Recent advances in the study of progranulin and its role in sepsis

Long non‑coding RNAs MALAT1, NEAT1 and DSCR4 can be serum biomarkers in predicting urosepsis occurrence and reflect disease severity

Sepsis commonly occurs in patients with serious infections. It severely threatens the health of patients and has very high mortality rates. Urosepsis is a type of sepsis in which the serious infection originates from the urinary system. Early diagnosis of the occurrence and severity of urogenital sepsis is crucial for improving patient prognosis. Long noncoding RNAs (LncRNAs) play important roles in the occurrence of a number of diseases, including sepsis, and can be potential biomarkers that predict disease development. The present study aimed to discover potential LncRNAs that can predict the occurrence of urosepsis. RNA-sequence data from patients with sepsis from the GEO database was analyzed and LncRNAs associated with sepsis were identified. The expression of LncRNAs associated with sepsis was tested in clinical urosepsis samples. Finally, the value of these LncRNAs in predicting urosepsis was verified using clinical samples. From the GEO database a total of nine LncRNAs (MALAT1, NEAT1, RMRP, LncIRX5, LINC01742, DSCR4, C22ORF34, LINC00381, and LINC01102) were identified that had expression changes corresponding with the occurrence of sepsis. Specifically, MALAT1, NEAT1 and DSCR4 revealed differential expression in patients with urosepsis. Moreover, MALAT1, and DSCR4 were shown to be significant risk indicators for urosepsis, and NEAT1 was shown to reflect disease severity. Therefore, the present study indicated that the LncRNAs, MALAT1, NEAT1 and DSCR4 can reflect the occurrence and severity of urosepsis and may act as potential biomarkers.

Progranulin in Musculoskeletal Inflammatory and Degenerative Disorders, Focus on Rheumatoid Arthritis, Lupus and Intervertebral Disc Disease: A Systematic Review

Progranulin (PGRN) is a glycoprotein formed by 593 amino acids encoded by the GRN gene. It has an important role in immunity and inflammatory response, as well as in tissue recovery. Its role in musculoskeletal inflammatory diseases such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and intervertebral disc degeneration disease (IVDD), is, nowadays, an important target to investigate. The objective of this review is to systematically sum up all the recent findings concerning PGRN as a target in the development and resolution of the inflammatory diseases. PubMed was examined with the terms combinations (Progranulin) AND (Lupus Erythematosus, Systemic), (Progranulin) AND (Arthritis, Rheumatoid), and (Progranulin) AND (Intervertebral Disc Degeneration). PubMed was examined with the terms combinations (Atsttrin) AND (Lupus Erythematosus, Systemic), (Atsttrin) AND (Arthritis, Rheumatoid), and (Atsttrin) AND (Intervertebral Disc Degeneration). Moreover, research through Web of Science was performed searching the same items. The inclusion criteria were: studies whose main topic were progranulin, or atsttrin, with emphasis on the three selected diseases. On the other hand, the exclusion criteria were studies that only focused on diseases not related to RA, lupus or IVDD, in addition to the previous published literature reviews. Since few results were obtained, we did not filter by year. The records assessed for eligibility were 23, including all the studies with the information in state of art of progranulin and its capability to be a potential target or treatment for each one of the selected diseases. As these results are descriptive and not clinical trials, we did not perform risk of bias methods. Within these results, many studies have shown an anti-inflammatory activity of PGRN in RA. PGRN levels in serum and synovial fluids in RA patients were reported higher than controls. On the other hand, serum levels were directly correlated with SLE disease activity index, suggesting an important role of PGRN as a player in the progression of inflammatory diseases and a therapeutical approach for the recovery. This review has some limitations due to the small number of studies in this regard; therefore, we highlight the importance and the necessity of further investigation. No external funding was implicated in this systematical review.

Progranulin regulates the development and function of NKT2 cells through EZH2 and PLZF

T helper 2 (Th2) cytokine production by invariant natural killer T (iNKT) cells is involved in the development of asthma, but the regulation of Th2 cytokines in iNKT cells remains unknown. Although it is known that progranulin (PGRN) induces the production of Th2 cytokines in iNKT cells in vivo, the underlying mechanism is not clear. This study aims to investigate the role of PGRN in iNKT cells. The effects of PGRN on the differentiation of iNKT cells was detected by flow cytometry. Then stimulation of iNKT cells and airway resistance were carried out to evaluate the function of PGRN on iNKT cells. Furthermore, the mechanisms of PGRN in regulating iNKT cells was investigated by RT-PCR, WB, confocal and luciferase reporter assays. The absolute number of iNKT cells decreased in PGRN KO mice despite an increase in the percentage of iNKT cells. Furthermore, analyzing the subsets of iNKT cells, we found that NKT2 cells and their IL-4 production were reduced. Mechanistically, the decrease in NKT2 cells in the PGRN KO mice was caused by increased expression of enhancer of zeste homolog 2 (EZH2), that in turn caused increased degradation and altered nuclear localization of PLZF. Interestingly, PGRN signaling decreased expression of EZH2 and treatment of the PGRN KO mice with the EZH2 specific inhibitor GSK343 rescued the defect in NKT2 differentiation, IL-4 generation, and PLZF expression. Altogether, We have revealed a new pathway (PGRN-EZH2-PLZF), which regulates the Th2 responses of iNKT cells and provides a potentially new target for asthma treatment.

Increased progranulin as an independent predictive biomarker for poor prognosis in sepsis

BACKGROUND

Recently, many diagnostic biomarkers were reported, but each had its own limitation. However, there is a need for an effective sensitivity and specificity of biomarker in diagnosis and prognosis of sepsis. In this context, progranulin (PGRN), at elevated levels, has been associated with poor prognosis in infectious diseases. Moreover, increased PGRN levels were seen in septic mice. As the prognostic value of PGRN in humans is unclear, we aimed to identify the predictive value of serum PGRN for the prognosis of sepsis.

METHODS

A total of 128 participants with sepsis and 58 healthy controls were recruited in this study. The levels of serum PGRN were detected by enzyme-linked immunosorbent assay. According to the outcomes, patients were divided into survival and non-survival groups.

RESULTS

Serum PGRN levels had upregulated in patients with sepsis compared with those in healthy controls (P < 0.001) as well as in non‑survivors compared with those in survivors (P < 0.001). Furthermore, serum PGRN levels exhibited positive correlation with hypersensitive C-reactive protein, procalcitonin, sepsis‑related organ failure assessment (SOFA) scores, and acute physiology and chronic health evaluation II (APACHE II) scores. PGRN had a higher predictive effect, especially the 28-day in-hospital mortality (p < 0.001), when using it with SOFA or APACHE II scores. Cox proportional regression analysis showed that PGRN was an independent predictor for 28-day mortality risk in sepsis.

CONCLUSIONS

PGRN, as a biomarker of sepsis, could improve the prognostic power of traditional parameters. This study is the first to report the clinical significance of PGRN levels in terms of the severity and prognosis of sepsis.

Integrated Single Cell and Bulk RNA-Seq Analysis Revealed Immunomodulatory Effects of Ulinastatin in Sepsis: A Multicenter Cohort Study

Sepsis is a leading cause of morbidity and mortality in the intensive care unit, which is caused by unregulated inflammatory response leading to organ injuries. Ulinastatin (UTI), an immunomodulatory agent, is widely used in clinical practice and is associated with improved outcomes in sepsis. But its underlying mechanisms are largely unknown. Our study integrated bulk and single cell RNA-seq data to systematically explore the potential mechanisms of the effects of UTI in sepsis. After adjusting for potential confounders in the negative binomial regression model, there were more genes being downregulated than being upregulated in the UTI group. These down-regulated genes were enriched in the neutrophil involved immunity such as neutrophil activation and degranulation, indicating the immunomodulatory effects of UTI is mediated via regulation of neutrophil activity. By deconvoluting the bulk RNA-seq samples to obtain fractions of cell types, the Myeloid-derived suppressor cells (MDSC) were significantly expanded in the UTI treated samples. Further cell-cell communication analysis revealed some signaling pathways such as ANEEXIN, GRN and RESISTIN that might be involved in the immunomodulatory effects of UTI. The study provides a comprehensive reference map of transcriptional states of sepsis treated with UTI, as well as a general framework for studying UTI-related mechanisms.

Progranulin as a Potential Therapeutic Target in Immune-Mediated Diseases

Progranulin (PGRN), a secretory glycoprotein consisting of 593 amino acid residues, is a key actor and regulator of multiple system functions such as innate immune response and inflammation, as well as tissue regeneration. Recently, there is emerging evidence that PGRN is protective in the development of a variety of immune-mediated diseases, including rheumatoid arthritis (RA), inflammatory bowel disease (IBD), type 1 diabetes mellitus (T1DM) and multiple sclerosis (MS) by regulating signaling pathways known to be critical for immunology, particularly the tumor necrosis factor alpha/TNF receptor (TNF-α/TNFR) signaling pathway. Whereas, the role of PGRN in psoriasis, systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) is controversial. This review summarizes the immunological functions of PGRN and its role in the pathogenesis of several immune-mediated diseases, in order to provide new ideas for developing therapeutic strategies for these diseases.