Calprotectin in cerebrospinal fluid of the HIV infected: a diagnostic marker of opportunistic central nervous system infection?

MRP8/14 Is a Molecular Signature Triggered by Dopamine in HIV Latent Myeloid Targets That Increases HIV Transcription and Distinguishes HIV+ Methamphetamine Users with Detectable CSF Viral Load and Brain Pathology

There is a significant overlap between HIV infection and substance-use disorders. Dopamine (DA) is the most abundantly upregulated neurotransmitter in methamphetamine abuse, with receptors (DRD1-5) that are expressed by neurons as well as by a large diversity of cell types, including innate immune cells that are the targets of HIV infection, making them responsive to the hyperdopaminergic environment that is characteristic of stimulant drugs. Therefore, the presence of high levels of dopamine may affect the pathogenesis of HIV, particularly in the brain. The stimulation of HIV latently infected U1 promonocytes with DA significantly increased viral p24 levels in the supernatant at 24 h, suggesting effects on activation and replication. Using selective agonists to different DRDs, we found that DRD1 played a major role in activating viral transcription, followed by DRD4, which increased p24 with a slower kinetic rate compared to DRD1. Transcriptome and systems biology analyses led to the identification of a cluster of genes responsive to DA, where S100A8 and S100A9 were most significantly correlated with the early increase in p24 levels following DA stimulation. Conversely, DA increased the expression of these genes' transcripts at the protein level, MRP8 and MRP14, respectively, which form a complex also known as calprotectin. Interestingly, MRP8/14 was able to stimulate HIV transcription in latent U1 cells, and this occurred via binding of the complex to the receptor for an advanced glycosylation end-product (RAGE). Using selective agonists, both DRD1 and DRD4 increased MRP8/14 on the surface, in the cytoplasm, as well as secreted in the supernatants. On the other hand, while DRD1/5 did not affect the expression of RAGE, DRD4 stimulation caused its downregulation, offering a mechanism for the delayed effect via DRD4 on the p24 increase. To cross-validate MRP8/14 as a DA signature with a biomarker value, we tested its expression in HIV+ Meth users' postmortem brain specimens and peripheral cells. MRP8/14+ cells were more frequently identified in mesolimbic areas such as the basal ganglia of HIV+ Meth+ cases compared to HIV+ non-Meth users or to controls. Likewise, MRP8/14+ CD11b+ monocytes were more frequent in HIV+ Meth users, particularly in specimens from participants with a detectable viral load in the CSF. Overall, our results suggest that the MRP8 and MRP14 complex may serve as a signature to distinguish subjects using addictive substances in the context of HIV, and that this may play a role in aggravating HIV pathology by promoting viral replication in people with HIV who use Meth.

Fecal Calprotectin in Children Can Differentiate Between Different Gastrointestinal Diseases

BACKGROUND: Calprotectin is a 36 kDa member of the S100 family of proteins. It is derived predominantly from neutrophils and has direct antimicrobial effects and a role within the innate immune response. Calprotectin is found in various body fluids in proportion to the degree of any existing inflammation and its concentration in feces is about 6 times that of plasma. Measurement of fecal calprotectin is a useful surrogate marker of gastrointestinal inflammation. It has a high negative predictive value in ruling out inflammatory bowel disease (IBD) in undiagnosed, symptomatic patients and high sensitivity for diagnosing the disease making it useful as a tool for prioritizing endoscopy. In patients with known IBD, fecal calprotectin can be a useful tool to assist management, providing evidence of relapse or mucosal healing to enable therapy to be intensified or reduced. AIM: The present study aimed to discuss the use of calprotectin for the diagnosis of IBD and some of the other ways in which the test may be useful in the management of gastroenterology patients. METHODS: A cross-sectional study on children with significant gastrointestinal diseases attending to pediatric department at Menoufia University, with a total number of 180 patients in addition to 30 normal children as control according to sample size calculation. The children are allocated into seven groups according to the final diagnosis to Group (1): 30 patients with IBD, Group (2): 20 patients with eosinophilic colitis, Group (3): 30 patients with Helicobacter pylori infection, Group (4): 40 patients with functional constipation, Group (5): 30 patients with cow milk allergy, Group (6): 30 patients with Celiac disease, and Group (7): 30 normal children as control. RESULTS: In cow milk protein allergic patients with marked GI presentation in the form of bloody diarrhea and/or abdominal distension, the mean fecal calprotectin (FC) was 1260 ± 625 μg/g. FC has decreased after 2−4 weeks of elimination of cow milk products to 420 ± 190 μg/g. Patient with inflammatory bowel disease had mean FC 4640 ± 850 μg/g, decreased after medical treatment and resolution of symptoms to 1360 ± 520 μg/g. In H. pylori infection detected by upper GI endoscopy and histopathology with positive stool antigen the mean FC was 78.9 ± 25.1 μg/g. Celiac disease patients had mean fecal calprotectin 456 ± 123 μg/g. Eosinophilic esophagitis had mean fecal calprotectin 4.2 ± 2.9 μg/g. Functional constipation patients had mean fecal calprotectin 23.6 ± 21.8 μg/g. Normal control children had mean fecal calprotectin 4.1 ± 6.9 μg/g. CONCLUSION: According to the results of previous studies, fecal calprotectin can be considered as a biomarker to differentiate between IBS and organic gastrointestinal disorders. However, due to the limitations of pre-analysis, a low fecal calprotectin concentration may not necessarily be considered as the reason for the absence of IBD.

S100 family proteins in inflammation and beyond

The S100 family proteins possess a variety of intracellular and extracellular functions. They interact with multiple receptors and signal transducers to regulate pathways that govern inflammation, cell differentiation, proliferation, energy metabolism, apoptosis, calcium homeostasis, cell cytoskeleton and microbial resistance. S100 proteins are also emerging as novel diagnostic markers for identifying and monitoring various diseases. Strategies aimed at targeting S100-mediated signaling pathways hold a great potential in developing novel therapeutics for multiple diseases. In this chapter, we aim to summarize the current knowledge about the role of S100 family proteins in health and disease with a major focus on their role in inflammatory conditions.

Calprotectin: Clinical Applications in Pediatrics

As seen over the past 20 years, calprotectin has evolved as a novel, non-invasive biomarker of gastrointestinal (GI) inflammation. We present this review of calprotectin in pediatrics. This article will focus on studies using calprotectin concentrations from different body fluids to monitor inflammation in different disease states and conditions. The ultimate goal of our group is to lay down a foundation as we consider using calprotectin prospectively as a marker of intestinal inflammation that could lead to further testing and possibly a marker of preparedness for feeding. We surveyed all published studies in English of calprotectin in neonates, infants, children, and adolescents through February 2014. We will discuss calprotectin's basic properties and analysis such as characteristics, identification, presence in body fluids, and maturational development. In addition, calprotectin's use in inflammatory diseases exploring both GI and non-GI conditions will be evaluated and compared with other serum markers presently available. Finally, a summary of our findings and discussion of future work that could be undertaken in order to render calprotectin as a more useful monitoring tool to the medical research community will complete the review.

Calprotectin and lactoferrin in the cerebrospinal fluid; biomarkers utilisable for differential diagnostics of bacterial and aseptic meningitis?

BACKGROUND

The aim of our work was to assess the diagnostic contribution of calprotectin and lactoferrin determinations in the cerebrospinal fluid when distinguishing between bacterial and aseptic meningitides.

METHODS

In 23 patients with bacterial meningitis (BM) and in 50 patients with aseptic meningitis (AM), we determined the concentrations of calprotectin, lactoferrin and the conventional biomarkers like glucose, total protein, lactate and polynuclear count in the cerebrospinal fluid (CSF). The discriminative power of the various parameters studied was determined by means of receiver operating characteristic (ROC) curves: the area under the curve (AUC), sensitivity, specificity, the positive likelihood ratio (+LR), and the negative likelihood ratio (-LR).

RESULTS

The diagnostic efficiency of calprotectin, lactoferrin, lactate, and polynuclear count when distinguishing between bacterial and aseptic meningitides, expressed by ROC curve parameters, was as follows: AUC (0.736, 0.946, 0.932, 0.932), sensitivity (86.2, 96.6, 90.0, 89.7), specificity (58.5, 92.4, 87.0, 90.6), +LR (2.08, 12.8, 6.9, 9.50), -LR (0.24, 0.04, 0.11, 0.11), respectively. The optimal cut point for calprotectin and lactoferrin was 191 ng/mL and 17.8 ng/mL, respectively.

CONCLUSIONS

Our findings show, that the determination of lactoferrin in the CSF was diagnostically the most efficient marker in distinguishing between bacterial and viral meningitides. Calprotectin was far less efficient diagnostic marker. The polynuclear count and lactate concentration showed a very good diagnostic efficiency as well. The determination of protein and glucose was diagnostically less beneficial.

Can Fecal Calprotectin Level Be Used as a Markers of Inflammation in the Diagnosis and Follow-Up of Cow's Milk Protein Allergy?

Purpose

Calprotectin is a cytosolic protein with immunomodulatory, antimicrobial, and antiproliferative actions. The concentration of calprotectin increases in infection, inflammation, and malignancy. We determined if calprotectin can be used as a marker for the diagnosis and follow-up of bowel inflammation in cow's milk protein allergy (CMPA).

Methods

In total, 32 patients newly diagnosed with CMPA were included (24 IgE-mediated, 8 non-IgE-mediated). In all subjects, a complete blood count, total IgE, cow's milk-specific IgE, and fecal calprotectin (FC) were assessed before and after a cow's milk protein (CMP) elimination diet was started. The results were compared with those of 39 healthy children.

Results

The mean FC value before the CMP elimination diet was 516±311 µg/g in the 32 patients with CMPA and 296±94 µg/g in the control group (P=0.011). The mean FC value after the diet in these patients was 254±169 µg/g, which was significantly different from the mean value before the CMP elimination diet (P<0.001). When we compared FC levels before the CMP elimination diet in the IgE-mediated group with the control group, we found no significant statistical difference (P=0.142). The mean FC value before the CMP elimination diet was 886±278 µg/g in the non-IgE-mediated group and 296±94 µg/g in the control group; this difference was statistically significant (P<0.001). In the IgE-mediated and non-IgE-mediated groups, FC values after CMP elimination diet were 218±90 µg/g and 359±288 µg/g, respectively, and FC values before CMP elimination diet were 392±209 µg/g and 886±278 µg/g, respectively; these differences were statistically significant (P=0.001 and P=0.025, respectively).

Conclusions

FC levels may be a useful marker for follow-up treatment and recurrence determination in CMPA.

The down regulation of neutrophil oxidative metabolism by S100A8 and S100A9: implication of the protease-activated receptor-2

S100A8 and S100A9 regulate polymorphonuclear neutrophils (PMNs) recruitment and represent 40% of PMN cytosolic protein weight. We have shown that S100A8/S100A9 inhibit PMN oxidative metabolism. The present study was designed to elucidate the mechanisms of this anti-oxidative effect. We hypothesized that the protease activated receptor-2 (PAR-2) played a role in the down-regulation of PMN oxidative metabolism by S100A8/S100A9. Freshly isolated PMNs were tested for their ability to oxidize dichlorofluorescin-diacetate. Functional inhibition of PAR-2 with ENMD-1068, the pepducin P2pal-21 or an antibody directed at PAR-2 cleavage/activation site, resulted in a significant inhibition of S100A8 and S100A9 anti-oxidative effect. Conversely, the controlled activation of PAR-2 potentiated S100 anti-oxidative effect. Taken together, the data indicate that the anti-oxidative effect of S100A8/A9 is initiated by PAR-2 activation. S100A8/S100A9 may therefore dampen inflammation without interfering with its initial strength. This finding opens translational possibilities to limit deleterious PMN activation with a dual PAR-2/S100 strategy.

S100A8 and S100A9 inhibit neutrophil oxidative metabolism in-vitro: involvement of adenosine metabolites

Neutrophils are short-lived granulocytic cells of the innate immune system specialized in the production of reactive oxygen species. S100A8 and S100A9 and their heterocomplex calprotectin play a role in neutrophil recruitment and represent 40% of neutrophil cytosolic protein weight. The present study was designed to test the effect of S100A8 and S100A9 on the rate of neutrophil oxidative metabolism. It is hypothesized that the two S100 proteins inhibit neutrophil associated oxidation. Granulocytes freshly isolated from healthy volunteers were tested for their ability to oxidize dichlorofluorescindiacetate (DCFH-DA) in-vitro. The data showed that S100A8 and S100A9 inhibited spontaneous and stimulated oxidation of the DCFH-DA probe by neutrophils. The inhibition of neutrophil oxidative metabolism by S100A8 and S100A9 was markedly reduced by the enzymatic activity of adenosine deaminase. Inhibitors of the P1 adenosine receptors also reduced the anti-oxidative effect of S100A8/A9 providing further support for the involvement of adenosine metabolites in S100A8/ A9 anti-oxidative effect.

Effect of human immunodeficiency virus infection on S100A8/A9 inhibition of peripheral neutrophils oxidative metabolism

Neutrophils are endowed with a highly active oxidative metabolism that is crucial for their antimicrobial functions but can produce oxidative conditions disruptive to the host. Opportunistic infections associated with HIV disease and ex vivo studies of neutrophils from HIV patients suggest that neutrophil dysfunctions significantly contribute to HIV disease. The calcium-binding proteins S100A8 and S100A9 are abundant cytosolic constituents of human neutrophils. Our previous work has shown that S100A8 and S100A9 inhibit neutrophil oxidative metabolism. In this study, we tested the hypothesis that neutrophils from HIV infected subjects respond differently to S100A8 and S100A9 when compared to neutrophils isolated from control HIV naive subjects. Neutrophils, freshly isolated from whole blood, were tested in a 96-well plate assay for their ability to oxidize the DCFH-DA probe. The neutrophils from HIV+ and HIV- subjects were stimulated with LPS and inhibited with recombinant S100A8 and S100A9. Our data indicate that when compared to neutrophils isolated from HIV- subjects, neutrophils from HIV+ subjects display an exaggerated response to LPS and a diminished response to S100A8 and S100A9 inhibition. Our data support our hypothesis and signify that, in HIV disease, dysregulated neutrophil responses to endotoxins stimulation and S100A8/A9 inhibition may contribute to a higher risk for oxidative stress associated ailments. The mechanism for the observed differences in neutrophil response and their biological significance in the course of HIV disease should be addressed in further studies.

IL-10-dependent S100A8 gene induction in monocytes/macrophages by double-stranded RNA

The S100 calcium-binding proteins S100A8 and S100A9 are elevated systemically in patients with viral infections. The S100A8-S100A9 complex facilitated viral replication in human CD4(+) T lymphocytes latently infected with HIV-1- and S100A8-induced HIV-1 transcriptional activity. Mechanisms inducing the S100 genes and the potential source of these proteins following viral activation are unknown. In this study, we show that S100A8 was induced in murine macrophages, and S100A8 and S100A9 in human monocytes and macrophages, by polyinosinic:polycytidylic acid, a dsRNA mimetic. Induction was at the transcriptional level and was IL-10 dependent. Similar to LPS-induced S100A8, induction by dsRNA was dependent on p38 and ERK MAPK. Protein kinase R (PKR) mediates antiviral defense and participates in MyD88-dependent/independent signaling triggered by TLR4 or TLR3. Like IL-10, S100 induction by polyinosinic:polycytidylic acid and by LPS was inhibited by the specific PKR inhibitor 2-aminopurine, indicating a novel IL-10, PKR-dependent pathway. Other mediators such as IFN-beta, which synergized with dsRNA, may also be involved. C/EBPbeta bound the defined promoter region in response to dsRNA. S100A8 was expressed in lungs of mice infected with influenza virus and was maximal at day 8 with strong immunoreactivity in epithelial cells lining the airways and in mononuclear cells and declined early in the recovery phase, implying down-regulation by mediator(s) up-regulated during resolution of the infection. IL-10 is implicated in viral persistence. Since S100A8/S100A9 levels are likely to be maintained in conditions where IL-10 is raised, these proteins may contribute to viral persistence in patients infected by some RNA viruses.

Myeloid-related protein (MRP)8/14 (calprotectin) and its subunits MRP8 and MRP14 in plaque-induced early gingival inflammation

BACKGROUND

The inflammatory myeloid-related protein, MRP8/14, also called calprotectin, and its subunits MRP8 and MRP14 have been detected and identified recently in gingival crevicular fluid (GCF). It has been suggested that the type and phase of inflammation can be discriminated on the basis of differences in the expression of calprotectin and its subunits, released during activation and/or death of granulocytes and monocytes. The purpose of this study was to quantify calprotectin and its subunits (MRPs) simultaneously in the GCF during the initial phase of experimentally induced gingivitis, and to examine their inter- and intra-individual variations.

MATERIAL AND METHODS

Fifteen healthy non-smoking subjects, aged 18-30, were involved in this study. An initial hygiene phase (days -11 to 0) was followed by 10 days of undisturbed plaque accumulation. At days -11, -3, 0, 10, 11, clinical parameters were recorded and GCF samples collected with Durapore strips from 12 sites in each subject. Quantitative analyses of total proteins, MRP8/14, MRP14 and MRP8 were performed by ELISA procedures.

RESULTS

During the experimental phase with no oral hygiene (days 0-10), the clinical parameters Plaque Index, Gingival Index (GI) and bleeding on probing increased as expected, confirming that plaque accumulation leads to gingival inflammation. Levels of the MRPs were individually variable. They increased with plaque accumulation in one-half of the subjects, and decreased in the other subjects. The levels of MRP8/14 and MRP14 at subject recruitment (day -11) could predict a significant part of the GI at day 10. Only minute amounts of the subunits MRP8 and MRP14 were detected in comparison with the complex MRP8/14 throughout the experiment. Considerable variations were noted among sites within subjects.

CONCLUSION

The expression of calprotectin in the early phase of experimental gingivitis is variable between subjects, and two groups of subjects can be differentiated according to their response patterns. Clinical parameters at the very first visit (day -11) seemed to be different in the two response groups. The results of the present investigation indicate that the inflammatory response to plaque accumulation depends on the initial status of the subjects, which may not be leveled out by the introduction of perfect oral hygiene. Whether these patterns reflect a different susceptibility to periodontal diseases remains to be determined.

Zinc, Iron, Copper, Selenium, Lactoferrin, and Ferritin in Human Pus

BACKGROUND

Restriction of zinc and iron available for microbial growth in tissues are well-recognized host defense mechanisms. The present studies were performed to characterize some constituents of human pus that may affect these important host defenses.

METHODS

Zinc, iron, copper, calcium, and magnesium in pus were measured using an atomic absorption spectrophotometer; selenium was measured fluorometrically. Ferritin was measured with a fluorometric enzyme immunoassay, and lactoferrin was measured with a radial diffusion assay. The growth of Escherichia coli at 37 degrees C was measured in pus supernate adjusted to pH 5.5 or 7.4, in boiled supernate, or in supernate adjusted with 1.3 mM iron or 0.9 mM zinc singly or together.

RESULTS

Zinc and iron concentrations in pus exceeded normal serum. Calcium and magnesium levels were 2- to 3-fold lower and higher, respectively, than normal serum values. Lactoferrin concentrations of were 880 +/- 48 microg/mL and ferritin levels were 20,726 +/- 2,667 ng/mL. Growth of an E coli strain was inhibited in pus at pH 5.5 but not at pH 7.4, and growth was enhanced by addition of iron or zinc to E coli suspended in pus at pH 6.7.

CONCLUSIONS

To our knowledge, this is the first report of the zinc, iron, copper, selenium, lactoferrin, and ferritin levels of human pus. These studies provide additional insight into host defense mechanisms mediated by the restriction of the bioavailability of zinc and iron in suppurative infection.

Calprotectin (S100A8/S100A9), an inflammatory protein complex from neutrophils with a broad apoptosis-inducing activity

Calprotectin, a complex of two calcium-binding proteins that belong to the S100 protein family, is abundant in the cytosolic fraction of neutrophils. A high level of calprotectin reportedly exists in extracellular fluid during various inflammatory conditions, such as rheumatoid arthritis, cystic fibrosis and abscesses. However, the exact biological role(s) of the factor is now under investigation. We recently observed that neutrophils contain a factor that shows growth-inhibitory and apoptosis-inducing activities against various cell types including tumor cells and normal fibroblasts, and we identified that factor as calprotectin. The findings suggest that calprotectin exerts a regulatory activity in inflammatory processes through its effect on the survival or growth states of cells participating in the inflammatory reaction. It is also possible that calprotectin, at a high concentration, might have a deleterious effect on fibroblasts and influence the recovery of inflammatory tissue. Therefore, the protein factor may be a new drug target to control inflammatory reactions. We found that a few of the Amaryllidaceae alkaloids effectively inhibited the growth-inhibitory and apoptosis-inducing activities of calprotectin. In this article, we focus on the biological functions of calprotectin in extracellular fluids, focusing on its apoptosis-inducing activity.

HIV-1 transcription and virus production are both accentuated by the proinflammatory myeloid-related proteins in human CD4+ T lymphocytes

S100A8, S100A9, and S100A12, collectively known as myeloid-related proteins (MRPs), are highly expressed by the myeloid cell lineage and are found in the extracellular milieu during infections and inflammatory conditions. Recent data showed high levels of MRPs in the serum of HIV type 1 (HIV-1)-infected patients which correlated with disease progression and low CD4(+) counts. Therefore, we set out to investigate the effect of MRPs on HIV-1 replication. We observed a 4- to 5-fold induction of virus production in J1.1, a human T lymphoid cell line latently infected with HIV-1, following treatment with MRPs. Using luciferase-based reporter gene assays, we demonstrated that MRPs induce a dose- and time-dependent activation of the HIV-1 long terminal repeat promoter region that could be blocked by specific anti-MRP polyclonal Abs and by physical denaturation of these proteins. The MRP-mediated induction was acting through the HIV-1 enhancer sequence and was dependent upon NF-kappaB activity. These latter results were also confirmed by EMSA experiments conducted in Jurkat cells and freshly isolated PBMCs. In conclusion, we demonstrate that MRPs induce HIV-1 transcriptional activity and viral replication in infected CD4(+) T-lymphocytes at concentrations similar to those found in the serum of HIV-1-infected patients.

Improved assay for fecal calprotectin

Fecal calprotectin is a marker of inflammatory and neoplastic disease in the lower gastrointestinal tract. A new fecal sample preparation procedure for the measurement of calprotectin has been developed, with higher calprotectin yield and lower contamination risk. Changes in the new method compared to the original [Roseth AG, Fagerhol MK, Aadland E, Schonsby H. Assessment of the neutrophil dominating protein calprotectin in feces. A methodologic study. Scand J Gastroenterol 1992;27(9):793-798] are smaller sample size, higher dilution of the sample, presence of dissociating agents in the extraction solution and procedure performed in closed disposable tubes. The extraction yield was 78% (41-100%) of total calprotectin, giving an overall five-fold increase compared to the original method. Samples with high calprotectin values were increased to a slightly higher degree, than low calprotectin samples, thus improving the separation between high and low calprotectin levels. Median calprotectin level in healthy subjects was 26 microg/g. Pathological samples with pancolitis showed levels up to 30000 microg/g. The mean C.V. (coefficient of variation) in blended feces was lower than that of unblended, suggesting uneven distribution of calprotectin. However, no significant difference between spot measurements was found when five samples from each of 47 stools were measured. Thus measurements of calprotectin in fecal samples were accurate and reproducible. No interference with foods or relevant oral pharmaceuticals or nutraceuticals was found.

Elevated serum macrophage inhibitory factor-related protein (MRP) 8/14 levels in advanced HIV infection and during disease exacerbation

To assess the value of MRP 8, MRP 14, and MRP 8/14 serum concentrations as markers of disease progression in HIV infection and as markers of intercurrent infections.

DESIGN

We measured MRP 8, MRP 14, and MRP 8/14 serum concentrations in 184 HIV-infected patients in various stages of disease with or without disease exacerbation and in 50 healthy control subjects. In clinically stable HIV-infection correlations of MRP levels with stage of HIV disease, CD4 counts, p24 antigen, and beta-2 microglobulin levels were studied. In patients with intercurrent illnesses, correlations of MRP levels with type of disease exacerbation and with CRP were calculated and compared with those found in stable HIV infection.

RESULTS

MRP 8/14 levels were significantly elevated and MRP 8 levels slightly decreased in stable HIV infection compared with HIV-negative controls. The CD4 cell count and MRP 8/14 levels correlated significantly in patients with AIDS. Despite higher values of MRP 8/14 during advanced disease, these were not significant predictors of progression to death. In patients with acute infections, MRP 8/14 levels were significantly elevated, compared with patients with illnesses of noninfectious origin. Levels of MRP 8/14 associated with acute infections were significantly higher in patients with AIDS than in patients during earlier stages of HIV infection.

CONCLUSIONS

Both stable HIV infection and advanced immunedeficiency are associated with an elevation of the MRP 8/14 complex and probably with a decline of MRP 8 serum levels. MRP 8/14 is preserved as a marker of acute infection in immunecompromised patients.

Human immunodeficiency virus type 1 infection of the brain

Direct infection of the central nervous system by human immunodeficiency virus type 1 (HIV-1), the causative agent of AIDS, was not appreciated in the early years of the AIDS epidemic. Neurological complications associated with AIDS were largely attributed to opportunistic infections that arose as a result of the immunocompromised state of the patient and to depression. In 1985, several groups succeeded in isolating HIV-1 directly from brain tissue. Also that year, the viral genome was completely sequenced, and HIV-1 was found to belong to a neurotropic subfamily of retrovirus known as the Lentivirinae. These findings clearly indicated that direct HIV-1 infection of the central nervous system played a role in the development of AIDS-related neurological disease. This review summarizes the clinical manifestations of HIV-1 infection of the central nervous system and the related neuropathology, the tropism of HIV-1 for specific cell types both within and outside of the nervous system, the possible mechanisms by which HIV-1 damages the nervous system, and the current strategies for diagnosis and treatment of HIV-1-associated neuropathology.