Pseudomonas aeruginosa biofilm is a potent inducer of phagocyte hyperinflammation

Objective

Pseudomonas aeruginosa effectively facilitate resistance to phagocyte killing by biofilm formation. However, the cross talk between biofilm components and phagocytes is still unclear. We hypothesize that a biofilm provides a concentrated extracellular source of LPS, DNA and exopolysaccharides (EPS), which polarize neighbouring phagocytes into an adverse hyperinflammatory state of activation.

Methods

We measured the release of a panel of mediators produced in vitro by murine neutrophils and macrophages exposed to various biofilm components of P. aeruginosa cultures.

Results

We found that conditioned media from a high biofilm-producing strain of P. aeruginosa, PAR5, accumulated high concentrations of extracellular bacterial LPS, DNA and EPS by 72 h. These conditioned media induced phagocytes to release a hyperinflammatory pattern of mediators, with enhanced levels of TNF-α, IL-6, IL12p40, PGE₂ and NO. Moreover, the phagocytes also upregulated COX-2 and iNOS with no influence on the expression of arginase-1.

Conclusions

Phagocytes exposed to biofilm microenvironment, called by us biofilm-associated neutrophils/macrophages (BANs/BAMs), display secretory properties similar to that of N1/M1-type phagocytes. These results suggest that in vivo high concentrations of LPS and DNA, trapped in biofilm by EPS, might convert infiltrating phagocytes into cells responsible for tissue injury without direct contact with bacteria and phagocytosis.

     

Snuff use and smoking among senior high school students: effects of a snuff sales ban

OBJECTIVES: The popularity of snuff especially among adolescents is rising. The association between long-term snuff use and oral cancer discovered in epidemiological studies has prompted a variety of preventive measures to be taken to reduce snuff use and prevent adoption of the habit. In this study, the effect of a recent (I March, 1995) snuff sales ban introduced in Finland was investigated. Further, the rates of smoking, snuff use, alcohol use and drug experimenting were investigated before the introduction of the ban to characterize the study population.
DESIGN AND SUBJECTS: Two questionnaire studies were carried out. The first was carried out 3 months prior to the ban in 1994 and the second 9 months after the ban in 1995 in a senior high school population in southwestern Finland. The participants were 793 students (aged 15–22 years) in the first survey and 545 students (aged 16–23) in the second. Associations between variables were analyzed using cross-tabulation and stepwise logistic regression. The effects of the ban were determined on the basis of direct questions in the second questionnaire relating to the snuff sales ban.
RESULTS: Snuff was used by 9% of the students participating in the first study. The results of the second questionnaire indicate that the implementation of the snuff sales ban reduced the rate of snuff use by 1% in the study population. The majority of the snuff users (76%) reported that they had maintained their snuff habit. Of those reporting that they were snuff users before implementation of the snuff sales ban, 12% had switched to smoking and 5% to drugs.
CONCLUSIONS: The results of the present study suggest that the snuff sales ban in this population with a high rate of snuff use had little effect on snuff use rates and may have some short-term negative consequences as some snuff users switch to other substitutes, such as smoking, with known adverse health effects.     

Air particulate matter SRM 1648a primes macrophages to hyperinflammatory response after LPS stimulation

Objective

Exposure to air particulate matter (PM) is associated with chronic inflammatory and autoimmune diseases. Macrophages are responsible for the regulation of chronic inflammation. However, whether PM affects macrophage polarization remains unclear. The aim of this study was to evaluate whether nontoxic concentrations of urban PM are able to prime macrophages to altered inflammatory response upon LPS challenge.

Methods

We used two forms of the urban particulate matter SRM 1648a, intact PM and PM deprived of organic compounds (PM?C). Peritoneal murine macrophages were exposed to different concentrations of PM for 24 h and then challenged with LPS. Production of inflammatory mediators by macrophages was measured to test immunostimulatory/priming capacity of PM.

Results

Particulate matter used at non-cytotoxic concentrations induced a dose-dependent production of proinflammatory cytokines (TNF-α, IL-6, IL-12p40). By contrast, PM?C were not able to stimulate macrophages. However, macrophages primed with both forms of PM show proinflammatory response upon LPS challenge.

Conclusions

Our data indicate that exposure of macrophages to low concentrations of PM may prime the cells to hyperinflammatory response upon contact with LPS. Further studies are necessary to explain whether the exposure of patients suffering from chronic inflammatory diseases to particulate matter is responsible for the exacerbation of clinical symptoms during bacterial infections.

     

Concomitant dysregulation of androgen secretion and dysfunction of adipose tissue induced insulin resistance

Hyperandrogenism and hyperinsulinemia have resulted from dysfunction of the theca cell of the ovary and adipose tissue and each one potentiates the other in patients with androgen excess disorders e.g., polycystic ovary disease and idiopathic hirsutism. Possible external and/or internal triggers can produce such cellular dysfunction. There is evidence that sodium valproate acts as a trigger of cellular dysfunction and produces both hyperinsulinemia and hyperandrogenism. Therefore, the elimination of these triggers can help the patients to recover from hyperinsulinemia, insulin resistance and hyperandrogenism.     

Successful renal transplantation in a family with a novel mutation in COL4A3 gene and autosomal recessive Alport syndrome

Alport syndrome (AS) is an inherited disorder of basement membranes caused by mutations affecting specific proteins of the type IV collagen family, presenting with nephropathy and extrarenal manifestations such as sensorineural deafness and ocular anomalies. Ten percentage to 15% of the patients with AS have autosomal recessive (ARAS) due to mutation in either COL4A3 or COL4A4 gene. We report a novel mutation in the COL4A3 gene in an Indian family with ARAS. The above‐mentioned genetic anomaly was a missense variation in exon 26 of the COL4A3 gene (chr2:228137797G>A; c.1891G>A) that resulted in the amino acid substitution of Arginine for Glycine at codon 631 (p.Gly631Arg) that was present in the heterozygous state in the asymptomatic parents and homozygous state in the male offspring who presented with early‐onset end‐stage renal disease, lenticonus and hearing loss. The patient (male offspring) underwent successful renal transplantation with his mother as a donor.