Real-time observation of magnetization and magnon dynamics in a two-dimensional topological antiferromagnet MnBi2Te4

Atomically thin van der Waals magnetic materials have not only provided a fertile playground to explore basic physics in the two-dimensional (2D) limit but also created vast opportunities for novel ultrafast functional devices. Here we systematically investigate ultrafast magnetization dynamics and spin wave dynamics in few-layer topological antiferromagnetic MnBi2Te4 crystals as a function of layer number, temperature, and magnetic field. We find laser-induced (de)magnetization processes can be used to accurately track the distinct magnetic states in different magnetic field regimes, including showing clear odd-even layer number effects. In addition, strongly field-dependent AFM magnon modes with tens of gigahertz frequencies are optically generated and directly observed in the time domain. Remarkably, we find that magnetization and magnon dynamics can be observed in not only the time-resolved magneto-optical Kerr effect but also the time resolved reflectivity, indicating strong correlation between the magnetic state and electronic structure. These measurements present the first comprehensive overview of ultrafast spin dynamics in this novel 2D antiferromagnet, paving the way for potential applications in 2D antiferromagnetic spintronics and magnonics as well as further studies of ultrafast control of both magnetization and topological quantum states.

Electric-field control of reversible electronic and magnetic transitions in two-dimensional oxide monolayer magnets

Atomically thin oxide magnetic materials are highly desirable due to the promising potential to integrate two-dimensional (2D) magnets into next-generation spintronics. Therefore, 2D oxide magnetism is expected to be effectively tuned by the magnetic and electrical fields, holding prospective for future low-dissipation electronic devices. However, the electric-field control of 2D oxide monolayer magnetism has rarely been reported. Here, we present the realization of 2D monolayer magnetism in oxide (SrRuO3)1/(SrTiO3)N (N = 1, 3) superlattices that shows an efficient and reversible phase transition through electric-field controlled proton (H+) evolution. By using ionic liquid gating to modulate the proton concentration in (SrRuO3)1/(SrTiO3)1 superlattice, an electric-field induced metal-insulator transition was observed, along with gradually suppressed magnetic ordering and modulated magnetic anisotropy. Theoretical analysis reveals that proton intercalation plays a crucial role in both electronic and magnetic phase transitions. Strikingly, SrTiO3 layers can act as a proton sieve, which have a significant influence on proton evolution. Our work stimulates the tuning functionality of 2D oxide monolayer magnetism by voltage control, providing potential for future energy-efficient electronics.

High-Resolution Transcriptomic Landscape of the Human Submandibular Gland

Saliva-secreting and transporting cells are part of the complex cellular milieu of the human salivary gland, where they play important roles in normal glandular physiology and diseased states. However, comprehensive molecular characterization, particularly at single-cell resolution, is still incomplete, in part due to difficulty in procuring normal human tissues. Here, we perform an in-depth analysis of male and female adult human submandibular gland (SMG) samples by bulk RNA sequencing (RNA-seq) and examine the molecular underpinnings of the heterogeneous cell populations by single-cell (sc) RNA-seq. Our results from scRNA-seq highlight the remarkable diversity of clusters of epithelial and nonepithelial cells that reside in the SMG that is also faithfully recapitulated by deconvolution of the bulk-RNA data sets. Our analyses reveal complex transcriptomic heterogeneity within both the ductal and acinar subpopulations and identify atypical SMG cell types, such as mucoacinar cells that are unique to humans and ionocytes that have been recently described in the mouse. We use CellChat to explore ligand-receptor interactome predictions that likely mediate crucial cell-cell communications between the various cell clusters. Finally, we apply a trajectory inference method to investigate specific cellular branching points and topology that offers insights into the dynamic and complex differentiation process of the adult SMG. The data sets and the analyses herein comprise an extensive wealth of high-resolution information and a valuable resource for a deeper mechanistic understanding of human SMG biology and pathophysiology.

Genetic Study of Elf5 and Ehf in the Mouse Salivary Gland

Salivary gland (SG) development, maturation, and homeostasis require coordinated roles of transcription factors (TFs) that dictate specific cell identities and fate. The ETS family of proteins are important transcriptional drivers of diverse cell lineages, tissue development, and differentiation programs and hence are also likely to play an important role in the SG. Here we have leveraged genomic and epigenomic data of the SG to examine the expression profile of ETS genes and identified 2 closely related paralogs, Elf5 and Ehf, that are highly expressed in distinct epithelial subpopulations. By using a well-defined mouse knockout model of Elf5, we show that Elf5, despite its enriched expression in the acinar cells, is functionally dispensable for maintaining the homeostatic state of the adult SG epithelium. The lack of a discernible phenotype of the Elf5-null SG might be due to possible functional redundancy with Ehf or other ETS factors. To probe this possibility and to examine the specific consequences of Ehf loss in the SG, we used CRISPR-Cas9 to generate mice in which the DNA-binding ETS domain of Ehf is disrupted due to an insertion mutation. We demonstrate that the Ehf mutant (EhfMut) mice exhibit a distinct cellular phenotype with decreased granular convoluted tubules that are accompanied by an increased accumulation of the intercalated Sox9-positive ductal cell population. Interestingly, the ductal phenotype of the EhfMut animals is highly pronounced in males, reaffirming the established sexual dimorphism of the SG that exists in rodents. Our results show that unlike Elf5, Ehf plays a nonredundant role in directing ductal cell differentiation of the SG and highlights the phenotypic subtlety in mutant mice of closely related TFs and the importance of careful consideration of cell type-specific studies.

A Global Vista of the Epigenomic State of the Mouse Submandibular Gland

The parotid, submandibular, and sublingual glands represent a trio of oral secretory glands whose primary function is to produce saliva, facilitate digestion of food, provide protection against microbes, and maintain oral health. While recent studies have begun to shed light on the global gene expression patterns and profiles of salivary glands, particularly those of mice, relatively little is known about the location and identity of transcriptional control elements. Here we have established the epigenomic landscape of the mouse submandibular salivary gland (SMG) by performing chromatin immunoprecipitation sequencing experiments for 4 key histone marks. Our analysis of the comprehensive SMG data sets and comparisons with those from other adult organs have identified critical enhancers and super-enhancers of the mouse SMG. By further integrating these findings with complementary RNA-sequencing based gene expression data, we have unearthed a number of molecular regulators such as members of the Fox family of transcription factors that are enriched and likely to be functionally relevant for SMG biology. Overall, our studies provide a powerful atlas of cis-regulatory elements that can be leveraged for better understanding the transcriptional control mechanisms of the mouse SMG, discovery of novel genetic switches, and modulating tissue-specific gene expression in a targeted fashion.

Erythropoietin Ameliorates Lung Injury by Accelerating Pulmonary Endothelium Cell Proliferation via Janus Kinase-Signal Transducer and Activator of Transcription 3 Pathway After Kidney Ischemia and Reperfusion Injury

BACKGROUND/AIMS

Kidney ischemia and reperfusion injury could cause microvascular barrier dysfunction, lung inflammatory cascades activation, and programmed cell death of pulmonary endothelium, leading to acute lung injury. Our study aimed at determining whether erythropoietin (EPO) can ameliorate lung dysfunction following renal ischemia and reperfusion (IR) injury and explored the underlying mechanisms.

METHODS

In vivo, C57BL/6 mice received EPO (6000 U/kg) before right renal vascular pedicles clamping for 30 minutes, followed by 24 hours of reperfusion. The lung histopathologic changes and inflammatory cytokines expression were assessed. In vitro, cultured human umbilical vein endothelial cells were treated with EPO, and apoptosis rate, proliferation capacity, and phosphorylation status of the Janus kinase-signal transducer and activator of transcription 3 (Jak-STAT3) pathway were measured respectively in the presence or absence of lipopolysaccharide stimulation.

RESULTS

In vivo, EPO remarkably attenuated pulmonary interstitial and alveolar epithelial edema caused by renal IR injury. In vitro, the proliferation capacity of human umbilical vein endothelial cells was significantly increased under EPO stimulation, which correlated with changes in Jak-STAT3 signaling.

CONCLUSION

Our data indicated that EPO is able to ameliorate acute lung tissue damage induced by renal IR, and at least in part, via the Jak-STAT3 pathway.

[The role of Tim-3 mRNA in acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation]

目的

探讨T细胞免疫球蛋白黏蛋白结构域分子3(Tim-3）mRNA表达在异基因造血干细胞移植（allo-HSCT）后急性移植物抗宿主病（aGVHD）中的作用。

方法

回顾性分析100例allo-HSCT患者，根据患者aGVHD状态[0（未发生）~Ⅰ度aGVHD组、Ⅱ~Ⅳ度aGVHD治疗前组、Ⅱ~Ⅳ度aGVHD治疗好转组]及移植后不同阶段（+14~＋30 d、+31~＋60 d、+61~＋100 d）比较各组外周血单个核细胞Tim-3 mRNA及血浆IFN-γ、IL-2水平。

结果

0~Ⅰ度aGVHD患者＋31~＋60 d Tim-3 mRNA相对定量（7.24±2.79）明显高于＋14~＋30 d(4.60±1.66）及＋61~＋100 d(3.86±1.36）（P值均<0.05）；+14~＋30 d、+31~＋60 d、+61~＋100 d Ⅱ~Ⅳ度aGVHD治疗前组的Tim-3 mRNA水平分别为9.54±3.05、10.14± 3.28、12.82±4.20，+14~+30 d、+61~＋100 d，均高于0~Ⅰ度aGVHD组及治疗好转组；+31~＋60 d Ⅱ~Ⅳ度aGVHD治疗前组明显高于治疗好转组（2.49±0.89），与0~Ⅰ度aGVHD组（7.24±2.79）相比差异无统计学意义；Ⅱ~Ⅳ度aGVHD组中Tim-3 mRNA水平在不同aGVHD程度、不同脏器之间比较差异均无统计学意义（P>0.05）。Ⅱ~Ⅳ度aGVHD治疗前组血浆IFN-γ、IL-2水平明显高于其他各组，治疗好转组血浆IFN-γ、IL-2水平与0~Ⅰ度aGVHD组比较差异无统计学意义。

结论

Tim-3在aGVHD的发生过程中发挥着重要作用。

Strong impact of acute kidney injury on survival after liver transplantation

Acute kidney injury (AKI) is a major complication in orthotopic liver transplantation (OLT). In an evaluation of Acute Kidney Injury Network (AKIN) criteria in liver transplanted patients, we retrospectively analyzed the usefulness of these criteria to predict survival of 193 consecutive patients at a single center who underwent primary OLT for clinical parameters and peak AKI. Postoperative AKI according to AKIN occurred in 60.1% of the patients, namely, stages 1, 2, and 3 in 30%, 13% and 17.1% respectively. Using multivariate logistic regression, AKIN stage 1 and 2 AKI were independently associated with the pre-OLT Model for End-Stage Liver Disease (MELD) score and age, while stage 3 AKI was independently associated with MELD and Acute Physiology and Chronic Health Evaluation (APACHE) II scores. The 28-day and 1-year mortality post-OLT of AKI patients were 15.5% and 25.9% respectively compared with 0% and 3.9% among non-AKI patients (P < .05 for both). The survival rates of non-AKI and stages 1, 2, and 3 AKI subjects were 96%, 85.5%, 84%, and 45.3%, respectively. Cox regression analysis showed independent risk factors for mortality during the first year after transplantation to include post-OLT AKI (12.1; P < .05), post-OLT infection (HR 4.7; P < .01), pre-OLT hypertension (HR 4.4; P < .01) hazard ratio [HR] and post-OLT APACHE II ≥10 (HR 3.6; P < .05). We concluded that AKI as defined by the AKIN criteria is a major complication of OLT linked to a poor outcomes. It remains to be evaluated whether aggressive perioperative therapy to prevent AKI can improve survival among OLT patients.

Preparation of Co2+/ZSM5 Catalysts by Solid-State Reaction: Influence of the Precursor on Cobalt Speciation

Co2+/ZSM5 catalysts (Co/Al = 1, overstoichiometric ratio) have been prepared by solid-state reaction at 500 °C in argon from H-ZSM5 and four Co(II) precursors: formate, nitrate, chloride and acetate. Co3O4 particles supported by the zeolite grains are the only cobalt-containing phases detected when formate is used. When cobalt nitrate is the precursor, Co3O4 particles appear to be independent from the grains. A fraction of cobalt has nevertheless migrated into the zeolite; this is linked with [Co(H2O)6](NO3)2 low melting point and wetting of the zeolite grains by the molten salt at the beginning of the thermal treatment. Catalysts prepared from cobalt chloride contain both nanometric Co3O4 particles on the support grains and cobalt ions inside the zeolitic channels. Ion exchange is possible, at least partly, due to the fact that unlike nitrate and formate, cobalt chloride has not decomposed before reaching the temperature at which the exchange process is activated. This process is chemically driven by the release of HCl in the gas phase. Finally, the major phase detected when cobalt acetate is the precursor is a poorly organized cobalt phyllosilicate surrounding zeolite grains. Acetate ions attack the zeolitic framework from outside during the solid-state reaction; cobalt ions are inserted in the silicate matrix and progressively migrate deeper in the grains upon thermal activation.

Incorporation of Co(II) in dealuminated BEA zeolite at lattice tetrahedral sites evidenced by XRD, FTIR, diffuse reflectance UV-Vis, EPR, and TPR

A CoSiBEA zeolite is prepared by a two-step postsynthesis method that consists of first creating vacant T-sites with associated silanol groups by dealumination of TEABEA zeolite with nitric acid and then impregnating the resulting SiBEA zeolite with an aqueous solution of Co(NO3)2. The incorporation of Co into lattice sites of SiBEA is evidenced by XRD. The consumption of OH groups is monitored by FTIR. The presence of Co in its II oxidation state and in tetrahedral coordination is evidenced by diffuse reflectance UV-vis and EPR spectroscopy. The very high reduction temperature (1120 K) of cobalt in CoSiBEA zeolite determined by TPR confirms that Co interacts strongly with the zeolite support, consistent with lattice tetrahedral (T(d)) coordination.

Expression of EGFR, HER-2 and p53 predictive of prognosis in muscle-invasive bladder cancer

15637

Background: The significance of over expression of Erb-1 (epidermal growth factor receptor/ EGFR) and Erb-2 (Her-2) has been reported in various tumors. The aim of this study was to investigate the correlation of the expression of EGFR, Her-2 and p53 with relapse free survival (RFS) and over all survival (OS) in patients with muscle invasive bladder cancer Methods: All patients with muscle invasive bladder cancer diagnosed at our institution between1993and 2004 were considered for the study. Immunohistochemical staining for EGFR, Her2 and p53 performed on formalin-fixed paraffin-embedded archival tissue was evaluated as positive or negative without knowledge of clinical outcome. Survival data determined by reviewing patients medical records were correlated with the staining results. Results: Of the 46 patients who qualified for the study, 40 had slides interpretable for Her 2 and p 53 staining and 38 had slides interpretable for EGFR staining. 35 of 38 were EGFR +ve, 22/40 were Her-2 +ve and 12/40 were p53+ve. The median age of the 46 patients was 67.5 years with a male/female ratio of 60% and 40%. 83% had clinical Stage 2; of those 42%, 23%, and 35% had pathological stages T2, T3 and T4 respectively. Six of 46 (13%), received adjuvant therapy. Tumor histology was pure transitional carcinoma in 56%, or with other components (squamous or adenocarcinoma) in 44%. Median follow-up was 48.8 months for RFS and 44.9 months for OS. Patients with positive EGFR had a median RFS of 34.8 months and median OS of 59.8 months. In patients with negative EGFR, median RFS and OS were not yet reached. Her 2 positive patients had median RFS of 19.2 months compared to 63.8 months in Her-2 negative patients. Her-2 negative patients had median OS of 59.7 months while median was not reached in Her 2 positive patients. Conclusions: While the differences are not statistically significant, the trends observed warrant prospective investigation of the prognostic significance of these markers in a larger population of muscle invasive bladder cancer patients.

No significant financial relationships to disclose.

Reduction of QM protein expression correlates with tumor grade in prostatic adenocarcinoma

The QM protein is a transcription cofactor inhibiting the activity of AP-1 transcription factors and is also a ribosomal protein participating in protein synthesis. While protein synthesis is known to be increased in many cancers, inhibition of AP-1 activity presumably suppresses development and growth of sex-hormone-regulated tumor cells. The present study is the first report on immunohistochemical data of QM in human prostatic tissues. Paraffin sections of human prostate cancer samples were immunohistochemically stained for QM. The staining scores were analyzed with the clinicopathologic data of the patients. QM protein expression was found in all normal prostate glands adjacent to prostate cancer and in various intraepithelial neoplasia (PIN). In prostate cancer, the staining intensity and stained areas were decreased, compared to the normal glands and PIN lesions; in high-grade tumors only some patches of tumor cells showed positivity. Intense (3+) staining was mostly observed in the Gleason grade three areas (48%) compared to grade 4 and 5 areas (22%), although both low and high-grade tumors showed similar percentages of weakly stained areas. Moreover, staining in prostatic adenocarcinoma was often topographically patchy and varied from negative or weak (1+) to intense (3+). There was an inverse correlation from normal to low-grade tumors and then to high-grade tumors. However, in high-grade tumors, the positive areas were mostly confined to peripheral aspects of tumors and were particularly strong in foci of perineural invasion. This preliminary study suggests that decreased QM expression may be associated with early development of prostate cancer, but later a high level of QM may facilitate progression of the tumors to a more aggressive phenotype.

Influence of V Content on the Nature and Strength of Acidic Sites in VSiβ Zeolite Evidenced by IR Spectroscopy

VSibeta zeolites prepared by a two-step postsynthesis method have been characterized by physical techniques. A significant reduction of intensity of the IR band near 3515 cm(-1) after impregnation of dealuminated beta zeolite with aqueous NH4VO3 indicates that V ions specifically react with hydrogen-bonded SiO-H groups of vacant T sites. IR bands at 3618 and 3645 cm(-1) are assigned to SiO-H groups interacting with V and to VO-H groups, respectively. In VSibeta, diffuse reflectance UV-visible data show that below 1.9 wt % V is present as lattice tetrahedral species and at higher content as extra-lattice octahedral species (mononuclear and polynuclear). VSibeta samples are EPR-silent at 298 or 77 K suggesting that there are no paramagnetic VIV ions. IR studies show that V-OH groups are less acidic than Si-OH-Al groups of parent HAlbeta zeolite. IR results of CO adsorption evidence three kinds of Lewis acidic sites, related to lattice mononuclear and extra-lattice mononuclear and polynuclear V species. Quantitative IR studies of ammonia and pyridine adsorption reveal that only about half of V introduced into zeolite is able to form either Brønsted or Lewis acidic sites.

Outcomes of a disease-management program for patients with recent osteoporotic fracture

INTRODUCTION

The purpose of this study was to evaluate outcomes of a disease-management program designed to increase rates of bone-mineral-density (BMD) testing and initiation of osteoporosis medication among patients with a recent osteoporotic fracture.

STUDY DESIGN

We identified 744 consecutive patients aged>or=55 years who were seen at either of 2 of 14 Kaiser Permanente medical facilities in Northern California (KPNC) after sustaining a fracture of the hip, spine, wrist, or humerus between April 2003 and May 2004. These patients were invited to participate in a study of the Fragile Fracture Management Program, whose protocol used fracture-risk assessment tools to determine treatment recommendations. Postfracture care of study participants was compared with usual postfracture care received by osteoporotic-fracture patients at 12 other KPNC facilities.

RESULTS

Of the 744 patients who were invited to participate in the study, 293 (39%) agreed to participate, and 169 (23%) completed the evaluation. Of these 169 patients (127 women, 42 men), 65 (51%) of the women and 7 (17%) of the men qualified for drug treatment; of these 72 patients, 6 (86%) of the men and 41 (63%) of the women accepted the offered treatment. At the two study locations, rates of care (BMD testing or prescribing osteoporosis medication) were about twice as high as rates of usual postfracture care observed at 12 other medical centers in KPNC.

CONCLUSIONS

Compared with patients who received usual care for osteoporotic fracture, patients participating in a postfracture disease management program had substantially higher rates of medical attention given for osteoporosis; however, the overall yield of the program was low. This low uptake rate was related to factors not previously appreciated: many patients refused participation in the program; a high proportion of younger women-and men of all ages-did not qualify for treatment; and treatment was refused by one in three study-qualified women and by one in seven study-qualified men. Additional efforts are needed to overcome patient barriers to improved osteoporosis evaluation, treatment and participation in postfracture programs.

Role of eicosanoids in prostate cancer progression

Metabolism of arachidonic acid through cyclooxygenase, lipoxygenase, or P450 epoxygenase pathways leads to the formation of various bioactive eicosanoids. In this review, we discuss alterations in expression pattern of eicosanoid-generating enzymes found during prostate tumor progression and expound upon their involvement in tumor cell proliferation, apoptosis, motility, and tumor angiogenesis. The expression of cyclooxygenase-2, 12-lipoxygenase, and 15-lipoxygenase-1 are up-regulated during prostate cancer progression. It has been demonstrated that inhibitors of cyclooxygenase-2, 5-lipoxygenase and 12-lipoxygenase cause tumor cell apoptosis, reduce tumor cell motility and invasiveness, or decrease tumor angiogenesis and growth. The eicosanoid product of 12-lipoxygenase, 12(S)-hydroeicosatetraenoic acid, is found to activate Erkl/2 kinases in LNCaP cells and PKCalpha in rat prostate AT2.1 tumor cells. Overexpression of 12-lipoxygenase and 15-lipoxygenase-1 in prostate cancer cells stimulate prostate tumor angiogenesis and growth, suggesting a facilitative role for 12-lipoxygenase and 15-lipoxygenase-1 in prostate tumor progression. The expression of 15-lipoxygenase-2 is found frequently to be lost during the initiation and progression of prostate tumors. 15(S)-hydroxyeicosatetraenoic acid, the product of 15-lipoxygenase-2, inhibits proliferation and causes apoptosis in human prostate cancer cells, suggesting an inhibitory role for 15-lipoxygenase-2 in prostate tumor progression. The regulation of prostate cancer progression by eicosanoids, in either positive or negative ways, provides an exciting possibility for management of this disease.

Interplay of anions and ligands on the nature and reducibility of NiOx/Al2O3 catalysts prepared by impregnation

When NiOx/Al2O3 catalysts (Ni wt% = 1.5) are prepared by impregnation using [NiL2(H2O)2]X2 as precursors (L = diamine, X = Cl- or NO3-), a supported oxidic or metallic phase can be selectively obtained after thermal treatment in N2 depending on the nature of the ligand and counter anion; the oxidic phase can be reduced at a lower temperature than the classical nickel aluminate phase obtained from [Ni-(H2O)6](NO3)2.

Ciliated epithelia in the urethra: case report and literature review

The presence of ciliated epithelial cells in the urethra has not been well recognized. Only two reports in the literature, both of which used scanning microscopy studies, have described this phenomenon. In this report, we illustrate the presence of scattered, ciliated epithelial cells in penile urethral biopsy specimens from a 38-year-old man with a history of bladder calculi and hematuria, by both light and transmission electron microscopy studies. The cilia in the urethra showed typical light microscopic and ultrastructural features of those seen in other organs. These ciliated cells are present in association with urothelial papilloma, condyloma acuminatum and acute inflammation of the urethra. These findings suggest that ciliated cells in the penile 0 urethra might be a consequence of metaplastic change of the urothelium, secondary to local stimulation or irritation.

Ovarian mixed-epithelial carcinomas with a microcystic pattern and signet-ring cells

Primary ovarian carcinomas with unusual histologic patterns can be difficult to differentiate from metastases. In this study, we reviewed 15 cases of mixed-epithelial carcinoma (12 serous, 1 serous and endometrioid, 1 endometrioid, 1 undifferentiated) with a predominant microcystic pattern and signet-ring cells. The patients' ages ranged from 31 to 78 (mean 58) years. The microcystic component in 11 patients had features of high-grade carcinoma and in 4 patients had features of low-grade carcinoma associated with areas of borderline tumor. The tumors in all 15 patients showed a predominant microcystic growth pattern composed of small cysts that were variable in size and shape. Signet-ring cells were also present in all cases (diffusely in nine cases, focally in six cases) within the neoplastic epithelial proliferation. Mucin was present in the lumina of some of the microcysts and in the cytoplasm of most of the signet-ring cells. A microcystic pattern and mucin-containing signet-ring cells can be seen as small foci or as a predominant component in primary epithelial nonmucinous ovarian carcinomas. It is important for pathologists to recognize these unusual findings in ovarian neoplasms, because they may produce a confusing apperance, even potentially suggesting a metastasis.

Mononuclear phagocyte differentiation, activation, and viral infection regulate matrix metalloproteinase expression: implications for human immunodeficiency virus type 1-associated dementia

The pathogenesis of human immunodeficiency virus type 1 (HIV-1)-associated dementia (HAD) is mediated mainly by mononuclear phagocyte (MP) secretory products and their interactions with neural cells. Viral infection and MP immune activation may affect leukocyte entry into the brain. One factor that influences central nervous system (CNS) monocyte migration is matrix metalloproteinases (MMPs). In the CNS, MMPs are synthesized by resident glial cells and affect the integrity of the neuropil extracellular matrix (ECM). To ascertain how MMPs influence HAD pathogenesis, we studied their secretion following MP differentiation, viral infection, and cellular activation. HIV-1-infected and/or immune-activated monocyte-derived macrophages (MDM) and human fetal microglia were examined for production of MMP-1, -2, -3, and -9. MMP expression increased significantly with MP differentiation. Microglia secreted high levels of MMPs de novo that were further elevated following CD40 ligand-mediated cell activation. Surprisingly, HIV-1 infection of MDM led to the down-regulation of MMP-9. In encephalitic brain tissue, MMPs were expressed within perivascular and parenchymal MP, multinucleated giant cells, and microglial nodules. These data suggest that MMP production in MP is dependent on cell type, differentiation, activation, and/or viral infection. Regulation of MMP expression by these factors may contribute to neuropil ECM degradation and leukocyte migration during HAD.