Second harmonic generation microscopy reveals altered collagen microstructure in usual interstitial pneumonia versus healthy lung

Kottmann, R. Matthew; Sharp, Jesse; Owens, Kristina M.; Salzman, Peter; Xiao, Guang‐Qian; Phipps, Richard P.; Sime, Patricia J.; Brown, Edward B.; Perry, Seth W.

doi:10.1186/s12931-015-0220-8

Cited by 40 publications

(36 citation statements)

References 57 publications

(72 reference statements)

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“…Specifically, patients with CTD-associated lung fibrosis typically have a spectrum of diseases including non-specific interstitial pneumonia (NSIP), NSIP with fibrosis, usual interstitial pneumonia (UIP) and cryptogenic organising pneumonia, all of which can be seen in multiple lung biopsies from the same individual 18. In some of these conditions the collagen fibrils within the extracellular matrix are smaller in diameter, less densely packed and more disorganised with lower levels of cross-linking than in UIP,19 making resolution more likely in response to therapy.…”

Section: Discussionmentioning

confidence: 99%

Transitions to different patterns of interstitial lung disease in scleroderma with and without treatment

et al. 2016

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Section: Discussionmentioning

confidence: 99%

Transitions to different patterns of interstitial lung disease in scleroderma with and without treatment

et al. 2016

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“…This resulted in a slice spacing of 3.4 µm, but the imaging acquisition time proved to be prohibitively long for imaging the entire lung at this higher resolution (≈ 40 min for a single z-stack). In all images reported here, lung structure was visualized by taking advantage of the intrinsic autofluorescence from cells and extracellular matrix of lung tissue [10][11][12] .…”

Section: Methodsmentioning

confidence: 99%

Self-organizing pattern of subpleural alveolar ducts

Mitzner¹,

Loube²,

Venezia³

et al. 2020

Sci Rep

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in this study we have utilized an optical clearing method to allow visualization of a heretofore undescribed subpleural acinar structural organization in the mammalian lung. the clearing method enables visualization of the lung structure deep below the visceral pleura in intact inflated lungs. In addition to confirming previous observations that the immediate subpleural alveoli are uniform in appearance, we document for the first time that the subpleural lung parenchyma is much more uniformly organized than the internal parenchyma. Specifically, we report that below the surface layer of alveoli, there is a striking parallel arrangement of alveolar ducts that all run perpendicular to the visceral pleural surface. A three dimensional visualization of alveolar ducts allowed for a calculation of the average inner to outer duct diameter ratio of 0.53 in these subpleural ducts. This unique, selforganizing parallel duct structure likely impacts both elastic recoil and the transmission of tethering forces in healthy and diseased lungs.Alveoli in the region just below the pleural surface have been examined by light microscopy since the 1930s 1-7 . These studies have often examined how the alveoli expand with lung inflation and how they might change with lung pathology. However, because light scattering from alveolar walls limits the depth of visualization with conventional light microscopy, there has always been some question as to whether this subpleural alveolar anatomy is representative of the structure throughout the lung. On the one hand the relatively thick visceral pleura forms a fixed boundary to one facet of an alveolus, and this must offer a level of constraint that is not present in internal alveoli. On the other hand, there are on the order of a dozen or so facets of an alveolus that are not constrained by being connected to the relatively thick pleura, so the degree to which the presence of a pleural boundary affects alveolar structure is not well understood. That there might be a difference in structural organization near the pleura was shown by a study where the mean airspace chord length was shown to be smaller when assessed closer to the visceral pleura 8 . Although it is clear from light microcopy that there are alveoli immediately under the pleural surface, there has been no information of how the alveolar duct might be oriented in this region. Traditionally, the terminal airways (respiratory bronchioles and alveolar ducts) are assumed to be somewhat randomly oriented in the lung. However, a random orientation would predict that a certain percentage of the ducts would run parallel to the pleural surface, a situation that would seem to be structurally and mechanically untenable.In the present work, we sought to address this anatomical issue by examining the subpleural terminal lung structure using confocal fluorescent microscopy of optically cleared lungs. The optical clearing method permits imaging in the mouse lung to depths exceeding 30 alveolar diameters into the lung, allowing optical serial section...

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“…SHG microscopy, which reveals changes in collagen microstructure, was used to evaluate collagen fiber organization. Unstained 22 μm-thick tissue sections were imaged for F SHG and B SHG signals using a multiphoton microscope (Nikon A1R MP+ Multiphoton), providing 2-photon (2P) excitation (41). The F SHG /B SHG pixel ratio was calculated to assess relative differences in fibrillar collagen microstructure (assessed as percent of collagen-rich area with F SHG /B SHG pixel intensity > 1).…”

Section: Methodsmentioning

confidence: 99%

TLR4-dependent fibroblast activation drives persistent organ fibrosis in skin and lung

Bhattacharyya

Wang²,

Qin

et al. 2018

JCI Insight

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Persistent fibrosis in multiple organs is the hallmark of systemic sclerosis (SSc). Recent genetic and genomic studies implicate TLRs and their damage-associated molecular pattern (DAMP) endogenous ligands in fibrosis. To test the hypothesis that TLR4 and its coreceptor myeloid differentiation 2 (MD2) drive fibrosis persistence, we measured MD2/TLR4 signaling in tissues from patients with fibrotic SSc, and we examined the impact of MD2 targeting using a potentially novel small molecule. Levels of MD2 and TLR4, and a TLR4-responsive gene signature, were enhanced in SSc skin biopsies. We developed a small molecule that selectively blocks MD2, which is uniquely required for TLR4 signaling. Targeting MD2/TLR4 abrogated inducible and constitutive myofibroblast transformation and matrix remodeling in fibroblast monolayers, as well as in 3-D scleroderma skin equivalents and human skin explants. Moreover, the selective TLR4 inhibitor prevented organ fibrosis in several preclinical disease models and mouse strains, and it reversed preexisting fibrosis. Fibroblast-specific deletion of TLR4 in mice afforded substantial protection from skin and lung fibrosis. By comparing experimentally generated fibroblast TLR4 gene signatures with SSc skin biopsy gene expression datasets, we identified a subset of SSc patients displaying an activated TLR4 signature. Together, results from these human and mouse studies implicate MD2/TLR4-dependent fibroblast activation as a key driver of persistent organ fibrosis. The results suggest that SSc patients with high TLR4 activity might show optimal therapeutic response to selective inhibitors of MD2/TLR4 complex formation.

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Second harmonic generation microscopy reveals altered collagen microstructure in usual interstitial pneumonia versus healthy lung

Cited by 40 publications

References 57 publications

Transitions to different patterns of interstitial lung disease in scleroderma with and without treatment

Transitions to different patterns of interstitial lung disease in scleroderma with and without treatment

Self-organizing pattern of subpleural alveolar ducts

TLR4-dependent fibroblast activation drives persistent organ fibrosis in skin and lung

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