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Hyperinflammation present in individuals with severe COVID-19 has been associated with an exacerbated cytokine production and hyperactivated immune cells. Endoplasmic reticulum stress leading to the unfolded protein response has been recently reported as an active player in inducing inflammatory responses. Once unfolded protein response is activated, GRP78, an endoplasmic reticulum–resident chaperone, is translocated to the cell surface (sGRP78), where it is considered a cell stress marker; however, its presence has not been evaluated in immune cells during disease. Here we assessed the presence of sGRP78 on different cell subsets in blood samples from severe or convalescent COVID-19 patients. The frequency of CD45+sGRP78+ cells was higher in patients with the disease compared to convalescent patients. The latter showed similar frequencies to healthy controls. In patients with COVID-19, the lymphoid compartment showed the highest presence of sGRP78+ cells versus the myeloid compartment. CCL2, TNF-α, C-reactive protein, and international normalized ratio measurements showed a positive correlation with the frequency of CD45+sGRP78+ cells. Finally, gene expression microarray data showed that activated T and B cells increased the expression of GRP78, and peripheral blood mononuclear cells from healthy donors acquired sGRP78 upon activation with ionomycin and PMA. Thus, our data highlight the association of sGRP78 on immune cells in patients with severe COVID-19.

Acute lymphocytic leukemia is the most common type of cancer in pediatric individuals. Glucose regulated protein (GRP78) is an endoplasmic reticulum chaperone that facilitates the folding and assembly of proteins and regulates the unfolded protein response pathway. GRP78 has a role in survival of cancer and metastasis and cell-surface associated GRP78 (sGRP78) is expressed on cancer cells but not in normal cells. Here, we explored the presence of sGRP78 in pediatric B-ALL at diagnosis and investigated the correlation with bona fide markers of leukemia. By using a combination of flow cytometry and high multidimensional analysis, we found a distinctive cluster containing high levels of sGRP78, CD10, CD19, and CXCR4 in bone marrow samples obtained from High-risk leukemia patients, which was absent in the compartment of Standard-risk leukemia. We confirmed that sGRP78+CXCR4+ blood-derived cells were more frequent in High-risk leukemia patients. Finally, we analyzed the dissemination capacity of sGRP78 leukemia cells in a model of xenotransplantation. sGRP78+ cells emigrated to the bone marrow and lymph nodes, maintaining the expression of CXCR4. Testing the presence of sGRP78 and CXCR4 together with conventional markers may help to achieve a better categorization of High and Standard-risk pediatric leukemia at diagnosis.

The process by which blood cells are generated has been widely studied in homeostasis and during pathogen-triggered inflammatory response. Recently, murine lungs have been shown to be a significant source of hematopoietic progenitors in a process known as extramedullary hematopoiesis. Using multiparametric flow cytometry, we have identified mesenchymal, endothelial, and hematopoietic progenitor cells that express the secreted small protein Isthmin 1 (ISM1). Further characterization of hematopoietic progenitor cells indicated that ISM1

Benzo[ghi]perylene is the most abundant polycyclic aromatic hydrocarbon in the atmosphere of highly polluted cities with high altitudes like Mexico City. We evaluated the in vitro cytotoxic and genotoxic effects that Benzo[ghi]perylene could induce to the bronchial cell line NL-20 after 3 h of exposure. Furthermore, exposed cells were washed and maintained for 24 h without the treatment (recovery time), in order to evaluate a persistent damage to the cells. We found that at 3 h of exposure, 20% and 47% of the cells displayed cytoplasmic vesicles (p 0.05) and ɣH2AX foci in the nuclei (p 0.05), respectively. Furthermore, 27% of cells showed translocation of the factor inductor apoptosis into the nuclei (p 0.05) and an increase of proliferating cells was also observed (21%, p 0.05). The cells after recovery time continued displaying morphological changes and ɣH2AX foci, despite of the increased expression (2-times fold change) of some DNA repair genes (p 0.05) found before the recovery time. We also found that the cell nuclei contained Benzo[ghi]perylene after the exposure and it remains there after the recovery time (p 0.01). Therefore, hereby we report the cytotoxic and genotoxic effects that Benzo[ghi]perylene is capable to induce to NL-20 cells.

Hematopoiesis is a highly regulated process and it’s widely described in bone marrow, the classical niche for hematopoietic stem cells (HSCs). The lungs are a novel niche of HSCs, as recently described by Lefrançais in 2017, however, little is known about the nature of these cells. Isthmin 1 (ISM1) is a secreted molecule important in developmental hematopoiesis in zebrafish; moreover, it is known that murine lungs express high levels of ISM1 and its secretion is altered after LPS challenge. In this work we performed multiparametric flow cytometry identifying a subpopulation of lung-resident HSCs expressing ISM1. Then we wanted to assess if HSCs ISM1+ cells are affected under inflammatory insults. Acute infection in mice with Pseudomonas aeruginosa showed that lung-derived HSCs ISM1+ are increased, indicating that the lung-HSCs are perturbed. Due to our model produced systemic inflammation we sought to investigate whether circulating ISM1+ cells were affected, we found that the percentage and absolute numbers of ISM1+ cells in blood were slightly diminished. Since ISM1 is a secreted molecule we evaluated its plasmatic levels by ELISA. We discovered a reduction in ISM1 plasmatic levels during murine sepsis with Pseudomonas aeruginosa. Then, we sought to analyze ISM1 levels in human inflammation; we retrieved samples from pediatric individuals with sepsis and adult patients with 2th and 3th grade burn injuries, and in both cases, we detected reduced levels of plasmatic ISM1. Our data suggest that ISM1 is likely a regulator of hematopoiesis in the lung but also may have a function in the regulation of systemic inflammation in mice and humans. We suggest that ISM1 is a novel biomarker of systemic inflammation.