Teil 4

Question 1

A laboratory has performed a whole body inhalation for a certain nanoparticle and has assessed the organ load of different organs. They could detect the nanoparticles for instance in the liver and the spleen of the animals. They concluded that the particles were taken up through the lung and have been transported to these secondary organs. a) Is this conclusion justified (please explain)? b) If you think it is not justified, what additional tests should be done in order to make such a conclusion?

Accepted Answer

a) not reasonable! •this is somehow possible => Systemic uptake via alveolar – capillary translocation •this mechanism is size dependent •they can just detect low amounts (approx. 2% of the lung dose could translocate to secondary organs) b) •they should measure the whole which is actually up taken by the animal (grooming, swallowing)•also they should measure the amount of swallowed NP => mark them with fluorescence marker (occurs often in whole body inhalation)

Question 2

a) Explain the mechanism for CNT toxicity in inhalation studies? b) Which physico-chemical parameters of the CNT are critical with respect to toxicity?

Accepted Answer

a) •CNT are mostly toxic by their size, shape (multi-needle fibre) and high surface reactivity b) •aspect ratio: aspect ratio (= length/ diameter) >3 => NP can’t be cleared, thin needle can pierce the cell •biopersistence => cell recruitment-injury-repair cycle is ongoing (clearance is insufficient) •Rigidy: the more rigid, the more needle-like (piercing of the cell, go into the cells without endocytosis) •Dustiness: can be inhaled easier => deposition into the lung

Question 3

Which of the following statements are right and which are wrong. a) The aerodynamic diameter of a particle decides about where inside the lung a particle will be primarily deposit. b) If particles reach the alvoeli of the lung this has to be considered in particular critical because inside the alveoli no clearance mechanisms exist. c) During inhalation particles may also directly reach the brain through olfactory bulb. d) Instillation and inhalation can be considered equivalent and will deliver similar results.

Accepted Answer

Which of the following statements are right and which are wrong. a) The aerodynamic diameter of a particle decides about where inside the lung a particle will be primarily deposit. b) If particles reach the alvoeli of the lung this has to be considered in particular critical because inside the alveoli no clearance mechanisms exist. c) During inhalation particles may also directly reach the brain through olfactory bulb. d) Instillation and inhalation can be considered equivalent and will deliver similar results.

Question 4

How much of biopersistent nanopartices that are deposited in the lung do you expect to be further transported into secondary organs in healthy conditions? a) Close to 100% b) Approx. 50% c) Little amounts, less then 5-10% => about 2% of the whole lung dose can translocate in the secondary organs

Accepted Answer

How much of biopersistent nanopartices that are deposited in the lung do you expect to be further transported into secondary organs in healthy conditions? c) Little amounts, less then 5-10% => about 2% of the whole lung dose can translocate in the secondary organs

Question 5

Which is the most influential parameter that determines transport efficiency into secondary organs for biopersistent NP?

Accepted Answer

•NP with a primary size (<100 nm but >10 nm)•agglomerate size between 100 nm and 1 μm•high density •Non-hygroscopic NP will not grow in size by water uptake, resulting in a higher chance to reach the alveoli•size distribution => the higher the difference, the higher the agglomeration

Question 6

a) Can you describe the difference between the two alveolar cell types? b) How this difference has an impact on the toxicology of NP?

Accepted Answer

a) •Type I cells: thin, flat, elongated => main cells in alveoli (covers 95% of the surface)•Type II cells: secrete pulmonary surfactant b) •human alveolar type I epithelial cells can internalize NP, whereas alveolar type II epithelial cells don’t

Question 7

Can you explain the adverse effect of a dose overload with NP?

Accepted Answer

•dose overload with NP → macrophages are eaten up with NP → still NP left, can be internalized by endocytosis and accumulate into the cells

Question 8

a) How are NP eliminated in the upper tracheobronchial and in the lower alveolar region? b) NP are usually not eliminated by the mucociliary escalator. Do you know why? c) Would it be possible to detect NP in secondary organs due to the elimination mechanism of the mucociliary escalator?

Accepted Answer

a) •tracheobronchial: by mucociliary escalator•alveolar region: are cleared by macrophages b) •The mucociliary escalator eliminates the majority of the inhaled particles of sizes greater than 6 μm => smaller particles rapidly reach the epithelium and preferentially deposit in the alveolar region c) •yes, NP which are eliminated by mucociliary escalator are propelled along with mucus out of trachea either by coughing or swallowing

Question 9

Which of these statements is truthful (with explanation)? a) In instillation studies it can be observed, that bigger particles in μm-range can be deposited, whereas in inhalation studies this can‘t be observed. b) Inhalation studies are less expensive, because the technical requirements and the amount of test substance are lower than in instillation studies, but they’re no accepted for regulatory purposes. c) Instilled doses are physiological, so they can be precisely controlled. d) In inhalation studies a continuous deposition and a equal distribution in the lungs are observable. e) An overload can just occur in instillation studies.

Accepted Answer

a) In instillation studies this can be observed, in inhalation studies that can be just observed in nm-range d) In inhalation studies a continuous deposition and a equal distribution in the lungs are observable, unlike instillation studies are characterized by high local concentrations and their unequal distribution

Question 10

a) Can you explain the low robustness of a whole-body study? b) By the other hand a nose-only study is often measured under non-physiological conditions. Why is that?

Accepted Answer

a) •grooming and swallowing cause an other internalization way of the NP•high amounts of NP are lost due to surface consumption b) •animal stress causes a irregular breathing => animal fights against the procedure

Question 11

a) How does the method of Broncho-Alveolar-Lavage work? b) Why is quartz often involved in those studies?

Accepted Answer

a) •a solution of 0,9% NaCl with our NP is instilled directly through a syringe into the nose of the mice and reaches fast the lungs of them => after their death the lung is taken out for measuring the differential analysis of cells b) •as a positive control => Quartz often induces inflammation

Question 12

Can you explain the assertion of a inflammation spidergramm?

Accepted Answer

•Quartz is used as a positive control => high cell number of Polymorphonuclear neutrophilic granulocytes, lymphocytes, macrophages and high concentration of enzymes like Lactate Dehydrogenase, Alkaline Phosphatase, N-Acetylaminglucosaminidase, γ-Glutamyltransferase •enzymes are used as a surrogate for cell toxicity and the cell are differentiated due to the kind of inflammation (PMN’s should be not so high in non-infectious ways) •pigment-grade TiO2 (200-300nm) is less toxic than nano-sized => deposition is less occuring

Question 13

What kind of physico-chemical properties are responsible for the a) impaired clearance of NP? b) deposition of NP? c) pulmonary inflammation of NP?

Accepted Answer

a) Impaired clearance •particle size: Particles/agglomerates of <100 nm are less efficiently phagocytised•shape: nano-fibres and –platelets are less efficiently cleared compared to spheres•charge: charged NP attract proteins and reduce their clearance (almost cationic → Phospholipids are negatively charged)•Resolving: none or slowly dissolving NP are less efficiently cleared compared to fast dissolving NP b) Deposition in alveoli (agglomerate) •NP with a primary size (<100 nm but >10 nm)•agglomerate size between 100 nm and 1 μm•high density •Non-hygroscopic NP will not grow in size by water uptake, resulting in a higher chance to reach the alveoli•size distribution => the higher the difference, the higher the agglomeration c) Pulmonary inflammation => after deposition in the alveoli •charge: Cationic particles are easily taken up by cells•resolving: fast dissolving NP can release toxic ions•surface: high surface reactivity can damage the lungs

Question 14

a) What is ALI? b) Do you an other in-vitro-method?

Accepted Answer

a) •dynamic direct exposure in vitro technique called air–liquid interface •offers a continuous contact between unmodified airborne chemicals and target cells and technically simulates in vivo inhalation exposure as closely as possible•particles not interacting with serum => no protein corona b) •triple-co-culture (epithelian cells are combined with macrophages and dendritic cells) => focuses on cell death, oxidative stress, inflammation•lung on a chip => shows an organ modell with effects of depositing or inflammation

Nanotoxikologie (Fach) / Teil 4 (Lektion)