Sialic acid plays a pivotal role in licensing Citrobacter rodentium's transition from the intestinal lumen to a mucosal adherent niche.

Enteric bacterial pathogens pose significant threats to human health; however, the mechanisms by which they infect the mammalian gut in the face of daunting host defenses and an established microbiota remain poorly defined. For the attaching and effacing (A/E) bacterial family member and murine pathogen Citrobacter rodentium, its virulence strategy likely involves metabolic adaptation to the host's intestinal luminal environment, as a necessary precursor to reach and infect the mucosal surface. Suspecting this adaptation involved the intestinal mucus layer, we found that C. rodentium was able to catabolize sialic acid, a monosaccharide derived from mucins, and utilize it as its sole carbon source for growth. Moreover, C. rodentium also sensed and displayed chemotactic activity toward sialic acid. These activities were abolished when the nanT gene, encoding a sialic acid transporter, was deleted (ΔnanT). Correspondingly, the ΔnanT C. rodentium strain was significantly impaired in its ability to colonize the murine intestine. Intriguingly, sialic acid was also found to induce the secretion of two autotransporter proteins, Pic and EspC, which possess mucinolytic and host-adherent properties. As a result, sialic acid enhanced the ability of C. rodentium to degrade intestinal mucus (through Pic), as well as to adhere to intestinal epithelial cells (through EspC). We thus demonstrate that sialic acid, a monosaccharide constituent of the intestinal mucus layer, functions as an important nutrient and a key signal for an A/E bacterial pathogen to escape the colonic lumen and directly infect its host's intestinal mucosa.

Fatal Fusarium solani species complex infections in elasmobranchs: the first case report for black spotted stingray (Taeniura melanopsila) and a literature review.

Fusarium species are environmental saprophytic fungi. Among the many Fusarium species, members of the Fusarium solani species complex (FSSC) are the most prevalent and virulent in causing human and animal infections. In this study, we describe the first case of fatal FSSC infection in a black spotted stingray and three concomitant infections in scalloped hammerhead sharks. In the stingray, cutaneous lesions were characterised by ulcers and haemorrhage of the ventral pectoral fin, or 'ray', especially around the head; while cutaneous lesions in the sharks were characterised by ulcers, haemorrhage, as well as white and purulent exudates at the cephalic canals of the cephalofoil and lateral line. Histological sections of the cutaneous lesions revealed slender (1-4 µm in diameter), branching, septate fungal hyphae. Internal transcribed spacer region and 28S nrDNA sequencing of the fungal isolates from the fish showed two isolates were F. keratoplasticum (FSSC 2) and the other two were FSSC 12. Environmental investigation revealed the FSSC strains isolated from water and biofilms in tanks that housed the elasmobranchs were also F. keratoplasticum and FSSC 12. Fusarium is associated with major infections in elasmobranchs and FSSC 12 is an emerging cause of infections in marine animals. DNA sequencing is so far the most reliable method for accurate identification of Fusarium species.

Changes in dietary fiber intake in mice reveal associations between colonic mucin O-glycosylation and specific gut bacteria.

The colonic mucus layer, comprised of highly O-glycosylated mucins, is vital to mediating host-gut microbiota interactions, yet the impact of dietary changes on colonic mucin O-glycosylation and its associations with the gut microbiota remains unexplored. Here, we used an array of omics techniques including glycomics to examine the effect of dietary fiber consumption on the gut microbiota, colonic mucin O-glycosylation and host physiology of high-fat diet-fed C57BL/6J mice. The high-fat diet group had significantly impaired glucose tolerance and altered liver proteome, gut microbiota composition, and short-chain fatty acid production compared to normal chow diet group. While dietary fiber inclusion did not reverse all high fat-induced modifications, it resulted in specific changes, including an increase in the relative abundance of bacterial families with known fiber digesters and a higher propionate concentration. Conversely, colonic mucin O-glycosylation remained similar between the normal chow and high-fat diet groups, while dietary fiber intervention resulted in major alterations in O-glycosylation. Correlation network analysis revealed previously undescribed associations between specific bacteria and mucin glycan structures. For example, the relative abundance of the bacterium Parabacteroides distasonis positively correlated with glycan structures containing one terminal fucose and correlated negatively with glycans containing two terminal fucose residues or with both an N-acetylneuraminic acid and a sulfate residue. This is the first comprehensive report of the impact of dietary fiber on the colonic mucin O-glycosylation and associations of these mucosal glycans with specific gut bacteria.

Fiber Supplements Derived From Sugarcane Stem, Wheat Dextrin and Psyllium Husk Have Different In Vitro Effects on the Human Gut Microbiota.

There is growing public interest in the use of fiber supplements as a way of increasing dietary fiber intake and potentially improving the gut microbiota composition and digestive health. However, currently there is limited research into the effects of commercially available fiber supplements on the gut microbiota. Here we used an in vitro human digestive and gut microbiota model system to investigate the effect of three commercial fiber products; NutriKane™, Benefiber® and Psyllium husk (Macro) on the adult gut microbiota. The 16S rRNA gene amplicon sequencing results showed dramatic fiber-dependent changes in the gut microbiota structure and composition. Specific bacterial OTUs within the families Bacteroidaceae, Porphyromonadaceae, Ruminococcaceae, Lachnospiraceae, and Bifidobacteriaceae showed an increase in the relative abundances in the presence of one or more fiber product(s), while Enterobacteriaceae and Pseudomonadaceae showed a reduction in the relative abundances upon addition of all fiber treatments compared to the no added fiber control. Fiber-specific increases in SCFA concentrations showed correlation with the relative abundance of potential SCFA-producing gut bacteria. The chemical composition, antioxidant potential and polyphenolic content profiles of each fiber product were determined and found to be highly variable. Observed product-specific variations could be linked to differences in the chemical composition of the fiber products. The general nature of the fiber-dependent impact was relatively consistent across the individuals, which may demonstrate the potential of the products to alter the gut microbiota in a similar, and predictable direction, despite variability in the starting composition of the individual gut microbiota.

Dog mastocytoma cells secrete a 92-kD gelatinase activated extracellularly by mast cell chymase.

Gelatinolytic metalloproteinases implicated in connective tissue remodeling and tumor invasion are secreted from several types of cells in the form of inactive zymogens. In this report, characterization of gelatinase activity secreted by the BR line of dog mastocytoma cells reveals a phorbol-inducible, approximately 92-kD, Ca2+ - and Zn2+ -dependent proenzyme cleaved over time to smaller, active forms. Incubation of cells with the general serine protease inhibitor, PMSF, prevented proenzyme cleavage and permitted its purification free of activation products. The NH2-terminal 13 amino acids of the purified mastocytoma progelatinase are 50-67% identical to those of human, mouse, and rabbit 92-kD progelatinase (gelatinase B; matrix metalloproteinase-9). Degranulation of mastocytoma cells using ionophore A23187 greatly accelerated proenzyme cleavage, suggesting that a serine protease present in secretory granules hydrolyzed the progelatinase to active fragments. To identify the activating protease, cells were coincubated with ionophore and a panel of selective serine protease inhibitors. Soybean trypsin inhibitor and succinyl-L-Ala-Ala-Pro-Phe-chloromethylketone, which inhibit mast cell chymase, prevented progelatinase activation. Inhibitors of tryptase and dog mast cell protease (dMCP)-3, i.e., aprotinin or bis(5-amidino-2-benzimidazolyl) methane (BABIM), did not. In further experiments using highly purified enzymes, mastocytoma cell chymase activated 92-kD progelatinase in the absence of other enzymes or cofactors; tryptase and dMCP-3, however, had no effect. These data demonstrate that dog mastocytoma cells secrete a metalloproteinase related to progelatinase B that is directly activated outside of the cell by exocytosed chymase, and provide the first demonstration of a cell that activates a matrix metalloproteinase it secretes by cosecreting an activating enzyme. In mastocytomas, this pathway may facilitate tumor invasion of surrounding tissues, and in normal mast cells, it could play a role in tissue remodeling and repair.

Cereal products derived from wheat, sorghum, rice and oats alter the infant gut microbiota in vitro.

The introduction of different nutrient and energy sources during weaning leads to significant changes in the infant gut microbiota. We used an in vitro infant digestive and gut microbiota model system to investigate the effect of four commercially available cereal products based on either wheat, sorghum, rice or oats, on the gut microbiota of six infants. Our results indicated cereal additions induced numerous changes in the gut microbiota composition. The relative abundance of bacterial families associated with fibre degradation, Bacteroidaceae, Bifidobacteriaceae, Lactobacillaceae, Prevotellaceae, Ruminococcaceae and Veillonellaceae increased, whilst the abundance of Enterobacteriaceae decreased with cereal additions. Corresponding changes in the production of SCFAs showed higher concentrations of acetate following all cereal additions, whilst, propionate and butyrate varied between specific cereal additions. These cereal-specific variations in the concentrations of SCFAs showed a moderate correlation with the relative abundance of potential SCFA-producing bacterial families. Overall, our results demonstrated clear shifts in the abundance of bacterial groups associated with weaning and an increase in the production of SCFAs following cereal additions.

Angiotensin II generation by mast cell alpha- and beta-chymases.

Mast cells secrete alpha- and beta-chymases. Primate alpha-chymases generate angiotensin (AT) II by selectively hydrolyzing AT I's Phe(8)-His(9) bond. This is distinct from the AT converting enzyme (ACE) pathway. In humans, alpha-chymase is the major non-ACE AT II-generator. In rats, beta-chymases destroy AT II by cleaving at Tyr(4)-Ile(5). Past studies predicted that AT II production versus destruction discriminates alpha- from beta-chymases and that Lys(40) in the substrate-binding pocket determines alpha-chymase Phe(8) specificity. This study examines these hypotheses by comparing AT II generation by human alpha-chymase (containing Lys(40)), dog alpha-chymase (lacking Lys(40)), and mouse mMCP-4 (a beta-chymase lacking Lys(40); orthologous to AT II-destroying rat chymase rMCP-1). The results suggest that human and dog alpha-chymase generate AT II exclusively and with comparable efficiency, although dog chymase contains Ala(40) rather than Lys(40). Furthermore, AT II is the major product generated by degranulation supernatants from cultured dog mast cells, which release tryptases and dipeptidylpeptidase as well as alpha-chymase. In contrast to rMCP-1, mMCP-4 beta-chymase readily generates AT II. Although there is competing AT I hydrolysis at Tyr(4), mMCP-4 does not destroy AT II quickly once it is formed. We conclude (1) that chymases are the dominant AT I-hydrolyzing mast cell peptidases, (2) that residues other than Lys(40) are key determinants of alpha-chymase AT I Phe(8) specificity, (3) that beta-chymases can generate AT II, and (4) that alpha- and beta-chymases are not strictly dichotomous regarding AT I cleavage specificity.

Porcine origin of human sputum trypsin?

From purulent cystic fibrosis (CF) sputum, previous investigators partially purified a trypsinlike protease. A similar purified enzyme is available commercially as "human sputum trypsin." To explore the nature and origin of this preparation, we purified and NH2 terminally sequenced its major protein component. The resulting sequence, Ile-Val-Gly-Gly-Tyr-Thr-(Cys)-Ala-Ala-Asn-Ser-Val/Ile-Pro-Tyr-Gln-Val -Ser-Leu-Asn-Ser, differs from known human proteins but is identical to porcine trypsin, including the Val/Ile polymorphism at residue 12. Specific activity and electrophoretic and inhibition profiles and immunoreactivity of sputum and porcine pancreatic trypsin are nearly identical. Because porcine trypsin is a major ingredient of digestive enzyme supplements taken by CF patients with pancreatic dysfunction, we propose that one or more lots of human sputum trypsin derive from enzyme supplements and are of porcine origin. The path by which trypsin ends up in sputum is unknown. Because sputum trypsin is active but susceptible to inactivation by plasma alpha1-proteinase inhibitor, it is unlikely to derive from trypsin absorbed into the bloodstream. However, it may originate from tracheally aspirated stomach contents or from digestive supplement-contaminated saliva mixed with expectorated sputum. The imbalance between proteases and antiproteases in CF bronchial secretions allows trypsin to remain active despite sensitivity to serpins and secretory leukocyte proteinase inhibitor. Furthermore, because sputum trypsin activates human progelatinase B, it may be responsible in part for the reported presence of activated matrix metalloproteinases in CF sputum.

Dog mast cell chymase: molecular cloning and characterization.

We cloned and characterized a cDNA coding for the complete amino acid sequence of dog mast cell chymase. The cDNA was identified by screening a dog mastocytoma cDNA library with an oligonucleotide probe based on the amino acid sequence of a fragment of dog mastocytoma chymase. The deduced amino acid sequence reveals a putative 21-residue prepropeptide followed by a catalytic domain of 228 residues. The primary structure of the preproenzyme shares features with rat mucosal mast cell chymase (RMCP II), several lymphocyte-associated proteases, and neutrophil cathepsin G. The common characteristics include an apparent activation peptide terminating in glutamic acid, strict conservation of an octapeptide (residues 9-16) in the N-terminal portion of the catalytic domain, and the presence of only six cysteines available for intramolecular disulfide bond formation. However, dog chymase differs in being modified by N-glycosylation. Although the dog chymase catalytic domain exhibits a similar level of sequence identity when compared with both RMCP II and the rat connective tissue mast cell chymase RMCP I (58% and 61%, respectively), the dog enzyme most closely resembles RMCP I in its high predicted net charge (+16) and in the presence of serine at the base of its putative primary substrate binding pocket. The dog chymase differs strikingly from dog mast cell tryptase in the preprosequence and in the structure of the catalytic domain. Therefore, chymase appears not to be closely related to tryptase and may not share a mechanism of activation, even though both enzymes are packaged and released together.

Purification and characterization of dog mast cell protease-3, an oligomeric relative of tryptases.

The existence of a protein approximately 48% identical with mast cell tryptases was predicted previously from a dog mastocytoma cDNA. Antibodies raised against a peptide based on the deduced sequence suggested that the protein (dog mast cell protease-3, dMCP-3) is expressed in mast cells. In this report, characterization of the protein purified from mastocytomas reveals an N-glycosylated, high molecular weight, tryptic serine protease, which appears to be a tetramer of catalytic subunits, approximately half of which are linked by disulfide bonds. The oligomeric complex yields a single NH2-terminal sequence, which is identical with that predicted by dMCP-3 cDNA. This finding, and the lack of closely related genes on blots of genomic DNA, predict that each subunit is the product of one gene. Although dMCP-3 binds to heparin, it is active and stable at low ionic strength in heparin's absence. It resists inactivation by inhibitors in plasma but is sensitive to small inhibitors, e.g. leupeptin and bis(5-amidino-2-benzimidazolyl)methane (BABIM). dMCP-3 hydrolyzes extended peptidyl p-nitroanilides ending in basic residues, with P1 arginine preferred to lysine; it hydrolyzes the Arg18-Ser19 bond of calcitonin gene-related peptide but cleaves neither vasoactive intestinal peptide nor casein. These data suggest that dMCP-3 is a unique serine protease whose stability, formation of intersubunit disulfide bonds, inhibitor susceptibilities and substrate preferences differ from those of its closest relatives, the mast cell tryptases.

Bis(5-amidino-2-benzimidazolyl)methane and related amidines are potent, reversible inhibitors of mast cell tryptases.

Tryptase is the major secretory protease of human mast cells and is proposed to be involved in neuropeptide processing and tissue inflammation. Exploration of the biology of tryptase has been hindered by the lack of potent, selective inhibitors. The current study explores the properties of aromatic diamidines as inhibitors of dog and human tryptase. The strongest inhibitors of tryptase in this series are bis(5-amidino-2-benzimidazolyl)methane (BABIM) and (5-amidino-2-benzimidazolyl)-(5-(N,N'-dimethylamidino)-2- benzimidazolyl)methane, which exhibit K(i) values of 1.8 and 1.4 nM, respectively, in blocking the hydrolysis of tosyl-L-Gly-Pro-Lys-4-nitroanilide by human tryptase. These compounds are approximately 10,000-fold more potent than benzamidine, and are the strongest reversible inhibitors of tryptase described to date. Other aromatic mono- and diamidines, including amiloride and pentamidine, are less potent. Nonetheless, they abolish tryptase activity at high inhibitor concentrations. The rank order of tryptase inhibitor potency parallels that of inhibitors tested against trypsin. BABIM, the only highly active member of this series whose potency against other targets has been examined previously, is a far stronger inhibitor of tryptase than of other trypsin-like serine proteases, including those involved with hemostasis, fibrinolysis and the complement system. Therefore, BABIM appears to have selective affinity for tryptase. In addition to inhibiting tryptase-induced hydrolysis of peptide-based chromogenic substrates, BABIM blocks completely the reversal of vasoactive intestinal peptide-induced relaxation of isolated trachea by dog tryptase. Thus, BABIM and related amidines are potent inhibitors of mast cell tryptases that may be useful in exploring mast cell protease biology.

Human tryptase as a potent, cell-specific mitogen: role of signaling pathways in synergistic responses.

Mast cells are hypothesized to participate in processes leading to tissue fibrosis in human lung and skin. To explore the possible involvement of mast cell mediators in fibrogenesis, the mitogenic activity of mast cell tryptase from human lung was examined in vitro. The results indicate that human tryptase is a potent inducer of DNA synthesis in fibroblasts from multiple sources, including human lung. As demonstrated by mitogenic responses in fibroblasts, but not in vascular smooth muscle cells, tryptase is a mitogen with target cell specificity. Additionally, specificity is demonstrated by the differences in mitogenic activity of tryptase in comparison with thrombin, a structurally related mitogenic proteinase. Examination of the mitogenic effects of tryptase in the presence of other mitogens reveals synergy with mitogens that act through receptors coupled to intrinsic tyrosine kinases (insulin, epidermal growth factor, and basic fibroblast growth factor) or to G proteins (thrombin and serotonin). In the latter case, studies in Chinese hamster lung fibroblasts using specific receptor agonists and antagonists or receptor-transfected cell lines reveal a requirement for the activation of a G protein (Gi) negatively coupled to adenylate cyclase to act synergistically with tryptase. These data establish that human tryptase is a potent and specific mitogen in vitro and suggest that mitogenic signals generated by tryptase can interact synergistically with signals generated by both tyrosine kinase-coupled and G protein-coupled growth factor receptors.

Dog mast cell alpha-chymase activates progelatinase B by cleaving the Phe88-Gln89 and Phe91-Glu92 bonds of the catalytic domain.

In prior work we showed that a metallogelatinase is secreted from dog mastocytoma cells and directly activated by exocytosed mast cell alpha-chymase. The current work identifies the protease as a canine homologue of progelatinase B (92-kDa gelatinase, MMP-9), determines the sites cleaved by alpha-chymase, and explores the regulation of gelatinase expression in mastocytoma cells. To obtain a cDNA encoding the complete sequence of mastocytoma gelatinase B, a 2. 3-kilobase clone encoding progelatinase was isolated from a BR mastocytoma library. The sequenced cDNA predicts a 704-amino acid protein 80% identical to human progelatinase B. Regions thought to be critical for active site latency, such as the Cys-containing propeptide sequence, PRCGVPD, and the catalytic domain sequence, HEFGHALGLDHSS, are entirely conserved. Cleavage of progelatinase B by purified dog alpha-chymase yielded an approximately 84-kDa product that contained two NH2-terminal amino acid sequences, QTFEGDLKXH and EGDLKXHHND, which correspond to residues 89-98 and 92-101 of the cDNA predicted sequence, respectively. Thus, alpha-chymase cleaves the catalytic domain of gelatinase B at the Phe88-Gln89 and Phe91-Glu92 bonds. Like BR cells, the C2 line of dog mastocytoma cells constitutively secrete progelatinase B which is activated by alpha-chymase. By contrast, non-chymase-producing C1 cells secrete a gelatinase B (which remains in its proform) only in response to 12-O-tetradecanoylphorbol-13-acetate. Whereas 12-O-tetradecanoylphorbol-13-acetate stimulation of BR cells produced a approximately 15-fold increase in gelatinase B mRNA expression, dexamethasone down-regulated its expression by approximately 5-fold. Thus, extracellular stimuli may regulate the amount of mast cell progelatinase B expressed by mast cells. These data further support a role for mast cell alpha-chymase in tissue remodeling involving gelatinase B-mediated degradation of matrix proteins.

Regulated expression, processing, and secretion of dog mast cell dipeptidyl peptidase I.

Dipeptidyl peptidase I (DPPI) is a cysteine protease found predominantly in myelomonocytic cells, cytotoxic T-cells, and mast cells. Recent studies identify an intracellular role for mast cell-DPPI (MC-DPPI) by activating prochymase and protryptase to their mature forms. To better define MC-DPPI and to explore the possibility of extracellular roles, we purified MC-DPPI from mastocytoma cells. We found the dog C2 mastocytoma cell line to be the richest source yet described for DPPI, purifying up to 200 microg of enzyme per g of cells. Dog MC-DPPI has an Mr of approximately 175,000 and consists of four subunits, each composed of a propeptide, light chain, and heavy chain. The heavy chain is N-glycosylated and is heterogeneously processed to three different forms. NH2-terminal sequences of the heavy chain and propeptide are identical to those predicted from a cDNA clone we sequenced from a mastocytoma cDNA library. The dog cDNA-derived sequence is 86% identical to that of human DPPI. Dog mastocytoma cells incubated with 12-O-tetradecanoylphorbol-13-acetate increase expression of MC-DPPI mRNA. MC-DPPI maintains its activity for dipeptide substrates at a neutral to alkaline pH. Cells stimulated with ionophore or substance P secrete MC-DPPI in parallel with the granule-associated mediators tryptase and histamine. Thus, dog mastocytoma cells secrete DPPI that is active at the pH of extracellular fluids, suggesting that MC-DPPI may act outside the cell.

Characterization of human gamma-tryptases, novel members of the chromosome 16p mast cell tryptase and prostasin gene families.

Previously, this laboratory identified clusters of alpha-, beta-, and mast cell protease-7-like tryptase genes on human chromosome 16p13.3. The present work characterizes adjacent genes encoding novel serine proteases, termed gamma-tryptases, and generates a refined map of the multitryptase locus. Each gamma gene lies between an alpha1H Ca2+ channel gene (CACNA1H) and a betaII- or betaIII-tryptase gene and is approximately 30 kb from polymorphic minisatellite MS205. The tryptase locus also contains at least four tryptase-like pseudogenes, including mastin, a gene expressed in dogs but not in humans. Genomic DNA blotting results suggest that gammaI- and gammaII-tryptases are alleles at the same site. betaII- and betaIII-tryptases appear to be alleles at a neighboring site, and alphaII- and betaI-tryptases appear to be alleles at a third site. gamma-Tryptases are transcribed in lung, intestine, and in several other tissues and in a mast cell line (HMC-1) that also expresses gamma-tryptase protein. Immunohistochemical analysis suggests that gamma-tryptase is expressed by airway mast cells. gamma-Tryptase catalytic domains are approximately 48% identical with those of known mast cell tryptases and possess mouse homologues. We predict that gamma-tryptases are glycosylated oligomers with tryptic substrate specificity and a distinct mode of activation. A feature not found in described tryptases is a C-terminal hydrophobic domain, which may be a membrane anchor. Although the catalytic domains contain tryptase-like features, the hydrophobic segment and intron-exon organization are more closely related to another recently described protease, prostasin. In summary, this work describes gamma-tryptases, which are novel members of chromosome 16p tryptase/prostasin gene families. Their unique features suggest possibly novel functions.

Inflammatory mast cells up-regulate angiogenesis during squamous epithelial carcinogenesis.

Expression of HPV16 early region genes in basal keratinocytes of transgenic mice elicits a multistage pathway to squamous carcinoma. We report that infiltration by mast cells and activation of the matrix metalloproteinase MMP-9/gelatinase B coincides with the angiogenic switch in premalignant lesions. Mast cells infiltrate hyperplasias, dysplasias, and invasive fronts of carcinomas, but not the core of solid tumors, where they degranulate in close apposition to capillaries and epithelial basement membranes, releasing mast-cell-specific serine proteases MCP-4 (chymase) and MCP-6 (tryptase). MCP-6 is shown to be a mitogen for dermal fibroblasts that proliferate in the reactive stroma, whereas MCP-4 can activate progelatinase B and induce hyperplastic skin to become angiogenic in an in vitro bioassay. Notably, premalignant angiogenesis is abated in a mast-cell-deficient (KITW/KITWWv) HPV16 transgenic mouse. The data indicate that neoplastic progression in this model involves exploitation of an inflammatory response to tissue abnormality. Thus, regulation of angiogenesis during squamous carcinogenesis is biphasic: In hyperplasias, dysplasias, and invading cancer fronts, inflammatory mast cells are conscripted to reorganize stromal architecture and hyperactivate angiogenesis; within the cancer core, upregulation of angiogenesis factors in tumor cells apparently renders them self-sufficient at sustaining neovascularization.

Chemotactic activity in aqueous humor from patients with anterior uveitis.

Anterior uveitis, inflammation of the iris or ciliary body of the eye, may be associated with a variety of systemic diseases. Although a leukocytic infiltrate is characteristic of anterior uveitis, few studies have sought to detect factors in aqueous humor that could attract neutrophils or monocytes into the anterior chamber. Using modified Boyden chambers, we found that a 5% concentration of aqueous humor from patients with anterior uveal inflammation induced monocyte movement comparable to optimal or near-optimal concentrations of C (complement)5a or platelet-derived growth factor. Aqueous humor from patients with anterior uveitis induced significantly more monocyte migration than did aqueous humor from two sets of controls (either patients undergoing cataract extraction or patients with posterior uveitis). "Checkerboard" or gradient analysis indicated that a majority of inflammatory disease samples induced monocyte chemotaxis (directed migration) while the control aqueous humor consistently induced chemokinesis (stimulated random migration) (P less than 0.02). Despite their ability to induce monocyte migration, samples tended to induce minimal neutrophil migration with the exception of aqueous humor that was obtained from one patient with acute anterior disease. This sample induced marked chemokinesis. Identification of chemotactic activity may clarify the pathogenesis of uveitis and the characterization of leukocyte migration factors in aqueous humor may help define subsets of anterior uveal inflammation.