concentrations of Y27632.

CONCLUSION

These data suggest that autoantibodies in subsets of adult diabetes having POAG (glaucoma suspects) and/or dementia inhibit neurite outgrowth and promote a reactive astrocyte morphology by a mechanism which may involve activation of the RhoA/p160 ROCK signaling pathway.

Basic fibroblast growth factor predicts cardiovascular disease occurrence in participants from the veterans affairs diabetes trial

AIM

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality in adults with type 2 diabetes mellitus. The aim of the present study was to test whether plasma basic fibroblast growth factor (bFGF) levels predict future CVD occurrence in adults from the Veterans Affairs Diabetes Trial (VADT).

METHODS

Nearly 400 veterans, 40 years of age or older having a mean baseline diabetes duration of 11.4 years were recruited from outpatient clinics at six geographically distributed sites in the VADT. Within the VADT, they were randomly assigned to intensive or standard glycemic treatment, with follow-up as much as seven and one-half years. CVD occurrence was examined at baseline in the patient population and during randomized treatment. Plasma bFGF was determined with a sensitive, specific two-site enzyme-linked immunoassay at the baseline study visit in all 399 subjects and repeated at the year 1 study visit in a randomly selected subset of 215 subjects.

RESULTS

One hundred and five first cardiovascular events occurred in these 399 subjects. The best fit model of risk factors associated with the time to first CVD occurrence (in the study) over a seven and one-half year period had as significant predictors: prior cardiovascular event [hazard ratio (HR) 3.378; 95% confidence intervals (CI) 3.079-3.807; P < 0.0001), baseline plasma bFGF (HR 1.008; 95% CI 1.002-1.014; P = 0.01), age (HR 1.027; 95% CI 1.004-1.051; P = 0.019), baseline plasma triglycerides (HR 1.001; 95% CI 1.000-1.002; P = 0.02), and diabetes duration-treatment interaction (P = 0.03). Intensive glucose-lowering was associated with significantly decreased hazard ratios for CVD occurrence (0.38-0.63) in patients with known diabetes duration of 0-10 years, and non-significantly increased hazard ratios for CVD occurrence (0.82-1.78) in patients with longer diabetes duration.

CONCLUSION

High level of plasma bFGF is a predictive biomarker of future CVD occurrence in this population of adult type 2 diabetes.

Anti-endothelial and anti-neuronal effects from auto-antibodies in subsets of adult diabetes having a cluster of microvascular complications

AIMS

To test autoantibodies from subsets of diabetes with painful neuropathy, maculopathy and nephropathy for effects in neurons.

METHODS

Protein-A eluates from plasma of 27 diabetic and 19 age-matched controls were tested for effects on endothelial cell survival, and neurite outgrowth in rat pheochromocytoma PC12 cells. Painful diabetic neuropathy or control autoantibodies were compared for binding to PC12-derived heparan sulfate proteoglycans. The mechanism of the effects from pathologic autoantibodies was investigated by changes in intracellular calcium in endothelial cells, whole cell current in neurons, or using the Rho kinase inhibitor Y27632.

RESULTS

Autoantibodies from diabetic patients with maculopathy, nephropathy, and painful neuropathy (n=5) caused significantly greater mean inhibition of neurite outgrowth (p<0.005) than diabetic or control patients with fewer or no complications (n=30). Painful diabetic autoantibodies (3 μg/mL) bound neuronal heparan sulfate proteoglycan (HSPG) more than autoantibodies from diabetic or control subjects without painful neuropathy (p<.0001). Inhibition of PC12 neurite outgrowth by the painful neuropathy antibodies was completely prevented by 1 μM concentrations of Y27632.

CONCLUSION

These results suggest anti-endothelial and anti-neuronal effects from auto-antibodies in a subset of diabetic patients with a cluster of microvascular complications.

Recurrent macular edema and stroke syndrome in type 1 diabetes mellitus with potent endothelial cell inhibitory autoantibodies

OBJECTIVE

To describe a case of type 1 diabetes mellitus with recurrent macular edema and stroke in association with potent endothelial cell inhibitory autoantibodies.

METHODS

The clinical, radiologic, and biochemical data from the study patient are presented, as is the bioactivity in endothelial cells from the immunoglobulin G fraction of the patient's serum.

RESULTS

A 52-year-old man with a 15-year history of poorly controlled type 1 diabetes mellitus had diabetic autonomic neuropathy, gastroparesis, depression, macular edema, proliferative retinopathy, diabetic nephropathy, refractory hypertension, and transient ischemic attacks that progressed to recurrent strokes despite aspirin therapy. Magnetic resonance imaging of the brain showed multi-focal, bilateral ischemic infarcts consistent with recurrent stroke affecting small vessels. The patient's serum contained endothelial cell inhibitory autoantibodies; the titer doubled during a 2-year period when the patient required repeated focal laser to treat macular edema and experienced transient ischemic attacks. The IgG autoantibodies induced stress fiber formation and apoptosis in endothelial cells and inhibited neurite outgrowth in rat pheochromocytoma PC12 cells.

CONCLUSIONS

Low concentrations of purified autoantibodies (1-2 μg/mL) induce endothelial cell contraction in vitro, suggesting a role for autoantibodies in modulating endothelial cell permeability, which may affect multiple target organs. Potent IgG autoantibodies may be a useful marker (with a possible pathophysiologic role) in an unusual syndrome characterized by poorly controlled diabetes, hypertension, dementia, and recurrent small-vessel stroke.

Increased plasma basic fibroblast growth factor is associated with coronary heart disease in adult type 2 diabetes mellitus

Basic fibroblast growth factor (bFGF) is a potent endothelial and smooth muscle cell mitogen that does not normally circulate. Plasma bFGF-like bioactivity was increased in association with persistent microalbuminuria (a risk marker for cardiovascular disease) in adult type 2 diabetes mellitus. In the present study, we tested whether baseline plasma bFGF immunoreactivity (IR) predicts the occurrence of a subset of cardiovascular disease outcomes in adults with advanced type 2 diabetes mellitus from the Veterans Affairs Diabetes Trial (mean: age, 59 years; diabetes duration, 11 years; baseline hemoglobin A(1c), 9.5%). Plasma bFGF-IR was determined with a sensitive and specific 2-site enzyme-linked immunoassay in 399 patients at the baseline visit. These results were then evaluated as possible predictors of the occurrence of prespecified cardiovascular or coronary heart disease end points. There was a borderline-significant association (P = .07) between plasma bFGF-IR and the main study cardiovascular disease outcome (myocardial infarction, congestive heart failure, cerebrovascular accident, amputation, cardiovascular death, coronary, cerebrovascular or peripheral revascularization, and inoperable coronary artery disease). Plasma bFGF-IR was significantly associated with the occurrence of coronary heart disease (P = .01). After adjusting for clinical risk factors, bFGF (hazard ratio [HR], 1.013; 95% confidence interval [CI], 1.007-1.019; P < .0001), prior macrovascular event (HR, 3.55; 95% CI, 2.154-5.839; P < .0001), and duration of diabetes (HR, 1.041; 95% CI, 1.012-1.071; P = .0055) were all significantly associated with time to first postrandomization coronary heart disease occurrence. These results suggest that increased plasma bFGF-IR may be a novel risk marker for coronary heart disease occurrence in adult men with advanced type 2 diabetes mellitus.

Autoantibodies in type 2 diabetes induce stress fiber formation and apoptosis in endothelial cells

CONTEXT

Macular edema contributes to visual impairment, and albuminuria is associated with increased cardiovascular mortality in adults with type 2 diabetes mellitus. These microvascular complications result from increased capillary leakage of plasma proteins whose causation is not completely understood.

OBJECTIVE

The objective of the present study was to test whether plasma from type 2 diabetes with maculopathy/albuminuria or control subjects contains autoantibodies that can induce apoptosis or activate Rho kinase (ROCK) in endothelial cells.

DESIGN

A cohort of Veterans Affairs Diabetes Trial adults (>40 yr of age) was randomized to standard vs. intensive glycemic treatment lasting 5-7.5 yr.

SETTING

The study was conducted in outpatient clinics.

PATIENTS

Case and age-matched control subjects who differed for the baseline presence of significant diabetic maculopathy and/or progression to macro-albuminuria were included in the study.

INTERVENTION

Pharmacological and lifestyle interventions in the Veterans Affairs Diabetes Trial generally resulted in substantially improved glycemic, blood pressure, and lipid levels.

RESULTS

Autoantibodies from patients with macular edema or progression to albuminuria potently induced caspase-dependent apoptosis in endothelial cells (up to 60%), whereas IgG from age-matched normal plasma caused much less apoptosis (<10%; P < 0.0001). The active inhibitory autoantibodies triggered stress fiber formation in endothelial cells likely through the activation of Rho guanosine 5'-triphosphatase, which could be nearly completed inhibited by 10 microm Y27632, a specific ROCK inhibitor.

CONCLUSIONS

These results suggest that autoantibodies from a subset of advanced type 2 diabetes may contribute to diabetic vascular complications by activating ROCK, inducing stress fiber formation and apoptosis in endothelial cells.

Endothelial cell inhibitory autoantibodies are associated with laser photocoagulation in adults from the Veterans Affairs Diabetes Trial

Basic fibroblast growth factor (bFGF) is a potent endothelial cell mitogen that does not normally circulate, but increases in microalbuminuric adult type 2 diabetes mellitus. Earlier work indicated an unexpected association between low levels of plasma bFGF immunoreactivity and the subsequent 4-year need for laser treatment in 172 patients from the Veterans Affairs Diabetes Trial (mean: age, 59 years; diabetes duration, 11 years; baseline hemoglobin A(1c), 9.5%). In the present study, we tested for an association between endothelial cell inhibitory autoantibodies in plasma and the need for laser treatment. Inhibitory activity in endothelial cells from the immunoglobulin G fractions of plasma was significantly associated (P = .002) with low plasma bFGF immunoreactivity. There was a significant association (P = .003) between endothelial cell inhibitory autoantibodies in baseline plasma and the time to occurrence of first laser treatment after 4 years of study treatment. After adjusting for other risk factors, endothelial cell inhibitory activity greater than 90% vs less than or equal to 90% (hazard ratio, 0.2; P = .003) and low-density lipoprotein cholesterol concentration (hazard ratio, 0.98; P = .02) were each significant predictors of the time to first postrandomization laser occurrence. These results suggest that circulating autoantibodies inhibitory in endothelial cells may contribute to the need for laser treatment in adult men with advanced type 2 diabetes mellitus. Among the possible risk factors evaluated, baseline insulin use was the only variable significantly inversely (P = .02) associated with the baseline occurrence of inhibitory endothelial cell autoantibodies. It could not be determined whether insulin use may decrease the occurrence of endothelial cell inhibitory autoantibodies in advancing adult type 2 diabetes mellitus.

Low plasma basic fibroblast growth factor is associated with laser photocoagulation treatment in adult type 2 diabetes mellitus from the Veterans Affairs Diabetes Trial

Basic fibroblast growth factor (bFGF) is a potent endothelial cell mitogen that does not normally circulate. Yet plasma bFGF-like bioactivity was increased in association with persistent microalbuminuria and retinopathy in adult type 2 diabetes mellitus. In the present study, we tested whether plasma bFGF immunoreactivity (IR) could predict the need for laser treatment of diabetic retinopathy in a baseline subset of advanced type 2 diabetes mellitus from the Veterans Affairs Diabetes Trial (mean: age, 59 years; diabetes duration, 11 years; baseline glycosylated hemoglobin, 9.5%). Plasma bFGF-IR was determined with a sensitive and specific 2-site enzyme-linked immunoassay in 172 patients at the baseline visit. Results were dichotomized at 4.5 pg/mL, the upper limit in healthy men. There was an unexpected significant association between low baseline plasma bFGF-IR level and the interim (4 years) need for laser treatment. First laser treatment was significantly more likely to be required in patients with low compared with high baseline bFGF (19% vs 6%, P = .03 for the difference). After adjusting for clinical risk factors, low vs high bFGF (hazard ratio [HR], 5.01; P = .012), duration of diabetes (HR, 1.05; P = .050), and low-density lipoprotein cholesterol concentration (HR, 0.98; P = .027) were all significantly associated with time to first laser occurrence. These and our prior results suggest that low plasma bFGF-IR may be a marker for the presence of anti-endothelial cell autoantibodies that may contribute to the need for laser photocoagulation treatment in adult men with advanced type 2 diabetes mellitus.

Neurotrophic effects of fibroblast growth factor-like autoantibodies in serum from three patients with breast cancer

Basic fibroblast growth factor (FGF) promotes branching neuritogenesis and survival in rat hippocampal neurons in vitro. Basic FGF is a broad spectrum mitogen which does not normally circulate, but increases in serum from a variety of cancers. In prior work, we described spontaneously-occurring fibroblast growth factor-like autoantibodies in serum from a subset of breast cancer patients with neurological complications. The FGF-like autoantibodies mimicked the potent endothelial cell growth-promoting activity of bFGF yet had remarkably increased stability (activity survived storage at 0-4 degrees C for up to 5 years). In the present study we tested whether FGF-like autoantibodies from breast cancer sera is neurotrophic or neuroprotective. We now report that FGF-like autoantibodies (2-3 microg/mL) from breast cancer sera promoted neuritogenesis in DIV 12 embryonic day 18 rat hippocampal neurons and neurite extension in undifferentiated rat pheochromocytoma PC12 cells. The FGF-like autoantibodies from a breast cancer patient with lupus were unique in protecting rat hippocampal neurons from glutamate-induced cell loss and promoting long-lasting neurite extension and survival in PC-12 cells (up to 25 days in vitro). Breast cancer sera FGF-like autoantibodies induced large sustained increases in inward cationic current associated with depolarization in hippocampal neurons that exceeded the electrophysiological effects of substantial concentrations of basic FGF. These results suggest that differences in potency or other unknown factors contribute to whether subsets of FGF-like autoantibodies from breast cancer sera exhibit long-lasting neurotrophic and neuroprotective effects or an early neurotrophic effect followed by accelerated late neuron death.

Plasma basic fibroblast growth factor is correlated with plasminogen activator inhibitor-1 concentration in adults from the Veterans Affairs Diabetes Trial

Basic fibroblast growth factor (bFGF) is a potent mitogen in endothelial and vascular smooth muscle cells that increases in serum from adults with coronary artery disease and in microalbuminuric type 2 diabetes mellitus. There has been no prior study of plasma bFGF as a possible cardiovascular risk marker in type 2 diabetes mellitus. In this study, we tested for a correlation between log plasma bFGF immunoreactivity (bFGF-IR) and baseline cardiovascular risk factors in a baseline subset of subjects with advanced type 2 diabetes mellitus from the Veterans Affairs Diabetes Trial ([mean] age, 60 years; hemoglobin A(1c), 9.5%; diabetes' duration, 11 years). Plasma bFGF-IR was determined with a sensitive, specific, 2-site enzyme-linked immunoassay in 281 patients at the baseline visit. Results were compared with baseline risk factors or baseline medication use. Baseline plasma bFGF-IR ranged from 0 to 141 pg/mL. Log plasma bFGF correlated significantly with non-Hispanic white race (P = .002), waist-hip ratio (P = .002), and plasminogen activator inhibitor-1 concentration (P < .0001). Log plasma bFGF correlated inversely with African American race (P = .0003). In multiple regression analysis, plasminogen activator inhibitor-1 and race were significantly correlated with log plasma bFGF. These results suggest a significant correlation between log plasma bFGF-IR and plasminogen activator inhibitor-1, a marker of hemostatic risk.

Validation of a novel risk estimation tool for predicting low bone density in Caucasian and African American men veterans

Osteoporosis in men is a frequently missed diagnosis. We developed an additive risk index, Mscore (male, "simple calculated osteoporosis risk estimation"), based on bone mineral density (BMD) at the femoral neck (FN) in 639 ambulatory older male veterans. Mscore was derived from the nearest whole number ratio among regression coefficients for 5 variables independently associated with osteoporosis. Mscore=[2 x (patient age in decades)-(weight in lb/10)+4 if gastrectomy, +4 if emphysema, +3 if two or more prior fractures+14]. Age and weight variable scores are truncated to integers (i.e., 7 if 75 yr, 18 if 185 lb). Increased risk is reflected in higher Mscore values. We validated Mscore in 197 Caucasian male patients (mean age, 69 yr): values of 9 or higher had 88% sensitivity, 57% specificity, and an area under the curve (AUC) of 0.84 for predicting osteoporosis at the FN (population prevalence, 11%). Mscore values ranged from -9 to 20 allowing us to define low (<9), moderate (9-13), or high (>13) risk categories. Two percent of low-risk men had osteoporosis, 36% or 55% of high-risk men had osteoporosis or osteopenia, respectively. In younger African American (n=134) male veterans (mean age, 61 yr), age and weight were the only variables independently predictive of FN BMD. A reduced Mscore(age-weight) (age and weight variable scores+14) at a cutoff threshold of 9 predicted osteoporosis in African American men (population prevalence, 3%) with a sensitivity of 100%, a specificity of 73%, and an AUC of 0.99. Finally, we compared Mscore with another validated osteoporosis self-assessment tool (OST). OST at a cutoff threshold of 4 or Mscore(age-weight) at a cutoff threshold of 9 performed similarly in both of our populations of Caucasian and African American men. In conclusion, a validated Mscore index with 5 variables was only slightly more robust for predicting osteoporosis in older Caucasian men than 2 (independently derived) risk indices based on age and weight. Mscore(age-weight) or OST is easy to use and can be applied in populations of younger African American men.

Persistent tumor-induced osteomalacia confirmed by elevated postoperative levels of serum fibroblast growth factor-23 and 5-year follow-up of bone density changes

OBJECTIVE

To describe a case of persistent tumor-induced osteomalacia, determine whether serum fibroblast growth factor-23 (FGF-23) levels postoperatively indicate incomplete tumor resection, and report lumbar spine and forearm bone mineral density (BMD) changes during 5 years of follow-up.

METHODS

We present clinical, radiologic, histologic, and bone densitometry data as well as serum FGF-23 levels (determined with use of a novel C-terminal enzyme-linked immunosorbent assay) from the study patient and discuss these findings in the context of previous literature.

RESULTS

A 52-year-old man, who presented with muscle weakness and multiple fractures, was found to have low values for serum phosphorus, serum 1,25-dihydroxyvitamin D, and maximal tubular reabsorption of phosphate per glomerular filtration rate, a high level of serum alkaline phosphatase, and a normal serum concentration of parathyroid hormone, characteristic of tumor-induced osteomalacia. Magnetic resonance imaging to evaluate an abnormality of the left foot revealed a soft tissue mass, biopsy of which confirmed the presence of a benign, phosphaturic, mesenchymal tumor. The baseline serum FGF-23 level (2,050 RU/mL) was more than 17 times the upper limit of normal for adults (23 to 118 RU/mL) and decreased substantially within 1 day after partial resection of the tumor but remained above normal postoperatively. BMD changes indicated rapid substantial recovery of vertebral BMD but ongoing loss of forearm bone density.

CONCLUSION

The serum FGF-23 level is high in a substantial proportion of patients with tumor-induced osteomalacia. The postoperative above normal levels of serum FGF-23 correlated with known persistence of tumor in our study patient. In a patient with normal renal function, such as our study patient, levels of serum FGF-23 studied with use of the C-terminal enzyme-linked immunosorbent assay reached their nadir within 24 hours postoperatively. This result suggests that this assay can provide clinicians with rapid prognostic information in patients with known or suspected residual tumor. BMD should be assessed at both appendicular and axial sites in patients with persistent tumor-induced osteomalacia.

Increased fibroblast growth factor-like autoantibodies in serum from a subset of patients with cancer-associated hypercalcemia

Basic fibroblast growth factor (bFGF) is a potent tumor angiogenesis factor which lacks an amino-terminal signal sequence and does not normally circulate in serum from normal subjects. Naturally-occurring autoantibodies which mimicked basic fibroblast growth factor were described in serum from patients with multiple endocrine neoplasia type 1 prolactinoma or sporadic growth-hormone-secreting adenoma associated with increased bFGF. Since bFGF was increased in serum from a variety of cancers, we used endothelial cell proliferation assay(s) to test for bioactivity in the IgG fraction of serum from 56 patients with cancer-associated hypercalcemia, and normal or control subjects. We now report increased IgG-like endothelial cell activity in serum from a hyper prolactinemic subset (4/19 breast cancer; 1/14 renal cancer; 0/23 lung cancer) of cancer-associated hypercalcemic subjects. Highest activity was found in serum from three breast cancer patients who suffered spinal cord compression/metastases. The activity had properties of antiidiotype bFGF antibodies including reaction with anti-human IgG antibodies, and complete neutralization by rabbit antibodies to intact bFGF. The activity in endothelial cells persisted after storage at 0-4 C for 5 yrs; and [prepared by SDS-PAGE and immunoblotting with anti-human IgG] had apparent mol wt corresponding to the heavy chains of IgG. Serum IgG-like activity from 5 of 5 breast cancer patients and 2 of 2 prostate cancer subjects tested [prepared by anti-bFGF antibody, protein-A immunoaffinity, and hydroxyapatite (HA) chromatography] yielded peak HA-adsorbed activity that eluted with 0.4 M sodium phosphate, and was neutralized 70% by antibodies to intact bFGF. Cancer sera mean peak specific activity (12.0 ng-eq bFGF/ug protein) (n = 7) significantly exceeded (P < 0.001) normal sera mean peak specific activity (0.46 ng-eq bFGF/ug protein) (n = 6) in the 0.4 M sodium phosphate eluate fraction from hydroxyapatite columns. These results imply that long-lasting, bioactive FGF-like autoantibodies may arise spontaneously (and contribute to pathophysiology) in subsets of cancer patients with osseous metastases.

Effect of intravenous bisphosphonates on release of basic fibroblast growth factor in serum of patients with cancer-associated hypercalcemia

Basic fibroblast growth factor (bFGF) is a potent tumor angiogenesis factor and normal constituent of bone extracellular matrix which does not normally circulate in serum of nonpregnant adult humans. We examined the effects of acute administration of intravenous bisphosphonates on release of bFGF in human serum. Twenty seven men and women (mean age, 64 yr) with cancer-associated hypercalcemia, the majority of whom had osseous metastases, were treated once with an intravenous bisphosphonate. Nearly all twelve patients with elevated baseline serum bFGF ranging from 5-27 pg/mL showed significant decreases in serum bFGF (2-7 days) after iv bisphosphonate treatment. The mathematical product of the patients' initial serum bFGF and intial serum calcium concentration, the 'Ca x bFGF product', was significantly negatively (r = -0.91, P < 0.001) correlated with the acute change in serum bFGF level. No consistent relationship was observed between serum bFGF and serum parathyroid hormone related peptide (PTHrP) levels in the hypercalcemic cancer patients. In a subset of patients with non-hematological malignancies and low baseline serum bFGF, acute changes in serum bFGF were significantly negatively (r = -0.66, P < 0.01) correlated with acute change in serum calcium concentration. These results indicate that release of bFGF in serum of patients with cancer-associated hypercalcemia likely depends predominantly on increased bone resorption. Acute change in low serum levels of bFGF in patients with cancer-associated hypercalcemia treated with intravenous bisphosphonates may be physiologically inversely regulated by acute change in the serum calcium concentration.

Increased basic fibroblast growth factor-like substance in plasma from a subset of middle-aged or elderly male diabetic patients with microalbuminuria or proteinuria

Basic fibroblast growth factor (bFGF) is a potent endothelial cell growth factor that does not normally circulate in healthy nonpregnant adults. bFGF has been reported in plasma from patients with certain tumors consistent with a postulated role in tumor angiogenesis. In the present study we used an endothelial cell bioassay to test for a bFGF-like substance in plasma and urine from patients with noninsulin-dependent diabetes mellitus. We found increased bFGF immunoreactivity that correlated with bFGF-like endothelial cell growth-promoting activity in plasma from a subset of diabetic patients with persistent microalbuminuria or overt proteinuria. Plasma (bFGF-like) growth-promoting activity was significantly correlated with glycosylated hemoglobin (P < 0.05), but not patient age, race, degree of proteinuria, or systolic blood pressure. In a group of microalbuminuric or proteinuric diabetic subjects well matched according to baseline clinical characteristics, plasma (bFGF-like) growth-promoting activity was significantly decreased (P < 0.0001) in the subgroup of patients who were being treated with an angiotensin-converting enzyme inhibitor simultaneous to blood drawing for plasma growth assay. In patients not treated with an angiotensin-converting enzyme inhibitor, multiple regression analysis showed that retinopathy was the only variable significantly associated with plasma growth-promoting activity. These results imply that plasma bFGF endothelial cell growth-promoting activity is increased and may contribute to pathophysiology in a heterogeneous subset of noninsulin-dependent diabetes mellitus patients with persistent microalbuminuria or overt proteinuria.

Circulating fibroblast growth factor-like autoantibodies in two patients with multiple endocrine neoplasia type 1 and prolactinoma

Basic fibroblast growth factor (bFGF) is a potent endothelial cell mitogen found in a variety of normal and tumor tissues. bFGF lacks a classical amino-terminal signal sequence and is not readily detectable in plasma from normal subjects. In earlier studies we showed increased bFGF-like mitogenic activity for parathyroid-derived endothelial cells and (increased) bFGF immunoreactivity (0.24-1.28 ng/mL) in plasma of subjects with multiple endocrine neoplasia type 1 (MEN-1). In the present study we examined the proliferative activity of MEN-1 and normal plasmas (applied to protein-A columns) in calf pulmonary artery endothelial cells. Protein-A-eluted activity in plasma from MEN-1 prolactinoma plasma exceeded activity from normal and MEN-1 nonprolactinoma plasma in three of eight MEN-1 subjects with untreated or recurrent prolactinoma. Protein-A-eluted active fractions from MEN-1 prolactinoma plasma had several properties of an immunoglobulin G, including affinity for antihuman immunoglobulin G (IgG) agarose, sensitivity to thiols, and (prepared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions) apparent mol wt corresponding to those of the heavy and light chains of IgG. The IgG fraction of MEN-1 prolactinoma plasma had far more activity in endothelial cells than did optimal concentrations of known growth factors or conditioned medium from prolactinoma cells. Endothelial cell bioactivity in protein-A-eluted fractions from MEN-1 prolactinoma plasma was neutralized 70% by rabbit antibodies to intact bFGF. These results imply novel growth stimulatory bFGF-like autoantibodies in a subset of MEN-1 patients with prolactinoma.

Increased basic fibroblast growth factor in plasma from multiple endocrine neoplasia type 1: relation to pituitary tumor

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterized by tumors of the parathyroids, pancreatic islets, and anterior pituitary. We previously reported a basic fibroblast growth factor (bFGF)-like substance in the plasma of subjects with MEN1. In the present study we used a novel sensitive specific 2-site immunoradiometric assay to test for bFGF in plasma. The assay employs immobilized affinity-purified N-terminal-specific anti-bFGF antibodies (antigen capture) and high affinity binding to radioiodinated heparin. bFGF-like immunoreactivity was undetectable (< 0.2 ng/mL) in normal subjects and in most unaffected relatives of MEN1 subjects. We found detectable bFGF ranging from 0.24-1.28 ng/mL in 21 of 50 subjects with MEN1. Seven of 8 MEN1 subjects with untreated pituitary tumors had detectable plasma bFGF-like immunoreactivity. Plasma bFGF-like immunoreactivity decreased after surgery for pituitary tumor in 4 patients and after initiation of bromocryptine therapy in 4 patients. bFGF was increased in the plasma of several subjects with sporadic endocrine disorders, including 3 with untreated or persistent acromegaly. We conclude that pituitary tumor is a possible source of high circulating bFGF immunoreactivity in MEN1 plasma.

Studies in a kindred with parathyroid carcinoma

We report a family with primary hyperparathyroidism in four patients in two generations with apparent autosomal dominant transmission. A fifth member was probably affected. Two cases had definite parathyroid carcinoma (PC), and two had parathyroid adenoma with atypical features that could represent an early stage of cancer. In each of our patients, one parathyroid gland was abnormal. Five other parathyroid glands (in two patients) were normal in histology and size. There was no evidence of neoplasia in other tissues. Constitutional karyotypes were normal in all four patients. We identified three chromosomal abnormalities (a reciprocal translocation between chromosomes 3 and 4, trisomy 7, and a pericentric inversion in chromosome 9) in cultured PC tissue from one patient. These chromosomal changes are of unclear significance. Analyses on tumor DNA from one case of PC and one of atypical adenoma showed no evidence of ras gene mutations, PTH gene rearrangement, or allelic loss from chromosome 11q13 (locus of the gene for multiple endocrine neoplasia type 1). This family shows susceptibility to cancer without antecedent hyperplasia in all parathyroids. It could help identify a novel tumor susceptibility gene.

Circulating fibroblast growth factor-like substance in familial multiple endocrine neoplasia type 1

Basic fibroblast growth factor (bFGF) is a potent endothelial cell mitogen found in a variety of normal and tumor tissues. Basic FGF lacks a classical signal sequence, and it is not clear how it is released from cells. bFGF or bFGF-like activity has not been previously demonstrated in plasma. In an earlier study we showed increased mitogenic activity for parathyroid-derived epithelial and mesenchymal cells in plasma of subjects with familial multiple endocrine neoplasia type 1 (FMEN1). In the present study we examined the growth-promoting activity of normal and FMEN1 plasmas [applied to heparin-Sepharose (HS) columns] in parathyroid-derived cloned endothelial cells. FMEN1 plasma HS-adsorbed activity exceeded normal plasma HS-adsorbed activity in 6 of 8 FMEN1 plasma samples. Peak (FMEN1 plasma) HS-adsorbed activity eluted with 0.1-0.3 M NaCl, was completely neutralized by specific antibodies against bFGF, and had an apparent mol wt of 110 kD. Active fractions from FMEN1 plasma prepared by gel filtration in 7 M urea displayed apparent mol wt of about 14-16 kD and showed increased apparent affinity for HS; recovered activity appeared principally in the 3.0-M NaCl eluate. Using a sensitive two-site immunoradiometric assay for bFGF we found 0.4 ng/mL bFGF-like immunoreactivity in the highly purified 3.0-M NaCl eluate from a HS column to which the active components from gel filtration of FMEN1 plasma in 7 M urea were applied. These results imply that bFGF or closely related factors circulate in FMEN1.

Clonality of parathyroid tumors in familial multiple endocrine neoplasia type 1

Familial multiple endocrine neoplasia type 1 (MEN-1) is characterized by tumors of the parathyroids, endocrine pancreas, and anterior pituitary. Since the gene associated with MEN-1, located on chromosome 11 (11q13), may normally inhibit tumor proliferation, tumors could arise from inactivation of one or both of the alleles. However, parathyroid tumors in patients with MEN-1 have been considered to result from polyclonal hyperplasia. Using genetic probes, we tested parathyroid tumors for a monoclonal component, represented by a loss of alleles at any of eight loci along chromosome 11. Ten of 16 tumors from 14 patients with familial MEN-1 had losses of alleles from chromosome 11. Tumors with losses were larger than those without (1.6 vs. 0.2 g; P less than 0.002), suggesting that a monoclonal adenoma may develop after a phase of polyclonal hyperplasia. In 7 of 10 tumors, the subregion of loss was less than the full length of chromosome 11 but always included one copy of the MEN-1 locus. Of 34 sporadic adenomas from patients without MEN-1, 9 showed similar allelic losses in chromosome 11; in 7 the losses included the apparent MEN-1 locus. We conclude that many "hyperplastic" parathyroid tumors in familial MEN-1 are in fact monoclonal and may progress or even begin to develop by inactivation of the MEN-1 gene (at 11q13) in a precursor cell. Some sporadic adenomas have allelic losses on chromosome 11, which may also involve the MEN-1 gene.

CCK-8 inhibits feeding-specific neurons in Navanax, an opisthobranch mollusc

Cholecystokinin has been implicated as a satiety factor in mammals because it inhibits feeding through peripheral and central mechanisms. The cellular mechanisms of the central actions of CCK have been difficult to study because of the complex circuitry of the mammalian brain. Navanax is an opisthobranch mollusc with a defined neural network for feeding behavior in which the central effects of CCK can be studied at the cellular level. Here we report the localization of CCK-immunoreactivity in neuronal cell bodies and varicose fibers in the buccal ganglion of Navanax and that CCK-8 inhibits buccal ganglion neurons selectively and at tenth picomolar concentrations: expansion motoneurons responsible for prey capture are strongly inhibited by CCK-8; circumferential motoneurons responsible for swallowing are weakly inhibited by CCK-8. A large cell, cell X, is described which is sensitive to very low doses of CCK-8. These data imply the existence of a CCK-like peptide with transmitter-like actions in the buccal ganglion of Navanax.