Kai Kaila

University of Helsinki | HY · Neuroscience Center and MIBS

Brain pH is a critical factor for determining neuronal activity, with alkalosis increasing and acidosis reducing excitability. Acid shifts in brain pH through the breathing of carbogen (5% CO 2 – 95% O 2 ) reduces seizure susceptibility in animal models and patients. The molecular mechanisms underlying this seizure protection remain to be fully elu...

The Na-K-2Cl cotransporter NKCC1 is widely expressed in cells within and outside the brain. However, our understanding of its roles in brain functions throughout development, as well as in neuropsychiatric and neurological disorders, has been severely hindered by the lack of reliable data on its developmental and (sub)cellular expression patterns....

In his editorial, Kevin Staley criticizes our recent work demonstrating the lack of effect of bumetanide in a novel model of neonatal seizures. The main points in our response are that (i) our work is on an asphyxia model, not one on ‘hypercarbia‐only’; (ii) clinically relevant parenteral doses of bumetanide applied in vivo lead to concentrations i...

The NKCC1 ion transporter contributes to the pathophysiology of common neurological disorders, but its function in microglia, the main inflammatory cells of the brain, has remained unclear to date. Therefore, we generated a novel transgenic mouse line in which microglial NKCC1 was deleted. We show that microglial NKCC1 shapes both baseline and reac...

Apolipoprotein E ε4 allele ( APOE4 ) has been shown to associate with increased susceptibility to SARS-CoV-2 infection and COVID-19 mortality in some previous genetic studies, but information on the role of APOE4 on the underlying pathology and parallel clinical manifestations is scarce. Here we studied the genetic association between APOE and COVI...

The Na–K–2Cl cotransporter NKCC1 and the neuron-specific K–Cl cotransporter KCC2 are considered attractive CNS drug targets because altered neuronal chloride regulation and consequent effects on GABAergic signaling have been implicated in numerous CNS disorders. While KCC2 modulators are not yet clinically available, the loop diuretic bumetanide ha...

Objective Birth asphyxia is a major cause of hypoxic–ischemic encephalopathy (HIE) in neonates and often associated with mortality, neonatal seizures, brain damage, and later life motor, cognitive, and behavioral impairments and epilepsy. Preclinical studies on rodent models are needed to develop more effective therapies for preventing HIE and its...

Objective Seizures are common in neonates recovering from birth asphyxia but there is general consensus that current pharmacotherapy is suboptimal and that novel antiseizure drugs are needed. We recently showed in a rat model of birth asphyxia that seizures are triggered by the post-asphyxia recovery of brain pH. Here our aim was to investigate whe...

Intracellular pH is a potent modulator of neuronal functions. By catalyzing (de)hydration of CO2 , intracellular carbonic anhydrase (CAi ) isoforms CA2 and CA7 contribute to neuronal pH buffering and dynamics. The presence of two highly active isoforms in neurons suggests that they may serve isozyme-specific functions unrelated to CO2 -(de)hydratio...

In this response to a commentary by Ben‐Ari and Delpire on our recent study on the pharmacology of neonatal seizures in a novel, physiologically validated rat model of birth asphyxia, we wish to rectify their inaccurate descriptions of our model and data. Furthermore, because Ben‐Ari and Delpire suggest that negative data on bumetanide from preclin...

Increased neuronal expression of the Na-K-2Cl cotransporter NKCC1 has been implicated in the generation of seizures and epilepsy. However, conclusions from studies on the NKCC1-specific inhibitor, bumetanide, are equivocal, which is a consequence of the multiple potential cellular targets and poor brain penetration of this drug. Here, we used Nkcc1...

KCC2, best known as the neuron-specific chloride-extruder that sets the strength and polarity of GABAergic currents during neuronal maturation, is a multifunctional molecule that can regulate cytoskeletal dynamics via its C-terminal domain (CTD). We describe the molecular and cellular mechanisms involved in the multiple functions of KCC2 and its sp...

The NKCC1 ion transporter contributes to the pathophysiology of common neurological disorders, but its function in microglia, the main inflammatory cells of the brain, has not been studied to date. Therefore, we generated a novel transgenic mouse line in which microglial NKCC1 was deleted. We show that microglial NKCC1 shapes both baseline and reac...

Objective Birth asphyxia (BA) is often associated with seizures that may exacerbate the ensuing hypoxic–ischemic encephalopathy. In rodent models of BA, exposure to hypoxia is used to evoke seizures, that commence already during the insult. This is in stark contrast to clinical BA, in which seizures are typically seen upon recovery. Here, we introd...

Ionotropic GABA transmission is mediated by anion (mainly Cl−)-permeable GABAA receptors (GABAARs). In immature neurons, GABA exerts depolarizing and sometimes functionally excitatory actions, based on active uptake of Cl− by the Na-K-2Cl cotransporter NKCC1. While functional evidence firmly shows NKCC1-mediated ion transport in immature and diseas...

Objective Neonatal seizures are the most frequent type of neurological emergency in newborn infants, often being a consequence of prolonged perinatal asphyxia. Phenobarbital is currently the most widely used antiseizure drug for treatment of neonatal seizures, but fails to stop them in ~50% of cases. In a neonatal hypoxia‐only model based on 11‐day...

Progressive myoclonus epilepsy of Unverricht-Lundborg type (EPM1) is a neurodegenerative disorder caused by loss-of-function mutations in the cystatin B (CSTB) gene. Progression of the clinical symptoms in EPM1 patients, including stimulus-sensitive myoclonus, tonic-clonic seizures, and ataxia, are well described. However, the cellular dysfunction...

[This corrects the article DOI: 10.1371/journal.pone.0233851.].

Brain interstitial pH (pHbrain) alterations play an important role in the mechanisms of neuronal injury in neonatal hypoxic-ischemic encephalopathy (HIE) induced by perinatal asphyxia. The newborn pig is an established large animal model to study HIE, however, only limited information on pHbrain alterations is available in this species and it is re...

Birth asphyxia (BA) is often associated with seizures which emerge during the recovery and may exacerbate the ensuing hypoxic-ischemic encephalopathy. In rodent models of BA, exposure to hypoxia is used to evoke seizures, which commence already during the insult. Here, we introduce a term-equivalent model of BA, in which seizures are triggered afte...

African naked mole-rats were likely the first mammals to evolve eusociality, and thus required adaptations to conserve energy and tolerate the low oxygen (O2) and high carbon dioxide (CO2) of a densely populated fossorial nest. As hypercapnia is known to suppress neuronal activity, we studied whether naked mole-rats might demonstrate energy savings...

Aim: To study brain-sparing physiological responses in a rodent model of birth asphyxia which reproduces the asphyxia-defining systemic hypoxia and hypercapnia. Methods: Steady or intermittent asphyxia was induced for 15-45 min in anesthetized 6- and 11-days old rats and neonatal guinea pigs using gases containing 5% or 9% O2 plus 20% CO2 (in N2...

KCC2, encoded in humans by the SLC12A5 gene, is a multifunctional neuron‐specific protein initially identified as the chloride (Cl−) extruder critical for hyperpolarizing GABAA receptor currents. Independently of its canonical function as a K‐Cl cotransporter, KCC2 regulates the actin cytoskeleton via molecular interactions mediated through its lar...

Aim To study brain-sparing physiological responses in a rodent model of birth asphyxia which reproduces the asphyxia-defining systemic hypoxia and hypercapnia. Methods Steady or intermittent asphyxia was induced for 15-45 min in anesthetized 6 and 11 days old rats and neonatal guinea pigs using gases containing 5% or 9% O 2 plus 20% CO 2 (in N 2 )...

Intracellular pH is a potent modulator of neuronal functions. By catalyzing (de)hydration of CO 2 , intracellular carbonic anhydrase (CA i ) isoforms CAII and CAVII contribute to neuronal pH buffering and dynamics. The presence of two highly active isoforms suggests that they form spatially distinct CA i pools enabling subcellular modulation of pH....

It is generally thought that hippocampal neurons of perinatal rats and mice lack transport-functional K-Cl cotransporter KCC2, and that Cl⁻ regulation is dominated by Cl⁻ uptake via the Na-K-2Cl cotransporter NKCC1. Here, we demonstrate a robust enhancement of spontaneous hippocampal network events (giant depolarizing potentials [GDPs]) by the KCC2...

Based on the potential role of Na-K-Cl cotransporters (NKCCs) in epileptic seizures, the loop diuretic bumetanide, which blocks the isoforms NKCC1 and NKCC2, has been tested as an adjunct with phenobarbital to suppress seizures. However, because of its physicochemical properties, bumetanide only poorly penetrates through the blood-brain barrier. Th...

Background Impaired brain oxygen delivery can trigger and exacerbate migraine attacks. Normoxic hypercapnia increases brain oxygen delivery markedly by vasodilation of the cerebral vasculature, and hypercapnia has been shown to abort migraine attacks. Stable normoxic hypercapnia can be induced by a compact partial rebreathing device. This pilot stu...

Mammalian birth is accompanied by a period of obligatory asphyxia, which consists of hypoxia (drop in blood O2 levels) and hypercapnia (elevation of blood CO2 levels). Prolonged, complicated birth can extend the asphyxic period, leading to a pathophysiological situation, and in humans, to the diagnosis of clinical birth asphyxia, the main cause of...

Significance The transition from placental to lung-based oxygen supply at mammalian birth involves an obligatory period of asphyxia, which is further aggravated by complications during delivery. This oxygen deprivation is a major threat to the fetal brain, and, under such conditions, hormonal and cardiovascular mechanisms are activated to enhance b...

In developing brain neuronal migration, dendrite outgrowth and dendritic spine outgrowth are controlled by Cdc42, a small GTPase of the Rho family, and its activators. Cdc42 function in promoting actin polymerization is crucial for glutamatergic synapse regulation. Here, we focus on GABAergic synapse-specific activator of Cdc42, collybistin (CB) an...

CB1 and CB2 isoforms are Ub conjugated. (A) HEK293T cells transfected with HA-Ubiquitin and V5-CB isoforms. The cells were treated with either DMSO or MG132 and analyzed for HA-Ub conjugation after IP for HA and WB for V5. Higher migrating V5 bands can be seen in MG132 treated samples. (B) HEK293T cells transfected with HA-Ub and V5-CB isoforms wer...

Ub mutants of CB do not show difference in eGFP-gephyrin clustering along proximal-distal axis. (A-E’) Morphological analysis of neurons co-transfected with eGFP-gephyin and CB1 ubiquitin mutants CB1SH3+ K491R/K492R or CB1SH3+ K491R/K492R. (F-H) Quantification of eGFP-gephyrin synaptic cluster density in neurons co-transfected with CB1SH3+ K491R/K4...

eGFP-CB1SH3- functions downstream of α2 GABAARs in newborn neurons. (A) Morphology of adult newborn neuron expressing eGFP in WT or Gabra2 KO background, and eGFP-CB1SH3- in Gabra2 KO background. (B-B”) Migration of adult newborn neurons in Gabra2 KO background is enhanced at 14 dpi compared to WT background. WT cells catch up at 28 dpi and 42 dpi....

Biochemical analysis for CB and Cdc42 interaction. (A-B) Bacterial overexpressed and purified GST-Cdc42 incubated with γsGTP or GDP to mimic active and inactive forms. GST, GST-Cdc42, GST-Cdc42 γsGTP or GST-CDC42 GDP incubated with HEK293T lysates overexpressing V5-CB1SH3+, V5-CB1SH3-, V5-CB2SH3+ or V5-CB2SH3- showing interaction between active and...

In developing brain neuronal migration, dendrite outgrowth and dendritic spine outgrowth are controlled by Cdc42, a small GTPase of the Rho family, and its activators. Cdc42 function in promoting actin polymerization is crucial for glutamatergic synapse regulation. Here, we focus on GABAergic synapse-specific activator of Cdc42, collybistin (CB) an...

Significance The control of intracellular Cl ⁻ and pH plays a crucial role in several neuronal functions, and the study of these processes would be helped by tools for their noninvasive optical measurement in vivo. In this study, we have performed combined measurements of Cl ⁻ and pH of individual pyramidal neurons by means of in vivo two-photon im...

The objective of this study was to evaluate the early changes in serial serum levels of copeptin and neuron-specific enolase (NSE) in neonates diagnosed with birth asphyxia, and to determine whether these biomarkers measured in the first 168 hours after birth are predictive of long-term neurodevelopmental outcome. Copeptin and NSE levels were measu...

Biomarker correlations with blood gas parameters. Correlations of copeptin at 6 h (row 1; A-C), copeptin at 12 h (row 2; D-F), NSE at 6 h (row 3; G-I) and NSE at 12 h (row 4; J-L) with blood pH (column 1; A, D, G and J), blood base excess (column 2; B, E, H and K) and blood lactate (column 3; C, F, I and L). All correlations were significant, r- an...

Gap junctions form electrical synapses that modulate neuronal activity by synchronizing action potential (AP) firing of cortical interneurons (INs). Gap junctions are thought to form predominantly within cortical INs of the same functional class and are therefore considered to act within discrete neuronal populations. Here, we challenge that view a...

Principle component analysis and unsupervised clustering of recorded interneurons (INs). Graphs depict the first four principles components and the unsupervised clustering groupings from each comparison for cells classified as fast-spiking (FS; open circles) or regular-spiking (RS; closed triangles).

Action potential (AP) firing patterns of FS-RS pairings. (A–C) Depicts the AP firing patterns, the first AP fired and gap junction coupling between the remaining FS and RS INs pairings not shown in Figure 4. Vpre indicates the pre-junctional neuron and Vpost the post-junctional neurons. (D) Principle component analysis and unsupervised clustering o...

Background: General anesthetics potentiating γ-aminobutyric acid (GABA)-mediated signaling are known to induce a persistent decrement in excitatory synapse number in the cerebral cortex when applied during early postnatal development, while an opposite action is produced at later stages. Here, the authors test the hypothesis that the effect of gen...

Background: Birth asphyxia, estimated to account for a million neonatal deaths annually, can cause a wide variety of neurodevelopmental impairments. There is a need to develop new, swift methods to identify those neonates who would benefit from neuroprotective treatments such as hypothermia. Objectives: To examine the utility of cord serum copepti...

Protocol Summary We report here an improved method for analyzing protein surface expression utilizing a cold-adapted trypsin. Preservation of activity of the enzyme at 0–4°C permits modification of the protease method of surface analysis to temperatures at which trafficking of mammalian plasmalemmal proteins is blocked. This is an important advanta...

Synaptic reorganization in the epileptic hippocampus involves altered excitatory and inhibitory transmission besides the rearrangement of dendritic spines, resulting in altered excitability, ion homeostasis, and cell swelling. The potassium-chloride cotransporter-2 (KCC2) is the main chloride extruder in neurons and hence will play a prominent role...

Under the influence of inflammation, people alter their breathing pattern and their response to CO2, which may have fatal consequences in newborn babies and relate to sudden infant death. We aimed to unravel the nature this neural network disturbance and the specific modulators involved. We report that CO2 elicits a gap junction-dependent release o...

Inflammation-induced release of prostaglandin E 2 (PGE 2) changes breathing patterns and the response to CO 2 levels. This may have fatal consequences in newborn babies and result in sudden infant death. To elucidate the underlying mechanisms, we present a novel breathing brainstem organotypic culture that generates rhythmic neural network and moto...

Febrile seizures are the most common type of convulsive events in children. It is generally assumed that the generalization of these seizures is a result of brainstem invasion by the initial limbic seizure activity. Using precollicular transection in 13-day-old rats to isolate the forebrain from the brainstem, we demonstrate that the forebrain is n...

Work on rodents demonstrated that steep upregulation of KCC2, a neuron-specific Cl(-) extruder of cation-chloride cotransporter (CCC) family, commences in supraspinal structures at around birth, leading to establishment of hyperpolarizing GABAergic responses. We describe spatiotemporal expression profiles of the entire CCC family in human brain. KC...

Electrical activity in neurons requires a seamless functional coupling between plasmalemmal ion channels and ion transporters. Although ion channels have been studied intensively for several decades, research on ion transporters is in its infancy. In recent years, it has become evident that one family of ion transporters, cation-chloride cotranspor...

A robust increase in the functional expression of the neuronal K-Cl cotransporter KCC2 during CNS development is necessary for the emergence of hyperpolarizing ionotropic GABAergic transmission. BDNF-TrkB signaling has been implicated in the developmental up-regulation of KCC2 and, in mature animals, in fast activity-dependent down-regulation of KC...