The awakening of dormant neuronal precursors in the adult and aged brain

Beyond the canonical neurogenic niches, there are dormant neuronal precursors in several regions of the adult mammalian brain. Dormant precursors maintain persisting post-mitotic immaturity from birth to adulthood, followed by staggered awakening, in a process that is still largely unresolved. Strikingly, due to the slow rate of awakening, some precursors remain immature until old age, which led us to question whether their awakening and maturation are affected by aging. To this end, we studied the maturation of dormant precursors in transgenic mice (DCX-CreERT2 /flox-EGFP) in which immature precursors were labelled permanently in vivo at different ages. We found that dormant precursors are capable of awakening at young age, becoming adult-matured neurons (AM), as well as of awakening at old age, becoming late AM. Thus, protracted immaturity does not prevent late awakening and maturation. However, late AM diverged morphologically and functionally from AM. Moreover, AM were functionally most similar to neonatal-matured neurons (NM). Conversely, late AM were endowed with high intrinsic excitability and high input resistance, and received a smaller amount of spontaneous synaptic input, implying their relative immaturity. Thus, late AM awakening still occurs at advanced age, but the maturation process is slow.

Survey of horse transportation in Switzerland: practices and issues

INTRODUCTION

This study aimed to describe equine transportation practices and transport-related behavioural and health problems in Switzerland and to identify possible associations between them. An online survey was disseminated to Swiss equine industry members and questioned respondents' details, transport practices (before, during, and after journeys), horse transport-related behavioural (TRPBs) and health problems (TRHPs) experienced in the previous 2 years. The survey generated 441 valid responses, analysed using descriptive statistics and logistic regression models (outcomes: TRPBs, TRHPs, injuries, diarrhea). Respondents were mainly women (79,5 %), younger than 50 years (75 %), and amateurs (80 %). Most of the respondents transported one or two horses (88,7 %), for a short (< 2 hours) journey (75,5 %). Pre-transport practices were performed by 72,1 % of respondents and horses' fitness for travel was assessed in the majority of cases (66,5 %). During the journey, horses were tethered (92,6 %) and monitored (52,7 %). The majority of respondents (74,9 %) assessed also the horses' fitness after travel. TRPBs were reported by 13,4 % of respondents. TRPBs' likelihood increased when the respondents were women, performed pre-transport practices and training for transport, did not assess drinking behaviour and general health before journey, and the horses experienced also TRHPs. TRHPs were reported by 34 % of the respondents and were associated with younger respondents, use of trucks, doing pre-transport practices, wearing protections, not monitoring horses during transport and preexisting TRPBs. Among TRHPs the most frequent were injuries (72,1 %) and diarrhea (41 %). The likelihood of injuries increased with younger respondents, use of trucks, wearing protections, lack of monitoring during transport and TRPBs. While younger respondents, longer journeys, wearing protections, lack of monitoring during transport, measuring rectal temperature after journeys and TRPBs increased the odds of reporting diarrhea. Even though our findings must be interpreted with caution due to survey limitations, considering that the found associations do not always mean causation, they highlight the strengths and weaknesses of transport practices in Switzerland and report evidence to implement current regulations on the protection of horse welfare during transport.

Age-related changes in layer II immature neurons of the murine piriform cortex

The recent identification of a population of non-newly born, prenatally generated "immature" neurons in the layer II of the piriform cortex (cortical immature neurons, cINs), raises questions concerning their maintenance or depletion through the lifespan. Most forms of brain structural plasticity progressively decline with age, a feature that is particularly prominent in adult neurogenesis, due to stem cell depletion. By contrast, the entire population of the cINs is produced during embryogenesis. Then these cells simply retain immaturity in postnatal and adult stages, until they "awake" to complete their maturation and ultimately integrate into neural circuits. Hence, the question remains open whether the cINs, which are not dependent on stem cell division, might follow a similar pattern of age-related reduction, or in alternative, might leave a reservoir of young, undifferentiated cells in the adult and aging brain. Here, the number and features of cINs were analyzed in the mouse piriform cortex from postnatal to advanced ages, by using immunocytochemistry for the cytoskeletal marker doublecortin. The abundance and stage of maturation of cINs, along with the expression of other markers of maturity/immaturity were investigated. Despite a marked decrease in this neuronal population during juvenile stages, reminiscent of that observed in hippocampal neurogenesis, a small amount of highly immature cINs persisted up to advanced ages. Overall, albeit reducing in number with increasing age, we report that the cINs are present through the entire animal lifespan.

Spinal Cord Injury and Loss of Cortical Inhibition

After spinal cord injury (SCI), the destruction of spinal parenchyma causes permanent deficits in motor functions, which correlates with the severity and location of the lesion. Despite being disconnected from their targets, most cortical motor neurons survive the acute phase of SCI, and these neurons can therefore be a resource for functional recovery, provided that they are properly reconnected and retuned to a physiological state. However, inappropriate re-integration of cortical neurons or aberrant activity of corticospinal networks may worsen the long-term outcomes of SCI. In this review, we revisit recent studies addressing the relation between cortical disinhibition and functional recovery after SCI. Evidence suggests that cortical disinhibition can be either beneficial or detrimental in a context-dependent manner. A careful examination of clinical data helps to resolve apparent paradoxes and explain the heterogeneity of treatment outcomes. Additionally, evidence gained from SCI animal models indicates probable mechanisms mediating cortical disinhibition. Understanding the mechanisms and dynamics of cortical disinhibition is a prerequisite to improve current interventions through targeted pharmacological and/or rehabilitative interventions following SCI.

Why Would the Brain Need Dormant Neuronal Precursors?

Dormant non-proliferative neuronal precursors (dormant precursors) are a unique type of undifferentiated neuron, found in the adult brain of several mammalian species, including humans. Dormant precursors are fundamentally different from canonical neurogenic-niche progenitors as they are generated exquisitely during the embryonic development and maintain a state of protracted postmitotic immaturity lasting up to several decades after birth. Thus, dormant precursors are not pluripotent progenitors, but to all effects extremely immature neurons. Recently, transgenic models allowed to reveal that with age virtually all dormant precursors progressively awaken, abandon the immature state, and become fully functional neurons. Despite the limited common awareness about these cells, the deep implications of recent discoveries will likely lead to revisit our understanding of the adult brain. Thus, it is timely to revisit and critically assess the essential evidences that help pondering on the possible role(s) of these cells in relation to cognition, aging, and pathology. By highlighting pivoting findings as well as controversies and open questions, we offer an exciting perspective over the field of research that studies these mysterious cells and suggest the next steps toward the answer of a crucial question: why does the brain need dormant neuronal precursors?

Enhancing Functional Recovery Through Intralesional Application of Extracellular Vesicles in a Rat Model of Traumatic Spinal Cord Injury

Local inflammation plays a pivotal role in the process of secondary damage after spinal cord injury. We recently reported that acute intravenous application of extracellular vesicles (EVs) secreted by human umbilical cord mesenchymal stromal cells dampens the induction of inflammatory processes following traumatic spinal cord injury. However, systemic application of EVs is associated with delayed delivery to the site of injury and the necessity for high doses to reach therapeutic levels locally. To resolve these two constraints, we injected EVs directly at the lesion site acutely after spinal cord injury. We report here that intralesional application of EVs resulted in a more robust improvement of motor recovery, assessed with the BBB score and sub-score, as compared to the intravenous delivery. Moreover, the intralesional application was more potent in reducing inflammation and scarring after spinal cord injury than intravenous administration. Hence, the development of EV-based therapy for spinal cord injury should aim at an early application of vesicles close to the lesion.

Functional Integration of Neuronal Precursors in the Adult Murine Piriform Cortex

The extent of functional maturation and integration of nonproliferative neuronal precursors, becoming neurons in the adult murine piriform cortex, is largely unexplored. We thus questioned whether precursors eventually become equivalent to neighboring principal neurons or whether they represent a novel functional network element. Adult brain neuronal precursors and immature neurons (complex cells) were labeled in transgenic mice (DCX-DsRed and DCX-CreER^T2 /flox-EGFP), and their cell fate was characterized with patch clamp experiments and morphometric analysis of axon initial segments. Young (DCX+) complex cells in the piriform cortex of 2- to 4-month-old mice received sparse synaptic input and fired action potentials at low maximal frequency, resembling neonatal principal neurons. Following maturation, the synaptic input detected on older (DCX−) complex cells was larger, but predominantly GABAergic, despite evidence of glutamatergic synaptic contacts. Furthermore, the rheobase current of old complex cells was larger and the maximal firing frequency was lower than those measured in neighboring age-matched principal neurons. The striking differences between principal neurons and complex cells suggest that the latter are a novel type of neuron and new coding element in the adult brain rather than simple addition or replacement for preexisting network components.

PSA Depletion Induces the Differentiation of Immature Neurons in the Piriform Cortex of Adult Mice

Immature neurons are maintained in cortical regions of the adult mammalian brain. In rodents, many of these immature neurons can be identified in the piriform cortex based on their high expression of early neuronal markers, such as doublecortin (DCX) and the polysialylated form of the neural cell adhesion molecule (PSA-NCAM). This molecule plays critical roles in different neurodevelopmental events. Taking advantage of a DCX-CreERT2/Flox-EGFP reporter mice, we investigated the impact of targeted PSA enzymatic depletion in the piriform cortex on the fate of immature neurons. We report here that the removal of PSA accelerated the final development of immature neurons. This was revealed by a higher frequency of NeuN expression, an increase in the number of cells carrying an axon initial segment (AIS), and an increase in the number of dendrites and dendritic spines on the immature neurons. Taken together, our results demonstrated the crucial role of the PSA moiety in the protracted development of immature neurons residing outside of the neurogenic niches. More studies will be required to understand the intrinsic and extrinsic factors affecting PSA-NCAM expression to understand how the brain regulates the incorporation of these immature neurons to the established neuronal circuits of the adult brain.

Structural and Functional Maturation of Rat Primary Motor Cortex Layer V Neurons

Rodent neocortical neurons undergo prominent postnatal development and maturation. The process is associated with structural and functional maturation of the axon initial segment (AIS), the site of action potential initiation. In this regard, cell size and optimal AIS length are interconnected. In sensory cortices, developmental onset of sensory input and consequent changes in network activity cause phasic AIS plasticity that can also control functional output. In non-sensory cortices, network input driving phasic events should be less prominent. We, therefore, explored the relationship between postnatal functional maturation and AIS maturation in principal neurons of the primary motor cortex layer V (M1LV), a non-sensory area of the rat brain. We hypothesized that a rather continuous process of AIS maturation and elongation would reflect cell growth, accompanied by progressive refinement of functional output properties. We found that, in the first two postnatal weeks, cell growth prompted substantial decline of neuronal input resistance, such that older neurons needed larger input current to reach rheobase and fire action potentials. In the same period, we observed the most prominent AIS elongation and significant maturation of functional output properties. Alternating phases of AIS plasticity did not occur, and changes in functional output properties were largely justified by AIS elongation. From the third postnatal week up to five months of age, cell growth, AIS elongation, and functional output maturation were marginal. Thus, AIS maturation in M1LV is a continuous process that attunes the functional output of pyramidal neurons and associates with early postnatal development to counterbalance increasing electrical leakage due to cell growth.

Extracellular Vesicles Can Deliver Anti-inflammatory and Anti-scarring Activities of Mesenchymal Stromal Cells After Spinal Cord Injury

Spinal cord injury is characterized by initial neural tissue disruption that triggers secondary damage and extensive non-resolving inflammation, which aggravates loss of function and hinders recovery. The early onset of inflammation following traumatic spinal cord injury underscores the importance of acute intervention after the initial trauma. Injections of mesenchymal stromal cells (MSCs) can reduce inflammation following spinal cord injury. We asked if extracellular vesicles (EVs) can substitute the anti-inflammatory and anti-scarring activities of their parental MSCs in a rat model of contusion spinal cord injury. We report that MSC-EVs were as potent as the parental intact cells in reducing the level of neuroinflammation for up to 2 weeks post-injury. Acute application of EVs after spinal cord injury was shown to robustly decrease the expression of pro-inflammatory cytokines in the spinal cord parenchyma in the very early phase of secondary damage. Moreover, the anti-scarring impact of MSC-EVs was even more efficient than the parental cells. We therefore conclude that anti-inflammatory and anti-scarring activities of MSC application can be mediated by their secreted EVs. In light of their substantial safety and druggability advantages, EVs may have a high potential in early therapeutic treatment following traumatic spinal cord injury.

Cellular Plasticity in the Adult Murine Piriform Cortex: Continuous Maturation of Dormant Precursors Into Excitatory Neurons

Neurogenesis in the healthy adult murine brain is based on proliferation and integration of stem/progenitor cells and is thought to be restricted to 2 neurogenic niches: the subventricular zone and the dentate gyrus. Intriguingly, cells expressing the immature neuronal marker doublecortin (DCX) and the polysialylated-neural cell adhesion molecule reside in layer II of the piriform cortex. Apparently, these cells progressively disappear along the course of ageing, while their fate and function remain unclear. Using DCX-CreER^T2/Flox-EGFP transgenic mice, we demonstrate that these immature neurons located in the murine piriform cortex do not vanish in the course of aging, but progressively resume their maturation into glutamatergic (TBR1⁺, CaMKII⁺) neurons. We provide evidence for a putative functional integration of these newly differentiated neurons as indicated by the increase in perisomatic puncta expressing synaptic markers, the development of complex apical dendrites decorated with numerous spines and the appearance of an axonal initial segment. Since immature neurons found in layer II of the piriform cortex are generated prenatally and devoid of proliferative capacity in the postnatal cortex, the gradual maturation and integration of these cells outside of the canonical neurogenic niches implies that they represent a valuable, but nonrenewable reservoir for cortical plasticity.

Role of putative voltage-sensor countercharge D4 in regulating gating properties of CaV1.2 and CaV1.3 calcium channels

Voltage-dependent calcium channels (Ca_V) activate over a wide range of membrane potentials, and the voltage-dependence of activation of specific channel isoforms is exquisitely tuned to their diverse functions in excitable cells. Alternative splicing further adds to the stunning diversity of gating properties. For example, developmentally regulated insertion of an alternatively spliced exon 29 in the fourth voltage-sensing domain (VSD IV) of Ca_V1.1 right-shifts voltage-dependence of activation by 30 mV and decreases the current amplitude several-fold. Previously we demonstrated that this regulation of gating properties depends on interactions between positive gating charges (R1, R2) and a negative countercharge (D4) in VSD IV of Ca_V1.1. Here we investigated whether this molecular mechanism plays a similar role in the VSD IV of Ca_V1.3 and in VSDs II and IV of Ca_V1.2 by introducing charge-neutralizing mutations (D4N or E4Q) in the corresponding positions of Ca_V1.3 and in two splice variants of Ca_V1.2. In both channels the D4N (VSD IV) mutation resulted in a  ̴5 mV right-shift of the voltage-dependence of activation and in a reduction of current density to about half of that in controls. However in Ca_V1.2 the effects were independent of alternative splicing, indicating that the two modulatory processes operate by distinct mechanisms. Together with our previous findings these results suggest that molecular interactions engaging D4 in VSD IV contribute to voltage-sensing in all examined Ca_V1 channels, however its striking role in regulating the gating properties by alternative splicing appears to be a unique property of the skeletal muscle Ca_V1.1 channel.

Two distinct voltage-sensing domains control voltage sensitivity and kinetics of current activation in CaV1.1 calcium channels

Alternative splicing of the skeletal muscle CaV1.1 voltage-gated calcium channel gives rise to two channel variants with very different gating properties. The currents of both channels activate slowly; however, insertion of exon 29 in the adult splice variant CaV1.1a causes an ∼30-mV right shift in the voltage dependence of activation. Existing evidence suggests that the S3-S4 linker in repeat IV (containing exon 29) regulates voltage sensitivity in this voltage-sensing domain (VSD) by modulating interactions between the adjacent transmembrane segments IVS3 and IVS4. However, activation kinetics are thought to be determined by corresponding structures in repeat I. Here, we use patch-clamp analysis of dysgenic (CaV1.1 null) myotubes reconstituted with CaV1.1 mutants and chimeras to identify the specific roles of these regions in regulating channel gating properties. Using site-directed mutagenesis, we demonstrate that the structure and/or hydrophobicity of the IVS3-S4 linker is critical for regulating voltage sensitivity in the IV VSD, but by itself cannot modulate voltage sensitivity in the I VSD. Swapping sequence domains between the I and the IV VSDs reveals that IVS4 plus the IVS3-S4 linker is sufficient to confer CaV1.1a-like voltage dependence to the I VSD and that the IS3-S4 linker plus IS4 is sufficient to transfer CaV1.1e-like voltage dependence to the IV VSD. Any mismatch of transmembrane helices S3 and S4 from the I and IV VSDs causes a right shift of voltage sensitivity, indicating that regulation of voltage sensitivity by the IVS3-S4 linker requires specific interaction of IVS4 with its corresponding IVS3 segment. In contrast, slow current kinetics are perturbed by any heterologous sequences inserted into the I VSD and cannot be transferred by moving VSD I sequences to VSD IV. Thus, CaV1.1 calcium channels are organized in a modular manner, and control of voltage sensitivity and activation kinetics is accomplished by specific molecular mechanisms within the IV and I VSDs, respectively.

Loss of the calcium channel β4 subunit impairs parallel fibre volley and Purkinje cell firing in cerebellum of adult ataxic mice

The auxiliary voltage-gated calcium channel subunit β4 supports targeting of calcium channels to the cell membrane, modulates ionic currents and promotes synaptic release in the central nervous system. β4 is abundant in cerebellum and its loss causes ataxia. However, the type of calcium channels and cerebellar functions affected by the loss of β4 are currently unknown. We therefore studied the structure and function of Purkinje cells in acute cerebellar slices of the β4 (-/-) ataxic (lethargic) mouse, finding that loss of β4 affected Purkinje cell input, morphology and pacemaker activity. In adult lethargic cerebellum evoked postsynaptic currents from parallel fibres were depressed, while paired-pulse facilitation and spontaneous synaptic currents were unaffected. Because climbing fibre input was spared, the parallel fibre/climbing fibre input ratio was reduced. The dendritic arbor of adult lethargic Purkinje cells displayed fewer and shorter dendrites, but a normal spine density. Accordingly, the width of the molecular and granular layers was reduced. These defects recapitulate the impaired cerebellar maturation observed upon Cav 2.1 ataxic mutations. However, unlike Cav 2.1 mutations, lethargic Purkinje cells also displayed a striking decrease in pacemaker firing frequency, without loss of firing regularity. All these deficiencies appear in late development, indicating the importance of β4 for the normal differentiation and function of mature Purkinje cells networks. The observed reduction of the parallel fibre input, the altered parallel fibre/climbing fibre ratio and the reduced Purkinje cell output can contribute to the severe motor impairment caused by the loss of the calcium channel β4 subunit in lethargic mice.

Physiological and pharmacological modulation of the embryonic skeletal muscle calcium channel splice variant CaV1.1e

CaV1.1e is the voltage-gated calcium channel splice variant of embryonic skeletal muscle. It differs from the adult CaV1.1a splice variant by the exclusion of exon 29 coding for 19 amino acids in the extracellular loop connecting transmembrane domains IVS3 and IVS4. Like the adult splice variant CaV1.1a, the embryonic CaV1.1e variant functions as voltage sensor in excitation-contraction coupling, but unlike CaV1.1a it also conducts sizable calcium currents. Consequently, physiological or pharmacological modulation of calcium currents may have a greater impact in CaV1.1e expressing muscle cells. Here, we analyzed the effects of L-type current modulators on whole-cell current properties in dysgenic (CaV1.1-null) myotubes reconstituted with either CaV1.1a or CaV1.1e. Furthermore, we examined the physiological current modulation by interactions with the ryanodine receptor using a chimeric CaV1.1e construct in which the cytoplasmic II-III loop, essential for skeletal muscle excitation-contraction coupling, has been replaced with the corresponding but nonfunctional loop from the Musca channel. Whereas the equivalent substitution in CaV1.1a had abolished the calcium currents, substitution of the II-III loop in CaV1.1e did not significantly reduce current amplitudes. This indicates that CaV1.1e is not subject to retrograde coupling with the ryanodine receptor and that the retrograde coupling mechanism in CaV1.1a operates by counteracting the limiting effects of exon 29 inclusion on the current amplitude. Pharmacologically, CaV1.1e behaves like other L-type calcium channels. Its currents are substantially increased by the calcium channel agonist Bay K 8644 and inhibited by the calcium channel blocker nifedipine in a dose-dependent manner. With an IC50 of 0.37 μM for current inhibition by nifedipine, CaV1.1e is a potential drug target for the treatment of myotonic dystrophy. It might block the excessive calcium influx resulting from the aberrant expression of the embryonic splice variant CaV1.1e in the skeletal muscles of myotonic dystrophy patients.

Molecular Interactions in the Voltage Sensor Controlling Gating Properties of CaV Calcium Channels

Voltage-gated calcium channels (CaV) regulate numerous vital functions in nerve and muscle cells. To fulfill their diverse functions, the multiple members of the CaV channel family are activated over a wide range of voltages. Voltage sensing in potassium and sodium channels involves the sequential transition of positively charged amino acids across a ring of residues comprising the charge transfer center. In CaV channels, the precise molecular mechanism underlying voltage sensing remains elusive. Here we combined Rosetta structural modeling with site-directed mutagenesis to identify the molecular mechanism responsible for the specific gating properties of two CaV1.1 splice variants. Our data reveal previously unnoticed interactions of S4 arginines with an aspartate (D1196) outside the charge transfer center of the fourth voltage-sensing domain that are regulated by alternative splicing of the S3-S4 linker. These interactions facilitate the final transition into the activated state and critically determine the voltage sensitivity and current amplitude of these CaV channels.

Cell-type-specific tuning of Cav1.3 Ca(2+)-channels by a C-terminal automodulatory domain

Cav1.3 L-type Ca(2+)-channel function is regulated by a C-terminal automodulatory domain (CTM). It affects channel binding of calmodulin and thereby tunes channel activity by interfering with Ca(2+)- and voltage-dependent gating. Alternative splicing generates short C-terminal channel variants lacking the CTM resulting in enhanced Ca(2+)-dependent inactivation and stronger voltage-sensitivity upon heterologous expression. However, the role of this modulatory domain for channel function in its native environment is unkown. To determine its functional significance in vivo, we interrupted the CTM with a hemagglutinin tag in mutant mice (Cav1.3DCRD(HA/HA)). Using these mice we provide biochemical evidence for the existence of long (CTM-containing) and short (CTM-deficient) Cav1.3 α1-subunits in brain. The long (HA-labeled) Cav1.3 isoform was present in all ribbon synapses of cochlear inner hair cells. CTM-elimination impaired Ca(2+)-dependent inactivation of Ca(2+)-currents in hair cells but increased it in chromaffin cells, resulting in hyperpolarized resting potentials and reduced pacemaking. CTM disruption did not affect hearing thresholds. We show that the modulatory function of the CTM is affected by its native environment in different cells and thus occurs in a cell-type specific manner in vivo. It stabilizes gating properties of Cav1.3 channels required for normal electrical excitability.

CACNA1D de novo mutations in autism spectrum disorders activate Cav1.3 L-type calcium channels

BACKGROUND

Cav1.3 voltage-gated L-type calcium channels (LTCCs) are part of postsynaptic neuronal signaling networks. They play a key role in brain function, including fear memory and emotional and drug-taking behaviors. A whole-exome sequencing study identified a de novo mutation, p.A749G, in Cav1.3 α1-subunits (CACNA1D), the second main LTCC in the brain, as 1 of 62 high risk-conferring mutations in a cohort of patients with autism and intellectual disability. We screened all published genetic information available from whole-exome sequencing studies and identified a second de novo CACNA1D mutation, p.G407R. Both mutations are present only in the probands and not in their unaffected parents or siblings.

METHODS

We functionally expressed both mutations in tsA-201 cells to study their functional consequences using whole-cell patch-clamp.

RESULTS

The mutations p.A749G and p.G407R caused dramatic changes in channel gating by shifting (~15 mV) the voltage dependence for steady-state activation and inactivation to more negative voltages (p.A749G) or by pronounced slowing of current inactivation during depolarizing stimuli (p.G407R). In both cases, these changes are compatible with a gain-of-function phenotype.

CONCLUSIONS

Our data, together with the discovery that Cav1.3 gain-of-function causes primary aldosteronism with seizures, neurologic abnormalities, and intellectual disability, suggest that Cav1.3 gain-of-function mutations confer a major part of the risk for autism in the two probands and may even cause the disease. Our findings have immediate clinical relevance because blockers of LTCCs are available for therapeutic attempts in affected individuals. Patients should also be explored for other symptoms likely resulting from Cav1.3 hyperactivity, in particular, primary aldosteronism.

Periorbital subcutaneous emphysema in rhinoplasty

In this article, the authors present a case of postrhinoplasty periorbital subcutaneous emphysema in a 35-year-old woman. This is an uncommon and benign rhinoplasty complication that can sometimes result from other pathologies such as barotrauma, hematoma, and allergic reaction. This patient's symptoms appeared to be a result of postanesthesia agitation. The patient's symptoms resolved after 1 week.

Intracellular glycine receptor function facilitates glioma formation in vivo

The neuronal function of Cys-loop neurotransmitter receptors is established; however, their role in non-neuronal cells is poorly defined. As brain tumors accumulate the neurotransmitter glycine, we studied expression and function of glycine receptors (GlyR) in glioma cells. Human brain tumor biopsies selectively expressed GlyR subunits with nuclear import signal (NLS, α1 and α3). The mouse glioma cell line GL261 expressed GlyR α1, and knock-down of α1 protein expression impaired self-renewal capacity and tumorigenicity of GL261 glioma cells as evidenced by the neurosphere assay and GL261 cell inoculation in vivo, respectively. We furthermore show that the pronounced tumorigenic effect of GlyR α1 relies on a new intracellular signaling function that depends on the NLS region in the large cytosolic loop and impacts on GL261 glioma cell gene regulation. Stable expression of GlyR α1 and α3 loops rescued self-renewal capacity of GlyR α1 knock-down cells, which demonstrates their functional equivalence. The new intracellular signaling function identified here goes beyond the well-established role of GlyRs as neuronal ligand-gated ion channels and defines NLS-containing GlyRs as novel potential targets for brain tumor therapies.

Astrocytes control GABAergic inhibition of neurons in the mouse barrel cortex

Astrocytes in the barrel cortex respond with a transient Ca2+ increase to neuronal stimulation and this response is restricted to the stimulated barrel field. In the present study we suppressed the astrocyte response by dialysing these cells with the Ca2+ chelator BAPTA. Electrical stimulation triggered a depolarization in stellate or pyramidal ‘regular spiking' neurons from cortex layer 4 and 2/3 and this response was augmented in amplitude and duration after astrocytes were dialysed with BAPTA. Combined blockade of GABAA and GABAB receptors mimicked the effect of BAPTA dialysis, while glutamate receptor blockers had no effect. Moreover, the frequency of spontaneous postsynaptic currents was increased after BAPTA dialysis. Outside the range of BAPTA dialysis astrocytes responded with a Ca2+ increase, but in contrast to control, the response was no longer restricted to one barrel field. Our findings indicate that astrocytes control neuronal inhibition in the barrel cortex.

Global N-acetylaspartate declines even in benign multiple sclerosis

BACKGROUND AND PURPOSE

Neuro-axonal damage is a well known sequelae of MS pathogeneses. Consequently, our aim was to test whether the ∼20% of patients with MS exhibiting a clinically benign disease course also have minimal neural dysfunction as reflected by the global concentration of their MR imaging marker NAA.

MATERIALS AND METHODS

Q(NAA) was obtained with nonlocalizing whole-head (1)H-MR spectroscopy in 43 patients with benign RRMS (30 women, 13 men; mean age, 44.7 ± 7.3 years of age) with 21.0 ± 4.4 years (range, 15-35 years) of disease duration from the first symptom and an EDSS score of 1.9 (range, 0-3). Q(NAA) was by divided by the brain volume (from MR imaging segmentation) to normalize it into WBNAA. All participants gave institutional review board-approved written informed consent, and the study was HIPAA compliant.

RESULTS

The patients' lesion load was 12.2 ± 7.7 cm(3). Their 8.3 ± 1.8 mmol/L WBNAA was 35% lower than that in controls (P < .001). Individual average loss rates (absolute loss compared with controls divided by disease duration) clustered around 0.22 ± 0.09 mmol/L/year (1.7%/year, assuming monotonic decline). This rate could be extrapolated from that already reported for patients with RRMS of much shorter disease duration. WBNAA did not correlate with lesion load or EDSS.

CONCLUSIONS

Normal WBNAA is not characteristic of benign MS and is not an early predictor of its course. These patients, therefore, probably benefit from successful compensation and sparing of eloquent regions. Because they may ultimately have a rapid decline once their brain plasticity is exhausted, they may benefit from treatment options offered to more affected patients.

Neuron-astrocyte interactions in the medial nucleus of the trapezoid body

The calyx of Held (CoH) synapse serves as a model system to analyze basic mechanisms of synaptic transmission. Astrocyte processes are part of the synaptic structure and contact both pre- and postsynaptic membranes. In the medial nucleus of the trapezoid body (MNTB), midline stimulation evoked a current response that was not mediated by glutamate receptors or glutamate uptake, despite the fact that astrocytes express functional receptors and transporters. However, astrocytes showed spontaneous Ca²⁺ responses and neuronal slow inward currents (nSICs) were recorded in the postsynaptic principal neurons (PPNs) of the MNTB. These currents were correlated with astrocytic Ca²⁺ activity because dialysis of astrocytes with BAPTA abolished nSICs. Moreover, the frequency of these currents was increased when Ca²⁺ responses in astrocytes were elicited. NMDA antagonists selectively blocked nSICs while D-serine degradation significantly reduced NMDA-mediated currents. In contrast to previous studies in the hippocampus, these NMDA-mediated currents were rarely synchronized.

A diffusion tensor MRI study of cervical cord damage in benign and secondary progressive multiple sclerosis patients

BACKGROUND

Diffusion tensor (DT) MRI enables quantification of the severity of brain and cervical cord pathology in multiple sclerosis (MS).

OBJECTIVE

To investigate DT MRI patterns of cervical cord damage in patients with benign MS (BMS) and secondary progressive MS (SPMS), in order to achieve a better understanding of the mechanisms underlying the development of irreversible disability in MS.

METHODS

Conventional and DT MRI scans of the cervical cord and brain were acquired from 40 BMS patients, 28 SPMS patients and 18 healthy individuals. Cervical cord and brain mean diffusivity (MD) and fractional anisotropy (FA) maps were created and average MD and FA were calculated. Cross sectional cord area (CSA) was also computed.

RESULTS

37 (92%) BMS patients and all (100%) SPMS patients had macroscopic cervical cord lesions. Compared with healthy individuals, BMS patients had higher average cord MD while SPMS patients had higher average cord MD, lower average cord FA and lower average CSA. Compared with BMS patients, SPMS patients had lower cord average FA and lower average CSA. In MS patients, Expanded Disability Status Scale (EDSS) was correlated with CSA (r = -0.47, p<0.0001), average cord FA (r = -0.37, p = 0.002) and brain T2 lesion volume (LV) (r = 0.34, p = 0.005). A multivariate regression model identified CSA, average cord FA and brain T2 LV as variables independently influencing the EDSS score (r = 0.58, p<0.0001).

CONCLUSIONS

Cervical cord damage outside focal macroscopic lesions is limited in patients with BMS. The assessment of cord and brain pathology provides complementary information to improve the understanding of disability accumulation in MS.

In-vivo evidence for stable neuroaxonal damage in the brain of patients with benign multiple sclerosis

OBJECTIVE

The term benign multiple sclerosis (BMS) is referred to patients who have a mild or absent disability several years after disease clinical onset. Axonal damage can be measured in vivo using proton MR spectroscopy ((1)H-MRS). In this study, we quantified the severity of "global" axonal damage in BMS and early relapsing-remitting (RR) MS patients, using whole brain N-acetylaspartate (WBNAA) (1)H-MRS, to better elucidate the structural correlates of a non-disabling disease evolution.

METHODS

WBNAA concentration was measured in 37 patients with BMS (mean disease duration 22.3 years) and 17 patients with early RRMS (mean disease duration 4.0 years), using an unlocalized (1)H-MRS sequence. Dual echo and T1-weighted scans were also obtained to measure T2-hyperintense lesion volume (TLV) and normalized brain volume (NBV).

RESULTS

TLV was higher in BMS (mean TLV = 13.1 mL) than in early RRMS patients (mean TLV = 7.2 mL) (P = 0.018), whereas neither NBV (mean NBV: 1491.0 mL in BMS vs 1520.3 mL in RRMS) nor WBNAA concentration (mean WBNAA: 10.5 mmol in BMS vs 11.4 mmol in RRMS) significantly differed between the two groups. In MS patients, no correlation was found between WBNAA concentration and Expanded Disability Status Scale (EDSS), TLV and NBV.

CONCLUSIONS

The similar WBNAA concentrations seen in BMS and early RRMS patients fit with the notion that a non-disabling long-term evolution of MS may be due, at least in part, to non-progression of pathology. Such a condition seems to be independent from MRI-visible lesions burden.

Serial whole-brain N-acetylaspartate concentration in healthy young adults

Although the concentration of N-acetylaspartate (NAA) is often used as a neuronal integrity marker, its normal temporal variations are not well documented. To assess them over the 1-2 year periods of typical clinical trials, the whole-brain NAA concentration was measured longitudinally, over 4 years, in a cohort of healthy young adults. No significant change (adjusted for both sex and age) was measured either interpersonally or intrapersonally over the entire duration of the study.

Diffusion anisotropy of the cervical cord is strictly associated with disability in amyotrophic lateral sclerosis

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with severe cervical cord damage due to degeneration of the corticospinal tracts and loss of lower motor neurones. Diffusion tensor magnetic resonance imaging (DT MRI) allows the measurement of quantities reflecting the size (such as mean diffusivity) and orientation (such as fractional anisotropy) of water-filled spaces in biological tissues.

METHODS

Mean diffusivity and fractional anisotropy histograms from the cervical cord of patients with ALS were obtained to: (1) quantify the extent of tissue damage in this critical central nervous system region; and (2) investigate the magnitude of the correlation of cervical cord DT MRI metrics with patients' disability and tissue damage along the brain portion of the corticospinal tracts. Cervical cord and brain DT MRI scans were obtained from 28 patients with ALS and 20 age-matched and sex-matched controls. Cord mean diffusivity and fractional anisotropy histograms were produced and the cord cross-sectional area was measured. Average mean diffusivity and fractional anisotropy along the brain portion of the corticospinal tracts were also measured.

RESULTS

Compared with controls, patients with ALS had significantly lower mean fractional anisotropy (p = 0.002) and cord cross-sectional area (p<0.001). Mean diffusivity histogram-derived metrics did not differ between the two groups. A strong correlation was found between mean cord fractional anisotropy and the ALS Functional Rating Score (r = 0.74, p<0.001). Mean cord and brain fractional anisotropy values correlated moderately (r = 0.37, p = 0.05).

CONCLUSIONS

Cervical cord DT MRI in patients with ALS allows the extent of cord damage to be graded. The conventional and DT MRI changes found are compatible with the presence of neuroaxonal loss and reactive gliosis, with a heterogeneous distribution of the pathological process between the brain and the cord. The correlation found between cord fractional anisotropy and disability suggests that DT MRI may be a useful adjunctive tool to monitor the evolution of ALS.

Reproducibility of the whole-brain N-acetylaspartate level across institutions, MR scanners, and field strengths

BACKGROUND AND PURPOSE

Radiologic markers in multicenter trials are often confounded by different instrumentation used. Our goal was to estimate the variance of the global concentration of the neuronal cell marker N-acetylaspartate (NAA) among research centers using MR imaging scanners of different models, from different manufacturers, and of different magnetic field strength.

MATERIALS AND METHODS

Absolute millimolar amounts of whole-brain NAA (WBNAA) were quantified with nonlocalizing proton MR spectroscopy in the brains of 101 healthy subjects (53 women, 48 men) aged 16-59 years (mean, 34.2 years). Twenty-three were scanned at 1 institute in a 1.5T Siemens Vision; 31 from another institute were studied with a 1.5T Siemens SP63; 36 were scanned at a third institute (24 with a 1.5T Vision, 12 with a 3T Siemens Trio); and 11 were obtained at a fourth institute using a 4T GE Signa 5.x. The NAA amounts were quantified with phantom-replacement and divided by the brain volume, segmented from MR imaging, to yield the concentration, a metric independent of brain size suitable for cross-sectional comparison.

RESULTS

The average WBNAA concentration among institutions was 12.2 +/- 1.2 mmol/L. The subjects' WBNAA distributions did not differ significantly (p > .237) among the 4 centers, regardless of scanner manufacturer, model, or field strength and irrespective of whether adjustments were made for age or sex.

CONCLUSION

Absolute quantification against a standard makes the WBNAA concentration insensitive to the MR hardware used to acquire it. This important attribute renders it a robust surrogate marker for multicenter neurologic trials.

Grey matter damage predicts the evolution of primary progressive multiple sclerosis at 5 years

Reliable prognostic markers of primary progressive (PP) multiple sclerosis evolution are still needed. Diffusion tensor (DT) MRI can quantify normal-appearing white matter (NAWM) and grey matter (GM) damage in multiple sclerosis patients. We investigated whether conventional and DT-MRI-derived measures can predict the long-term clinical evolution of PP multiple sclerosis. In 54 PP multiple sclerosis patients, conventional and DT-MRI scans of the brain and T1-weighted scans of the cervical cord were acquired at baseline and after a median follow-up of 15 months. Another clinical evaluation was performed, 56 months after baseline, in 52 patients. Measures of lesion load, brain and cord atrophy were obtained. Histograms of the mean diffusivity (MD) and fractional anisotropy (FA) values from the NAWM and GM were analysed. At follow-up, 35 patients (65%) experienced a confirmed disability progression. Baseline expanded disability status scale score and average GM MD were independent predictors of subsequent clinical deterioration in a multivariable model (Nagelkerke R2: 0.44; discriminating ability: 81%). A lower level of disability and a more severe GM damage identify PP multiple sclerosis patients with an increased risk of disease progression over the subsequent 5 years. These data may be relevant to select patients for future exploratory phase II trials.

Grading cervical cord damage in neuromyelitis optica and MS by diffusion tensor MRI

The authors assessed the ability of diffusion tensor MRI to grade cervical cord damage in 10 patients with neuromyelitis optica, 10 patients with multiple sclerosis, and 10 healthy controls. The three groups differed in terms of average mean diffusivity (p = 0.008) and average fractional anisotropy (p = 0.04). There was a correlation between the Expanded Standard Disability Status Scale score and cord average mean diffusivity (r = 0.52, p = 0.02).

MR imaging assessment of brain and cervical cord damage in patients with neuroborreliosis

BACKGROUND AND PURPOSE

Neuroborreliosis is frequently indistinguishable from multiple sclerosis (MS) on both clinical and radiologic grounds. By using MR imaging, we assessed "occult" brain white matter (WM), brain gray matter (GM), and cervical cord damage in patients with neuroborreliosis in an attempt to achieve a more accurate picture of tissue damage in these patients, which might contribute to the diagnostic work-up.

METHODS

We studied 20 patients with neuroborreliosis and 11 sex- and age-matched control subjects. In all subjects, we acquired dual echo, T1-weighted, diffusion tensor (DT) and magnetization transfer (MT) MR imaging scans of the brain and fast short-tau inversion recovery and MT MR imaging scans of the cervical cord. T2-visible lesion load was measured by using a local thresholding segmentation technique. Mean diffusivity and fractional anisotropy histograms of the brain and cervical cord MT ratio histograms were produced. Normalized brain volumes (NBV) were measured by using SIENAx.

RESULTS

Brain T2-visible lesions were detected in 12 patients, whereas no occult damage in the normal-appearing WM and GM was disclosed by using MT and DT MR imaging. No macroscopic lesions were found in the cervical cord, which was also spared by occult pathology. NBV did not differ between patients with neuroborreliosis and control subjects.

CONCLUSION

This study shows that, contrary to what happens in MS, occult brain tissue damage and cervical cord pathology are not frequent findings in patients with neuroborreliosis. These observations might be useful in the diagnostic work-up of patients with neuroborreliosis and T2 brain lesions undistinguishable from those of MS.

Influence of aging on brain gray and white matter changes assessed by conventional, MT, and DT MRI

BACKGROUND

Conventional MRI can reveal decreases in brain volumes with aging but fails to provide information about the underlying microstructural modifications. Magnetization transfer (MT) and diffusion tensor (DT) MRI can in part overcome these limitations.

OBJECTIVE

To investigate the influence of aging on conventional and MT and DT MRI-derived measurements in brain white (WM) and gray (GM) matter.

METHODS

Dual-echo, T1-weighted, MT and DT MR images of the brain were obtained in 89 healthy subjects (age range 11 to 76 years). Normalized GM and WM volumes were measured and MT ratio (MTR) and mean diffusivity (MD) histograms produced for both tissue compartments.

RESULTS

Normalized brain (r = -0.78), GM (r = -0.75), and WM (r = -0.34) volumes and the number of brain T2 hyperintensities (r = 0.49) were correlated with age. Additionally, all GM MT- and DT-derived parameters also correlated with age (r values ranging from 0.28 to 0.64), whereas only the peak height (ph) of the normal-appearing (NA) WM MD histogram did so (r = -0.34). After correcting for the number of T2 hyperintensities, gender, and the corresponding normalized tissue volumes, only the correlations between age and GM average MD (r = 0.24), GM-MD-ph (r = -0.37), and NAWM-MD-ph (r = -0.29) remained significant. A multivariate regression analysis including both brain tissues variables retained the GM volume (beta = -0.18, SE = 0.02, p < 0.001) and the GM average MD (beta = 45, SE = 19, p = 0.02) as independent predictors of subject's age.

CONCLUSIONS

Brain white matter and gray matter have different vulnerabilities to aging. Microstructural imaging is important to achieve a complete picture of the complex changes occurring in the aging brain.

Axonal injury in early multiple sclerosis is irreversible and independent of the short-term disease evolution

OBJECTIVE

To define the nature and the temporal evolution of neuronal/axonal injury in patients at the earliest clinical stage of multiple sclerosis (MS), using whole brain N-acetylaspartate (WBNAA) proton MR spectroscopy (1H-MRS).

METHODS

Thirty-five patients at presentation with clinically isolated syndromes (CIS) and MRI evidence of disease dissemination in space were studied. The following scans of the brain were acquired within 3 months from the onset of the disease and after 12 months: 1) dual-echo; 2) WBNAA 1H-MRS; 3) pre- and postcontrast T1-weighted. The same scans were obtained in 12 age-matched healthy subjects, without contrast administration. In patients, conventional MRI scans were also repeated 3 months after the first scanning session, to assess the presence of early disease dissemination in time (DIT).

RESULTS

Over the study period, 24 patients showed MRI evidence of disease DIT, thus fulfilling the criteria for a diagnosis of MS. The average WBNAA amount was lower in CIS patients than in controls both at baseline (13.7 vs 16.9 mM, p < 0.001) and at 1-year follow-up (12.6 vs 16.2 mM, p < 0.001), but the average yearly percentage change of WBNAA did not differ between the two groups. No MRI or 1H-MRS quantities were significantly associated with the disease DIT over the study period.

CONCLUSION

Irreversible brain damage associated with axonal dysfunction occurs at a very early stage in patients with clinically isolated syndromes, but it does not seem to be related with the disease evolution in the subsequent short-term period.

Evidence for progressive gray matter loss in patients with relapsing-remitting MS

Little is known about the temporal evolution of gray matter damage occurring early in the course of multiple sclerosis (MS). The authors investigated the evolution of gray matter volume loss in 117 patients with relapsing-remitting MS, scanned monthly for a 9-month period. Time-trend analysis revealed a decrease of gray matter volumes over the study period (p < 0.001). This study shows that gray matter damage in relapsing-remitting MS evolves markedly over a short period of observation.

A whole brain MR spectroscopy study from patients with Alzheimer's disease and mild cognitive impairment

Brain damage in Alzheimer's disease (AD) and mild cognitive impairment (MCI) is widespread with involvement of large portions of the neocortex and the subcortical white matter. A quantitative measure of neuronal damage of the entire brain might be valuable in the context of large-scale, longitudinal studies of these patients. This study investigated the extent of neuroaxonal injury of patients with AD and MCI using a novel unlocalized proton magnetic resonance spectroscopy ((1)H-MRS) technique, which allows quantification of the concentration of N-acetylaspartate from the whole of the brain tissue (WBNAA). Conventional brain MRI and WBNAA were obtained from 28 AD patients, 27 MCI patients and 25 age-matched controls. Normalized brain volume (NBV) was also measured using an automated segmentation technique. WBNAA and NBV showed a significant heterogeneity between groups (P < 0.001). WBNAA concentration was different between controls and MCI patients (P = 0.003), but not between MCI and AD patients (P = 0.33). NBV differed both between controls and MCI patients (P = 0.02) and between MCI and AD patients (P = 0.03). A multivariate regression model retained WBNAA as the best MRI predictor of the Mini Mental State Examination score (P = 0.001). Significant neuronal damage, which is related to the extent of cognitive decline, can be quantified in the whole brain tissue of patients with AD, using a novel (1)H-MRS approach. The demonstration in patients with MCI of MR structural and metabolic findings, intermediate between those of healthy volunteers and those of AD patients, indicates that neuronal damage is already evident and widespread in individuals with MCI before they are clinically demented.

Long-term clinical outcome of primary progressive MS: Predictive value of clinical and MRI data

The authors sought to identify clinical and MRI predictors of outcome in primary progressive multiple sclerosis (PPMS). Clinical and MRI assessments were performed at baseline and 2 and 5 years (clinical only). At baseline, disease duration, expanded disability status scale (EDSS) and brain volume predicted outcome. Adding short-term change variables, baseline EDSS, changes in T2* lesion load and cord area, and number of new lesions were predictive. Clinical and MRI variables predict long-term outcome in PPMS.

An MT MRI study of the cervical cord in clinically isolated syndromes suggestive of MS

Cervical cord magnetization transfer ratio (MTR) histograms were obtained from 45 patients at presentation with clinically isolated syndromes (CIS) suggestive of multiple sclerosis (MS). The mean values of MTR histogram-derived metrics were not different between CIS patients and healthy control subjects or between patients with and without evidence of disease dissemination in time. Only three patients showed significantly lower cord MTR values than control subjects. These findings suggest the absence of intrinsic structural damage of the cervical cord soon after the onset of CIS suggestive of MS, even in those patients with an early evolution to MS.

Quantification of cervical cord pathology in primary progressive MS using diffusion tensor MRI

OBJECTIVE

To investigate the extent and severity of cervical cord damage using diffusion tensor MRI (DT-MRI) and histogram analysis in patients with primary progressive MS (PPMS).

METHODS

Diffusion-weighted sensitivity-encoded (SENSE) echoplanar images of the cervical cord and brain dual-echo and diffusion-weighted scans were acquired from 24 patients with PPMS and 13 healthy controls. Cord and brain mean diffusivity and fractional anisotropy histograms were produced. An analysis of variance model, adjusting for cord volume, was used to compare cord DT-MRI parameters from controls and patients.

RESULTS

Compared to healthy controls, PPMS patients had reduced cervical cord cross-sectional area and average cord fractional anisotropy (p = 0.007), and increased cord mean diffusivity (p = 0.024). No correlations were found between DT-MRI metrics of the cord and quantities obtained from conventional and DT-MRI of the brain.

CONCLUSIONS

DT-MRI of the cervical cord can quantify the extent of diffuse cord pathology in patients with PPMS. Such cord diffusivity changes in patients with PPMS are likely to reflect irreversible axonal injury and reactive gliosis and seem to be independent of brain damage.

Human allogeneic melanoma-reactive T-helper lymphocyte clones: functional analysis of lymphocyte-melanoma interactions

Lymphocyte clones were isolated from CD4+ peripheral-blood lymphocytes (PBL) of melanoma (Me) patient 9923 (HLA-DR7, DQw2, w6), co-cultured for 30 days with autologous accessory cells, allogeneic Me (Me 1811) (HLA-DR7, DQw1, w2), IL-1 beta (2 U/ml) and IL-2 (15 IU/ml). The 55 clones tested displayed a CD3+, CD4+, CD8-, T-cell receptor (TCR) alpha/beta+, gamma/delta- phenotype. Twenty clones were assayed for proliferation in the presence of Me 1811 and B-lymphoblastoid cell line (LCL) 1811, both expressing HLA-class-I and -II (DR7 and DQw2 shared with patient 9923), intercellular adhesion molecule-1 (ICAM-1) and lymphocyte-function-associated antigen-3 (LFA-3) molecules. Eight clones were found to be reactive to Me 1811 but not to LCL 1811. Specificity analysis of these 8 clones revealed that each of them proliferated only to Me 1811, not to other 14 Me and 12 different LCL, suggesting recognition of melanoma-associated antigen (MAA) expressed on the stimulating Me. One clone (103) was analyzed in more detail. A wider specificity analysis showed that it reacted to Me 1811 but not to 10 other Me expressing or not HLA-DR7, 5 normal melanocyte cultures (2 of them typing HLA-DR7-positive when exposed to interferon-gamma--IFN-gamma), 4 tumors other than Me and 20 different LCL. Clones did not show proliferation in the presence of autologous Me cells. Clone proliferation in response to Me 1811 was significantly inhibited by monoclonal antibodies (MAbs) directed to CD3, TCR alpha/beta, TCR beta chain V12, CD4 and HLA-DR. Moreover, following stimulation with Me 1811, clone 103 showed increased surface expression of CD25 (IL-2 receptor) and CD71 (transferrin receptor) and produced significant amounts of IL-2 and IFN-gamma. The supernatant taken from co-culture of clone 103 with Me 1811 augmented the cytotoxicity of PBL 9923 and other allogeneic PBL against K562 and Me 1811. Thus, the lymphocyte clone 103 is a CD4+ Th clone which uses its CD3/TCR alpha/beta complex to recognize an MAA in conjunction with HLA-DR7. Availability of this type of reagent may prove useful to identify and characterize MAA recognized by T lymphocytes.

Cancer patients' lymphocytes contain CD3+ CD4+ cells that proliferate in response to autologous tumor cells in the presence of exogenous low-dose interleukin-2 and autologous accessory cells

To see whether cancer patients possess CD3+ CD4+ lymphocytes able to proliferate in response to autologous tumor cells (Auto-Tu), this lymphocyte subset was isolated either by positive or negative selection, both methods resulting in highly enriched CD4+ populations. Unseparated and isolated CD3+ CD4+ lymphocytes were then assayed for proliferating activity in the presence or absence of various amounts of Auto-Tu, with or without recombinant interleukin-2 (IL-2) (1.5-15 U/ml) and DR+ adherent cells or E- lymphocytes as autologous accessory cells (Auto-AC). Isolated CD3+ CD4+ lymphocytes were stimulated by Auto-Tu alone in only 1 out of 12 cases. CD3+ CD4+ cells failed to proliferate significantly in response to low doses of IL-2 alone but the addition of Auto-Tu caused stimulation in 8 out of 12 cases (67%). The further addition of Auto-AC to Auto-Tu + IL-2 resulted in enhanced response of isolated CD3+ CD4+ lymphocytes in 6 out of 8 cases tested. When reactivities to Auto-Tu in the presence of IL-2 and IL-2 + Auto-AC were considered together, positive responses of CD3+ CD4+ lymphocytes were seen in 11 out of 12 cases (92%). On the other hand, unseparated lymphocytes were stimulated by Auto-Tu alone in none out of 12 cases. Unseparated lymphocytes, however, responded to IL-2 in 11 out of 12 cases; such a response was increased by the addition of Auto-Tu in only 2 cases. Moreover, the IL-2 proliferation of unseparated lymphocytes was suppressed in 4 and in 3 out of 12 cases tested when Auto-Tu or Auto-Tu + Auto-AC were added respectively. These data indicate that lymphocytes of cancer patients contain CD3+ CD4+ cells that are usually unable to proliferate in response to Auto-Tu only. This proliferation, however, occurs when low doses of exogenous IL-2 are present and can be further amplified by the addition of Auto-AC. No response of CD4+ cells is observed in the presence of DR+ Auto-AC + IL-2 except in 2 out of 7 cases tested (28%), suggesting an Auto-Tu-restricted reactivity of CD3+ CD4+ lymphocytes in the majority of cases.