Hyaluronate in bronchoalveolar lavage fluid: a new marker in sarcoidosis reflecting pulmonary disease

Serum hyaluronic acid and procollagen III, N-terminal propeptide levels are highly associated with disease severity and predict the progression of COVID-19

Background

The coronavirus disease 2019 (COVID-19) pandemic is a rapidly evolving global emergency and continuously poses a serious threat to public health, highlighting the urgent need of identifying biomarkers for disease severity and progression. In order to early identify severe and critical patients, we retrospectively analyze the clinical characteristics and risk indicators of severe disease in patients with corona virus disease 2019 (COVID-19).

Methods

A total of 420 confirmed COVID-19 patients were included in the study. According to the "Diagnosis and Treatment of novel coronavirus Pneumonia (10th Edition)", the cases were divided into mild group (n = 243) and severe group (n =177). Laboratory parameters were analyzed in combination with clinical data.

Results

Male patients over 46 years who have smoking habits were more likely to suffer from severe COVID-19. Critically ill patients had lower lymphocyte counts and red blood cell counts, and higher white blood cell counts (P<0.05). Expectedly, serum inflammatory factors (NLR, PLR, LMR, CLR, PCT, CRP), coagulation markers (APTT, PT, TT, FIB, D-Dimer), Myocardial damage markers (hs-TNT, LDH) were significantly increased (P<0.05) in severe COVID-19 patients. Surprisedly, those patients showed obviously elevated levels of common tumor markers (ProGRP, CYFRA21-1, SCC, NSE) (P<0.05). In this case, the levels of tumor marker reflected more the condition of inflammation than the growth of tumor. More importantly, HA and PIIIN-P were highly associated with COVID-19 severity. The AUC of the ROC curve for the diagnosis of severe COVID-19 by HA and PIIIN-P was 0.826. Meanwhile, HA was positively correlated with myocardial damage markers (hs-TNT, LDH). PIIIN-P was positively correlated with myocardial damage markers (hs-TNT, LDH) and inflammatory factors (NLR, PLR, LMR, CLR, ProGRP, SCC, PCT, CRP). On the contrary, PIIIN-P was negatively correlated with pulmonary function indexes (oxygenation index and oxygen saturation of hemoglobin).

Conclusion

HA and PIIIN-P are highly associated with disease severity and progression of COVID-19 and can be used as new markers for the prediction of severe COVID-19.

Modulators of inflammation in Bronchopulmonary Dysplasia

Over 50 years after its first description, Bronchopulmonary Dysplasia (BPD) remains a devastating pulmonary complication in preterm infants with respiratory failure and develops in 30-50% of infants less than 1000-gram birth weight. It is thought to involve ventilator- and oxygen-induced damage to an immature lung that results in an inflammatory response and ends in aberrant lung development with dysregulated angiogenesis and alveolarization. Significant morbidity and mortality are associated with this most common chronic lung disease of childhood. Thus, any therapies that decrease the incidence or severity of this condition would have significant impact on morbidity, mortality, human costs, and healthcare expenditure. It is clear that an inflammatory response and the elaboration of growth factors and cytokines are associated with the development of BPD. Numerous approaches to control the inflammatory process leading to the development of BPD have been attempted. This review will examine the anti-inflammatory approaches that are established or hold promise for the prevention or treatment of BPD.

The Receptor for Hyaluronan-Mediated Motility (CD168) promotes inflammation and fibrosis after acute lung injury

Acute lung injury results in early inflammation and respiratory distress, and later fibrosis. The glycosaminoglycan hyaluronan (HA) and the Receptor for Hyaluronan-Mediated Motility (RHAMM, CD168) have been implicated in the response to acute lung injury. We hypothesized that, compared to wild type (WT) mice, RHAMM knockout (KO) mice would be protected from, whereas mice with macrophage-specific transgenic overexpression of RHAMM (TG) would have worse inflammation, respiratory distress and fibrosis after intratracheal (IT) bleomycin. Compared to WT mice, 10 days after IT bleomycin, RHAMM KO mice had less weight loss, less increase in respiratory rate, and fewer CD45+ cells in the lung. At day 28, compared to injured WT animals, injured RHAMM KO mice had lower M1 macrophage content, as well as decreased fibrosis as determined by trichrome staining, Ashcroft scores and lung HPO content. Four lines of transgenic mice with selective overexpression of RHAMM in macrophages were generated using the Scavenger Receptor A promoter driving a myc-tagged full length RHAMM cDNA. Baseline expression of RHAMM and CD44 was the same in WT and TG mice. By flow cytometry, TG bone marrow-derived macrophages (BMDM) had increased cell surface RHAMM and myc, but equal CD44 expression. TG BMDM also had 2-fold increases in both chemotaxis to HA and proliferation in fetal bovine serum. In TG mice, increased inflammation after thioglycollate-induced peritonitis was restricted to macrophages and not neutrophils. For lung injury studies, non-transgenic mice given bleomycin had respiratory distress with increased respiratory rates from day 7 to 21. However, TG mice had higher respiratory rates from 4 days after bleomycin and continued to increase respiratory rates up to day 21. At 21 days after IT bleomycin, TG mice had increased lung macrophage accumulation. Lavage HA concentrations were 6-fold higher in injured WT mice, but 30-fold higher in injured TG mice. At 21 days after IT bleomycin, WT mice had developed fibrosis, but TG mice showed exaggerated fibrosis with increased Ashcroft scores and HPO content. We conclude that RHAMM is a critical component of the inflammatory response, respiratory distress and fibrosis after acute lung injury. We speculate that RHAMM is a potential therapeutic target to limit the consequences of acute lung injury.

Early Effect of Exogenous Na Hyaluronate on Mucociliary Clearance

Background

An animal study is performed to determine the early effect of 1% Na hyaluronate on mucociliary clearance function.

Methods

One percent of Na hyaluronate was introduced into the maxillary sinuses of rabbits by anterior antrostomy. A physiological solution of 1% NaCl was introduced into the maxillary sinuses of a control group to equalize the influence of Na for both groups. The treatment material was sprayed with an atomizer for coating the maxillary sinus lining. Technetium-99m diethylenetriamine pentaacetate dynamic scintigraphic imaging was performed to evaluate mucociliary clearance function on all rabbits 72 hours after the surgical procedure.

Results

Although the mean rate of mucociliary clearance of the Na hyaluronate group was slightly worse than the control group; there was no statistically significant difference between them.

Conclusion

There is no early effect of exogenous 1% Na hyaluronate on mucociliary clearance function.

The Rise and Fall of Hyaluronan in Respiratory Diseases

In normal airways, hyaluronan (HA) matrices are primarily located within the airway submucosa, pulmonary vasculature walls, and, to a lesser extent, the alveoli. Following pulmonary injury, elevated levels of HA matrices accumulate in these regions, and in respiratory secretions, correlating with the extent of injury. Animal models have provided important insight into the role of HA in the onset of pulmonary injury and repair, generally indicating that the induction of HA synthesis is an early event typically preceding fibrosis. The HA that accumulates in inflamed airways is of a high molecular weight (>1600 kDa) but can be broken down into smaller fragments (<150 kDa) by inflammatory and disease-related mechanisms that have profound effects on HA pathobiology. During inflammation in the airways, HA is often covalently modified with heavy chains from inter-alpha-inhibitor via the enzyme tumor-necrosis-factor-stimulated-gene-6 (TSG-6) and this modification promotes the interaction of leukocytes with HA matrices at sites of inflammation. The clearance of HA and its return to normal levels is essential for the proper resolution of inflammation. These data portray HA matrices as an important component of normal airway physiology and illustrate its integral roles during tissue injury and repair among a variety of respiratory diseases.

Lovastatin Inhibits Low Molecular Weight Hyaluronan Induced Chemokine Expression via LFA-1 and Decreases Bleomycin-Induced Pulmonary Fibrosis

BACKGROUND

Lovastatin has a unique ability to bind Leukocyte Function Antigen-1 (LFA-1), an integrin necessary for the full expression of inflammatory cytokines induced by the low molecular weight form of the extracellular matrix glycosaminoglycan hyaluronan (LMW HA). We hypothesized that lovastatin could inhibit LMW HA inflammatory signals via interaction with LFA-1, and attenuate bleomycin induced pulmonary fibrosis.

METHODS

We evaluated the effects of lovastatin, pravastatin, LFA-1 blocking antibodies, and a novel LFA-1 inhibitor LFA 878 on LMW HA induced cytokine production in alveolar macrophages. We evaluated the effect of lovastatin in a bleomycin model of lung injury.

RESULTS

Lovastatin immediately inhibited the LMW HA induced cytokine MIP 1-α (p=0.001) independent of HMG CoA reductase. Pravastatin showed no inhibitory profile when administered simultaneously with LMW HA. LFA-1 blocking antibodies and the small molecule statin derivative LFA 878 showed an inhibitory profile similar to lovastatin. Lovastatin showed decreased fibrosis on histopathology and improved survival at day 14, with a decrease in fibrocytes noted at day 8.

CONCLUSION

Lovastatin and LFA 878 inhibit LMW HA inflammatory signaling independent of HMG-CoA decreasing the chemotactic cytokine MIP 1-α. Lovastatin treatment improves survival in bleomycin lung injury with decreased fibrocytes and fibrosis.

Serum biomarkers in nonalcoholic steatohepatitis: value for assessing drug effects?

Nonalcoholic steatohepatitis (NASH) is a common chronic liver disease throughout the world. In the USA, approximately 3-5% of the population are affected, and the prevalence of this condition is increasing. NASH is associated with an increased risk of liver-related morbidity, such as cirrhosis and fibrosis, as well as cardiovascular disease, and in spite of several clinical studies investigating putative new drugs, no approved treatment is currently available. This is partly due to the nature of the disease. NASH is a complex, slowly progressing disease, and confirmatory clinical trials have long treatment durations and require invasive end points (a liver biopsy). Such invasive assessments are only accepted in confirmatory trials; clinical studies in the exploratory clinical development phase must rely on noninvasive biomarkers as the primary end point. Experimental and clinical research continues to achieve validation and qualification of biomarkers in NASH, which will hopefully assist the development of new treatments for NASH patients.

Recognition of damage-associated molecular patterns related to nucleic acids during inflammation and vaccination

All mammalian cells are equipped with large numbers of sensors for protection from various sorts of invaders, who, in turn, are equipped with molecules containing pathogen-associated molecular patterns (PAMPs). Once these sensors recognize non-self antigens containing PAMPs, various physiological responses including inflammation are induced to eliminate the pathogens. However, the host sometimes suffers from chronic infection or continuous injuries, resulting in production of self-molecules containing damage-associated molecular patterns (DAMPs). DAMPs are also responsible for the elimination of pathogens, but promiscuous recognition of DAMPs through sensors against PAMPs has been reported. Accumulation of DAMPs leads to massive inflammation and continuous production of DAMPs; that is, a vicious circle leading to the development of autoimmune disease. From a vaccinological point of view, the accurate recognition of both PAMPs and DAMPs is important for vaccine immunogenicity, because vaccine adjuvants are composed of several PAMPs and/or DAMPs, which are also associated with severe adverse events after vaccination. Here, we review as the roles of PAMPs and DAMPs upon infection with pathogens or inflammation, and the sensors responsible for recognizing them, as well as their relationship with the development of autoimmune disease or the immunogenicity of vaccines.

Antioxidant protects against increases in low molecular weight hyaluronan and inflammation in asphyxiated newborn pigs resuscitated with 100% oxygen

BACKGROUND

Newborn resuscitation with 100% oxygen is associated with oxidative-nitrative stresses and inflammation. The mechanisms are unclear. Hyaluronan (HA) is fragmented to low molecular weight (LMW) by oxidative-nitrative stresses and can promote inflammation. We examined the effects of 100% oxygen resuscitation and treatment with the antioxidant, N-acetylcysteine (NAC), on lung 3-nitrotyrosine (3-NT), LMW HA, inflammation, TNFα and IL1ß in a newborn pig model of resuscitation.

METHODS & PRINCIPAL FINDINGS

Newborn pigs (n = 40) were subjected to severe asphyxia, followed by 30 min ventilation with either 21% or 100% oxygen, and were observed for the subsequent 150 minutes in 21% oxygen. One 100% oxygen group was treated with NAC. Serum, bronchoalveolar lavage (BAL), lung sections, and lung tissue were obtained. Asphyxia resulted in profound hypoxia, hypercarbia and metabolic acidosis. In controls, HA staining was in airway subepithelial matrix and no 3-NT staining was seen. At the end of asphyxia, lavage HA decreased, whereas serum HA increased. At 150 minutes after resuscitation, exposure to 100% oxygen was associated with significantly higher BAL HA, increased 3NT staining, and increased fragmentation of lung HA. Lung neutrophil and macrophage contents, and serum TNFα and IL1ß were higher in animals with LMW than those with HMW HA in the lung. Treatment of 100% oxygen animals with NAC blocked nitrative stress, preserved HMW HA, and decreased inflammation. In vitro, peroxynitrite was able to fragment HA, and macrophages stimulated with LMW HA increased TNFα and IL1ß expression.

CONCLUSIONS & SIGNIFICANCE

Compared to 21%, resuscitation with 100% oxygen resulted in increased peroxynitrite, fragmentation of HA, inflammation, as well as TNFα and IL1ß expression. Antioxidant treatment prevented the expression of peroxynitrite, the degradation of HA, and also blocked increases in inflammation and inflammatory cytokines. These findings provide insight into potential mechanisms by which exposure to hyperoxia results in systemic inflammation.

Hyaluronic acid : perspectives in lung diseases

Hyaluronic acid (HA) is a non-sulphated glycosaminoglycan. It is a natural polymer characterised by a coiled linear chain in particularly well-hydrated configuration composed of repeating disaccaride units. In mammals, its molecular weight can be extremely wide, ranging from 20 to 4,000 kDa. High molecular mass forms are provided with anti-inflammatory properties. A unique characteristic of HA is hydration (up to 6,000 molecules water/molecule of HA) with a major role in the regulation of fluid balance in the interstitium, a fundamental activity on the amorphous colloidal matrix gluing connective cell and fibers, and many other biological functions including lubrication, solute transport and microcirculatory exchange. HA has been widely used in the treatment of eye, ear, joint and skin disorders; in the last 15 years HA has been also proposed successfully in the treatment of a number of lung diseases in vitro, experimental animals and humans. In particular, inhaled HA at relatively high molecular weight has been proven to prevent bronchoconstiction induced in asthmatics by direct and indirect challenges such as inhalation of methacholine, inhalation of ultrasonically nebulised distilled water, muscular exercise. More recently, in patients affected by chronic obstructive pulmonary diseases, we have demonstrated that repeated administrations of inhaled HA (daily, for 8 weeks) induce significant increase in bronchial patency as well as progressive lung deflation with decrease of residual volume. In conclusion there are elements that can let us state that is perhaps time to change the focus to connective tissue and extracellular matrix substances such as HA, in order to prevent and treat chronic lung diseases.

The role of TLRs in neutrophil activation

Neutrophils are key innate immune effector cells that are rapidly recruited to sites of infection and inflammation to provide early defence against invading microorganisms. This function is facilitated by the expression of Toll-like receptor (TLR) family members by neutrophils, allowing the recognition of an extensive repertoire of pathogen-associated molecular patterns (PAMPs) and thus triggering the response to invading pathogens. TLR activation leads to important cellular processes including reactive oxygen species (ROS) generation, cytokine production and increased survival, all of which can contribute to the pathogenesis of chronic inflammation when signalling becomes dysregulated. In turn, inflammation and tissue injury results in the release of endogenous TLR ligands, known as damage-associated molecular patterns (DAMPs), which are a rapidly growing class of potent inflammatory stimuli. DAMPs act in an autocrine manner, alerting the host of damage, but can also amplify inflammation leading to further tissue damage. This review highlights recent literature on neutrophil TLR function and regulation during disease, and provides an overview of the recently emerging area of neutrophil responses to DAMPs.

DAMPening inflammation by modulating TLR signalling. Mediators Inflamm. 2010;2010. [PMID: 20706656 PMCID: PMC2913853 DOI: 10.1155/2010/672395]

Damage-associated molecular patterns (DAMPs) include endogenous intracellular molecules released by activated or necrotic cells and extracellular matrix (ECM) molecules that are upregulated upon injury or degraded following tissue damage. DAMPs are vital danger signals that alert our immune system to tissue damage upon both infectious and sterile insult. DAMP activation of Toll-like receptors (TLRs) induces inflammatory gene expression to mediate tissue repair. However, DAMPs have also been implicated in diseases where excessive inflammation plays a key role in pathogenesis, including rheumatoid arthritis (RA), cancer, and atherosclerosis. TLR activation by DAMPs may initiate positive feedback loops where increasing tissue damage perpetuates pro-inflammatory responses leading to chronic inflammation. Here we explore the current knowledge about distinct signalling cascades resulting from self TLR activation. We also discuss the involvement of endogenous TLR activators in disease and highlight how specifically targeting DAMPs may yield therapies that do not globally suppress the immune system.

Anti-oxidant inhibition of hyaluronan fragment-induced inflammatory gene expression

Background

The balance between reactive oxygen species (ROS) and endogenous anti-oxidants is important in maintaining healthy tissues. Excessive ROS states occur in diseases such as ARDS and Idiopathic Pulmonary Fibrosis. Redox imbalance breaks down the extracellular matrix component hyaluronan (HA) into fragments that activate innate immune responses and perpetuate tissue injury. HA fragments, via a TLR and NF-κB pathway, induce inflammatory gene expression in macrophages and epithelial cells. NAC and DMSO are potent anti-oxidants which may help balance excess ROS states.

Methods

We evaluated the effect of H₂O₂, NAC and DMSO on HA fragment induced inflammatory gene expression in alveolar macrophages and epithelial cells.

Results

NAC and DMSO inhibit HA fragment-induced expression of TNF-α and KC protein in alveolar and peritoneal macrophages. NAC and DMSO also show a dose dependent inhibition of IP-10 protein expression, but not IL-8 protein, in alveolar epithelial cells. In addition, H₂O₂ synergizes with HA fragments to induce inflammatory genes, which are inhibited by NAC. Mechanistically, NAC and DMSO inhibit HA induced gene expression by inhibiting NF-κB activation, but NAC had no influence on HA-fragment-AP-1 mediated gene expression.

Conclusion

ROS play a central role in a pathophysiologic "vicious cycle" of inflammation: tissue injury generates ROS, which fragment the extracellular matrix HA, which in turn synergize with ROS to activate the innate immune system and further promote ROS, HA fragment generation, inflammation, tissue injury and ultimately fibrosis. The anti-oxidants NAC and DMSO, by inhibiting the HA induced inflammatory gene expression, may help re-balance excessive ROS induced inflammation.

The adenosine a2a receptor inhibits matrix-induced inflammation in a novel fashion

Endogenous mediators within the inflammatory milieu play a critical role in directing the scope, duration, and resolution of inflammation. High-molecular-weight extracellular matrix hyaluronan (HA) helps to maintain homeostasis. During inflammation, hyaluronan is broken down into fragments that induce chemokines and cytokines, thereby augmenting the inflammatory response. Tissue-derived adenosine, released during inflammation, inhibits inflammation via the anti-inflammatory A2 adenosine receptor (A2aR). We demonstrate that adenosine modulates HA-induced gene expression via the A2aR. A2aR stimulation inhibits HA fragment-induced pro-fibrotic genes TNF-alpha, keratinocyte chemoattractant (KC), macrophage inflammatory protein (MIP)-2, and MIP-1alpha while simultaneously synergizing with hyaluronan fragments to up-regulate the TH1 cytokine IL-12. Interestingly, A2aR stimulation mediates these affects via the novel cAMP-activated guanine nucleotide exchange factor EPAC. In addition, A2aR-null mice are more susceptible to bleomycin-induced lung injury, consistent with a role for endogenous adenosine in inhibiting the inflammation that may lead to fibrosis. Indeed, the bleomycin treated A2aR-null mice demonstrate increased lung inflammation, HA accumulation, and histologic damage. Overall, our data elucidate the opposing roles of tissue-derived HA fragments and adenosine in regulating noninfectious lung inflammation and support the pursuit of A2aR agonists as a means of pharmacologically inhibiting inflammation that may lead to fibrosis.

Hyaluronan facilitates transforming growth factor-beta1-mediated fibroblast proliferation

This study aims to understand the role of the matrix polysaccharide hyaluronan (HA) in influencing fibroblast proliferation and thereby affecting wound healing outcomes. To determine mechanisms that underlie scarred versus scar-free healing, patient-matched dermal and oral mucosal fibroblasts were used as models of scarring and non-scarring fibroblast phenotypes. Specifically, differences in HA generation between these distinct fibroblast populations have been examined and related to differences in transforming growth factor-beta(1) (TGF-beta(1))-dependent proliferative responses and Smad signaling. There was a differential growth response to TGF-beta(1), with it inducing proliferation in dermal fibroblasts but an anti-proliferative response in oral fibroblasts. Both responses were Smad3-dependent. Furthermore, the two fibroblast populations also demonstrated differences in their HA regulation, with dermal fibroblasts generating increased levels of HA, compared with oral fibroblasts. Inhibition of HA synthesis in dermal fibroblasts was shown to abrogate the TGF-beta(1)-mediated induction of proliferation. Inhibition of HA synthesis also led to an attenuation of Smad3 signaling in dermal fibroblasts. Microarray analysis demonstrated no difference in the genes involved in TGF-beta(1) signaling between dermal and oral fibroblasts, whereas there was a distinct difference in the pattern of genes involved in HA regulation. In conclusion, these two distinct fibroblast populations demonstrate a differential proliferative response to TGF-beta(1), which is associated with differences in HA generation. TGF-beta(1) regulates proliferation through Smad3 signaling in both fibroblast populations; however, it is the levels of HA generated by the cells that influence the outcome of this response.

Changes in hyaluronan concentration in tissues and body fluids in disease states

Proteins which specifically bind hyaluronan have been used to develop sensitive immunoassay-like analytical techniques. These assays have made it possible to analyse hyaluronan concentrations in nanogram amounts in tissues and body fluids. The normal adult human circulating level of hyaluronan varies between 10 and 100 micrograms/l. Increased levels of serum hyaluronan (greater than 1 mg/l) have been found in inflammatory rheumatic diseases such as rheumatoid arthritis, scleroderma and psoriatic arthritis. Even higher levels occur in serum from patients with cirrhotic liver diseases and in patients with malignant mesothelioma. Elevated serum hyaluronan levels are a sign either of increased production and/or outflow from the tissues or of decreased elimination of the polysaccharide in the liver endothelial cells or in other parts of the reticuloendothelial system or through the kidneys. The serum concentration is also influenced by increased age and by the degree of physical activity. Important information on pathological processes has been gained by analysing the hyaluronan concentration in other body fluids such as urine, perfusion fluid from the intestine and bronchoalveolar lavage fluid. In the future these analyses should also be useful in clinical work.

Involvement of hyaluronan in regulation of fibroblast phenotype

This study aimed to understand the role of the matrix polysaccharide, hyaluronan (HA), in influencing the scarring process by assessing its impact on regulating fibroblast behavior. Donor-matched human oral and dermal fibroblasts were used as models of nonscarring and scarring fibroblast phenotypes, respectively. Phenotypic differences in these two fibroblast populations were assessed and related to differences in HA synthesis and assembly. The two fibroblast populations showed intrinsic differences in their response to the profibrotic cytokine, transforming growth factor-beta1 (TGFbeta1), in that oral fibroblasts were resistant to TGFbeta1-driven myofibroblastic differentiation. In dermal fibroblasts, differentiation was associated with an induction of HA synthase (HAS1 and HAS2) transcription and assembly of pericellular HA coats. In comparison, resistance to differentiation in oral fibroblasts was associated with failure of induction of HAS1 and HAS2 transcription and failure of pericellular coat assembly. Furthermore, inhibition of HA synthesis in dermal fibroblasts significantly attenuated TGFbeta1-mediated differentiation. Interleukin-1beta stimulation resulted in induction of HAS1 and HAS2 transcription but did not induce phenotypic differentiation or induce HA coat assembly. In addition, neither overexpression nor down-regulation of HAS1 (the isoform uniquely deficient in nonscarring oral fibroblasts) influenced phenotypic differentiation. In conclusion, inhibiting HA synthesis modulates TGFbeta1-dependent responses in these cells preventing fibroblast to myofibroblast differentiation. Moreover, HA pericellular coat assembly, rather than HAS isoform expression, appears to be associated with phenotypic differentiation.

Controlled drug delivery to the lung: Influence of hyaluronic acid solution conformation on its adsorption to hydrophobic drug particles

This work reports investigations into the interaction and adsorption of the hydrophilic polymer hyaluronic acid (HA) onto the surface of the hydrophobic corticosteroid drug fluticasone propionate (FP). The eventual aim is to formulate a bioadhesive pulmonary drug delivery system with prolonged action that avoids rapid clearance from the lungs by the mucociliary escalator. Adsorption isotherms detailing the adsorption of HA from aqueous HA solution concentrations ranging from 0.14 to 0.0008% (w/v) to a fixed FP particle concentration of 0.1% (w/v) were investigated. The method of preparing FP particles with HA molecules adsorbed on their surfaces (FP/HA particles) involved suspension of the FP either in hydrated HA solution or in water followed by addition of solid HA, centrifugation of the solids to form a pellet, washing the pellet several times with water until no HA was found in the supernatant and then freeze drying the suspension obtained by dispersing the final pellet. The freeze dried powder was then analysed for adsorbed HA using a Stains-all assay. The influence of order of addition of HA to FP, time for the adsorption process, and temperature of preparation on the adsorption isotherms was investigated. The non-equilibrium adsorption isotherms produced generally followed the same trend, in that as the HA solution concentration increased, the amount of HA adsorbed increased to a maximum at a solution concentration of approximately 0.1% (w/v) and then decreased. The maxima in the adsorption isotherms were close to the change from secondary to tertiary conformation in the HA solutions. Below the maxima, adsorption occurred via interaction of FP with the hydrophobic patches along the HA chains in the secondary structures. Above the maxima, secondary HA molecules aggregate in solution to form tertiary network structures. Adsorption from tertiary structure was reduced because strong interactions between the HA molecules limited the availability of hydrophobic patches for adsorption of HA onto FP. The influence of preparation variables on adsorption was also related to the availability of hydrophobic patches for adsorption.

Hyaluronan fragments act as an endogenous danger signal by engaging TLR2

Upon tissue injury, high m.w. hyaluronan (HA), a ubiquitously distributed extracellular matrix component, is broken down into lower m.w. (LMW) fragments, which in turn activate an innate immune response. In doing so, LMW HA acts as an endogenous danger signal alerting the immune system of a breach in tissue integrity. In this report, we demonstrate that LMW HA activates the innate immune response via TLR-2 in a MyD88-, IL-1R-associated kinase-, TNFR-associated factor-6-, protein kinase Czeta-, and NF-kappaB-dependent pathway. Furthermore, we show that intact high m.w. HA can inhibit TLR-2 signaling. Finally, we demonstrate that LMW HA can act as an adjuvant promoting Ag-specific T cell responses in vivo in wild-type but not TLR-2(null) mice.

Threat matrix: low-molecular-weight hyaluronan (HA) as a danger signal

Whether or not T cell receptor engagement leads to full activation or tolerance is determined by the context in which the antigen is encountered. Antigen presented by activated APCs in the presence of costimulation leads to full T cell activation, while antigen presented by resting APCs leads to tolerance. Pathogen-associated molecular patterns in the form of toll-like receptor ligands play a critical role in activating APCs and promoting T cell activation. In this review we hypothesize that low-molecular-weight species of the extracellular matrix polymer hyaluronan also performs this function by acting as an endogenous danger signal.

Hyaluronic acid, an accurate serum marker for severe hepatic fibrosis in patients with non-alcoholic fatty liver disease

AIM

To determine whether serum hyaluronic acid reliably predicts the severity of hepatic fibrosis in patients with non-alcoholic fatty liver disease (NAFLD).

METHODS

We studied 79 patients with histologically confirmed NAFLD. Hyaluronic acid was measured in serum obtained at the time of liver biopsy. Severity of fibrosis was staged based on Brunt's classification. The prediction levels for fibrosis were determined by area under the receiver operating characteristic curve (AUC).

RESULTS

The logarithm of serum hyaluronic acid was significantly different among the stages of fibrosis (P<0.0001, analysis of variance) and had a significant positive correlation with the degrees of fibrosis after adjusting for age and serum albumin (partial r=0.44, P<0.0001). AUCs were 0.67, 0.87, 0.89, and 0.92 for any levels of fibrosis, > or =moderate fibrosis, > or =severe fibrosis, and cirrhosis, all of which were significantly higher than 0.5 (P<0.05). The cut-off value of serum hyaluronic acid of 46.1 mug/l was associated with the highest AUC for severe fibrosis, yielding a sensitivity of 85% and a specificity of 80%. The corresponding positive and negative predictive values were 51% and 96%, when assuming prevalence of severe fibrosis in NAFLD patients of 20% at referral centers.

CONCLUSIONS

Measurement of serum hyaluronic acid is useful to identify NAFLD patients with severe fibrosis.

Expression and role of the hyaluronan receptor RHAMM in inflammation after bleomycin injury

Lung injury is associated with increased concentrations of hyaluronan (hyaluronic acid, HA). HA modifies cell behavior through interaction with cell-associated receptors such as receptor for HA-mediated motility (RHAMM, CD168). Using a function blocking anti-RHAMM antibody (R36), we investigated the expression and role of RHAMM in the inflammatory response to intratracheal bleomycin in rats. Immunostaining showed increased expression of RHAMM in macrophages 4-7 d after injury. Surface biotin labeling of cells isolated by lavage confirmed increased surface expression of a 70-kD RHAMM after lung injury, and in situ hybridization demonstrated increased RHAMM mRNA in macrophages responding to injury. Time-lapse cinemicrography demonstrated a 5-fold increase in motility of alveolar macrophages from bleomycin-treated animals that was completely blocked by R36 in vitro. Further, HA-stimulated macrophage chemotaxis was also inhibited by R36. Daily administration of R36 to injured animals resulted in a 40% decrease in macrophage accumulation 7 d after injury. Further, H&E staining of tissue sections showed that bleomycin-mediated changes in lung architecture were improved with R36 treatment. Taken together with previous results showing the inhibitory effects of HA-binding peptide on inflammation and fibrosis, we conclude that the interaction of RHAMM with HA is a critical component of the recruitment of inflammatory cells to the lung after injury.

CD44 signaling through focal adhesion kinase and its anti-apoptotic effect

Adhesion molecules can initiate intracellular signaling. Engagement of CD44 either by its natural ligand hyaluronan or a specific antibody on a cell line induced tyrosine phosphorylation and activation of focal adhesion kinase (FAK), which then associated with phosphatidylinositol 3-kinase (PI3K) and activated mitogen-activated protein kinase at its downstream. However, the introduction of dominant negative Rho into the cells inhibited the CD44-stimulated FAK phosphorylation. Cells expressing CD44 were significantly resistant to etoposide-induced apoptosis. This anti-apoptotic effect was cancelled by the inhibition of either Rho, FAK or PI3K. These results may indicate a signaling pathway from CD44 to mediate the resistance against drug-induced apoptosis in cancer cells.

Serum hyaluronic acid concentrations are increased in cystic fibrosis patients with liver disease

AIM

To determine whether serum hyaluronic acid (HA) concentrations are abnormal in patients with cystic fibrosis (CF) liver disease, and if so, whether the abnormality is associated with disease severity.

METHODS

A total of 74 patients with CF were assessed for evidence of liver involvement as indicated by clinical, ultrasound, and biochemical findings. Serum hyaluronic acid concentrations were measured and compared with concentrations in 293 normal controls. Lung function in the CF patients was also recorded.

RESULTS

Thirty four CF patients had no evidence of liver disease; in these, serum HA concentrations were similar to those in healthy controls (median (range): 16.1 (9.4-75.1) v 15 (1-77) microg/l). Nineteen CF patients had established liver disease detected by clinical and ultrasound examination, with significantly increased HA concentrations (56.1 (26-355) microg/l). Serum HA concentrations were also significantly increased, although to a lesser extent, in 21 CF patients with an abnormal liver ultrasound scan alone (22.4 (9.5-43.4) microg/l). There was no correlation between serum HA concentration and lung function.

CONCLUSION

Serum HA concentrations were significantly increased in children with clinical or ultrasound evidence of liver disease, being higher in those with more advanced hepatic damage. Despite the inflammation and fibrosis present in CF lungs there was no correlation between HA concentration and lung function, suggesting that high concentrations were a failure of hepatic clearance rather than overproduction in the lung. Longitudinal measurement of HA concentrations may prove a useful marker for the development of significant liver damage in CF patients.

Effect of air pollution and environmental tobacco smoke on serum hyaluronate concentrations in school children

OBJECTIVES

To evaluate serum hyaluronate concentrations relative to air pollution, environmental tobacco smoke (ETS), and respiratory health in Japanese school children.

METHODS

Respiratory symptoms and serum IgE concentrations were examined in 1037 school children living in four communities in Japan with differing levels of air pollution. Serum hyaluronate concentrations were assayed in 230 children, consisting of all the children who had symptoms of either asthma or wheeze (65 and 50 subjects, respectively) and normal controls adjusted for sex, school grade, and school without these symptoms (115 subjects).

RESULTS

Although serum hyaluronate concentrations did not differ for either asthma or wheeze, the concentrations were significantly higher in children living in communities with higher levels of air pollution. Children with asthma or wheeze and those with serum IgE concentrations of 250 IU/ml or above showed differences in hyaluronate concentrations that related to the degree of air pollution in the communities. In children with higher serum IgE concentrations, the hyaluronate concentrations among subjects exposed to ETS were significantly higher than among those without exposure to ETS.

CONCLUSIONS

The present results suggest that serum hyaluronate concentration is related to the degree of air pollution and exposure to ETS. Children with asthma or wheeze and children with higher IgE concentrations are considered to be more susceptible to environmental factors.

Hyaluronic acid in cultured ovine tracheal cells and its effect on ciliary beat frequency in vitro

Hyaluronic acid (hyaluronan, or HA) is secreted by submucosal glands, but its function in airway secretions other than influencing the rheology of mucus is not fully understood. HA is known to modulate cell behavior and to enhance sperm motility. Because sperm tails and cilia have the same microtubular structure, we studied the effect of HA on ciliary beat frequency (CBF) in vitro. CBF of cultured ovine airway epithelial cells was measured continuously by digital video microscopy. After removal of endogenous HA by hyaluronidase, cells were exposed to 50 to 100 microg/mL of HA at different times in culture. No change in CBF in response to HA was seen in cells cultured less than 7 days. After 7 days, however, 6 of 10 measured cells (from three different sheep) showed a transient CBF increase from a baseline of 6.4 +/- 0.3 Hz (mean +/- SE) to 7.4 +/- 0.4 Hz or 16% above baseline (p < 0.05). At these time points (but not before), cytochemical staining was positive for endogenous HA using a biotinylated HA-binding protein. These data suggest that HA can increase CBF of tracheal epithelial cells only late in culture when HA is able to bind to an unspecified cell surface structure. Because this binding has a physiological effect, we hypothesize that it is an HA-binding receptor, that is either transiently expressed late in culture or initially destroyed by the protease treatment for cell dispersion.

Silica and its antagonistic effects on transforming growth factor-beta in lung fibroblast extracellular matrix production

BACKGROUND

Silicosis, a pneumoconiosis marked by interstitial pulmonary fibrosis, is caused by inhalation of free crystalline silica particles. When silica particles are injected into the lower lung, they are translocated across the epithelium into the interstitial space, where macrophage-derived growth factors affect lung fibroblast proliferation and collagen deposition. We hypothesized that silica may act directly on pulmonary fibroblasts modifying extracellular matrix (ECM) synthesis and that the effects of silica may be mediated by transforming growth factor-beta (TGFbeta) overproduction.

METHODS

To test this hypothesis, we studied a human lung fibroblast cell line (WI-1003) exposed to silica in vitro. We investigated cell morphology by electron microscopic procedure, cell growth, collagen production, and glycosaminoglycans (GAG) composition by radiolabeled precursors. Cytokine and growth factor synthesis were evaluated by specific enzyme-linked immunoadsorbent assay kits and Northern blotting analysis.

RESULTS

Pulmonary fibroblasts internalized silica particles without detectable cell damage. Silica directly stimulated collagen synthesis and decreased the amount of 3H-glucosamine-labeled GAG. Silica-treated fibroblasts secreted less TGFbeta than untreated controls, antagonized the stimulatory effect of TGFbeta on ECM synthesis, and reversed TGFbeta-induced inhibition of cell proliferation. Northern blotting analysis showed increased interleukin-1alpha (IL-1alpha) mRNA after silica treatment. IL-1alpha had no influence on collagen synthesis but increased the number of WI-1003 fibroblasts.

CONCLUSIONS

These results support our hypothesis that lung fibroblasts are direct silica targets. However, contradicting our hypothesis, silica antagonized TGFbeta activities through a TGFbeta downregulation and an IL-1alpha upregulation. The complex pattern of TGFbeta and IL-1alpha regulation in pulmonary fibroblasts is imbalanced by silica exposure and might play a key role in silica-mediated pulmonary fibrosis.

Regulation of plasminogen activator inhibitor-1 and urokinase by hyaluronan fragments in mouse macrophages

Pulmonary inflammation and fibrosis are characterized by increased turnover and production of the extracellular matrix as well as an impairment of lung fibrinolytic activity. Although fragments of the extracellular matrix component hyaluronan induce macrophage production of inflammatory mediators, the effect of hyaluronan on the fibrinolytic mediators plasminogen activator inhibitor (PAI)-1 and urokinase-type plasminogen activator (uPA) is unknown. This study demonstrates that hyaluronan fragments augment steady-state mRNA, protein, and inhibitory activity of PAI-1 as well as diminish the baseline levels of uPA mRNA and inhibit uPA activity in an alveolar macrophage cell line. Hyaluronan fragments alter macrophage expression of PAI-1 and uPA at the level of gene transcription. Similarly, hyaluronan fragments augment PAI-1 and diminish uPA mRNA levels in freshly isolated inflammatory alveolar macrophages from bleomycin-treated rats. These data suggest that hyaluronan fragments influence alveolar macrophage expression of PAI-1 and uPA and may be a mechanism for regulating fibrinolytic activity during lung inflammation.

Activation and transforming growth factor-beta production in eosinophils by hyaluronan

To investigate whether extracellular matrix glycosaminoglycan hyaluronan (HA) modulates eosinophil activation and transforming growth factor (TGF)-beta production by eosinophils, human peripheral blood eosinophils (purity > 99%) from 12 patients with mild to moderate asthma or six healthy subjects were isolated and incubated with increasing concentrations of low molecular weight (mol wt) HA ( approximately 0.2 x 10(6) D) or high mol wt HA (3.0 to approximately 5.8 x 10(6) D). We found that the low mol wt HA has a pronounced effect on eosinophil survival in both patients with asthma and healthy subjects in a dose-dependent fashion on Days 2 and 4. Whereas the high mol wt HA had a smaller effect on eosinophil survival than did the low mol wt HA. The HA-mediated eosinophil survival was partially but significantly inhibited ( approximately 50% inhibition) by a blocking monoclonal antibody for CD44, a specific receptor of HA, and largely inhibited by an anti-granulocyte macrophage colony-stimulating factor (GM-CSF) neutralizing antibody but not by an anti-interleukin (IL)-3 or anti-IL-5 neutralizing antibody. In addition, the low mol wt HA increased GM-CSF messenger RNA (mRNA) expression and protein secretion by eosinophils in a dose-dependent fashion, suggesting that the HA-mediated eosinophil survival is due mainly to induction of GM-CSF release through partial CD44 signaling. Furthermore, we demonstrated that the low mol wt HA results in morphologic changes in eosinophils such as transforming from a round to a spindle shape and in homotypic aggregation, upregulates intercellular adhesion molecule-1 expression, and increases TGF-beta mRNA expression and protein secretion by eosinophils. These observations suggest previously unforeseen interactions between eosinophils and low mol wt extracellular matrix and, thus, novel pathways by which eosinophils may contribute to the regulation of airway inflammation and airway remodeling.

An increase in hyaluronan by lung fibroblasts: a biomarker for intensity and activity of interstitial pulmonary fibrosis?

The purpose of the present study was to clarify the roles of hyaluronan (HA) production of lung fibroblasts in the pathogenesis of pulmonary fibrosis. Quantitative and comparative assessments of the HA levels in bronchoalveolar lavage fluid (BALF) and lung fibroblast-conditioned media (F-CM) were made at various stages during the development of bleomycin-induced pulmonary fibrosis in rats. In bleomycin-treated animals, the HA levels in F-CM increased significantly (P < 0.01) on day 1 after bleomycin treatment, peaked on day 3, and then gradually declined and returned to control values on days 14-28. The HA concentrations of BALF in the bleomycin group were significantly increased (P < 0.01) on day 3, were maximal on day 7, and thereafter gradually decreased, remaining significantly above normal values (P < 0.01) on day 14, but returning to control values by day 28. In the bleomycin group, the HA levels both in BALF and in F-CM were significantly correlated with the cell components in BALF and there was a significant correlation between the HA concentration in BALF and in the F-CM. Lung fibroblasts were activated and produced increased HA which resulted in excessive accumulation of HA in the lung in the early stage of pulmonary fibrosis; the increased HA synthesis of lung fibroblasts and enhanced HA concentrations of BALF might reflect the intensity of alveolitis and the disease activity.

Induction and Regulation of Macrophage Metalloelastase by Hyaluronan Fragments in Mouse Macrophages

Although the metalloproteinase murine metalloelastase (MME) has been implicated in lung disorders such as emphysema and pulmonary fibrosis, the mechanisms regulating MME expression are unclear. Low m.w. fragments of the extracellular matrix component hyaluronan (HA) that accumulate at sites of lung inflammation are capable of inducing inflammatory gene expression in macrophages (Mφ). The purpose of this study was to examine the effect of HA fragments on the expression of MME in alveolar Mφ. The mouse alveolar Mφ cell line MH-S was stimulated with HA fragments over time, total RNA was isolated, and Northern blot analysis was performed. HA fragments induced MME mRNA in a time-dependent fashion, with maximal levels at 6 h. HA fragments also induced MME protein expression as well as enzyme activity. The induction of MME gene expression was specific for low m.w. HA fragments and dependent upon new protein synthesis; it occurred at the level of gene transcription. We also examined the effect of HA fragments on MME expression in inflammatory alveolar Mφ from bleomycin-injured rat lungs. Although normal rat alveolar Mφ did not express MME mRNA in response to HA fragments, alveolar Mφ from the bleomycin-treated rats responded to HA fragment stimulation by increasing MME mRNA levels. Furthermore, baseline and HA fragment-induced MME gene expression in alveolar Mφ from bleomycin-treated rats was inhibited by IFN-γ. These data suggest that HA fragments may be an important mechanism for the expression of MME by Mφ in inflammatory lung disorders.

Hyaluronan fragments synergize with interferon-gamma to induce the C-X-C chemokines mig and interferon-inducible protein-10 in mouse macrophages

Hallmarks of chronic inflammation and tissue fibrosis are increased influx of activated inflammatory cells, mediator release, and increased turnover and production of the extracellular matrix (ECM). Recent evidence has suggested that fragments of the ECM component hyaluronan play a role in chronic inflammation by inducing macrophage expression of chemokines. Interferon-gamma (IFN-gamma), an important regulator of macrophage functions, has been shown to induce the C-X-C chemokines Mig and IP-10. These chemokines affect T-cell recruitment and inhibit angiogenesis. The purpose of this investigation was to determine the effect of hyaluronan (HA) on IFN-gamma-induced Mig and IP-10 expression in mouse macrophages. We found a marked synergy between HA and IFN-gamma on Mig and IP-10 mRNA and protein expression in mouse macrophages. This was most significant with Mig, which was not induced by HA alone. The synergy was specific for HA, was not dependent on new protein synthesis, was not mediated by tumor necrosis factor-alpha, was selective for Mig and IP-10, and occurred at the level of gene transcription. These data suggest that the ECM component HA may influence chronic inflammatory states by working in concert with IFN-gamma to alter macrophage chemokine expression.

Regulation of Hyaluronan-Induced Chemokine Gene Expression by IL-10 and IFN-γ in Mouse Macrophages

Turnover of the extracellular matrix (ECM), activation of macrophages, and accumulation of chemokines/cytokines are all hallmarks of chronic inflammation. Extracellular matrix components, such as hyaluronan (HA), have recently been shown to influence macrophage effector functions, such as the release of inflammatory chemokines and cytokines. Although low m.w. fragments of the glycosaminoglycan HA induce macrophages to secrete numerous inflammatory mediators, the mechanisms regulating ECM-induced macrophage activation are poorly understood. We have examined the effects of IL-10 and IFN-γ on HA-induced chemokine gene expression in primary mouse macrophages. We found that IL-10 and IFN-γ independently inhibit HA-induced expression of macrophage inflammatory protein-1α (MIP-1α), MIP-1β, and KC at both the mRNA and protein levels. Whereas IL-10 inhibited most of the HA-induced chemokines tested, IFN-γ selectively inhibited only MIP-1α, MIP-1β, and KC. This inhibition did not require prestimulation and occurred even when the cytokines were added up to 3 h after stimulation with HA. For MIP-1α, the inhibition by IFN-γ occurred at the level of transcription, whereas IL-10 predominantly decreased the stability of MIP-1α mRNA. IFN-γ and IL-10 equally inhibited macrophage expression of MIP-1β mRNA at the level of transcription, but MIP-1β mRNA stability was decreased to a greater extent by IL-10. These data identify a previously unrecognized role for IL-10 and IFN-γ as regulators of ECM-induced macrophage expression of inflammatory chemokines.

Biochemical changes in sarcoidosis

Biochemical markers in sarcoidosis are closely related to the immunological events and the activity of inflammatory effector cells at sites of granuloma formation. The markers can be measured in serum, then reflecting whole body concentration, or in BAL fluid, then indicating activity in the lung. Only calcium and ACE serum levels have gained a proven value in the clinical field.

Mechanism of impaired local hyaluronan turnover in bleomycin-induced lung injury in rat

Hyaluronan, a linear polysaccharide, is accumulated in lung interstitium during different pathological conditions, causing interstitial edema and thereby impaired lung function. We investigated the mechanism of local hyaluronan turnover during the early phase of bleomycin-induced fibrotic lung injury in rats. The binding of [3H]hyaluronan to alveolar macrophages (AM) established from bleomycin-treated rats 1 and 5 days after induction of injury was decreased 8- and 15-fold, respectively, compared with that of AM from saline-treated control counterparts, but at day 14 returned almost to the normal level. Data was confirmed by quantitative cytochemistry, using fluorescein-labeled hyaluronan. Analysis of the expression of CD44, a receptor for hyaluronan, by Western blotting revealed a 30% increase of CD44 molecules expressed on AM from bleomycin-treated rats at day 5 compared with control rats. In particular a lower molecular mass form of CD44 appeared. No expression of the receptor for hyaluronan-mediated motility (RHAMM) could be detected. The internalization and degradation of [3H]hyaluronan by AM, obtained from bleomycin-treated rats at days 1, 5, and 14, were decreased about 65%, 35%, and 30%, respectively, compared with AM from the control rats. The AM lysosomal hyaluronidase activity did not differ significantly between bleomycin-treated and control rats. Our results indicate that a decreased hyaluronan binding capacity of AM may account for the impairment of internalization and thereby degradation of excessive hyaluronan during the early phase of fibrotic lung injury.

Localization of hyaluronan in human liver sinusoids: a histochemical study using hyaluronan-binding protein

Circulating hyaluronan is mostly derived from lymph, fibroblast and Ito cells in the liver, and more than 90% of hyaluronan is degraded in hepatic sinusoidal endothelial cells. Thus, elevated serum hyaluronan is regarded as an indication of hepatic fibrosis with activated Ito cells and dysfunctional sinusoidal endothelial cells. We studied the distribution of hyaluronan in human liver sinusoids to determine the influences on elevated hyaluronan levels in sera. Histochemical examination was made using hyaluronan-binding protein (HABP) and serial sections of liver tissue for staining of alpha-smooth muscle actin (ASMA) (an indicator of activated Ito cells) and of ulex europaeus agglutinin I lectin (UEA-1) (closely related to hepatic sinusoidal capillarization). Positive staining, indicating the presence of hyaluronan, was noted in fibrous regions around the portal tracts, areas of focal necrosis in the liver parenchyma, and walls of the sinusoids in chronic hepatitis. In this group, hyaluronan-positive areas corresponded to positive ASMA staining and faint staining of UEA-1. On the contrary, in liver cirrhosis, UEA-1-positive areas were essentially identical to hyaluronan-positive areas and to ASMA-negative areas in sinusoidal walls. Hyaluronan and ASMA could be detected in the same areas of sinusoidal walls in chronic hepatitis, but not in liver cirrhosis. Hyaluronan appears to be mainly related to the staining of activated Ito cells in chronic hepatitis. Therefore, we concluded that in chronic hepatitis, the production of hyaluronan was accelerated in Ito cells; however, degradation of hyaluronan by sinusoidal endothelial cells continued. On the contrary, in liver cirrhosis, hyaluronan production decreased in Ito cells, and a marked transformation of sinusoidal endothelial cells with hepatic sinusoidal capillarization indicated loss of the ability to degrade hyaluronan. These different mechanisms in chronic hepatitis and liver cirrhosis may operate in the sinusoidal walls and may cause the elevation of hyaluronan in sera.

Serum immunoglobulin E and hyaluronate levels in children living along major roads

To assess the effects of automobile exhaust on human health, we determined serum concentrations of total immunoglobulin E and hyaluronate in 185 schoolchildren who lived in a district that contained major roads. Serum immunoglobulin E levels were elevated in children who had asthma or wheezing, but levels did not differ with respect to distance of their homes from the major roads. Serum hyaluronate levels were higher in children who lived less than 50 m from the roadside, compared with children who resided a greater distance from roads. The difference, however, was significant only in a subgroup of children in whom immunoglobulin E levels exceeded 250 IU/ml. Our results suggest that serum hyaluronate levels in children reflect the effects of traffic-related air pollution. Children with high immunoglobulin E levels appeared to be particularly susceptible to the effects of automobile exhaust.

Transient increases in albumin and hyaluronan in bronchoalveolar lavage fluid after quitting smoking: possible signs of reparative mechanisms

Inhalation of tobacco smoke results in an accumulation of cells in the lower respiratory tract. The inflammatory response in the alveoli and lung interstitium may also be reflected by increased bronchoalveolar lavage (BAL) fluid concentrations of extracellular matrix components. The present study investigated the influence of smoking on the BAL fluid concentrations of albumin (ALB), hyaluronan (HA) and fibronectin (FN). Lavage fluids from 18 smokers were analysed before and at 1, 3, 6, 9 and 15 months after smoking cessation. Never-smokers (n = 112) served as a reference group. The total cell concentration and the concentrations of macrophages, lymphocytes, neutrophils and eosinophils were higher (P < 0.001-0.01) in smokers' BAL fluid than in never-smokers', but the values returned to normal within 9 months of smoking cessation. The HA concentration was higher (P < 0.001) in smokers' than in never-smokers' BAL fluid, but FN and ALB did not differ. Transient increases in the concentrations of ALB and HA (P < 0.01 for both) was observed within 6 months of smoking cessation. These findings indicate a temporary heightened alveolar-capillary permeability and an increased production and/or degradation of HA, being enhanced following smoking cessation. The findings probably reflect an initiation of a reparative process.

Pleural macrophages differentially alter pleural mesothelial cell glycosaminoglycan production

Glycosaminoglycans are produced in abundance by the pleural mesothelium and likely participate in the inflammatory response to pleural injury. Because intrapleural tetracycline (TCN) results in pleural macrophage influx and pleural fibrosis, this study attempted to define the role of pleural macrophage products on mesothelial glycosaminoglycan (GAG) production. Pleural macrophages were isolated 72 h after intrapleural TCN or intrapleural carrageenan (CAR), a substance that recruits pleural macrophages without producing pleural fibrosis. Macrophage cultured for 24 h produced a conditioned medium that was added to pleural mesothelial cell culture containing [3H]-glucosamine and was compared to control cultures treated with RPMI culture media alone or with the addition of TCN or CAR. After 72 h, GAGs were isolated by pronase digestion, cetyl pyridinium precipitation, and MgCl2 and ethanol extraction. The majority of GAGs were found in the culture media as compared to the combined mesothelial cell and basement membrane fractions of control mesothelial cells (883 +/- 33 vs. 216 +/- 16, cpm, counts per minute), TCN-treated (792 +/- 48 vs. 204 +/- 18 cpm), CAR-treated (849 +/- 45 vs. 223 +/- 13 cpm), and macrophage-conditioned media-treated mesothelial cells (TCN macrophage-conditioned media: 1420 +/- 42 vs. 356 +/- 11 cpm; CAR macrophage-conditioned media: 1241 +/- 38 vs. 339 +/- 10 cpm) (all p < .05). Media samples were enzymatically digested and individual GAG species were separated by Sephadex G-50 column chromatography. TCN macrophage-conditioned media induced more GAG production by the mesothelial cell into the cell media (1420 +/- 42 cpm) than CAR macrophage-conditioned media (1241 +/- 38 cpm) (p < .05), which was predominantly a difference in hyaluronate production (342 +/- 53 cpm vs. 186 +/- 7 cpm) (P. < .05). The results show that pleural macrophages modulate mesothelial GAG production during tetracycline pleural injury. Increases in mesothelial cell hyaluronate production may be important in the fibrotic response to chemical pleural injury.

Increased levels of hyaluronan and albumin after intestinal challenge in adult patients with cow's milk intolerance

BACKGROUND

The mechanisms for adverse reactions to foods in the gastrointestinal tract are poorly understood. Presently, only limited possibilities are available for identification of adverse immunological reactions to different foods.

OBJECTIVE

The intestinal inflammatory reactions in adult patients with a history of milk-related gastrointestinal symptoms were studied after intestinal challenges by a jejunal perfusion technique and compared with the reactions in a control group.

METHODS

Five skin-prick test and radioallergosorbent test negative and lactose tolerant patients with a history of milk-related gastrointestinal symptoms, verified by double-blind placebo-controlled challenge, and eight healthy controls were investigated. Perfusions were performed allowing analyses of a well-defined 'closed' jejunal segment. Milk perfusions were performed in patients and controls after an overnight fast. Ten millilitres of milk were administered to the segment at 3 mL/min. The jejunal fluid levels of hyaluronan (hyaluronic acid) and albumin were measured.

RESULTS

In the five patients the milk challenges induced as a mean fivefold increased levels of hyaluronan compared with prestimulation values, whereas no such increases were seen in the control subjects. Albumin, as a marker of plasma leakage, was also increased in the patients but not in the control subjects.

CONCLUSION

The underlying mechanisms for locally increased levels of hyaluronan and also albumin in the intestinal lumen may be secretion of lymph rich in hyaluronan and reflect the mucosal oedema. This capacity of the intestinal mucosa to react with lymph leakage towards a locally infused allergen may be a possible way to delineate gastrointestinal reactions in food-related disorders.

Kinetic retrieval of eosinophil cationic protein, hyaluronan, secretory IgA, albumin, and urea during BAL in healthy subjects

Determination of absolute concentrations of various soluble components of the epithelial lining fluid (ELF) may be valuable to estimate inflammatory activities within the underlying lung tissue. Internal standards may then be used as markers of dilution of bronchoalveolar lavage (BAL). The aim of this study was to determine whether different dwell times would affect the relationship between the concentrations of any of the three potential internal standards (secretory IgA [SIgA], albumin, and urea), and the concentrations of two potential markers of inflammation (eosinophil cationic protein [ECP] and hyaluronan [HA]) in BAL. A series of aliquots of BAL fluid were aspirated every 60 s up to 8 min after a bolus instillation of saline solution in 20 healthy subjects (10 smokers). The BAL concentrations of albumin and urea increased with time, consistent with continuous diffusion from the body water pool, absorption of the BAL fluid, or both. The rate constant of diffusion was 1,000 times higher for urea than for albumin (3.38 x 10(-1) and 3.64 x 10(-4), respectively), reflecting the difference in molecular weights, and in agreement with the notion that albumin and urea appeared in BAL fluid by a rate-limited procedure related to osmotic transfer. Biexponential increases of SIgA were recorded, suggesting a two-compartmental origin of this compound, normally located to mucosal membranes and presumed to be dissolved in ELF. Time-dependent increases in BAL fluid of HA also were recorded, but on the other hand, the ECP concentrations tended to level off after an initial increase, suggesting that the bulk of ECP appeared in BAL by a nonosmotic mechanism. We conclude that the kinetics of these three internal standards in BAL fluid differs greatly from each other and from the kinetics of the two selected markers of inflammation. Consequently, internal standards for determination of absolute concentrations of markers of inflammation in ELF should be carefully selected because of the requirement of matched kinetics of the markers.

Hyaluronan and myeloperoxidase in human peritoneal fluid during genital inflammation

The changes in concentration of hyaluronan (HYA) and myeloperoxidase in peritoneal fluid (PF) were studied during genital intraperitoneal inflammation. PF were collected from 111 women undergoing laparatomy for adhesiolysis and reconstructive surgery of the fallopian tubes, or laparoscopy in search of causes of infertility or low abdominal pain. When the number of leukocytes in the PF had been counted, the fluid samples were centrifuged and the supernatants analyzed for the concentrations of HYA and of myeloperoxidase. During genital inflammation, whether post-operative or postinfectious, leukocytosis and elevated levels of HYA and myeloperoxidase were found in the PF. Concentrations of these substances in the PF may be usable as clinical markers for genital inflammation.

Hyaluronan and myeloperoxidase in human peritoneal fluid during genital inflammation

The changes in concentration of hyaluronan (HYA) and myeloperoxidase in the peritoneal fluid (PF) were studied during genital intraperitoneal inflammation. PF were collected from 111 women undergoing laparotomy for adhesiolysis and reconstructive surgery of the fallopian tubes or laparoscopy in search of causes of infertility or low abdominal pain. When the number of leukocytes in the PF had been counted, the fluid samples were centrifuged and the supernatants analyzed for the concentrations of HYA and myeloperoxidase. During genital inflammation, whether postoperative or postinfectious, leukocytosis and elevated levels of HYA and myeloperoxidase were found in the PF. Concentrations of these substances in the PF may be usable as clinical markers for genital inflammation.

Concentration and turnover of intraperitoneal hyaluronan during inflammation

Aseptic peritonitis was induced in rabbits by intraperitoneal injection of irritating agents, mainly starch suspensions. The inflammatory response was followed in the peritoneal lavage fluid by cell counts (average increase about 800-fold the first day) and hyaluronan concentration (average increase about 200-fold on the second and third days). The turnover rate of hyaluronan was studied by injecting tritium-labeled hyaluronan intraperitoneally and by following the appearance of tritiated water in serum. In control animals given trace amounts of hyaluronan, half-lives of 1-14 h were recorded. When the labeled polysaccharide had been mixed with 10 mg/ml of unlabeled hyaluronan, the half-life was approximately one day. Rabbits with ongoing peritonitis exhibited half-lives between 1 and 16 h. It was concluded that there was a large individual variation in uptake kinetics, that the removal process could be receptor mediated, and that the increase in intraperitoneal hyaluronan in peritonitis mainly was due to an increased production of the polysaccharide rather than a decreased rate of removal.

Cytokine regulation of human lung fibroblast hyaluronan (hyaluronic acid) production. Evidence for cytokine-regulated hyaluronan (hyaluronic acid) degradation and human lung fibroblast-derived hyaluronidase

We characterized the mechanisms by which recombinant (r) tumor necrosis factor (TNF), IFN-gamma, and IL-1, alone and in combination, regulate human lung fibroblast hyaluronic acid (HA) production. Each cytokine stimulated fibroblast HA production. The combination of rTNF and rIFN-gamma resulted in a synergistic increase in the production of high molecular weight HA. This was due to a synergistic increase in hyaluronate synthetase activity and a simultaneous decrease in HA degradation. In contrast, when rTNF and rIL-1 were combined, an additive increase in low molecular weight HA was noted. This was due to a synergistic increase in hyaluronate synthetase activity and a simultaneous increase in HA degradation. Human lung fibroblasts contained a hyaluronidase that, at pH 3.7, depolymerized high molecular weight HA to 10-40 kD end products of digestion. However, hyaluronidase activity did not correlate with fibroblast HA degradation. Instead, HA degradation correlated with fibroblast-HA binding, which was increased by rIL-1 plus rTNF and decreased by rIFN-gamma plus rTNF. Recombinant IL-1 and rTNF weakly stimulated and rIL-1 and rTNF in combination further augmented the levels of CD44 mRNA in lung fibroblasts. In contrast, rIFN-gamma did not significantly alter the levels of CD44 mRNA in unstimulated or rTNF stimulated cells. These studies demonstrate that rIL-1, rTNF, and rIFN-gamma have complex effects on biosynthesis and degradation which alter the quantity and molecular weight of the HA produced by lung fibroblasts. They also show that fibroblast HA degradation is mediated by a previously unrecognized lysosomal-type hyaluronidase whose function may be regulated by altering fibroblast-HA binding. Lastly, they suggest that the CD44 HA receptor may be involved in this process.