Systematic Review of the Clinical Characteristics and Management of Isaac Syndrome.

OBJECTIVES: Isaac syndrome (IS) is a condition characterized by peripheral nerve hyperexcitability caused by voltage-gated potassium channel (VGKC)-complex antibodies. Muscle twitching, stiffness, hypertrophy, and dysautonomic characteristics, such as hyperhidrosis, are common manifestations. The syndrome can be autoimmune or paraneoplastic, with thymoma being a common cause of paraneoplastic IS. Furthermore, this condition could be handed down from one generation to another. However, there is limited information regarding outcomes, relapses, associated syndromes, associated malignancies (other than thymoma), and treatment options. Despite its rarity, there remains a need for effective management strategies for patients with IS. To address this gap, we conducted a systematic review to summarize the most common and effective treatments of IS in immunomodulatory agents and symptomatic medications, as well as to describe outcomes, relapses, and associated malignancies. Altogether, this review serves to guide clinical practice recommendations for IS and highlight areas for further research. METHODS: We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol to conduct a systematic review of cases reposted through the PubMed and Google Scholar databases. The terms "Isaac Syndrome" and "Acquired Neuromyotonia" were used. The Joanna Briggs Institute's critical appraisal tool was used to evaluate the quality of the included studies. RESULTS: We identified 61 case reports and 4 case series, comprising a total of 70 patients with IS (mean age at onset: 42.5 ± 18 years, and 69% were males). Fourteen cases reported relapses. Thymoma was the most common malignancy associated with IS, followed by lymphoma. Among various serum antibodies, voltage-gated potassium channel-complex antibodies were the most reported antibodies elevated in IS (reported in 38 patients and elevated in 21 patients [55.2%]), followed by acetylcholine ganglionic receptor antibodies, which were reported in 30% of patients (n = 21) and were elevated in 5 cases. The most common electromyography findings were myokymic discharges (n = 22), followed by fasciculations (n = 21) and neuromyotonia (n = 19). For treatment, combining anticonvulsants such as carbamazepine with immunotherapy therapy showed the best results in controlling the symptoms. Among immunotherapy therapies, the combination of plasma exchange plus intravenous high-dose steroids achieved the best results in the acute treatment of IS ([n = 6], with improvement noted in 83.3% [n = 5] of cases). Among the symptomatic treatments with anticonvulsants, carbamazepine was the most efficacious anticonvulsant in treatment of IS, with an average effective dosing of 480 mg/day (carbamazepine was used in 32.3% of acute treatment strategies [n = 23], with improvement noted in 73.9% [n = 17] of cases). CONCLUSIONS: IS a rare neuromuscular syndrome that tends to affect middle-aged men. These patients should be screened for thymoma and other malignancies such as lymphomas. The management of IS symptoms can be challenging, but based on our review, the combination of multiple immunosuppressives such as IV steroids and plasmapheresis with anticonvulsants such as carbamazepine seems to achieve the best results.

Lance-Adams Syndrome: Case series and literature review.

Background: Lance-Adams Syndrome (LAS) is a rare complication of successful cardiopulmonary resuscitation (CPR). It is a form of posthypoxic myoclonus characterized by action or intention myoclonus developing days to months after an hypoxic insult to the brain. LAS, especially early in a patient's clinical course, can be challenging to diagnose. Electroencephalogram (EEG) pattern of midline spike-wave discharge associated with favorable prognosis. There is no consensus in treatment of LAS but use of various anti-epileptic medications has been documented in literature. Case Presentation: In this case series, all of the patients presented after achieving return of spontaneous circulation (ROSC) and subsequently developed myoclonus. EEG findings beyond the initial hospitalization continued to show later showed changes consistent with LAS in three of the four patients. Different combinations of AEDs were used in the management of LAS with variable success and adverse effects. Conclusion: Our cases highlight that the characteristic EEG pattern can be useful in the diagnosis of LAS and allow for better prognostication and management in patients with posthypoxic myoclonus. We reviewed the available literature to better understand the prevalence, mechanism, clinical presentation, diagnosis, and management of LAS.

Transient headache and neurological deficits with cerebrospinal fluid lymphocytosis syndrome: A comprehensive systematic review of 93 patients from 57 studies.

BACKGROUND: Headache with neurologic deficits and cerebrospinal fluid lymphocytosis, previously also termed pseudomigraine with temporary neurologic symptoms and lymphocytic pleocytosis, is a self-limiting syndrome characterized by moderate to severe headache associated with focal neurological deficits occurring in the context of lymphocytosis in the cerebrospinal fluid. As a consequence of its rarity, data regarding headache with neurologic deficits and cerebrospinal fluid lymphocytosis is sparse. Therefore, we conducted this review to analyze data related to 93 patients of headache with neurologic deficits and cerebrospinal fluid lymphocytosis, to characterize their demographics, clinical manifestations, investigations and treatment options. METHODS: We performed a systematic review of cases reported through PubMed and Google scholar database, using Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol. Keywords used were 'Headache with Neurologic Deficits and cerebrospinal fluid lymphocytosis', 'Headache with neurologic deficits and cerebrospinal fluid lymphocytosis syndrome'. The quality of the included studies was assessed using the Joanna Briggs Institute Critical Appraisal Tool. RESULTS: We analyzed a total of 93 cases of headache with neurologic deficits and cerebrospinal fluid lymphocytosis with a mean age of 28.8 years at onset. Seventy patients (75.2%) were adults, while 23 (24.7%) belonged to the pediatric age group. Comparing these groups, mean age at onset was 32.5 years and 14.3 years, respectively. The average duration of follow-up was 11.08 months. Thirty percent of patients experienced relapsing episodes of headache with neurologic deficits and cerebrospinal fluid lymphocytosis symptoms. The most common type of headache reported was unilateral severe throbbing episodic headache. Other associated symptoms included sensory deficit (60%) and motor deficits (54.8%). The least common symptoms were nystagmus and agraphia, which were reported in one patient each. Antiviral agents were a common treatment option in the acute phase (n = 23 patients [23.6%]), while Flunarizine was the most commonly used agent in the chronic setting (n = 3 patients [3.2%]). While most of the patients had normal brain magnetic resonance imaging, 20 patients had magnetic resonance imaging abnormalities, including (but not limited to) non-specific white matter lesions (eight patients) and meningeal enhancement (six patients). The most common electroencephalographic findings included diffuse and focal slowing. The mean cerebrospinal fluid opening-pressure was 240.5 mmH2O. Cerebrospinal fluid protein was elevated in 59 (63.4%) patients, with a mean value of 114 mg/dL. Two patients in our cohort were found to have cerebrospinal fluid oligoclonal bands. CONCLUSION: Headache with neurologic deficits and cerebrospinal fluid lymphocytosis tends to affect young individuals with a slight male predominance. Unilateral severe throbbing episodic headache with associated hemi-paresthesia and hemiparesis were the most common symptoms based on our review. Elevated cerebrospinal fluid opening-pressure can be seen in headache with neurologic deficits and cerebrospinal fluid lymphocytosis syndrome. Early recognition of the syndrome is paramount. Antivirals were found to be among the most widely used treatments in the acute setting. Magnetic resonance imaging of the brain is mostly normal. Diffuse and focal slowing were among the most common electroencephalographic findings. Cerebral flow abnormalities on perfusion scans are not uncommon in headache with neurologic deficits and cerebrospinal fluid lymphocytosis. Prospective studies with a larger sample size are needed to validate our findings and guide the clinical care of these patients.

Spinal epidural venous engorgement-Potential imaging confounder after diagnostic lumbar puncture.

Intracranial hypotension is a result of low Cerebrospinal fluid (CSF) pressure caused by either spontaneous or postoperative leakage. The classic presentation of spontaneous intracranial hypotension is acute orthostatic headache, but the diagnosis can sometimes be challenging as some patients may present with atypical initial presentations including cervical pain as well as cervical radiculopathy secondary to cervical spine venous engorgement. We described a 42-year-old female patient who presented initially with neuropathic pain symptoms as well as weakness involving both lower extremities for which she underwent diagnostic lumbar puncture with concern regarding demyelinating neuropathy. However, subsequently she developed postural headache as well as severe cervical pain which was attributed to cervical epidural venous engorgement in setting of intracranial hypotension based on cervical spine magnetic resonance imaging (MRI) findings. She was managed conservatively, and repeated cervical spine MRI 3 days later showed prominent improvement in the imaging findings. Spinal epidural venous engorgement can occur secondary to intracranial hypotension (mainly post lumbar puncture), and can present clinically with neck pain or even symptoms of radiculopathy. Since the findings can mimic more serious conditions, it is extremely important to consider this condition in the differential diagnosis of an enhancing epidural collection in the cervical spine, particularly when intracranial hypotension is suspected.

Modified Atkins diet versus ketogenic diet in children with drug-resistant epilepsy: A meta-analysis of comparative studies.

INTRODUCTION: The modified Atkins diet (MAD), a less restrictive form of the ketogenic diet (KD), has gained popularity and is proposed to be an alternative to the traditional KD in the management of drug-resistant epilepsy (DRE). However, the evidence to support this hypothesis remains limited. In this meta-analysis, we aimed to evaluate the efficacy and tolerability of MAD compared to traditional KD in children with DRE. METHOD: We systematically searched multiple databases through March 2022 for all the studies that evaluated the clinical utility of MAD versus KD for DRE in a pediatric population. The primary outcome was the proportion of children who had seizure frequency reduction (SFR) > 50%. The secondary outcomes were SFR >90%, seizure freedom, and diet-related side effects. All measurements were taken 6 months after starting the regimens. Pooled risk ratio (RR) and corresponding 95% confidence intervals (CIs) were calculated and combined using random-effects model meta-analysis. RESULTS: Six studies, with 397 patients with DRE (201 followed MAD vs. 196 with KD), were included. There was a significant difference in the proportion of patients who attained SFR >50% favoring the traditional KD (RR: 0.63; 95% CI: 0.47-0.83; P = 0.001). However, there was no significant differences in SFR >90% (RR: 0.73; 95% CI: 0.49-1.10; P = 0.13) or the proportion of patients who had seizure freedom (RR: 0.83; 95% CI: 0.49-1.41; P = 0.49). Furthermore, both regimens had comparable safety profiles (RR: 1.00; 95% CI: 0.95-1.05; P = 0.96). CONCLUSIONS: Our meta-analysis demonstrated the superiority of traditional KD over MAD in achieving SFR > 50% at 6 months in pediatric patients with DRE. However, SFR > 90% and seizure freedom were comparable between KD and MAD at 6 months. The tolerability profile between the two regimens was similar as well. Large-scale RCTs are necessary to validate our findings.

Clinical characteristics, management, and outcomes of CLIPPERS: A comprehensive systematic review of 140 patients from 100 studies.

INTRODUCTION: Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) is a rare inflammatory disorder of the central nervous system, characterized by symptoms referable to the brainstem and cerebellum such as, diplopia, gait ataxia and cerebellar dysarthria. The features and outcomes of CLIPPERS remains uncertain. we conducted this comprehensive systematic review to summarize all the existing studies that described CLIPPERS in the literature and to provide a quantitative assessment on the clinical characteristics, management, and outcomes of this rare syndrome. METHODS: A comprehensive search of PubMed and Web of Science databases was conducted from inception until January 15, 2022, was conducted. We only included the cases that clearly reported probable or definite diagnosis of CLIPPERS based on Taieb et al.'s criteria. The quality of the included studies was assessed using the JBI Critical Appraisal Tool. Descriptive statistics were performed to analyze the studies. Data were expressed as mean and standard deviation (SD) for continuous variables and proportions for categorical variables. RESULTS: We identified 100 case reports and series including a total of 140 patients with CLIPPERS (mean age: 46±18 years and males were 60%). The average follow-up duration was 32.27±57.8 months. Ataxia was the most common presenting symptom. Sixteen percent of the cases were associated with malignancy, mostly hematologic malignancies. The overall relapse rate was 59.2%, and the duration of steroid therapy was considerably shorter in the relapsed cases than in the non-relapsed (mean 6.19±7.9 vs. 10.14±12.1 days, respectively, P = 0.04). The overall mortality rate was 10%, but mortality in patients with malignancy was 30% and it was 12% in patients with relapses. In the case of steroid dosing (less than 20 mg/d versus greater than 20 mg/d) there was no significant modification in the risk of relapse. CONCLUSION: CLIPPERS is a rare clinical syndrome that affects mainly middle-aged males. Diagnosis of CLIPPERS is often challenging, and delays in diagnosis and treatment can lead to unfavorable outcomes. Therefore, neurologists should maintain a high index of suspicion for CLIPPERS in any patient presenting with symptoms and signs referrable to the brainstem. These patients should be screened for associated malignancies, especially hematological malignancies. The cases associated with malignancy tend to have worse outcomes. The relapse rate is relatively high. The relapse rate may be associated with worse mortality. Based on our findings, we recommend that CLIPPERS be treated with high-dose steroid therapy for at least ten days during the acute phase with a very slow taper. Prospective studies with a larger sample size are needed to validate our findings and guide the clinical care of these patients.

Rare pitfall in the magnetic resonance imaging of status epilepticus.

Brain MRI in Status Epilepticus (SE) is often helpful in diagnosis, lateralization and localization of the seizure focus. MRI changes in SE include predominantly ipsilateral diffusion weighted imaging (DWI) changes in the hippocampus and pulvinar or similar changes involving basal ganglia, thalamus, cerebellum, brain stem and external capsule (Chatzikonstantinou et al., 2011 [1]). These changes are thought to be due to transient vasogenic and cytotoxic edema due to either transient damage or breakdown of blood brain barrier, proportional to the frequency and duration of the epileptic activity (Amato et al., 2001 [2]). Such changes may also be reflected on T2- weighted and T2-Fluid-Attenuated Inversion Recovery (FLAIR) sequences of MRI. Herein, we present a case of a transient FLAIR cerebrospinal fluid (CSF) hyperintensity on the second MRI brain in a patient with focal status epilepticus. This imaging finding led to diagnostic confusion and was initially thought to represent subarachnoid hemorrhage. However, lumbar puncture, brain computed tomography (CT), and a follow-up brain MRI ruled out that possibility and other CSF pathologies. We concluded that the transient FLAIR changes in the second brain MRI were related to a rare imaging pitfall caused by Gadolinium enhancement of CSF on the FLAIR sequence, popularly referred to as hyperintense acute reperfusion marker (HARM).

Isaac Syndrome with Intractable Neuropathic Pain Features: A Case Report.

Isaac syndrome (IS) is a peripheral nerve hyperexcitability state associated with voltage-gated potassium channel (VGKC) complex antibodies. Major manifestations are muscle twitching, stiffness, hypertrophy, and dysautonomic features such as hyperhidrosis [Ahmed and Simmons. Muscle Nerve. 2015;52(1):5-12]. Neuropathic pain is a rare manifestation. We describe a case of IS characterized by muscle twitching and intractable neuropathic pain. Diagnostic workup included elevated VGKC complex antibodies and EMG/NC that showed neuromyotonic discharges. Neuropathic pain was initially difficult to relieve even after using multiple medications, including opiates, benzodiazepines, anticonvulsants, and intravenous immunoglobulin (IVIg). Moderate pain control was eventually achieved with long-term use of carbamazepine and subcutaneous immunoglobulin (SCIg). Common manifestations of IS are muscle twitching, stiffness hypertrophy, and dysautonomia [Ahmed and Simmons. Muscle Nerve. 2015;52(1):5-12]. Sensory manifestations such as neuropathic pain are rare, but, as illustrated by our patient, can be the most distressing symptom. In our patient, not only was neuropathic pain disabling but it also showed the least response to IVIg. The use of 200 mg of long-acting carbamazepine twice daily with weekly SCIg demonstrated the best response. This case highlights an uncommon but potentially resistant symptom of IS.

Acute Lymphoblastic Leukemia Masquerading as Guillain-Barré Syndrome.

INTRODUCTION: Neurological manifestations of acute lymphoblastic leukemia (ALL) have been reported as cranial neuropathies or meningeal symptoms most common in children. However, ALL can rarely involve the nerve roots causing symmetrical polyradiculopathy which can present with rapid onset paralysis, mimicking Guillain-Barré Syndrome (GBS). The symmetrical polyradiculopathy can be the earliest manifestation of ALL occurring even before the hematological and systemic manifestations. CASE REPORT: We report a case of a healthy 29-year-old man who presented with subacute bilateral lower extremity weakness and numbness preceded by a respiratory infection. He was initially treated as a suspected (GBS) but cerebrospinal fluid (CSF) findings suggested an alternative diagnosis. His prior TB exposure created a diagnostic confusion. Lumbar spine magnetic resonance imaging revealed nerve root enhancements at L4-L5 and L5-S1 that are seen in GBS and TB arachnoidids. Brain magnetic resonance imaging demonstrated bilateral distention of the optic nerve sheath complexes with CSF suggestive of intracranial hypertension. CSF revealed elevated protein, nucleated cells 2145 leukocytes/mm 3 , numerous atypical lymphoid cells. He was later diagnosed with ALL associated symmetrical polyradiculopathy presenting with GBS-like symptoms. CONCLUSION: Symmetrical polyradiculopathy is a rare complication of ALL and can be confused with acute inflammatory demyelinating polyneuropathy. ALL associated polyradiculopathy in young individuals can be clinically indistinguishable from GBS. Our case highlights that when CSF findings are atypical for GBS, ALL should be considered on the differential diagnosis in patients presenting with GBS like symptoms.

Successful Mechanical Thrombectomy for Basilar Artery Occlusion in a Seven-Year-Old Male.

Acute arterial strokes in children are rare but can potentially cause lasting and often permanent neurological deficits. Mechanical thrombectomy has a well-established efficacy and safety profile in adult stroke management, but in the pediatric population, it is yet to be proven efficacious and safe. We present a case of a seven-year-old male who presented with multiple episodes of generalized tonic-clonic seizures after sustaining a neck injury by falling from a trampoline. National Institutes of Health (NIH) on presentation was 21. Neurological exam revealed dilated nonreactive pupils, dysconjugate gaze, severe dysarthria, bilateral ptosis, and movement of upper and lower extremities only to noxious stimuli. Magnetic resonance imaging (MRI) of brain without contrast revealed infarcted areas in the left pons, midbrain, and cerebellar regions. Computed tomographic angiogram (CTA) of head demonstrated left vertebral artery dissection with associated complete occlusion of the distal basilar artery. Successful recanalization was achieved with mechanical thrombectomy six hours after presentation. Mechanical thrombectomy treatment resulted in a significant neurological recovery with NIH of 1. This case supports the growing evidence of the efficacy and safety of mechanical thrombectomy in children.

Endovascular Therapy for Childhood Ischemic Stroke.

BACKGROUND Ischemic stroke can have a tremendously negative impact on the fitness and well-being of a child. Because endovascular interventions may be of benefit in the adult stroke population, many investigators have recently evaluated the safety and benefits of pharmacological and non-pharmacological options in the pediatric stroke population and compared pediatric patients to their adult counterparts. Some of these trials have had promising results, showing the positive effects of endovascular treatment in children with arterial acute ischemic stroke due to large-vessel occlusion (LVO). The 2015 American Heart Association/American Stroke Association guidelines suggest that mechanical thrombectomy with stent retrievers may be a consideration in some patients who are younger than 18 years and have severe LVO, when treatment (groin puncture) is initiated within 6 h of symptom onset. However, the method remains under-studied in this age group. CASE REPORT A 7-year-old girl presented with migraine-like headache, right arm and facial weakness, and expressive aphasia 9.5 h after symptom onset. Her PEDS-NIH stroke scale score was 4. Upon further investigations, she was found to have a left middle cerebral artery cryptogenic stroke with a distal left M1 clot, which was successfully treated with mechanical thrombectomy. Huge improvement was noticed during her subsequent physical examination. CONCLUSIONS Endovascular therapy offers an exciting treatment option for the management of pediatric stroke. The extent of safety of mechanical thrombectomy among children who present with large-vessel occlusion over an extended time window remains unknown and warrants further investigations.

Mimicking a Psychiatric Disorder: Heroin-Induced Leukoencephalopathy.

Toxic leukoencephalopathy is a rare cause of encephalopathy. We describe two cases of toxic leukoencephalopathy associated with opiate abuse where they were misdiagnosed and admitted to the psychiatric ward. In our case series, both patients presented with behavioral changes, restlessness, pressured speech, and cognitive impairment for which they were initially labeled as psychiatric patients and were treated as such. However, after an extensive workup to elucidate the etiology of alteration in mental status, toxic leukoencephalopathy associated with heroin abuse was found to be the culprit in both cases. Toxic leukoencephalopathy is a rare condition that can be caused by inhalation of heroin. Clinically, it may present with confusion, behavioral changes, extrapyramidal symptoms, generalized motor deficit, unresponsiveness and even death. Our cases highlight the importance of recognizing the psychiatric presentation of toxic leukoencephalopathy.

Neurological Predictors of Clinical Outcomes in Hospitalized Patients With COVID-19.

Introduction: Multiple risk factors of mortality have been identified in patients with COVID-19. Here, we sought to determine the effect of a history of neurological disorder and development of neurological manifestations on mortality in hospitalized patients with COVID-19. Methods: From March 20 to May 20, 2020, hospitalized patients with laboratory confirmed or highly suspected COVID-19 were identified at four hospitals in Ohio. Previous history of neurological disease was classified by severity (major or minor). Neurological manifestations during disease course were also grouped into major and minor manifestations. Encephalopathy, ischemic or hemorrhagic stroke, and seizures were defined as major manifestations, whereas minor neurological manifestations included headache, anosmia, dysgeusia, dizziness or vertigo, and myalgias. Multivariate logistic regression models were used to determine significant predictors of mortality in patients with COVID-19 infection. Results: 574/626 hospitalized patients were eligible for inclusion. Mean age of the 574 patients included in the analysis was 62.8 (SD 17.6), with 298 (51.9%) women. Of the cohort, 240(41.8%) patients had a prior history of neurological disease (HND), of which 204 (35.5%) had a major history of neurological disease (HND). Mortality rates were higher in patients with a major HND (30.9 vs. 15.4%; p = 0.00002), although this was not a significant predictor of death. Major neurological manifestations were recorded in 203/574 (35.4%) patients during disease course. The mortality rate in patients who had major neurological manifestations was 37.4% compared to 11.9% (p = 2 × 10-12) in those who did not. In multivariate analysis, major neurological manifestation (OR 2.1, CI 1.3-3.4; p = 0.002) was a predictor of death. Conclusions: In this retrospective study, history of pre-existing neurological disease in hospitalized COVID-19 patients did not impact mortality; however, development of major neurological manifestations during disease course was found to be an independent predictor of death. Larger studies are needed to validate our findings.

Neurological involvement of coronavirus disease 2019: a systematic review.

BACKGROUND: In December 2019, unexplained cases of pneumonia emerged in Wuhan, China, which were found to be secondary to the novel coronavirus SARS-CoV-2. On March 11, 2020, the WHO declared the Coronavirus Disease 2019 (COVID-2019) outbreak, a pandemic. OBJECTIVE: To clarify the neurological complications of SARS-CoV-2 infection including the potential mechanisms and therapeutic options. METHODS: We conducted a systematic literature search from December 01, 2019 to May 14, 2020 using multiple combinations of keywords from PubMed and Ovid Medline databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We included articles with cases of COVID-19 where neurological involvement was evident. RESULTS: We were able to identify 82 cases of COVID-19 with neurological complications. The mean age was 62.3 years. 37.8% of the patients were women (n = 31). 48.8% of the patients (n = 40) had cerebrovascular insults, 28% (n = 23) had neuromuscular disorders, and 23% of the patients (n = 19) had encephalitis or encephalopathy. CONCLUSIONS: Neurological manifestations of COVID-19 are not rare, especially large vessel stroke, Guillain-Barre syndrome, and meningoencephalitis. Moving forward, further studies are needed to clarify the prevalence of the neurological complications of SARS-CoV-2 infection, investigate their biological backgrounds, and test treatment options. Physicians should be cautious not to overlook other neurological diagnoses that can mimic COVID-19 during the pandemic.

Interleukin-8: novel roles in human airway smooth muscle cell contraction and migration.

In patients with cystic fibrosis (CF) and asthma, elevated levels of interleukin-8 (IL-8) are found in the airways. IL-8 is a CXC chemokine that is a chemoattractant for neutrophils through CXCR1 and CXCR2 G protein-coupled receptors. We hypothesized that IL-8 acts directly on airway smooth muscle cells (ASMC) in a way that may contribute to the enhanced airway responsiveness and airway remodeling observed in CF and asthma. The aim of this study was to determine whether human ASMC (HASMC) express functional IL-8 receptors (CXCR1 and CXCR2) linked to cell contraction and migration. Experiments were conducted on cells harvested from human lung specimens. Real-time PCR and fluorescence-activated cell sorting analysis showed that HASMC expressed mRNA and protein for both CXCR1 and CXCR2. Intracellular Ca(2+) concentration ([Ca(2+)](i)) increased from 115 to 170 nM in response to IL-8 (100 nM) and decreased after inhibition of phospholipase C (PLC) with U-73122. On blocking the receptors with specific neutralizing antibodies, changes in [Ca(2+)](i) were abrogated. IL-8 also contracted the HASMC, decreasing the length of cells by 15%, and induced a 2.5-fold increase in migration. These results indicate that HASMC constitutively express functional CXCR1 and CXCR2 that mediate IL-8-triggered Ca(2+) release, contraction, and migration. These data suggest a potential role for IL-8 in causing abnormal airway structure and function in asthma and CF.

LY-294002 [2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one] affects calcium signaling in airway smooth muscle cells independently of phosphoinositide 3-kinase inhibition.

Phosphoinositide 3-kinase (PI3K) may potentially influence intracellular [Ca(2+)](i) concentration by several mechanisms. We have investigated the effects of phosphoinositide 3-kinase (PI3K) inhibitors wortmannin and LY-294002 [2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one] on Ca(2+) signaling in rat airway smooth muscle (ASM) cells using fura-2 and imaging methodology. Wortmannin (1 microM) and LY-294002 (1 and 10 microM) had opposite effects: wortmannin caused a small increase, whereas LY-294002 caused a significant decrease of peak Ca(2+) responses to serotonin (5-HT). LY-294002 (10 microM) diminished 5-HT-induced ASM cell contraction, measured as a change in cell surface area, and inositol phosphate formation, measured by anion exchange chromatography. Thin layer chromatography revealed that the levels of phospholipase C (PLC) substrate phosphatidylinositol 4,5-bisphosphate were not affected. SDS polyacrylamide gel electrophoresis and Western blotting have shown that both wortmannin and LY-294002 inhibited platelet-derived growth factor-induced PI3K activation. However, PI3K activation could not be detected after 5-HT stimulation. The specific casein kinase-2 (CK2) inhibitor 5,6-dichloro-1-beta-d-ribofuranosyl-benzimidazole (10-40 microM) reduced 5-HT-triggered responses to a similar extent as LY-294002. We conclude that LY-294002 modulates Ca(2+) signaling in rat ASM independently of its action on PI3K by acting on, or upstream of, PLC, possibly by inhibiting CK2.