Collagen is a major structural protein in the matrix of animal cells and the most widely distributed and abundant functional protein in mammals. Collagen’s good biocompatibility, biodegradability and biological activity make it a very valuable biomaterial. According to the source of collagen, it can be broadly categorized into two types: one is animal collagen; the other is recombinant collagen. Animal collagen is mainly extracted and purified from animal connective tissues by chemical methods, such as acid, alkali and enzyme methods, etc. Recombinant collagen refers to collagen produced by gene splicing technology, where the amino acid sequence is first designed and improved according to one’s own needs, and the gene sequence of improved recombinant collagen is highly consistent with that of human beings, and then the designed gene sequence is cloned into the appropriate vector, and then transferred to the appropriate expression vector. The designed gene sequence is cloned into a suitable vector, and then transferred to a suitable expression system for full expression, and finally the target protein is obtained by extraction and purification technology. Recombinant collagen has excellent histocompatibility and water solubility, can be directly absorbed by the human body and participate in the construction of collagen, remodeling of the extracellular matrix, cell growth, wound healing and site filling, etc., which has demonstrated significant effects, and has become the focus of the development of modern biomedical materials. This paper firstly elaborates the structure, type, and tissue distribution of human collagen, as well as the associated genetic diseases of different types of collagen, then introduces the specific process of producing animal source collagen and recombinant collagen, explains the advantages of recombinant collagen production method, and then introduces the various systems of expressing recombinant collagen, as well as their advantages and disadvantages, and finally briefly introduces the application of animal collagen, focusing on the use of animal collagen in the development of biopharmaceutical materials. In terms of application, it focuses on the use of animal disease models exploring the application effects of recombinant collagen in wound hemostasis, wound repair, corneal therapy, female pelvic floor dysfunction (FPFD), vaginal atrophy (VA) and vaginal dryness, thin endometritis (TE), chronic endometritis (CE), bone tissue regeneration in vivo, cardiovascular diseases, breast cancer (BC) and anti-aging. The mechanism of action of recombinant collagen in the treatment of FPFD and CE was introduced, and the clinical application and curative effect of recombinant collagen in skin burn, skin wound, dermatitis, acne and menopausal urogenital syndrome (GSM) were summarized. From the exploratory studies and clinical applications, it is evident that recombinant collagen has demonstrated surprising effects in the treatment of all types of diseases, such as reducing inflammation, promoting cell proliferation, migration and adhesion, increasing collagen deposition, and remodeling the extracellular matrix. At the end of the review, the challenges faced by recombinant collagen are summarized: to develop new recombinant collagen types and dosage forms, to explore the mechanism of action of recombinant collagen, and to provide an outlook for the future development and application of recombinant collagen.

The innate immune system can be boosted in response to subsequent triggers by pre-exposure to microbes or microbial products, known as “trained immunity”. Compared to classical immune memory, innate trained immunity has several different features. Firstly, the molecules involved in trained immunity differ from those involved in classical immune memory. Innate trained immunity mainly involves innate immune cells (e.g., myeloid immune cells, natural killer cells, innate lymphoid cells) and their effector molecules (e.g., pattern recognition receptor (PRR), various cytokines), as well as some kinds of non-immune cells (e.g., microglial cells). Secondly, the increased responsiveness to secondary stimuli during innate trained immunity is not specific to a particular pathogen, but influences epigenetic reprogramming in the cell through signaling pathways, leading to the sustained changes in genes transcriptional process, which ultimately affects cellular physiology without permanent genetic changes (e.g., mutations or recombination). Finally, innate trained immunity relies on an altered functional state of innate immune cells that could persist for weeks to months after initial stimulus removal. An appropriate inducer could induce trained immunity in innate lymphocytes, such as exogenous stimulants (including vaccines) and endogenous stimulants, which was firstly discovered in bone marrow derived immune cells. However, mature bone marrow derived immune cells are short-lived cells, that may not be able to transmit memory phenotypes to their offspring and provide long-term protection. Therefore, trained immunity is more likely to be relied on long-lived cells, such as epithelial stem cells, mesenchymal stromal cells and non-immune cells such as fibroblasts. Epigenetic reprogramming is one of the key molecular mechanisms that induces trained immunity, including DNA modifications, non-coding RNAs, histone modifications and chromatin remodeling. In addition to epigenetic reprogramming, different cellular metabolic pathways are involved in the regulation of innate trained immunity, including aerobic glycolysis, glutamine catabolism, cholesterol metabolism and fatty acid synthesis, through a series of intracellular cascade responses triggered by the recognition of PRR specific ligands. In the view of evolutionary, trained immunity is beneficial in enhancing protection against secondary infections with an induction in the evolutionary protective process against infections. Therefore, innate trained immunity plays an important role in therapy against diseases such as tumors and infections, which has signature therapeutic effects in these diseases. In organ transplantation, trained immunity has been associated with acute rejection, which prolongs the survival of allografts. However, trained immunity is not always protective but pathological in some cases, and dysregulated trained immunity contributes to the development of inflammatory and autoimmune diseases. Trained immunity provides a novel form of immune memory, but when inappropriately activated, may lead to an attack on tissues, causing autoinflammation. In autoimmune diseases such as rheumatoid arthritis and atherosclerosis, trained immunity may lead to enhance inflammation and tissue lesion in diseased regions. In Alzheimer’s disease and Parkinson’s disease, trained immunity may lead to over-activation of microglial cells, triggering neuroinflammation even nerve injury. This paper summarizes the basis and mechanisms of innate trained immunity, including the different cell types involved, the impacts on diseases and the effects as a therapeutic strategy to provide novel ideas for different diseases.

Purpose: This study assessed the performance of the ultrasound-guided attenuation parameter (UGAP) in diagnosing and grading hepatic steatosis in patients with metabolic dysfunctionassociated steatotic liver disease (MASLD). Magnetic resonance imaging proton density fat fraction (MRI-PDFF) served as the reference standard. Methods: Patients with hepatic steatosis were enrolled in this prospective study and underwent UGAP measurements. MRI-PDFF values of ≥5%, ≥15%, and ≥25% were used as references for the diagnosis of steatosis grades ≥S1, ≥S2, and S3, respectively. Spearman correlation coefficients and area under the receiver operating characteristic curves (AUCs) were calculated. Results: Between July 2023 and June 2024, the study included 88 patients (median age, 40 years; interquartile range [IQR], 36 to 46 years), of whom 54.5% (48/88) were men and 45.5% (40/88) were women. Steatosis grades exhibited the following distribution: 22.7% (20/88) had S0, 50.0% (44/88) had S1, 21.6% (19/88) had S2, and 5.7% (5/88) had S3. The success rate for UGAP measurements was 100%. The median UGAP value was 0.74 dB/cm/MHz (IQR, 0.65 to 0.82 dB/ cm/MHz), and UGAP values were positively correlated with MRI-PDFF (r=0.77, P<0.001). The AUCs of UGAP for the diagnoses of ≥S1, ≥S2, and S3 steatosis were 0.91, 0.90, and 0.88, respectively. In the subgroup analysis, 98.4% (60/61) of patients had valid controlled attenuation parameter (CAP) values. UGAP measurements were positively correlated with CAP values (r=0.65, P<0.001). Conclusion Using MRI-PDFF as the reference standard, UGAP demonstrates good diagnostic performance in the detection and grading of hepatic steatosis in patients with MASLD.

Background/Aims: Extended hepatectomy combined with caudate lobe resection has been approved for the radical resection of hilar cholangiocarcinoma. There was a lack of credible research on the clinical value of caudate lobectomy (CL) for intrahepatic cholangiocarcinoma involving the hepatic hilus when combined with hepatectomy. We aimed to compare the short-term and long-term outcomes of the combined procedure with those of only CL for curative resection of intrahepatic cholangiocarcinoma involving the hepatic hilus. Methods: This single-center retrospective cohort study of patients with hilar cholangiocarcinoma was conducted from January 2007 to December 2021. Patients who underwent radical resection were enrolled in this study. The short-term and long-term clinical outcomes of the groups were compared before and after propensity score matching (PSM). Results: A total of 282 patients were included. There were no statistically significant differences in perioperative clinical outcomes between the CL group and the non-CL group before and after PSM. Compared to patients in the non-CL group, patients in the CL group had significantly longer overall survival before and after PSM (p=0.007 before PSM, p=0.033 after PSM). Moreover, compared to the non-CL group, the CL group had longer disease-free survival before and after PSM (p<0.001 before PSM, p=0.019 after PSM). Conclusions The postoperative complications of the CL group were comparable to those of the non-CL group. CL improved the long-term survival of patients with intrahepatic cholangiocarcinoma involving the hepatic hilus when combined with hepatectomy. Therefore, hepatectomy combined with caudate lobe resection should be performed for patients with hilar cholangiocarcinoma.

Purpose: This study assessed the performance of the ultrasound-guided attenuation parameter (UGAP) in diagnosing and grading hepatic steatosis in patients with metabolic dysfunctionassociated steatotic liver disease (MASLD). Magnetic resonance imaging proton density fat fraction (MRI-PDFF) served as the reference standard. Methods: Patients with hepatic steatosis were enrolled in this prospective study and underwent UGAP measurements. MRI-PDFF values of ≥5%, ≥15%, and ≥25% were used as references for the diagnosis of steatosis grades ≥S1, ≥S2, and S3, respectively. Spearman correlation coefficients and area under the receiver operating characteristic curves (AUCs) were calculated. Results: Between July 2023 and June 2024, the study included 88 patients (median age, 40 years; interquartile range [IQR], 36 to 46 years), of whom 54.5% (48/88) were men and 45.5% (40/88) were women. Steatosis grades exhibited the following distribution: 22.7% (20/88) had S0, 50.0% (44/88) had S1, 21.6% (19/88) had S2, and 5.7% (5/88) had S3. The success rate for UGAP measurements was 100%. The median UGAP value was 0.74 dB/cm/MHz (IQR, 0.65 to 0.82 dB/ cm/MHz), and UGAP values were positively correlated with MRI-PDFF (r=0.77, P<0.001). The AUCs of UGAP for the diagnoses of ≥S1, ≥S2, and S3 steatosis were 0.91, 0.90, and 0.88, respectively. In the subgroup analysis, 98.4% (60/61) of patients had valid controlled attenuation parameter (CAP) values. UGAP measurements were positively correlated with CAP values (r=0.65, P<0.001). Conclusion Using MRI-PDFF as the reference standard, UGAP demonstrates good diagnostic performance in the detection and grading of hepatic steatosis in patients with MASLD.

Purpose: This study assessed the performance of the ultrasound-guided attenuation parameter (UGAP) in diagnosing and grading hepatic steatosis in patients with metabolic dysfunctionassociated steatotic liver disease (MASLD). Magnetic resonance imaging proton density fat fraction (MRI-PDFF) served as the reference standard. Methods: Patients with hepatic steatosis were enrolled in this prospective study and underwent UGAP measurements. MRI-PDFF values of ≥5%, ≥15%, and ≥25% were used as references for the diagnosis of steatosis grades ≥S1, ≥S2, and S3, respectively. Spearman correlation coefficients and area under the receiver operating characteristic curves (AUCs) were calculated. Results: Between July 2023 and June 2024, the study included 88 patients (median age, 40 years; interquartile range [IQR], 36 to 46 years), of whom 54.5% (48/88) were men and 45.5% (40/88) were women. Steatosis grades exhibited the following distribution: 22.7% (20/88) had S0, 50.0% (44/88) had S1, 21.6% (19/88) had S2, and 5.7% (5/88) had S3. The success rate for UGAP measurements was 100%. The median UGAP value was 0.74 dB/cm/MHz (IQR, 0.65 to 0.82 dB/ cm/MHz), and UGAP values were positively correlated with MRI-PDFF (r=0.77, P<0.001). The AUCs of UGAP for the diagnoses of ≥S1, ≥S2, and S3 steatosis were 0.91, 0.90, and 0.88, respectively. In the subgroup analysis, 98.4% (60/61) of patients had valid controlled attenuation parameter (CAP) values. UGAP measurements were positively correlated with CAP values (r=0.65, P<0.001). Conclusion Using MRI-PDFF as the reference standard, UGAP demonstrates good diagnostic performance in the detection and grading of hepatic steatosis in patients with MASLD.

Background/Aims: Extended hepatectomy combined with caudate lobe resection has been approved for the radical resection of hilar cholangiocarcinoma. There was a lack of credible research on the clinical value of caudate lobectomy (CL) for intrahepatic cholangiocarcinoma involving the hepatic hilus when combined with hepatectomy. We aimed to compare the short-term and long-term outcomes of the combined procedure with those of only CL for curative resection of intrahepatic cholangiocarcinoma involving the hepatic hilus. Methods: This single-center retrospective cohort study of patients with hilar cholangiocarcinoma was conducted from January 2007 to December 2021. Patients who underwent radical resection were enrolled in this study. The short-term and long-term clinical outcomes of the groups were compared before and after propensity score matching (PSM). Results: A total of 282 patients were included. There were no statistically significant differences in perioperative clinical outcomes between the CL group and the non-CL group before and after PSM. Compared to patients in the non-CL group, patients in the CL group had significantly longer overall survival before and after PSM (p=0.007 before PSM, p=0.033 after PSM). Moreover, compared to the non-CL group, the CL group had longer disease-free survival before and after PSM (p<0.001 before PSM, p=0.019 after PSM). Conclusions The postoperative complications of the CL group were comparable to those of the non-CL group. CL improved the long-term survival of patients with intrahepatic cholangiocarcinoma involving the hepatic hilus when combined with hepatectomy. Therefore, hepatectomy combined with caudate lobe resection should be performed for patients with hilar cholangiocarcinoma.

Background/Aims: Extended hepatectomy combined with caudate lobe resection has been approved for the radical resection of hilar cholangiocarcinoma. There was a lack of credible research on the clinical value of caudate lobectomy (CL) for intrahepatic cholangiocarcinoma involving the hepatic hilus when combined with hepatectomy. We aimed to compare the short-term and long-term outcomes of the combined procedure with those of only CL for curative resection of intrahepatic cholangiocarcinoma involving the hepatic hilus. Methods: This single-center retrospective cohort study of patients with hilar cholangiocarcinoma was conducted from January 2007 to December 2021. Patients who underwent radical resection were enrolled in this study. The short-term and long-term clinical outcomes of the groups were compared before and after propensity score matching (PSM). Results: A total of 282 patients were included. There were no statistically significant differences in perioperative clinical outcomes between the CL group and the non-CL group before and after PSM. Compared to patients in the non-CL group, patients in the CL group had significantly longer overall survival before and after PSM (p=0.007 before PSM, p=0.033 after PSM). Moreover, compared to the non-CL group, the CL group had longer disease-free survival before and after PSM (p<0.001 before PSM, p=0.019 after PSM). Conclusions The postoperative complications of the CL group were comparable to those of the non-CL group. CL improved the long-term survival of patients with intrahepatic cholangiocarcinoma involving the hepatic hilus when combined with hepatectomy. Therefore, hepatectomy combined with caudate lobe resection should be performed for patients with hilar cholangiocarcinoma.

Purpose: This study assessed the performance of the ultrasound-guided attenuation parameter (UGAP) in diagnosing and grading hepatic steatosis in patients with metabolic dysfunctionassociated steatotic liver disease (MASLD). Magnetic resonance imaging proton density fat fraction (MRI-PDFF) served as the reference standard. Methods: Patients with hepatic steatosis were enrolled in this prospective study and underwent UGAP measurements. MRI-PDFF values of ≥5%, ≥15%, and ≥25% were used as references for the diagnosis of steatosis grades ≥S1, ≥S2, and S3, respectively. Spearman correlation coefficients and area under the receiver operating characteristic curves (AUCs) were calculated. Results: Between July 2023 and June 2024, the study included 88 patients (median age, 40 years; interquartile range [IQR], 36 to 46 years), of whom 54.5% (48/88) were men and 45.5% (40/88) were women. Steatosis grades exhibited the following distribution: 22.7% (20/88) had S0, 50.0% (44/88) had S1, 21.6% (19/88) had S2, and 5.7% (5/88) had S3. The success rate for UGAP measurements was 100%. The median UGAP value was 0.74 dB/cm/MHz (IQR, 0.65 to 0.82 dB/ cm/MHz), and UGAP values were positively correlated with MRI-PDFF (r=0.77, P<0.001). The AUCs of UGAP for the diagnoses of ≥S1, ≥S2, and S3 steatosis were 0.91, 0.90, and 0.88, respectively. In the subgroup analysis, 98.4% (60/61) of patients had valid controlled attenuation parameter (CAP) values. UGAP measurements were positively correlated with CAP values (r=0.65, P<0.001). Conclusion Using MRI-PDFF as the reference standard, UGAP demonstrates good diagnostic performance in the detection and grading of hepatic steatosis in patients with MASLD.

Background/Aims: Extended hepatectomy combined with caudate lobe resection has been approved for the radical resection of hilar cholangiocarcinoma. There was a lack of credible research on the clinical value of caudate lobectomy (CL) for intrahepatic cholangiocarcinoma involving the hepatic hilus when combined with hepatectomy. We aimed to compare the short-term and long-term outcomes of the combined procedure with those of only CL for curative resection of intrahepatic cholangiocarcinoma involving the hepatic hilus. Methods: This single-center retrospective cohort study of patients with hilar cholangiocarcinoma was conducted from January 2007 to December 2021. Patients who underwent radical resection were enrolled in this study. The short-term and long-term clinical outcomes of the groups were compared before and after propensity score matching (PSM). Results: A total of 282 patients were included. There were no statistically significant differences in perioperative clinical outcomes between the CL group and the non-CL group before and after PSM. Compared to patients in the non-CL group, patients in the CL group had significantly longer overall survival before and after PSM (p=0.007 before PSM, p=0.033 after PSM). Moreover, compared to the non-CL group, the CL group had longer disease-free survival before and after PSM (p<0.001 before PSM, p=0.019 after PSM). Conclusions The postoperative complications of the CL group were comparable to those of the non-CL group. CL improved the long-term survival of patients with intrahepatic cholangiocarcinoma involving the hepatic hilus when combined with hepatectomy. Therefore, hepatectomy combined with caudate lobe resection should be performed for patients with hilar cholangiocarcinoma.