Robust T Cell Immunity in Convalescent Individuals with Asymptomatic or Mild COVID-19.

SARS-CoV-2-specific memory T cells will likely prove critical for long-term immune protection against COVID-19. Here, we systematically mapped the functional and phenotypic landscape of SARS-CoV-2-specific T cell responses in unexposed individuals, exposed family members, and individuals with acute or convalescent COVID-19. Acute-phase SARS-CoV-2-specific T cells displayed a highly activated cytotoxic phenotype that correlated with various clinical markers of disease severity, whereas convalescent-phase SARS-CoV-2-specific T cells were polyfunctional and displayed a stem-like memory phenotype. Importantly, SARS-CoV-2-specific T cells were detectable in antibody-seronegative exposed family members and convalescent individuals with a history of asymptomatic and mild COVID-19. Our collective dataset shows that SARS-CoV-2 elicits broadly directed and functionally replete memory T cell responses, suggesting that natural exposure or infection may prevent recurrent episodes of severe COVID-19.

Dynamic MAIT Cell Recovery after Severe COVID-19 Is Transient with Signs of Heterogeneous Functional Anomalies.

Mucosal-associated invariant T (MAIT) cells are an abundant population of unconventional T cells in humans and play important roles in immune defense against microbial infections. Severe COVID-19 is associated with strong activation of MAIT cells and loss of these cells from circulation. In the present study, we investigated the capacity of MAIT cells to recover after severe COVID-19. In longitudinal paired analysis, MAIT cells initially rebounded numerically and phenotypically in most patients at 4 mo postrelease from the hospital. However, the rebounding MAIT cells displayed signs of persistent activation with elevated expression of CD69, CD38, and HLA-DR. Although MAIT cell function was restored in many patients, a subgroup displayed a predominantly PD-1high functionally impaired MAIT cell pool. This profile was associated with poor expression of IFN-γ and granzyme B in response to IL-12 + L-18 and low levels of polyfunctionality. Unexpectedly, although the overall T cell counts recovered, normalization of the MAIT cell pool failed at 9-mo follow-up, with a clear decline in MAIT cell numbers and a further increase in PD-1 levels. Together, these results indicate an initial transient period of inconsistent recovery of MAIT cells that is not sustained and eventually fails. Persisting MAIT cell impairment in previously hospitalized patients with COVID-19 may have consequences for antimicrobial immunity and inflammation and could potentially contribute to post-COVID-19 health problems.

Changes in circulating extracellular vesicle cargo are associated with cognitive decline after major surgery: an observational case-control study.

BACKGROUND: Postoperative neurocognitive decline is a frequent complication triggered by unclear signalling mechanisms. This observational case-control study investigated the effects of hip or knee replacement surgery on the composition of circulating extracellular vesicles (EVs), potential periphery-to-brain messengers, and their association with neurocognitive outcomes. METHODS: We mapped the microRNAome and proteome of plasma-derived EVs from 12 patients (six with good and six with poor neurocognitive outcomes at 3 months after surgery) at preoperative and postoperative timepoints (4, 8, 24, and 48 h). Complement C3-EV association was confirmed by flow cytometry in plasma- and cerebrospinal fluid (CSF)-derived EVs, with total plasma and CSF C3 and C3a concentrations determined using enzyme-linked immunosorbent assay. RESULTS: Differential expression analysis found eight dysregulated EV microRNAs (miRNAs) exclusively in the poor neurocognitive outcomes group. Pathway analysis suggested potential downregulation of proliferative pathways and activation of extracellular matrix and inflammatory response pathways in EV target tissues. Proteome analysis revealed a time-dependent increase in immune-related EV proteins, including complement system proteins, notably EV surface-associated C3. Such upward kinetics was detected earlier in the poor neurocognitive outcomes group. Interestingly, CSF-derived EVs from the same group showed a drastic drop of C3 at 48 h with unchanged concentrations in the good neurocognitive outcomes group. Functionally, the complement system was activated in both patient groups in plasma, but only in the poor neurocognitive outcomes group in CSF. CONCLUSIONS: Our findings highlight the impact of surgery on plasma- and CSF-derived EVs, particularly in patients with poor neurocognitive outcomes, indicating a potential role for EVs. The small sample size necessitates verification with a larger patient cohort.

Major alterations in the mononuclear phagocyte landscape associated with COVID-19 severity.

Dendritic cells (DCs) and monocytes are crucial mediators of innate and adaptive immune responses during viral infection, but misdirected responses by these cells may contribute to immunopathology. Here, we performed high-dimensional flow cytometry-analysis focusing on mononuclear phagocyte (MNP) lineages in SARS-CoV-2-infected patients with moderate and severe COVID-19. We provide a deep and comprehensive map of the MNP landscape in COVID-19. A redistribution of monocyte subsets toward intermediate monocytes and a general decrease in circulating DCs was observed in response to infection. Severe disease coincided with the appearance of monocytic myeloid-derived suppressor cell-like cells and a higher frequency of pre-DC2. Furthermore, phenotypic alterations in MNPs, and their late precursors, were cell-lineage-specific and associated either with the general response against SARS-CoV-2 or COVID-19 severity. This included an interferon-imprint in DC1s observed in all patients and a decreased expression of the coinhibitory molecule CD200R in pre-DCs, DC2s, and DC3 subsets of severely sick patients. Finally, unsupervised analysis revealed that the MNP profile, alone, pointed to a cluster of COVID-19 nonsurvivors. This study provides a reference for the MNP response to SARS-CoV-2 infection and unravels mononuclear phagocyte dysregulations associated with severe COVID-19.

High-dimensional profiling reveals phenotypic heterogeneity and disease-specific alterations of granulocytes in COVID-19.

Since the outset of the COVID-19 pandemic, increasing evidence suggests that the innate immune responses play an important role in the disease development. A dysregulated inflammatory state has been proposed as a key driver of clinical complications in COVID-19, with a potential detrimental role of granulocytes. However, a comprehensive phenotypic description of circulating granulocytes in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected patients is lacking. In this study, we used high-dimensional flow cytometry for granulocyte immunophenotyping in peripheral blood collected from COVID-19 patients during acute and convalescent phases. Severe COVID-19 was associated with increased levels of both mature and immature neutrophils, and decreased counts of eosinophils and basophils. Distinct immunotypes were evident in COVID-19 patients, with altered expression of several receptors involved in activation, adhesion, and migration of granulocytes (e.g., CD62L, CD11a/b, CD69, CD63, CXCR4). Paired sampling revealed recovery and phenotypic restoration of the granulocytic signature in the convalescent phase. The identified granulocyte immunotypes correlated with distinct sets of soluble inflammatory markers, supporting pathophysiologic relevance. Furthermore, clinical features, including multiorgan dysfunction and respiratory function, could be predicted using combined laboratory measurements and immunophenotyping. This study provides a comprehensive granulocyte characterization in COVID-19 and reveals specific immunotypes with potential predictive value for key clinical features associated with COVID-19.

COVID-19-specific metabolic imprint yields insights into multiorgan system perturbations.

Corona disease 2019 (COVID-19) affects multiple organ systems. Recent studies have indicated perturbations in the circulating metabolome linked to COVID-19 severity. However, several questions pertain with respect to the metabolome in COVID-19. We performed an in-depth assessment of 1129 unique metabolites in 27 hospitalized COVID-19 patients and integrated results with large-scale proteomic and immunology data to capture multiorgan system perturbations. More than half of the detected metabolic alterations in COVID-19 were driven by patient-specific confounding factors ranging from comorbidities to xenobiotic substances. Systematically adjusting for this, a COVID-19-specific metabolic imprint was defined which, over time, underwent a switch in response to severe acute respiratory syndrome coronavirus-2 seroconversion. Integration of the COVID-19 metabolome with clinical, cellular, molecular, and immunological severity scales further revealed a network of metabolic trajectories aligned with multiple pathways for immune activation, and organ damage including neurological inflammation and damage. Altogether, this resource refines our understanding of the multiorgan system perturbations in severe COVID-19 patients.

Targeted plasma proteomics reveals signatures discriminating COVID-19 from sepsis with pneumonia.

BACKGROUND: COVID-19 remains a major public health challenge, requiring the development of tools to improve diagnosis and inform therapeutic decisions. As dysregulated inflammation and coagulation responses have been implicated in the pathophysiology of COVID-19 and sepsis, we studied their plasma proteome profiles to delineate similarities from specific features. METHODS: We measured 276 plasma proteins involved in Inflammation, organ damage, immune response and coagulation in healthy controls, COVID-19 patients during acute and convalescence phase, and sepsis patients; the latter included (i) community-acquired pneumonia (CAP) caused by Influenza, (ii) bacterial CAP, (iii) non-pneumonia sepsis, and (iv) septic shock patients. RESULTS: We identified a core response to infection consisting of 42 proteins altered in both COVID-19 and sepsis, although higher levels of cytokine storm-associated proteins were evident in sepsis. Furthermore, microbiologic etiology and clinical endotypes were linked to unique signatures. Finally, through machine learning, we identified biomarkers, such as TRIM21, PTN and CASP8, that accurately differentiated COVID-19 from CAP-sepsis with higher accuracy than standard clinical markers. CONCLUSIONS: This study extends the understanding of host responses underlying sepsis and COVID-19, indicating varying disease mechanisms with unique signatures. These diagnostic and severity signatures are candidates for the development of personalized management of COVID-19 and sepsis.

2023 American Society of Anesthesiologists Practice Guidelines for Monitoring and Antagonism of Neuromuscular Blockade: A Report by the American Society of Anesthesiologists Task Force on Neuromuscular Blockade.

These practice guidelines provide evidence-based recommendations on the management of neuromuscular monitoring and antagonism of neuromuscular blocking agents during and after general anesthesia. The guidance focuses primarily on the type and site of monitoring and the process of antagonizing neuromuscular blockade to reduce residual neuromuscular blockade.

Good clinical research practice (GCRP) in pharmacodynamic studies of neuromuscular blocking agents III: The 2023 Geneva revision.

The set of guidelines for good clinical research practice in pharmacodynamic studies of neuromuscular blocking agents was developed following an international consensus conference in Copenhagen in 1996 (Viby-Mogensen et al., Acta Anaesthesiol Scand 1996, 40, 59-74); the guidelines were later revised and updated following the second consensus conference in Stockholm in 2005 (Fuchs-Buder et al., Acta Anaesthesiol Scand 2007, 51, 789-808). In view of new devices and further development of monitoring technologies that emerged since then, (e.g., electromyography, three-dimensional acceleromyography, kinemyography) as well as novel compounds (e.g., sugammadex) a review and update of these recommendations became necessary. The intent of these revised guidelines is to continue to help clinical researchers to conduct high-quality work and advance the field by enhancing the standards, consistency, and comparability of clinical studies. There is growing awareness of the importance of consensus-based reporting standards in clinical trials and observational studies. Such global initiatives are necessary in order to minimize heterogeneous and inadequate data reporting and to improve clarity and comparability between different studies and study cohorts. Variations in definitions of endpoints or outcome variables can introduce confusion and difficulties in interpretation of data, but more importantly, it may preclude building of an adequate body of evidence to achieve reliable conclusions and recommendations. Clinical research in neuromuscular pharmacology and physiology is no exception.

Cardiopulmonary haemodynamic effects and gas exchange during apnoeic oxygenation with high-flow and low-flow nasal oxygen: A large animal study.

BACKGROUND: Apnoeic oxygenation with high-flow nasal oxygen prolongs the safe apnoeic period during induction of general anaesthesia. However, central haemodynamic effects and the characteristics of central gaseous exchange remain unexplored. OBJECTIVE: To describe mean pulmonary arterial pressure along with arterial and mixed venous blood gases and central haemodynamic parameters during apnoeic oxygenation with low-flow and high-flow nasal oxygen in pigs. DESIGN: Experimental crossover study. SETTING: Animal study of 10 healthy Swedish landrace pigs at Karolinska Institutet, Sweden, April-May 2021. INTERVENTION: The pigs were anaesthetised, their tracheas intubated and their pulmonary arteries catheterised. The animals were preoxygenated and paralysed before apnoea. Apnoeic periods between 45 and 60 min were implemented with either 70 or 10 l min -1 100% O 2 delivered via nasal catheters. In addition, seven animals underwent an apnoea without fresh gas flow. Cardiopulmonary parameters and blood gases were measured repeatedly. MAIN OUTCOME MEASURES: Mean pulmonary arterial pressure during apnoeic oxygenation with high-flow and low-flow oxygen. RESULTS: Nine pigs completed two apnoeic periods of at least 45 min with a Pa O 2 not lower than 13 kPa. The mean pulmonary arterial pressure increased during 45 min of apnoea, from 18 ±â€Š1 to 33 ±â€Š2 mmHg and 18 ±â€Š1 to 35 ±â€Š2 mmHg, at 70 and 10 l min -1 O 2 , respectively ( P  < 0.001); there was no difference between the groups ( P  = 0.87). The Pa CO 2 increased by 0.48 ±â€Š0.07 and 0.52 ±â€Š0.04 kPa min -1 , at 70 and 10 l min -1 O 2 , respectively; there was no difference between the groups ( P  = 0.22). During apnoea without fresh gas flow, the SpO 2 declined to less than 85% after 155 ±â€Š11 s. CONCLUSION: During apnoeic oxygenation in pigs, the mean pulmonary arterial pressure increased two-fold and Pa CO 2 five-fold after 45 min, while the arterial oxygen levels were maintained over 13 kPa, irrespective of high-flow or low-flow oxygen.

The Karolinska KI/K COVID-19 Immune Atlas: An open resource for immunological research and educational purposes.

The Karolinska KI/K COVID-19 Immune Atlas project was conceptualized in March 2020 as a part of the academic research response to the developing SARS-CoV-2 pandemic. The aim was to rapidly provide a curated dataset covering the acute immune response towards SARS-CoV-2 infection in humans, as it occurred during the first wave. The Immune Atlas was built as an open resource for broad research and educational purposes. It contains a presentation of the response evoked by different immune and inflammatory cells in defined naïve patient-groups as they presented with moderate and severe COVID-19 disease. The present Resource Article describes how the Karolinska KI/K COVID-19 Immune Atlas allow scientists, students, and other interested parties to freely explore the nature of the immune response towards human SARS-CoV-2 infection in an online setting.

The Karolinska NeuroCOVID study protocol: Neurocognitive impairment, biomarkers and advanced imaging in critical care survivors.

BACKGROUND: This is the study plan of the Karolinska NeuroCOVID study, a study of neurocognitive impairment after severe COVID-19, relating post-intensive care unit (ICU) cognitive and neurological deficits to biofluid markers and MRI. The COVID-19 pandemic has posed enormous health challenges to individuals and health-care systems worldwide. An emerging feature of severe COVID-19 is that of temporary and extended neurocognitive impairment, exhibiting a myriad of symptoms and signs. The causes of this symptomatology have not yet been fully elucidated. METHODS: In this study, we aim to investigate patients treated for severe COVID-19 in the ICU, as to describe and relate serum-, plasma- and cerebrospinal fluid-borne molecular and cellular biomarkers of immune activity, coagulopathy, cerebral damage, neuronal inflammation, and degeneration, to the temporal development of structural and functional changes within the brain as evident by serial MRI and extensive cognitive assessments at 3-12 months after ICU discharge. RESULTS: To date, we have performed 51 3-month follow-up MRIs in the ICU survivors. Of these, two patients (~4%) have had incidental findings on brain MRI findings requiring activation of the Incidental Findings Management Plan. Furthermore, the neuropsychological and neurological examinations have so far revealed varying and mixed patterns. Several patients expressed cognitive and/or mental concerns and fatigue, complaints closely related to brain fog. CONCLUSION: The study goal is to gain a better understanding of the pathological mechanisms and neurological consequences of this new disease, with a special emphasis on neurodegenerative and neuroinflammatory processes, in order to identify targets of intervention and rehabilitation.

Neuroinflammatory markers associate with cognitive decline after major surgery: Findings of an explorative study.

OBJECTIVE: Long-term cognitive decline is an adverse outcome after major surgery associated with increased risk for mortality and morbidity. We studied the cerebrospinal fluid (CSF) and serum biochemical inflammatory response to a standardized orthopedic surgical procedure and the possible association with long-term changes in cognitive function. We hypothesized that the CSF inflammatory response pattern after surgery would differ in patients having long-term cognitive decline defined as a composite cognitive z score of ≥1.0 compared to patients without long-term cognitive decline at 3 months postsurgery. METHODS: Serum and CSF biomarkers of inflammation and blood-brain barrier (BBB) integrity were measured preoperatively and up to 48 hours postoperatively, and cognitive function was assessed preoperatively and at 2 to 5 days and 3 months postoperatively. RESULTS: Surgery was associated with a pronounced increase in inflammatory biomarkers in both CSF and blood throughout the 48-hour study period. A principal component (PC) analysis was performed on 52 inflammatory biomarkers. The 2 first PC (PC1 and PC2) construct outcome variables on CSF biomarkers were significantly associated with long-term cognitive decline at 3 months, but none of the PC construct serum variables showed a significant association with long-term cognitive decline at 3 months. Patients both with and patients without long-term cognitive decline showed early transient increases of the astroglial biomarkers S-100B and glial fibrillary acidic protein in CSF, and in BBB permeability (CSF/serum albumin ratio). INTERPRETATION: Surgery rapidly triggers a temporal neuroinflammatory response closely associated with long-term cognitive outcome postsurgery. The findings of this explorative study require validation in a larger surgical patient cohort. Ann Neurol 2020;87:370-382.

Effects of sevoflurane anaesthesia on radioligand binding to monoamine oxidase-B in vivo.

BACKGROUND: The molecular actions underlying the clinical effects of inhaled anaesthetics such as sevoflurane and isoflurane are not fully understood. Unexpected observations in positron emission tomography (PET) studies with [11C]AZD9272, a metabotropic glutamate receptor 5 (mGluR5) radioligand with possible affinity for monoamine oxidase-B (MAO-B), suggest that its binding is sensitive to anaesthesia with sevoflurane. The objective of the present study was to assess the effects of sevoflurane anaesthesia on the binding of [11C]AZD9272 and of [11C]L-deprenyl-D2, a radioligand selective for MAO-B in non-human primates (NHPs). METHODS: Altogether, 12 PET measurements were conducted with a high-resolution research tomograph using the ligands [11C]AZD9272 or [11C]L-deprenyl-D2 in six cynomolgus monkeys anaesthetised with sevoflurane or ketamine/xylazine. RESULTS: The specific binding of [11C]AZD9272 and [11C]L-deprenyl-D2 was markedly reduced during anaesthesia with sevoflurane compared with ketamine/xylazine. The reduction was 80-90% (n=3) for [11C]AZD9272 and 77-80% (n=3) for [11C]L-deprenyl-D2. CONCLUSIONS: Sevoflurane anaesthesia inhibited radioligand binding to MAO-B in the primate brain. The observation of lower MAO-B binding at clinically relevant concentrations of sevoflurane warrants further exploration of the potential role of MAO-B related mechanisms in regulation of systemic blood pressure during anaesthesia.

Association between cerebrospinal fluid biomarkers of neuronal injury or amyloidosis and cognitive decline after major surgery.

BACKGROUND: Postoperative neurocognitive decline is a frequent complication in adult patients undergoing major surgery with increased risk for morbidity and mortality. The mechanisms behind cognitive decline after anaesthesia and surgery are not known. We studied the association between CSF and blood biomarkers of neuronal injury or brain amyloidosis and long-term changes in neurocognitive function. METHODS: In patients undergoing major orthopaedic surgery (knee or hip replacement), blood and CSF samples were obtained before surgery and then at 4, 8, 24, 32, and 48 h after skin incision through an indwelling spinal catheter. CSF and blood concentrations of total tau (T-tau), neurofilament light, neurone-specific enolase and amyloid ß (Aß1-42) were measured. Neurocognitive function was assessed using the International Study of Postoperative Cognitive Dysfunction (ISPOCD) test battery 1-2 weeks before surgery, at discharge from the hospital (2-5 days after surgery), and at 3 months after surgery. RESULTS: CSF and blood concentrations of T-tau, neurone-specific enolase, and Aß1-42 increased after surgery. A similar increase in serum neurofilament light was seen with no overall changes in CSF concentrations. There were no differences between patients having a poor or good late postoperative neurocognitive outcome with respect to these biomarkers of neuronal injury and Aß1-42. CONCLUSIONS: The findings of the present explorative study showed that major orthopaedic surgery causes a release of CSF markers of neural injury and brain amyloidosis, suggesting neuronal damage or stress. We were unable to detect an association between the magnitude of biomarker changes and long-term postoperative neurocognitive dysfunction.

Biomarkers for oxidative stress and organ injury during Transnasal Humidified Rapid-Insufflation Ventilatory Exchange compared to mechanical ventilation in adults undergoing microlaryngoscopy: A randomised controlled study.

BACKGROUND: Apnoeic oxygenation using Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) during general anaesthesia prolongs the safe apnoeic period. However, there is a gap of knowledge how THRIVE-induced hyperoxia and hypercapnia impact vital organs. The primary aim of this randomised controlled trial was to characterise oxidative stress and, secondary, vital organ function biomarkers during THRIVE compared to mechanical ventilation (MV). METHODS: Thirty adult patients, American Society of Anesthesiologists (ASA) 1-2, undergoing short laryngeal surgery under general anaesthesia were randomised to THRIVE, FI O2 1.0, 70 L min-1 during apnoea or MV. Blood biomarkers for oxidative stress, malondialdehyde and TAC and vital organ function were collected (A) preoperatively, (B) at procedure completion and (C) at PACU discharge. RESULTS: Mean apnoea time was 17.9 (4.8) min and intubation to end-of-surgery time was 28.1 (12.8) min in the THRIVE and MV group, respectively. Malondialdehyde increased from 11.2 (3.1) to 12.7 (3.1) µM (P = .02) and from 9.5 (2.2) to 11.6 (2.6) µM (P = .003) (A to C) in the THRIVE and MV group, respectively. S100B increased from 0.05 (0.02) to 0.06 (0.02) µg L-1 (P = .005) (A to C) in the THRIVE group. No increase in TAC, CRP, leukocyte count, troponin-T, NTproBNP, creatinine, eGFRcrea or NSE was demonstrated during THRIVE. CONCLUSION: While THRIVE and MV was associated with increased oxidative stress, we found no change in cardiac, inflammation or kidney biomarkers during THRIVE. Further evaluation of stress and inflammatory response and cerebral and cardiac function during THRIVE is needed.

Characteristics and outcomes of patients with COVID-19 admitted to ICU in a tertiary hospital in Stockholm, Sweden.

BACKGROUND: Information on characteristics and outcomes of intensive care unit (ICU) patients with COVID-19 remains limited. We examined characteristics, clinical course and early outcomes of patients with COVID-19 admitted to ICU. METHODS: We included all 260 patients with COVID-19 admitted to nine ICUs at the Karolinska University Hospital (Stockholm, Sweden) between 9 March and 20 April 2020. Primary outcome was in-hospital mortality among patients with definite outcomes (discharged from ICU or death), as of 30 April 2020 (study end point). Secondary outcomes included ICU length of stay, the proportion of patients receiving mechanical ventilation and renal replacement therapy, and hospital discharge destination. RESULTS: Of 260 ICU patients with COVID-19, 208 (80.0%) were men, the median age was 59 (IQR 51-65) years, 154 (59.2%) had at least one comorbidity, and the median duration of symptoms preceding ICU admission was 11 (IQR 8-14) days. Sixty-two (23.8%) patients remained in ICU at study end point. Among the 198 patients with definite outcomes, ICU length of stay was 12 (IQR, 6-18) days, 163 (82.3%) received mechanical ventilation, 28 (14.1%) received renal replacement therapy, 60 (30.3%) died, 62 (31.3%) were discharged home, 47 (23.7%) were discharged to ward, and 29 (14.6%) were discharged to another health care facility. On multivariable logistic regression analysis, older age and admission from the emergency department was associated with higher mortality. CONCLUSION: This study presents detailed data on clinical characteristics and early outcomes of consecutive patients with COVID-19 admitted to ICU in a large tertiary hospital in Sweden.

The impact of damage-associated molecular patterns on the neurotransmitter release and gene expression in the ex vivo rat carotid body.

NEW FINDINGS: What is the central question of this study? Are carotid bodies (CBs) modulated by the damage-associated molecular patterns (DAMPs) and humoral factors of aseptic tissue injury? What are the main findings and their importance? DAMPs (HMGB1, S100 A8/A9) and blood plasma from rats subjected to tibia surgery, a model of aseptic injury, stimulate the release of neurotransmitters (ATP, dopamine) and TNF-α from ex vivo rat CBs. All-thiol HMGB1 mediates upregulation of immune-related biological pathways. These data suggest regulation of CB function by endogenous mediators of innate immunity. ABSTRACT: The glomus cells of carotid bodies (CBs) are the primary sensors of arterial partial O2 and CO2 tensions and moreover serve as multimodal receptors responding also to other stimuli, such as pathogen-associated molecular patterns (PAMPs) produced by acute infection. Modulation of CB function by excessive amounts of these immunomodulators is suggested to be associated with a detrimental hyperinflammatory state. We have hypothesized that yet another class of immunomodulators, endogenous danger-associated molecular patterns (DAMPs), released upon aseptic tissue injury and recognized by the same pathogen recognition receptors as PAMPs, might modulate the CB activity in a fashion similar to PAMPs. We have tested this hypothesis by exposing rat CBs to various DAMPs, such as HMGB1 (all-thiol and disulfide forms) and S100 A8/A9 in a series of ex vivo experiments that demonstrated the release of dopamine and ATP, neurotransmitters known to mediate CB homeostatic responses. We observed a similar response after incubating CBs with conditioned blood plasma obtained from the rats subjected to tibia surgery, a model of aseptic injury. In addition, we have investigated global gene expression in the rat CB using an RNA sequencing approach. Differential gene expression analysis showed all-thiol HMGB1-driven upregulation of a number of prominent pro-inflammatory markers including Il1α and Il1ß. Interestingly, conditioned plasma had a more profound effect on the CB transcriptome resulting in inhibition rather than activation of the immune-related pathways. These data are the first to suggest potential modulation of CB function by endogenous mediators of innate immunity.

Lung volume changes in Apnoeic Oxygenation using Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) compared to mechanical ventilation in adults undergoing laryngeal surgery.

BACKGROUND: Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) using high-flow 100% oxygen during apnoea has gained increased use during difficult airway management and laryngeal surgery due to a slower carbon dioxide rise compared to traditional apnoeic oxygenation. We have previously demonstrated high arterial oxygen partial pressures and an increasing arterial-alveolar carbon dioxide difference during THRIVE. Primary aim of this study was to characterise lung volume changes measured with electrical impedance tomography during THRIVE compared to mechanical ventilation. METHODS: Thirty adult patients undergoing laryngeal surgery under general anaesthesia were randomised to THRIVE or mechanical ventilation. Subjects were monitored with electrical impedance tomography and repeated blood gas measurement perioperatively. The THRIVE group received 100% oxygen at 70 l min-1 during apnoea. The mechanical ventilation group was intubated and normoventilated with an FiO2 of 0.4. RESULTS: Mean age were 48.2 (19.9) and 51.3 (12.3) years, and BMI 26.0 (4.5) and 26.0 (3.9) in the THRIVE and mechanical ventilation group respectively. Mean apnoea time in the THRIVE group was 17.9 (4.8) min. Mean apnoea to end-of-surgery time was 28.1 (12.8) min in the mechanical ventilation group. No difference in delta End Expiratory Lung Impedance was seen between groups over time. In the THRIVE group all but three subjects were well oxygenated during apnoea. THRIVE was discontinued for the three patients who desaturated. CONCLUSIONS: No difference in lung volume change over time, measured by electrical impedance tomography, was detected when using THRIVE compared to mechanical ventilation during laryngeal surgery.

Disrupted Neuroglial Metabolic Coupling after Peripheral Surgery.

Immune-related events in the periphery can remotely affect brain function, contributing to neurodegenerative processes and cognitive decline. In mice, peripheral surgery induces a systemic inflammatory response associated with changes in hippocampal synaptic plasticity and transient cognitive decline, however, the underlying mechanisms remain unknown. Here we investigated the effect of peripheral surgery on neuronal-glial function within hippocampal neuronal circuits of relevance to cognitive processing in male mice at 6, 24, and 72 h postsurgery. At 6 h we detect the proinflammatory cytokine IL-6 in the hippocampus, followed up by alterations in the mRNA and protein expression of astrocytic and neuronal proteins necessary for optimal energy supply to the brain and for the reuptake and recycling of glutamate in the synapse. Similarly, at 24 h postsurgery the mRNA expression of structural proteins (GFAP and AQP4) was compromised. At this time point, functional analysis in astrocytes revealed a decrease in resting calcium signaling. Examination of neuronal activity by whole-cell patch-clamp shows elevated levels of glutamatergic transmission and changes in AMPA receptor subunit composition at 72 h postsurgery. Finally, lactate, an essential energy substrate produced by astrocytes and critical for memory formation, decreases at 6 and 72 h after surgery. Based on temporal parallels with our previous studies, we propose that the previously reported cognitive decline observed at 72 h postsurgery in mice might be the consequence of temporal hippocampal metabolic, structural, and functional changes in astrocytes that lead to a disruption of the neuroglial metabolic coupling and consequently to a neuronal dysfunction.SIGNIFICANCE STATEMENT A growing body of evidence suggests that surgical trauma launches a systemic inflammatory response that reaches the brain and associates with immune activation and cognitive decline. Understanding the mechanisms by which immune-related events in the periphery can influence brain processes is essential for the development of therapies to prevent or treat postoperative cognitive dysfunction and other forms of cognitive decline related to immune-to-brain communication, such as Alzheimer's and Parkinson's diseases. Here we describe the temporal orchestration of a series of metabolic, structural, and functional changes after aseptic trauma in mice related to astrocytes and later in neurons that emphasize the role of astrocytes as key intermediaries between peripheral immune events, neuronal processing, and potentially cognition.