Neutrophils play a crucial role in eliminating bacteria that invade the human body; however, cathepsin G can induce biofilm formation in a non-biofilm-forming Staphylococcus epidermidis 1457 strain, suggesting that neutrophil proteases may be involved in biofilm formation. Cathepsin G, cathepsin B, proteinase-3, and metalloproteinase-9 (MMP-9) from neutrophils were tested on the biofilm induction in commensal (skin isolated) and clinical non-biofilm-forming S. epidermidis isolates. From 81 isolates, 53 (74%) were aap⁺, icaA⁻, icaD⁻ genotype, and without the capacity of biofilm formation under conditions of 1% glucose, 4% ethanol or 4% NaCl, but these 53 non-biofilm-forming isolates induced biofilm by the use of different neutrophil proteases. Of these, 62.3% induced biofilm with proteinase-3, 15% with cathepsin G, 10% with cathepsin B and 5% with MMP -9, where most of the protease-induced biofilm isolates were commensal strains (skin). In the biofilm formation kinetics analysis, the addition of phenylmethylsulfonyl fluoride (PMSF; a proteinase-3 inhibitor) showed that proteinase-3 participates in the cell aggregation stage of biofilm formation. A biofilm induced with proteinase-3 and DNAse-treated significantly reduced biofilm formation at an early time (initial adhesion stage of biofilm formation) compared to untreated proteinase-3-induced biofilm (p < 0.05). A catheter inoculated with a commensal (skin) non-biofilm-forming S. epidermidis isolate treated with proteinase-3 and another one without the enzyme were inserted into the back of a mouse. After 7 days of incubation period, the catheters were recovered and the number of grown bacteria was quantified, finding a higher amount of adhered proteinase-3-treated bacteria in the catheter than non-proteinase-3-treated bacteria (p < 0.05). Commensal non-biofilm-forming S. epidermidis in the presence of neutrophil cells significantly induced the biofilm formation when multiplicity of infection (MOI) 1:0.01 (neutrophil:bacteria) was used, but the addition of a cocktail of protease inhibitors impeded biofilm formation. A neutrophil:bacteria assay did not induce neutrophil extracellular traps (NETs). Our results suggest that neutrophils, in the presence of commensal non-biofilm-forming S. epidermidis, do not generate NETs formation. The effect of neutrophils is the production of proteases, and proteinase-3 releases bacterial DNA at the initial adhesion, favoring cell aggregation and subsequently leading to biofilm formation.

Actualmente la nanotecnología es parte de la cuarta revolución industrial, ha aportado los avances científico-tecnológicos más importantes que haya conocido la humanidad. Gracias a ella ha sido posible aumentar la velocidad de los procesadores de computadoras, desarrollar materiales inteligentes, excluir contaminantes del agua, tierra y aire, diagnosticar y excluir a células cancerosas y en la liberación controlada de fármacos. Sin embargo, existen riesgos para el ser humano, en primer lugar, los efectos biológicos y químicos provocados por la exposición a las nanopartículas y, la eliminación de estos materiales al medio ambiente, que pueden afectar a los organismos y ecosistemas. La nanotoxicología determina la relación entre estructura y función de las nanopartículas con su toxicidad. En los últimos años se ha buscado reglamentar la bioseguridad en el uso de nanopartículas. Este trabajo aborda una revisión bibliográfica extensa de las pruebas toxicológicas para evaluar los efectos en la salud, provocados por la exposición a las nanopartículas