Cerebrospinal fluid levels of soluble CD14 in inflammatory and non-inflammatory diseases of the CNS: upregulation during bacterial infections and viral meningitis

High throughput spatial immune mapping reveals an innate immune scar in post-COVID-19 brains

The underlying pathogenesis of neurological sequelae in post-COVID-19 patients remains unclear. Here, we used multidimensional spatial immune phenotyping and machine learning methods on brains from initial COVID-19 survivors to identify the biological correlate associated with previous SARS-CoV-2 challenge. Compared to healthy controls, individuals with post-COVID-19 revealed a high percentage of TMEM119+P2RY12+CD68+Iba1+HLA-DR+CD11c+SCAMP2+ microglia assembled in prototypical cellular nodules. In contrast to acute SARS-CoV-2 cases, the frequency of CD8+ parenchymal T cells was reduced, suggesting an immune shift toward innate immune activation that may contribute to neurological alterations in post-COVID-19 patients.

Usefulness of cerebrospinal fluid presepsin (soluble CD14 subtype) as a new marker in the diagnosis of neurosurgical postoperative meningitis

Objective

To determine the usefulness of cerebrospinal fluid (CSF) presepsin in the diagnosis of neurosurgical postoperative meningitis (POM).

Methods

The study included patients admitted to the Department of Neurosurgery, Toho University Medical Center Omori Hospital from May 1, 2020 to March 31, 2022 with suspected meningitis after neurosurgery who clinically required CSF sampling and patients who underwent CSF sampling for examination of idiopathic normal pressure hydrocephalus (iNPH). Participants were divided into a POM and a postoperative non meningitis (PONM) group based on the POM diagnostic criteria established for this study. The control group included patients from whom a CSF sample for iNPH was collected by tap test.

Results

A total of 238 CSF samples were collected from 90 patients. There were 39 samples in the POM, 180 samples in the PONM, and 19 samples in the control group. CSF presepsin levels in the POM were significantly higher than in the PONM group (1764.5 and 440.9 pg./mL, respectively; p < 0.0001). The control group had CSF presepsin levels of 95.5 pg./mL. A cutoff value of 669 pg./mL for CSF presepsin in POM and PONM groups had 76.9% sensitivity and 78.3% specificity for the diagnosis of POM. In analyzes including only subarachnoid hemorrhage (SAH) cases (123 samples), CSF presepsin (1251.2 pg./mL) in the POM was significantly higher than in the PONM subgroup (453.9 pg./mL; p < 0.0001). The cutoff value for presepsin in CSF among patients with SAH (669 pg./mL) had 87.5% sensitivity and 76.6% specificity, similar to that of all patients.

Conclusion

CSF presepsin is a useful marker in the diagnosis of neurosurgical POM even in patients with blood components, such as SAH. When POM is suspected, measurement of CSF presepsin may be recommended in addition to a general CSF examination.

Diagnostic efficacy of serum presepsin for postoperative infectious complications: a meta-analysis

Background

Postoperative infectious complications (PICs) are major concerns. Early and accurate diagnosis is critical for timely treatment and improved outcomes. Presepsin is an emerging biomarker for bacterial infections. However, its diagnostic efficacy for PICs across surgical specialties remains unclear.

Methods

In this study, a systematic search on MEDLINE, Embase, Google Scholar, and Cochrane Library was performed on September 30, 2023, to identify studies that evaluated presepsin for diagnosing PICs. PIC is defined as the development of surgical site infection or remote infection. Pooled sensitivity, specificity, and hierarchical summary receiver operating characteristic (HSROC) curves were calculated. The primary outcome was the assessment of the efficacy of presepsin for PIC diagnosis, and the secondary outcome was the investigation of the reliability of procalcitonin or C-reactive protein (CRP) in the diagnosis of PICs.

Results

This meta-analysis included eight studies (n = 984) and revealed that the pooled sensitivity and specificity of presepsin for PIC diagnosis were 76% (95% confidence interval [CI] 68%-82%) and 83% (95% CI 75%-89%), respectively. The HSROC curve yielded an area under the curve (AUC) of 0.77 (95% CI 0.73-0.81). Analysis of six studies on procalcitonin showed a combined sensitivity of 78% and specificity of 77%, with an AUC of 0.83 derived from the HSROC. Meanwhile, data from five studies on CRP indicated pooled sensitivity of 84% and specificity of 79%, with the HSROC curve yielding an AUC of 0.89.

Conclusion

Presepsin exhibits moderate diagnostic accuracy for PIC across surgical disciplines. Based on the HSROC-derived AUC, CRP has the highest diagnostic efficacy for PICs, followed by procalcitonin and presepsin. Nonetheless, presepsin demonstrated greater specificity than the other biomarkers. Further study is warranted to validate the utility of and optimize the cutoff values for presepsin.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42023468358.

Comparison of presepsin and Mid-regional pro-adrenomedullin in the diagnosis of sepsis or septic shock: a systematic review and meta-analysis

BACKGROUND

The early diagnosis of sepsis is hampered by the lack of reliable laboratory measures. There is growing evidence that presepsin and Mid-regional pro-adrenomedullin (MR-proADM) are promising biomarkers in the diagnosis of sepsis. This study was conducted to evaluate and compare the diagnostic value of MR-proADM and presepsin in sepsis patients.

METHODS

We searched Web of Science, PubMed, Embase, China national knowledge infrastructure, and Wanfang up to 22th July, 2022, for studies evaluating the diagnosis performance of presepsin and MR-proADM in adult sepsis patients. Risk of bias was assessed using quadas-2. Pooled sensitivity and specificity were calculated using bivariate meta-analysis. Meta-regression and subgroup analysis were used to find source of heterogeneity.

RESULTS

A total of 40 studies were eventually selected for inclusion in this meta-analysis, including 33 for presepsin and seven for MR-proADM. Presepsin had a sensitivity of 0.86 (0.82-0.90), a specificity of 0.79 (0.71-0.85), and an AUC of 0.90 (0.87-0.92). The sensitivity of MR-proADM was 0.84 (0.78-0.88), specificity was 0.86 (0.79-0.91), and AUC was 0.91 (0.88-0.93). The profile of control group, population, and standard reference may be potential sources of heterogeneity.

CONCLUSIONS

This meta-analysis demonstrated that presepsin and MR-proADM exhibited high accuracy (AUC ≥ 0.90) in the diagnosis of sepsis in adults, with MR-proADM showing significantly higher accuracy than presepsin.

The Role of Inflammation and Infection in Age-Related Neurodegenerative Diseases: Lessons From Bacterial Meningitis Applied to Alzheimer Disease and Age-Related Macular Degeneration

Age-related neurodegenerative diseases, such as Alzheimer disease (AD) and age-related macular degeneration (AMD), are multifactorial and have diverse genetic and environmental risk factors. Despite the complex nature of the diseases, there is long-standing, and growing, evidence linking microbial infection to the development of AD dementia, which we summarize in this article. Also, we highlight emerging research findings that support a role for parainfection in the pathophysiology of AMD, a disease of the neurosensory retina that has been shown to share risk factors and pathological features with AD. Acute neurological infections, such as Bacterial Meningitis (BM), trigger inflammatory events that permanently change how the brain functions, leading to lasting cognitive impairment. Neuroinflammation likewise is a known pathological event that occurs in the early stages of chronic age-related neurodegenerative diseases AD and AMD and might be triggered as a parainfectious event. To date, at least 16 microbial pathogens have been linked to the development of AD; on the other hand, investigation of a microbe-AMD relationship is in its infancy. This mini-review article provides a synthesis of existing evidence indicating a contribution of parainfection in the aetiology of AD and of emerging findings that support a similar process in AMD. Subsequently, it describes the major immunopathological mechanisms that are common to BM and AD/AMD. Together, this evidence leads to our proposal that both AD and AMD may have an infectious aetiology that operates through a dysregulated inflammatory response, leading to deleterious outcomes. Last, it draws fresh insights from the existing literature about potential therapeutic options for BM that might alleviate neurological disruption associated with infections, and which could, by extension, be explored in the context of AD and AMD.

The Potentials of Melatonin in the Prevention and Treatment of Bacterial Meningitis Disease

Bacterial meningitis (BM) is an acute infectious central nervous system (CNS) disease worldwide, occurring with 50% of the survivors left with a long-term serious sequela. Acute bacterial meningitis is more prevalent in resource-poor than resource-rich areas. The pathogenesis of BM involves complex mechanisms that are related to bacterial survival and multiplication in the bloodstream, increased permeability of blood-brain barrier (BBB), oxidative stress, and excessive inflammatory response in CNS. Considering drug-resistant bacteria increases the difficulty of meningitis treatment and the vaccine also has been limited to several serotypes, and the morbidity rate of BM still is very high. With recent development in neurology, there is promising progress for drug supplements of effectively preventing and treating BM. Several in vivo and in vitro studies have elaborated on understanding the significant mechanism of melatonin on BM. Melatonin is mainly secreted in the pineal gland and can cross the BBB. Melatonin and its metabolite have been reported as effective antioxidants and anti-inflammation, which are potentially useful as prevention and treatment therapy of BM. In bacterial meningitis, melatonin can play multiple protection effects in BM through various mechanisms, including immune response, antibacterial ability, the protection of BBB integrity, free radical scavenging, anti-inflammation, signaling pathways, and gut microbiome. This manuscript summarizes the major neuroprotective mechanisms of melatonin and explores the potential prevention and treatment approaches aimed at reducing morbidity and alleviating nerve injury of BM.

Cerebrospinal Fluid Presepsin As a Marker of Nosocomial Infections of the Central Nervous System: A Prospective Observational Study

Background

Nosocomial CNS infection (NI-CNS) is a common and serious complication in neurocritical care patients. Timely, accurate diagnosis of NI-CNS is crucial, yet current infection markers lack specificity and/or sensitivity. Presepsin (PSP) is a novel biomarker of macrophage activation. Its utility in NI-CNS has not been explored. We first determined the normal range of cerebrospinal fluid (CSF) PSP in a control group without brain injury before collecting data on CSF PSP levels in neurocritical care patients. Samples were analyzed in four groups defined by systemic and neurological infection status.

Results

CSF PSP levels in 15 control patients without neurological injury were 50–100 pg/ml. Ninety-seven CSF samples were collected from 21 neurocritical care patients. In patients without NI-CNS or systemic infection, CSF PSP was 340.4 ± 201.1 pg/ml. Isolated NI-CNS was associated with CSF PSP levels of 640.8 ± 235.5 pg/ml, while levels in systemic infection without NI-CNS were 580.1 ± 329.7 pg/ml. Patients with both NI-CNS and systemic infection had CSF PSP levels of 1,047.7 ± 166.2 pg/ml. In neurocritical care patients without systemic infection, a cut-off value of 321 pg/ml gives sensitivity and specificity for NI-CNS of 100 and 58.3%, respectively.

Conclusion

CSF PSP may prove useful in diagnosing NI-CNS, but its current utility is as an additional marker only.

Microglial/macrophage markers CHI3L1, sCD14, and sCD163 in CSF and serum of pediatric inflammatory and non-inflammatory neurological disorders: A case-control study and reference ranges

OBJECTIVE

To assess the role of microglia and macrophages in neuroinflammatory disorders in children via biomarkers, and establish control reference ranges.

METHODS

In an IRB-approved case-control study of 98 children, the concentrations of CSF/serum CHI3L1, sCD14, and sCD163 were measured by ELISA. Groups were controls (non-inflammatory neurological disorders, NIND, n=37), opsoclonus-myoclonus syndrome (OMS, n=37), and other inflammatory neurological disorders (OIND, n=24).

RESULTS

In control CSF, median concentrations (ng/ml) were 25 (IQR 16,41) for CHI3L1 and 42 (26,160) for sCD14; in serum, 16 (12,22) for CHI3L1, and 431 (270,957) for sCD163. The median CSF concentration of CHI3L1 in OIND was significantly higher than controls (2.9-fold, P<0.0001) and OMS (1.6-fold higher than controls, NS). The CSF sCD14 concentration was 1.9-fold higher in OIND (P=0.008) and 1.4-fold higher in OMS than controls. sCD163, below detection limits in CSF, was not significantly increased in OIND or OMS sera.

CONCLUSIONS

CSF CHI3L1 and sCD14 elevations hold promise as immunomarkers in pediatric OIND, especially in high-expression individuals. These results provide evidence of innate immune system involvement in several pediatric neuroinflammatory disorders. Pediatric control data on CSF microglia/macrophage activation markers are hereby available for other investigators.

Diagnostic accuracy of presepsin (sCD14-ST) for prediction of bacterial infection in cerebrospinal fluid samples from children with suspected bacterial meningitis or ventriculitis

Children with temporary external ventricular drains (EVD) are prone to nosocomial infections. Diagnosis of bacterial meningitis and ventriculitis in these children is challenging due to frequent blood contamination of cerebrospinal fluid (CSF) and the presence of chemical ventriculitis. The aim of this study was to compare diagnostic accuracy of presepsin (sCD14-ST), a novel biomarker of bacterial infection in CSF, to predict bacterial infection in comparison to the accuracy of established biomarkers like those demonstrated in biochemical analysis of CSF. We conducted a prospective study with 18 children with suspected bacterial meningitis or ventriculitis who had 66 episodes of disease. CSF samples were taken from external ventricular drainage. We measured presepsin in CSF, as well as CSF leukocyte count, glucose, and proteins. CSF was also taken to prove bacterial infection with culture methods or with 16S rRNA gene broad-range PCR (SepsiTest; Molzym, Germany). Infection was clinically confirmed in 57 (86%) episodes of suspected meningitis or ventriculitis. Chemical ventriculitis was diagnosed in 9 (14%) episodes of suspected meningitis or ventriculitis. Diagnostic accuracies presented as area under the curve (AUC) for sCD14-ST, leukocytes, and proteins measured in CSF were 0.877 (95% confidence interval [CI], 0.793 to 0.961), 0.798 (95% CI, 0.677 to 0.920), and 0.857 (95% CI, 0.749 to 0.964), respectively. With CSF culture, we detected bacteria in 17 samples, compared to 37 detected with broad-range PCR. It was found that presepsin was present at a significantly higher level in children with clinically proven ventriculitis than in those without meningitis or ventriculitis. Diagnostic accuracies of presepsin were superior to those of leukocytes or proteins in CSF. Presepsin-guided 16S rRNA gene PCR could be used in everyday clinical practice to improve etiological diagnosis of meningitis and ventriculitis and to prescribe more appropriate antibiotics.

Early ART After Cryptococcal Meningitis Is Associated With Cerebrospinal Fluid Pleocytosis and Macrophage Activation in a Multisite Randomized Trial

INTRODUCTION

Earlier antiretroviral therapy (ART) initiation in cryptococcal meningitis resulted in higher mortality compared with deferred ART initiation (1-2 weeks vs 5 weeks postmeningitis diagnosis). We hypothesized this was due to ART-associated immune pathology, without clinically recognized immune reconstitution inflammatory syndrome.

METHODS

Three macrophage activation markers and 19 cytokines/chemokines were measured from cryopreserved cerebrospinal fluid (CSF) and serum during the Cryptococcal Optimal ART Timing (COAT) trial. Comparisons were made between trial arms (early vs deferred) at 1, 8, 14, and 21 days following meningitis diagnosis.

RESULTS

More participants with early ART initiation had CSF white cell count (WCC) ≥5/µL at day 14 (58% vs 40%; P = .047), after a median of 6-days ART. Differences were mainly driven by participants with CSF WCC <5/µL at meningitis diagnosis: 28% (10/36) of such persons in the early ART group had CSF WCC ≥5/µL by day 14, compared with 0% (0/27) in the deferred arm (P = .002). Furthermore, Kampala participants (the largest site) receiving early ART had higher day-14 CSF levels of interleukin-13 (P = .04), sCD14 (P = .04), sCD163 (P = .02), and CCL3/MIP-1α (P = .02), suggesting increased macrophage/microglial activation.

CONCLUSIONS

Early ART initiation in cryptococcal meningitis increased CSF cellular infiltrate, macrophage/microglial activation, and T helper 2 responses within the central nervous system. This suggests that increased mortality from early ART in the COAT trial was immunologically mediated.

Soluble CD163 as a marker of macrophage activity in newly diagnosed patients with multiple sclerosis

BACKGROUND

Soluble CD163 (sCD163) is a macrophage specific protein known to be up-regulated in serum from patients with multiple sclerosis (MS).

OBJECTIVE

To investigate sCD163 in serum and CSF (cerebrospinal fluid) from patients undergoing MS diagnostic work-up and analyse its potential as a diagnostic biomarker.

METHODS

After a full MS diagnostic work-up, including collection of paired samples of CSF and serum, 183 patients were evaluated for inclusion in this study. Patients were divided into groups based on their diagnosis. Patients with normal clinical and paraclinical findings were grouped as symptomatic controls. Serum and CSF levels of sCD163 were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

sCD163 could be measured in all serum and CSF samples. A high sCD163 CSF/serum ratio in relation to molecular weight was found, strongly indicating local production in the CNS. Median levels of sCD163 were significantly decreased in serum and significantly elevated in CSF in patients with relapsing-remitting, and primary-progressive MS. There were, however, some overlaps of the measures between groups. In a receiver operating characteristic (ROC) analysis sCD163 CSF/serum ratio had an area under the curve of 0.72.

CONCLUSION

The sCD163 CSF/serum ratio was significantly increased in patients with MS and may reflect macrophage activation in MS lesions. These results suggest that primary progressive MS also is driven by inflammation in which the innate immune system plays a pivotal role.

Impaired functions of macrophage from cystic fibrosis patients: CD11b, TLR-5 decrease and sCD14, inflammatory cytokines increase

BACKGROUND

Early in life, cystic fibrosis (CF) patients are infected with microorganisms. The role of macrophages has largely been underestimated in literature, whereas the focus being mostly on neutrophils and epithelial cells. Macrophages may however play a significant role in the initiating stages of this disease, via an inability to act as a suppressor cell. Yet macrophage dysfunction may be the first step in cascade of events leading to chronic inflammation/infection in CF. Moreover, reports have suggested that CFTR contribute to altered inflammatory response in CF by modification of normal macrophage functions.

OBJECTIVES

In order to highlight possible intrinsic macrophage defects due to impaired CFTR, we have studied inflammatory cytokines secretions, recognition of pathogens and phagocytosis in peripheral blood monocyte-derived macrophages from stable adult CF patients and healthy subjects (non-CF).

RESULTS

In CF macrophage supernatants, concentrations of sCD14, IL-1β, IL-6, TNF-α and IL-10 were strongly raised. Furthermore expression of CD11b and TLR-5 were sorely decreased on CF macrophages. Beside, no difference was observed for mCD14, CD16, CD64, TLR-4 and TLR1/TLR-2 expressions. Moreover, a strong inhibition of phagocytosis was observed for CF macrophages. Elsewhere CFTR inhibition in non-CF macrophages also led to alterations of phagocytosis function as well as CD11b expression.

CONCLUSIONS

Altogether, these findings demonstrate excessive inflammation in CF macrophages, characterized by overproduction of sCD14 and inflammatory cytokines, with decreased expression of CD11b and TLR-5, and impaired phagocytosis. This leads to altered clearance of pathogens and non-resolution of infection by CF macrophages, thereby inducing an exaggerated pro-inflammatory response.

Role of soluble CD14 in cerebrospinal fluid as a regulator of glial functions

Proteomic analysis of cerebrospinal fluid (CSF) samples derived from patients with Alzheimer's disease (AD) or Parkinson's disease (PD) was performed. On the basis of liquid chromatography-tandem mass spectrometry, two-dimensional gel electrophoresis analysis, and Western blot validation, it was found that the level of soluble form of monocyte differentiation antigen CD14 precursor was elevated in CSF from AD or PD patients compared with normal subjects. The soluble CD14 protein and mRNA expression was detected in microglia cells, indicating that microglia may be a cellular source of soluble CD14 in CSF. Next, the role of soluble CD14 in the regulation of glial functions was investigated. Soluble CD14 inhibited lipopolysaccharide (LPS)- or LPS/interferon-gamma-induced nitric oxide production and cell death of microglia and astrocytes. Soluble CD14 suppressed glial neurotoxicity in a coculture of glia/neuroblastoma. In addition, soluble CD14 moderately enhanced phagocytic activity of microglia. These results suggest that microglia-derived soluble CD14 is a candidate CSF biomarker for AD and PD, and the soluble CD14 may inhibit glial activation by interfering with LPS effects.

Serum sCD14, polymorphism of CD14(-260) and periodontal infection

BACKGROUND AND AIMS

CD14 is a co-receptor involved in the recognition of Gram-negative and positive bacteria. Infections are known to influence serum sCD14 levels, and CD14 gene promoter polymorphism (CD14 C-260T) has been reported to be associated with many infectious diseases. Our aim was to investigate whether serum sCD14 concentration is associated with periodontal infection and the CD14(-260) genotype.

SUBJECTS AND METHODS

The periodontal status of 56 subjects with chronic periodontitis and 28 controls was clinically examined. Serum sCD14 concentration was analyzed using ELISA and CD14(-260) genotype using polymerase chain reaction (PCR).

RESULTS

The mean concentration of sCD14 in serum was significantly higher in subjects with periodontitis than in control subjects (4.9 microg ml(-1)vs 3.8 microg ml(-1), P < 0.001). Serum sCD14 concentration associated significantly with the extent of advanced periodontal disease. In a regression analysis including both subject groups, the CD14(-260) genotype was a significant determinant for serum sCD14 concentration. After stratification by periodontal health status (periodontitis vs controls), the influence of the CD14(-260) genotype on serum sCD14 concentration was seen only in the control group.

CONCLUSIONS

Periodontal infection is associated with the serum concentration of sCD14. Moderate to severe periodontal infection overshadows the influence of the genotype on serum sCD14 concentration.

Soluble CD14: role in atopic disease and recurrent infections, including otitis media

Soluble CD14 (sCD14) is a part of innate immunity that has been implicated in many diseases, including allergic diseases. However, many influencing factors and confounders, including gender-gene-environment interactions, may complicate interpretations of the observed associations to allergic diseases. In this paper, we review current literature describing the functions of sCD14 and its associations with common (recurrent) infections and with allergic diseases. Because sCD14 is involved with immunologic responses to infections, and exposure to microbial compounds is debated as a protective or a trigger factor for allergy development, these factors-which include genotypes, gender, age, microbial agents (from the environment and infection), and tobacco smoke-cannot be assessed independently. We conclude that confounding effects are important and must be considered to understand the role of sCD14 in allergic development.

CD14 mediates cross talk between mononuclear cells and fibroblasts for upregulation of matrix metalloproteinase 9 by Borrelia burgdorferi

Lyme disease is an infection caused by a tick-borne spirochete, Borrelia burgdorferi. Matrix metalloproteinase 9 (MMP-9) was selectively upregulated in the erythema migrans skin lesions of patients with acute Lyme disease. In this study, the mechanism of upregulation of MMP-9 was investigated in vitro and in vivo. The concentrations of MMP-9 and soluble CD14 were markedly elevated in serum from patients with acute Lyme disease and were also upregulated in U937 cells by B. burgdorferi in a time- and concentration-dependent manner. MMP-9 mRNA was expressed at baseline in fibroblasts in the presence or absence of B. burgdorferi. However, when fibroblasts were incubated with supernatants from U937 cells with B. burgdorferi or recombinant CD14, the expression of MMP-9 was significantly increased. This effect was completely abolished by the anti-CD14 antibody. These data suggest that the upregulation of MMP-9 by B. burgdorferi involves the CD14 pathway in infiltrating inflammatory cells. Fibroblasts could be recruited to amplify local production of MMP-9 by acquiring CD14 from macrophages.

Discrepancies of NKT cells expression in peripheral blood and in cerebrospinal fluid from Behçet's disease

The precise role of natural killer T (NKT) cells in the pathogenesis of Behçet's disease (BD) remains unknown. The frequency, cytokine profile and heterogeneity of NKT cells were studied in peripheral blood mononuclear cells (PBMC) from 42BD patients and in cerebrospinal fluid (CSF) samples from 9 neuro-BD patients. Flow cytometry revealed a decreased frequency of NKT cells in PBMC from BD patients (median: 0.06%; range: 0%-0.3%) when compared to healthy controls (median: 0.23%; range: 0.1%-0.7%; P<0.01). NKT cells were biased toward a Th(1)-like phenotype, with a significant decrease of IL-4/IFN-gamma ratio in BD (median: 0.049; range: 0.01-0.13) vs. healthy controls (median: 0.82; range: 0.4-1.33; P<0.01). NKT cells were increased in CSF-BD samples (median: 0.18%; range: 0.1%-0.4%), when compared to CSF-NIND patients (median: 0.05%; range: 0.01%-0.09%; P<0.01). Based on the reactivity of PBMC-derived NKT cells toward alpha-galactosylceramide (alpha-GalCer), 80% of BD patients were non-responsive. At the opposite, the reactivity of NKT cells in CSF from BD patients was not impaired. BD-CSF NKT cells exhibited an increased expression of IFN-gamma-producing cells, demonstrating that CSF-NKT cells were functional, and biased toward a Th(1)-like phenotype. These data suggest that functional NKT cells are recruited into BD inflammatory sites contributing to BD pathogenesis.

R-form LPS, the master key to the activation ofTLR4/MD-2-positive cells

Lipopolysaccharide (endotoxin, LPS) is a major recognition marker for the detection of gram-negative bacteria by the host and a powerful initiator of the inflammatory response to infection. Using S- and R-form LPS from wild-type and R-mutants of Salmonella and E. coli, we show that R-form LPS readily activates mouse cells expressing the signaling receptor Toll-like receptor 4/myeloid differentiation protein 2 (TLR4/MD-2), while the S-form requires further the help of the LPS-binding proteins CD14 and LBP, which limits its activating capacity. Therefore, the R-form LPS under physiological conditions recruits a larger spectrum of cells in endotoxic reactions than S-form LPS. We also show that soluble CD14 at high concentrations enables CD14-negative cells to respond to S-form LPS. The presented in vitro data are corroborated by an in vivo study measuring TNF-alpha levels in response to injection of R- and S-form LPS in mice. Since the R-form LPS constitutes ubiquitously part of the total LPS present in all wild-type bacteria its contribution to the innate immune response and pathophysiology of infection is much higher than anticipated during the last half century.

Protein expression pattern in experimental pneumococcal meningitis

In this study, we investigated cytokine expression during experimental pneumococcal meningitis. Mice were intracisternally infected with Streptococcus pneumoniae and treated with ceftriaxone starting at 24 h after infection. At different time points before and after antibiotic therapy, the cytokine expression pattern was determined in mouse brains using protein arrays. Underlining the power of this method, the meningitis-relevant cytokines interleukin-1beta (IL-1beta), IL-6, KC, macrophage inflammatory protein-2 (MIP-2), and monocyte chemoattractant protein-1 (MCP-1/CCL2) were markedly elevated in infected animals. Newly identified proteins during the acute stage of the disease (until 30 h after infection) included lymphotactin (XCL-1), MIP-1gamma (CCL9) and MCP-5 (CCL12), cytokine responsive gene- 2 (CRG-2/CXCL10) and CXCL16, and insulin-like growth factor binding protein 3 (IGFBP3). During later stages, an induction of T-cell activation-3 (TCA-3/CCL1), platelet factor-4 (PF-4/CXCL4) and stromal derived factor-1alpha (SDF-1alpha/CXCL13), and IL-4 was observed. The validity of this method was supported by an additional ELISA analysis of the expression profile of CXCL16 and IGFBP3, which was identical to that observed by protein array. In conclusion, the use of protein array technology led to an extension of the current picture of protein expression in pneumococcal meningitis. Most important, new factors that might play a role in pneumococcal meningitis were identified.

CD14 deficiency leads to increased MIP-2 production, CXCR2 expression, neutrophil transmigration, and early death in pneumococcal infection

CD14 is a myeloid receptor for bacterial cell membrane/wall components, for which we previously showed a strong induction in cerebrospinal fluid (CSF) during meningitis. Here, we studied CD14 function in murine Streptococcus pneumoniae meningitis by using wild-type (WT), CD14(-/-) mice, and WT mice pretreated with neutralizing anti-CD14 antibodies. Early polymorphonuclear leukocytes (PMN) immigration was more pronounced in CSF of CD14(-/-) than of WT mice. This was not a result of altered adherence molecule expression in blood and CSF PMN or brain endothelial cells. Macrophage inflammatory protein-2 (MIP-2) and keratinocyte-derived chemokine levels were similar in CSF in both strains, but MIP-2 was higher in infected brain and in brain-derived endothelial cells infected in vitro in CD14(-/-) than in WT mice. CD14(-/-) PMN demonstrated increased expression of CXC chemokine receptor 2 (CXCR2) after infection and stronger in vitro chemotaxis than WT PMN toward CSF from WT or CD14(-/-) mice and toward MIP-2. Excess PMN migration in CD14(-/-) mice did not result in improved bacterial clearing but in increased tumor necrosis factor in CSF, higher disease severity, and earlier death. Pretreatment with anti-CXCR2 reduced PMN infiltration into CSF and brain MIP-2 production and abolished earlier mortality in CD14(-/-) mice. In conclusion, CD14 plays a protective role in pneumococcal meningitis by slowing PMN migration via MIP-2 and CXCR2 modulation.

The Differential Effect of Genetic Variation on Soluble CD14 Levels in Human Plasma and Milk

PROBLEM

The protein CD14 is a pattern recognition receptor for bacterial lipopolysaccharide (LPS). Whether genetic variation has the same influence on soluble CD14 (sCD14) levels in human plasma and milk remains to be determined.

METHOD OF STUDY

We measured sCD14 levels in plasma during pregnancy (n = 196) and in milk in the postpartum (n = 152) for women genotyped for the single nucleotide polymorphisms (SNPs) at positions -1619, -550, and -159 from the transcription start site of the CD14 gene.

RESULTS

Plasma- and milk-sCD14 levels differed significantly both by CD14/-1619 and CD14/-550 genotypes and by haplotypes. Most interestingly, sCD14 levels were regulated differentially by the same genetic variants in plasma and milk, with the CD14/-550T allele and the corresponding are ATC haplotype associated with high sCD14 in milk but low sCD14 in plasma. A correlation between sCD14 levels in plasma and milk was absent (r = 0.091, P = NS).

CONCLUSIONS

Our findings suggest the existence of cell-specific regulation mechanisms of CD14 gene expression.

Reduced interferon gamma production and soluble CD14 levels in early life predict recurrent wheezing by 1 year of age

It is unknown whether reduced production of IFNgamma in early life, before any lower respiratory tract illness, is a risk factor for recurrent wheezing in infancy. We followed 238 infants prospectively from birth to 1 year of age. At birth and at 3 months of age, IFNgamma production from polyclonally stimulated peripheral blood mononuclear cells and soluble CD14 (sCD14) levels in plasma were measured. The odds of developing recurrent wheezing (assessed by questionnaire) in the first year of life were up to 4.5 times higher for children in the lowest quartile of IFNgamma production at 3 months (p = 0.0005) and 3.2 times higher for children in the lowest quartile of sCD14 levels at birth (p = 0.004) as compared with children in the other 3 combined quartiles of IFNgamma and sCD14, respectively. Findings were confirmed in the multivariate analysis. IFNgamma production at 3 months and sCD14 levels at birth were correlated (r = 0.188, p = 0.031). Our findings from a longitudinal cohort suggest that impaired IFNgamma production at 3 months and reduced plasma-sCD14 levels at birth significantly increase the risk of developing recurrent wheezing in the first year of life.

RPE CD14 immunohistochemical, genetic, and functional expression

CD14 is the primary receptor for lipopolysaccharide (LPS)that plays important roles in host defense and subserves other host-related biological functions. We previously identified CD14 on cultured human retinal pigment epithelial (HRPE) cells using immunocytochemical techniques. In this study, we investigated immunoreactive HRPE CD14 expression by immunohistochemically staining HRPE cells and HRPE cells in sections of human eyes with anti-CD14 monoclonal antibodies (mAb). Constitutive HRPE gene and protein expression were confirmed by semiquantitative PCR and western blotting. ELISA for cell-associated and secreted (s) HRPE CD14 revealed that specific digestion by phosphoinositol-specific phospholipase C (PI-PLC) significantly reduced (P<0.01) cell-associated HRPE CD14 which was not modulated by LPS or gamma-IFN. ELISA of the conditioned media (CM) of HRPE cells treated with PI-PLC contained significantly more (P<0.001) sCD14, but sCD14 was not modulated by LPS or gamma-IFN. FACS analysis confirmed HRPE cell surface CD14. To show functional CD14, fluorescently-labelled LPS and CD14 were demonstrated to show significant co-localization on live, cultured HRPE cells in close proximity (<7A) as demonstrated by resonance energy transfer of the fluorescent ligands (P<0.0001). Significant inhibition (P<0.001) of LPS-induced IL-8 secretion, as measured by ELISA, occurred in the presence of function blocking anti-CD14 mAb. Significant inhibition of LPS-induced HRPE IL-8 secretion by PKC, PTK, PI3 kinase, and p38 kinase inhibitors indicated cell mediators responsible for LPS-induced HRPE chemokine secretion. This study demonstrates that HRPE cells express functional CD14 in vitro and in situ along at the outer blood-retina barrier.

The macrophage activity marker sCD14 is increased in patients with multiple sclerosis and upregulated by interferon beta-1b

The soluble form of the CD14 molecule (sCD14), a macrophage activity marker, was measured in the plasma of 17 patients with primary progressive multiple sclerosis (PPMS) and 20 patients with relapsing remitting MS (RRMS). In patients with PPMS, sCD14 levels were determined before and after treatment with interferon beta (IFNB). In both PPMS and in RRMS, sCD14 levels were significantly elevated compared to healthy controls. In patients with PPMS, sCD14 levels increased significantly during the first 3 months of IFNB therapy, then slightly decreased, but still remained elevated compared with levels before therapy. Therefore, the elevated sCD14 levels may be a marker in evaluating biological response to IFNB therapy.

Infiltrating CD14+ monocytes and expression of CD14 by activated parenchymal microglia/macrophages contribute to the pool of CD14+ cells in ischemic brain lesions

CD14, a key pattern recognition receptor of the innate immune system, is a surface molecule on monocytic cells involved in cellular activation. We investigated 18 autopsy cases of focal cerebral infarctions (FCI) by immunohistochemistry to examine CD14 expression following ischemia. Controls confirmed constitutive CD14 expression by few perivascular cells. In contrast to quiescent CD14- parenchymal microglial cells, following ischemia activated microglia/macrophages expressed abundant CD14. In FCI, CD14+ cells increased both in perivascular spaces and in brain parenchyma within 1-2.5 days and remained elevated until late stages. Early CD14 expression suggests an essential part of CD14 in the acute inflammatory response following stroke.

Biomarker discovery in urine by proteomics

A hypothesis was formed that it would be possible to isolate an adequate amount of protein from a patient, having normal renal function, to identify biological markers of a particular disease state using a variety of proteomics techniques. To support this hypothesis, three samples of urine were collected from a volunteer: first when healthy, later when experiencing acute inflammation due to a pilonidal abcess, and again later still after successful recovery from the condition. The urine from these samples was processed by solid-phase extraction to concentrate and desalt the endogenous proteins and peptides. The proteins and peptides from these urine samples were analyzed in three different experiments: (1) traditional two-dimensional gel electrophoresis followed by proteolysis and mass spectrometric identification of various protein spots, (2) whole mixture proteolysis followed by one-dimensional packed capillary liquid chromatography and tandem mass spectrometry, (3) whole mixture proteolysis followed by two-dimensional capillary liquid chromatography and tandem mass spectrometry. In all three cases, a set of proteins was identified representing putative biomarkers. Each of these proteins was then found to have been previously linked in the scientific literature to inflammation. One acute phase reactant in particular, orosomucoid, was readily observed in all three experiments to dramatically increase in abundance, thereby supporting the hypothesis.

The lipopolysaccharide co-receptor CD14 is present and functional in seminal plasma and expressed on spermatozoa

CD14 is a 54 000-molecular weight (MW) glycolipid-anchored membrane glycoprotein, expressed on myeloid cells, which functions as a member of the lipopolysaccharide (LPS) receptor complex. Soluble forms of CD14 have been reported in plasma, cerebrospinal fluid, amniotic fluid and breast milk. In plasma and breast milk, soluble CD14 has been implicated as a regulator of T- and B-cell activation and function. Expression of CD14 in the male reproductive system has not previously been investigated. We here show that soluble CD14 is present in seminal plasma at levels comparable to those in serum. Spermatozoa expressed CD14 on their membranes, as demonstrated by fluorescence microscopy and flow cytometry. Post-vasectomy, the levels of seminal plasma CD14 (spCD14) were much reduced, implying an origin distal to the point of transection of the vas deferens. Ultracentrifugation analyses demonstrated that spCD14 was not associated with lipid complexes, indicating that it lacks the glycolipid anchor. Purified spCD14 mediated activation by LPS of CD14-negative cells. These findings suggest that CD14 may play a hitherto unexplored role in immune defence and cell activation in the male reproductive tract.

A novel flow cytometric assay to quantify soluble CD14 concentration in human serum

BACKGROUND

CD14, the major lipopolysaccharide (LPS)-binding protein of myeloid cells, is found as a soluble molecule in human serum. Recent data describe the presence of elevated soluble CD14 (sCD14) concentration in various disorders, confirming disease activity. A novel, easy, and rapid flow cytometric assay was developed to measure sCD14 levels in serum.

METHODS

The assay is based on the competition between membrane-expressed CD14 of isolated monocytes from healthy volunteers and sCD14 in the sample sera for binding to anti-CD14 monoclonal antibodies (mAb; 26ic or 60bca). The amount of cell-associated mAb is determined with a fluorescein isothiocyanate (FITC)-labeled anti-mouse conjugate and flow cytometry. The fluorescence signal is inversely proportional with the amount of serum sCD14. Using dilutions of a standard serum, the concentration of sCD14 in the samples is calculated and compared with results obtained by a commercial sCD14 enzyme-linked immunosorbent assay (ELISA).

RESULTS

After optimization, the assay showed log-log linearity of 122.1-984.7 ng/ml sCD14 using mAb 26ic and 29.5-246.2 ng/ml sCD14 using mAb 60bca. It revealed similar results as the ELISA (mAb 26ic: r = 0.88, mAb 60bca: r = 0.92) and provided significantly elevated sCD14 levels in systemic lupus erythematosus patients compared with controls (26ic: 2,213 versus 1,676 ng/ml, P < 0.002; 60bca: 2,625 versus 1,907 ng/ml, P < 0.0002). Receiver operating characteristic curve analysis suggested a reasonable diagnostic efficacy of sCD14 quantification in this autoimmune disease.

CONCLUSIONS

The method is easy, rapid, sensitive, and can be used in the follow-up of patients suffering from sepsis or chronic inflammatory disorders.

Soluble CD14 levels in gingival crevicular fluid of subjects with untreated adult periodontitis

BACKGROUND

This study determined soluble CD14 (sCD14) levels in gingival crevicular fluid (GCF) and their potential relationship to periodontal conditions in adult periodontitis.

METHODS

GCF was collected from 15 patients with untreated adult periodontitis. sCD14 levels were determined by ELISA and presented as total amount (ng/site) and concentration (microg/ml). The periodontal examination consisted of plaque index (PI), bleeding index (BI), probing depth (PD), and clinical attachment level (CAL). PD and CAL were measured with an electronic probe.

RESULTS

sCD14 was detected in all 15 subjects and was found in 59% (62/105) of the sampled sites. The percentage of sites with sCD14 varied greatly, ranging from 14% to 100%. The mean total amount of sCD14 was 1.71+/-0.40, range 0.03 to 5.41 ng/site; the concentration of sCD14 was 14.04+/-4.15, range 0.16 to 51.74 microg/ml. No significant difference in clinical data was found between the sites with and without detectable levels of sCD14. However, on the basis of the individual profile of sCD14 levels, i.e., those individuals with >50% of the sites containing sCD14 and mean levels of sCD14 >5.0 microg/ml, the 15 subjects were divided into a high sCD14 group (9 subjects) and a low sCD14 group (6 subjects). Compared to the high group, the low group showed greater mean PD and a higher percentage of sites with PD > or = 5.0 mm (P <0.05). Consistent with this, sCD14 concentrations showed a negative correlation with PD (r(s) = -0.636, P = 0.0174).

CONCLUSIONS

The present study shows that sCD14 levels in GCF varied greatly among subjects with untreated adult periodontitis. Individuals with higher levels of sCD14 in GCF and more sites containing sCD14 had fewer deep pockets. The negative correlation between GCF sCD14 levels and probing depth implies a crucial role of sCD14 in bacterially induced periodontal destruction. The relationship between GCF sCD14 levels and probing depth warrants further investigations.