Deposition of microparticles by neutrophils onto inflamed epithelium: a new mechanism to disrupt epithelial intercellular adhesions and promote transepithelial migration

Neutrophil [polymorphonuclear leukocyte (PMN)] transepithelial migration (TEM) is a hallmark of inflammatory mucosal disorders. PMN TEM is associated with epithelial injury; however, mechanisms involved in this process are not well defined. The current work describes a new mechanism whereby deposition of PMN membranederived microparticles (PMNâ MPs) onto intestinal epithelial cells (IECs) during TEM leads to loss of epithelial cadherins, thus promoting epithelial injury and increased PMN recruitment. PMNâ MPs secreted by activated PMNs during TEM displayed a high level of enzymatically activematrixmetalloproteinase 9 (MMPâ 9), and were capable of mediating potent effects on IEC integrity. Isolated PMNâ MPs efficiently bound to IEC monolayers and induced cleavage of desmogleinâ 2 (DSGâ 2) but not Eâ cadherin, leading to disruption of IEC intercellular adhesions. Furthermore, PMNâ MP binding to intestinal epithelium in vitro in transwell assays and in vivo in ligated intestinal loop preparations facilitated increases in PMN TEM. These effects were MMPâ 9 dependent and were reversed in the presence of specific pharmacological inhibitors. Finally, we demonstrated that IEC Dsgâ 2 serves as a barrier for migrating PMNs, and its removal by PMNâ MPâ associated MMPâ 9 facilitates PMNtrafficking across epithelial layers. Our findings thus implicate PMNâ MPs in PMNâ mediated inflammation and epithelial damage, as observed in inflammatory disorders ofmucosal surfaces.â Butinâ Israeli, V., Houser, M.C., Feng, M., Thorp, E. B., Nusrat, A., Parkos, C. A, Sumagin, R. Deposition of microparticles by neutrophils onto inflamed epithelium: anewmechanism to disrupt epithelial intercellular adhesions and promote transepithelialmigration. FASEB J. 30, 4007â 4020 (2016). www.fasebj.orgPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154234/1/fsb2fasebj30120734r.pd

DNA-Free Recombinant SV40 Capsids Protect Mice from Acute Renal Failure by Inducing Stress Response, Survival Pathway and Apoptotic Arrest

Viruses induce signaling and host defense during infection. Employing these natural trigger mechanisms to combat organ or tissue failure is hampered by harmful effects of most viruses. Here we demonstrate that SV40 empty capsids (Virus Like Particles-VLPs), with no DNA, induce host Hsp/c70 and Akt-1 survival pathways, key players in cellular survival mechanisms. We postulated that this signaling might protect against organ damage in vivo. Acute kidney injury (AKI) was chosen as target. AKI is critical, prevalent disorder in humans, caused by nephrotoxic agents, sepsis or ischemia, via apoptosis/necrosis of renal tubular cells, with high morbidity and mortality. Systemic administration of VLPs activated Akt-1 and upregulated Hsp/c70 in vivo. Experiments in mercury-induced AKI mouse model demonstrated that apoptosis, oxidative stress and toxic renal failure were significantly attenuated by pretreatment with capsids prior to the mercury insult. Survival rate increased from 12% to >60%, with wide dose response. This study demonstrates that SV40 VLPs, devoid of DNA, may potentially be used as prophylactic agent for AKI. We anticipate that these finding may be projected to a wide range of organ failure, using empty capsids of SV40 as well as other viruses

Regulation of Nucleotide Excision Repair by Nuclear Lamin B1

<div><p>The nuclear lamins play important roles in the structural organization and function of the metazoan cell nucleus. Recent studies on B-type lamins identified a requirement for lamin B1 (LB1) in the regulation of cell proliferation in normal diploid cells. In order to further investigate the function of LB1 in proliferation, we disrupted its normal expression in U-2 OS human osteosarcoma and other tumor cell lines. Silencing LB1 expression induced G1 cell cycle arrest without significant apoptosis. The arrested cells are unable to mount a timely and effective response to DNA damage induced by UV irradiation. Several proteins involved in the detection and repair of UV damage by the nucleotide excision repair (NER) pathway are down-regulated in LB1 silenced cells including DDB1, CSB and PCNA. We propose that LB1 regulates the DNA damage response to UV irradiation by modulating the expression of specific genes and activating persistent DNA damage signaling. Our findings are relevant to understanding the relationship between the loss of LB1 expression, DNA damage signaling, and replicative senescence.</p></div

Immunoblotting of NER associated proteins.

<p>Sc and shLB1 cells were harvested 8, 24 and 48 hr after UV irradiation and total cell lysates were analyzed. Non-irradiated cells from the same transfections are labeled (ct). GAPDH detection served as loading control.</p

Transient silencing of LB1 induces growth arrest in U-2 OS cells.

<p>A. The protein levels of LB1, LB2, and LA and C were assayed by immunoblotting at day 3 after electroporation with the vector encoding shRNA (shLB1) or a scrambled sequence (Sc). B. Relative expression levels of <i>LMNB1</i>, <i>LMNB2</i>, and <i>LMNA</i> mRNA in cells were determined by qRT-PCR at day 3 after silencing using GAPDH as a reference gene. The error bars represent standard deviation of the mean (n = 5). C. Growth rate of shLB1 and Sc cells were compared for 5 days following silencing. Growth rate was evaluated as previously described <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069169#pone.0069169-Shimi2" target="_blank">[17]</a> (n = 6, p = 5.24 ×10⁻⁷); error bars represent standard deviations.</p

Silencing LB1 expression in U-2 OS cells dramatically delays detection and repair of DNA damage induced by UV.

<p>Silenced and control cells were irradiated with 20 J/m² UV, fixed and stained at 8, 24, 48 and 80 hr with antibodies to LB1 (green) and 53BP1 (red); LB1 (green) and pRPA32 (red); and γH2AX (green) and DDB1 (red). No UV samples were from the same transfections. The borders of the nuclei were marked in white in the far right panels. Images of single representative nuclei are shown.</p

Delayed NER following UV irradiation of LB1 silenced cells.

<p>A. Detection of apoptosis in control (Sc) and LB1 silenced (shLB1) cells after 20 J/m² UV irradiation. Irradiated cells were harvested at 0, 24, 48 and 80 hr after irradiation, stained for Annexin V/PI, and examined by FACS (n = 4); error bars represent standard deviations. B. Detection of CPD by ELISA. Silenced and control cells where irradiated with 20 J/m² UV and harvested at the indicated times. CPD lesions were detected in genomic DNA by ELISA as described in Materials and Methods. The experiment was repeated 4 times, and each DNA sample was assayed by ELISA in quadruplicate; error bars represent standard deviations. Asterisks mark time points where significant differences in CPD clearance were observed between control (Sc) and LB1 silenced cells (shLB1): 8 hr p = 0.0057; 16 hr p = 0.001; 24 hr p = 0.0058; and 48 hr p = 0.0001.</p

Relative expression analysis of genes associated with NER.

<p>Expression analysis of NER, cell cycle regulation and DNA damage detection factors in LB1 silenced and control cells. mRNA from Sc and shLB1 U-2 OS cells was prepared at 3 days after silencing and analyzed by qRT-PCR using GAPDH as a reference gene. The change in expression of a specific gene was considered significant if the “fold change” was higher than 1.7 or lower than 0.6.</p

Deposition of microparticles by neutrophils onto inflamed epithelium: a new mechanism to disrupt epithelial intercellular adhesions and promote transepithelial migration

Neutrophil [polymorphonuclear leukocyte (PMN)] transepithelial migration (TEM) is a hallmark of inflammatory mucosal disorders. PMN TEM is associated with epithelial injury; however, mechanisms involved in this process are not well defined. The current work describes a new mechanism whereby deposition of PMN membranederived microparticles (PMNâ MPs) onto intestinal epithelial cells (IECs) during TEM leads to loss of epithelial cadherins, thus promoting epithelial injury and increased PMN recruitment. PMNâ MPs secreted by activated PMNs during TEM displayed a high level of enzymatically activematrixmetalloproteinase 9 (MMPâ 9), and were capable of mediating potent effects on IEC integrity. Isolated PMNâ MPs efficiently bound to IEC monolayers and induced cleavage of desmogleinâ 2 (DSGâ 2) but not Eâ cadherin, leading to disruption of IEC intercellular adhesions. Furthermore, PMNâ MP binding to intestinal epithelium in vitro in transwell assays and in vivo in ligated intestinal loop preparations facilitated increases in PMN TEM. These effects were MMPâ 9 dependent and were reversed in the presence of specific pharmacological inhibitors. Finally, we demonstrated that IEC Dsgâ 2 serves as a barrier for migrating PMNs, and its removal by PMNâ MPâ associated MMPâ 9 facilitates PMNtrafficking across epithelial layers. Our findings thus implicate PMNâ MPs in PMNâ mediated inflammation and epithelial damage, as observed in inflammatory disorders ofmucosal surfaces.â Butinâ Israeli, V., Houser, M.C., Feng, M., Thorp, E. B., Nusrat, A., Parkos, C. A, Sumagin, R. Deposition of microparticles by neutrophils onto inflamed epithelium: anewmechanism to disrupt epithelial intercellular adhesions and promote transepithelialmigration. FASEB J. 30, 4007â 4020 (2016). www.fasebj.or