Expression and significance of procalcitonin, leukotriene B4, serum amyloid A, and C-reactive protein in children with different types of pneumonia: An observational study.

This study aimed to investigate the expression and significance of serum procalcitonin (PCT), leukotriene B4 (LTB4), Serum amyloid A (SAA), and C-reactive protein (CRP) in children with different types of pneumonia caused by different pathogenic infections. One hundred and one children with pneumonia admitted to The Fifth People Hospital of Zhuhai from July 2019 to June 2020 were enrolled and divided into 38 cases in the bacterial group, 30 cases in the mycoplasma group, and 33 cases in the virus group according to the different types of pathogens. The patients were divided into 42 cases in the noncritical group, 33 cases in the critical group, and 26 cases in the very critical group according to the pediatric clinical illness score (PCIS), and 30 healthy children were selected as the control group during the same period. Comparison of serum PCT, SAA: bacterial group > mycoplasma group > viral group > control group with significant differences (P < .05). Receiver operator characteristic (ROC) analysis showed that the area under the curves (AUCs) of serum PCT, LTB4, SAA, and CRP for the diagnosis of bacterial pneumonia were 1.000, 0.531, 0.969, and 0.833, respectively, and the AUCs for the diagnosis of mycoplasma pneumonia were 0.653, 0.609, 0.547, and 0.652, respectively, and the AUCs for the diagnosis of viral pneumonia were 0.888, 0.570, 0.955, and 1.000, respectively. Comparison of serum PCT, LTB4, SAA: very critical group > critical group > noncritical group > control group, with significant differences (P < .05). Serum PCT, LTB4, and SAA were negatively correlated with PCIS score by Pearson analysis (P < .05). Serum PCT and SAA showed diagnostic value for bacterial pneumonia, and serum SAA and CRP showed diagnostic value for viral pneumonia; serum PCT, LTB4, and SAA correlate with severity of disease and show higher expression with worsening of the condition.

Serum Amyloid A as a non-invasive predictive biomarker of mucosal healing in ulcerative colitis patients.

Ulcerative colitis is a chronic immune-mediated inflammatory condition of large intestine that is frequently associated with inflammation of the rectum but often extends proximally to involve other areas of the colon. The ultimate target of therapy is complete healing in the form of clinical remission, complete endoscopic and histological healing, and transmural healing for which endoscopy is mandatory. Colonoscopy may not always be applicable due to possible complications in active ulcerative colitis. Therefore, non-invasive biomarkers are needed to avoid the disadvantageous complications of invasive diagnostic procedures. The aim of this study was to evaluate the role of serum Amyloid-A (SAA) as a non-invasive predictive biomarker of mucosal healing in comparison to different laboratory biomarkers, and endoscopic activity scores. The study included 100 ulcerative colitis patients classified into two groups: 50 patients in clinical, and biochemical remission and 50 patients in activity. Complete blood picture, C-reactive protein, erythrocyte sedimentation rate, fecal calprotectin, and SAA were measured and recorded, colonoscopies with histopathological examination were done for all patients. SAA levels were significantly higher in patients with active ulcerative colitis than in clinical remission patients (p < 0.001). In clinical, remission patients without full mucosal healing, SAA was positively correlated with endoscopic disease activity represented with Mayo score, Mayo endoscopic sub-score and Ulcerative Colitis Endoscopic Index of Severity (UCEIS) (p < 0.001). However, there was no significant correlation between SAA and endoscopic scores among the activity patients' group. The cut off value of SAA for determining disease activity was > 5.199 µg/ml with 100 % sensitivity, specificity of 92 %, and accuracy of 99.6%. In conclusion, SAA can be used for prediction of mucosal healing in ulcerative colitis remission patients despite not being superior to fecal calprotectin. However, it was unable to differentiate between the different disease activities or extents.

Simultaneous determination of inflammatory factors SAA and LTF based on stable element labeling and inductively coupled plasma mass spectrometry to aid in the diagnosis of infection.

OBJECTIVE: The clinical value of Serum amyloid A (SAA) and Lactoferrin (LTF) has received significant attention, but their detection methods are inadequate, which limits their application. This study aims to develop a dual detection method based on stable element labeling strategies and inductively coupled plasma mass spectrometry (ICP-MS) for SAA/LTF and to assess whether it can be widely used in clinical practice. METHODS: A duplex immunoassay system based on sandwich method was constructed. After optimization, methodological evaluation was performed with the guidelines of Clinical Laboratory Standards Institute (CLSI). Finally, 131 plasma samples were collected to analyze whether the new method is suitable for clinical detection. RESULTS: The LoB, LLoQ, ULoQ, and linear range of the assay were 1.09 ng/mL, 3 ng/mL, 1500 ng/mL, 3-1500 ng/mL for SAA and 0.85 ng/mL, 2 ng/mL, 1200 ng/mL, 2-1200 ng/mL for LTF respectively. The recovery rates were 95.01% to 106.26%, the intra-batch precision of low, intermediate, and high-level samples was <8%, and the inter-batch of them was <11%, the deviation of interference test results was less than±10%. The Area Under the Curve (AUC) was 0.9809 for SAA, 0.8599 for LTF, and 0.9986 for combination. CONCLUSION: The quantitative duplex immunoassay for SAA/LTF has high accuracy, good precision, and high specificity, which meets the clinical testing requirements and can be widely used in clinical practice.

Historic characteristics and mortality of patients in the Swiss Amyloidosis Registry.

AIMS OF THE STUDY: Systemic amyloidoses are rare protein-folding diseases with heterogeneous, often nonspecific clinical presentations. To better understand systemic amyloidoses and to apply state-of-the-art diagnostic pathways and treatment, the interdisciplinary Amyloidosis Network was founded in 2013 at University Hospital Zurich. In this respect, a registry was implemented to study the characteristics and life expectancy of patients with amyloidosis within the area covered by the network. Patient data were collected retrospectively for the period 2005-2014 and prospectively from 2015 onwards. METHODS: Patients aged 18 years or older diagnosed with any subtype of systemic amyloidosis were eligible for inclusion if they were treated in one of the four referring centres (Zurich, Chur, St Gallen, Bellinzona). Baseline data were captured at the time of diagnosis. Follow-up data were assessed half-yearly for the first two years, then annually. RESULTS: Between January 2005 and March 2020, 247 patients were screened, and 155 patients with confirmed systemic amyloidosis were included in the present analysis. The most common amyloidosis type was light-chain (49.7%, n = 77), followed by transthyretin amyloidosis (40%, n = 62) and amyloid A amyloidosis (5.2%, n = 8). Most patients (61.9%, n = 96) presented with multiorgan involvement. Nevertheless, single organ involvement was seen in all types of amyloidosis, most commonly in amyloid A amyloidosis (75%, n = 6). The median observation time of the surviving patients was calculated by the reverse Kaplan-Meier method and was 3.29 years (95% confidence interval [CI] 2.33-4.87); it was 4.87 years (95% CI 3.14-7.22) in light-chain amyloidosis patients and 1.85 years (95% CI 1.48-3.66) in transthyretin amyloidosis patients, respectively. The 1-, 3- and 5-year survival rates were 87.0% (95% CI 79.4-95.3%), 68.5% (95% CI 57.4-81.7%) and 66.0% (95% CI 54.6-79.9%) respectively for light-chain amyloidosis patients and 91.2% (95% CI 83.2-99.8%), 77.0% (95% CI 63.4-93.7%) and 50.6% (95% CI 31.8-80.3%) respectively for transthyretin amyloidosis patients. There was no significant difference between the two groups (p = 0.81). CONCLUSION: During registry set-up, a more comprehensive work-up of our patients suffering mainly from light-chain amyloidosis and transthyretin amyloidosis was implemented. Survival rates were remarkably high and similar between light-chain amyloidosis and transthyretin amyloidosis, a finding which was noted in similar historic registries of international centres. However, further studies are needed to depict morbidity and mortality as the amyloidosis landscape is changing rapidly.

Hepatocytes coordinate immune evasion in cancer via release of serum amyloid A proteins.

T cell infiltration into tumors is a favorable prognostic feature, but most solid tumors lack productive T cell responses. Mechanisms that coordinate T cell exclusion are incompletely understood. Here we identify hepatocyte activation via interleukin-6/STAT3 and secretion of serum amyloid A (SAA) proteins 1 and 2 as important regulators of T cell surveillance of extrahepatic tumors. Loss of STAT3 in hepatocytes or SAA remodeled the tumor microenvironment with infiltration by CD8+ T cells, while interleukin-6 overexpression in hepatocytes and SAA signaling via Toll-like receptor 2 reduced the number of intratumoral dendritic cells and, in doing so, inhibited T cell tumor infiltration. Genetic ablation of SAA enhanced survival after tumor resection in a T cell-dependent manner. Likewise, in individuals with pancreatic ductal adenocarcinoma, long-term survivors after surgery demonstrated lower serum SAA levels than short-term survivors. Taken together, these data define a fundamental link between liver and tumor immunobiology wherein hepatocytes govern productive T cell surveillance in cancer.

MMPs-related risk model identification and SAA1 promotes clear cell renal cell carcinoma migration via ERK-AP1-MMPs axis.

Matrix Metalloproteinases (MMPs) have been demonstrated to be essential in facilitating the migration and metastasis of clear cell renal cell carcinoma (ccRCC). However, the ability of the MMP family to predict clinical outcomes and guide optimal therapeutic strategies for ccRCC patients remains incompletely understood. In this investigation, we initially conducted a thorough examination of the MMP family in pan-cancer. Notably, MMPs exhibited distinctive significance in ccRCC. Following this, we undertook an extensive analysis to evaluate the clinical value of MMPs and potential mechanisms by which MMPs contribute to the progression of ccRCC. A novel stratification method and prognostic model were developed based on MMPs in order to enhance the accuracy of prognosis prediction for ccRCC patients and facilitate personalized treatment. By conducting multi-omics analysis and transcriptional regulation analysis, it was hypothesized that SAA1 plays a crucial role in promoting ccRCC migration through MMPs. Subsequently, in vitro experiments confirmed that SAA1 regulates ccRCC cell migration via the ERK-AP1-MMPs axis. In conclusion, our study has explored the potential value of the MMP family as prognostic markers for ccRCC and as guides for medication regimens. Additionally, we have identified SAA1 as a crucial factor in the migration of ccRCC.

Structural studies of a serum amyloid A octamer that is primed to scaffold lipid nanodiscs.

Serum amyloid A (SAA) is a highly conserved acute-phase protein that plays roles in activating multiple pro-inflammatory pathways during the acute inflammatory response and is commonly used as a biomarker of inflammation. It has been linked to beneficial roles in tissue repair through improved clearance of lipids and cholesterol from sites of damage. In patients with chronic inflammatory diseases, elevated levels of SAA may contribute to increased severity of the underlying condition. The majority of circulating SAA is bound to lipoproteins, primarily high-density lipoprotein (HDL). Interaction with HDL not only stabilizes SAA but also alters its functional properties, likely through altered accessibility of protein-protein interaction sites on SAA. While high-resolution structures for lipid-free, or apo-, forms of SAA have been reported, their relationship with the HDL-bound form of the protein, and with other possible mechanisms of SAA binding to lipids, has not been established. Here, we have used multiple biophysical techniques, including SAXS, TEM, SEC-MALS, native gel electrophoresis, glutaraldehyde crosslinking, and trypsin digestion to characterize the lipid-free and lipid-bound forms of SAA. The SAXS and TEM data show the presence of soluble octamers of SAA with structural similarity to the ring-like structures reported for lipid-free ApoA-I. These SAA octamers represent a previously uncharacterized structure for lipid-free SAA and are capable of scaffolding lipid nanodiscs with similar morphology to those formed by ApoA-I. The SAA-lipid nanodiscs contain four SAA molecules and have similar exterior dimensions as the lipid-free SAA octamer, suggesting that relatively few conformational rearrangements may be required to allow SAA interactions with lipid-containing particles such as HDL. This study suggests a new model for SAA-lipid interactions and provides new insight into how SAA might stabilize protein-lipid nanodiscs or even replace ApoA-I as a scaffold for HDL particles during inflammation.

Detection of haptoglobin and serum amyloid A as biomarkers in naturally infected Mycoplasma bovis calves.

The livestock sector of Pakistan is increasing rapidly and it plays important role both for rural community and national economy. It is estimated that almost 8 million rural people are involved in livestock rearing and earning about 35-40 % of their income from the livestock sector. Mycoplasma bovis (M. bovis) infection causes significant economic losses in dairy animals especially young calf in the form of clinical illnesses such as pneumonia, poly-arthritis, respiratory distress and mortality. M. bovis is hard to diagnose and control because of uneven disease appearance and it is usually noticed in asymptomatic animals. For the identification of M. bovis in sub-clinical and clinical samples, determination of acute phase proteins i.e., haptoglobin (Hp) and serum amyloid A (SAA) are important tools for the timely diagnosis of disease. Therefore, early diagnosis of disease and hemato-biochemical changes are considered beneficial tools to control the infectious agent to uplift the economy of the dairy farmers. For this purpose, blood samples were collected from 200 calves of Bovidae family. Serum was separated from blood samples to determine the concentration of Hp and SAA, while blood samples were processed to determine hematological changes in blood from calves by using hematological analyzer. The blood plasma obtained from the blood samples was processed to measure oxidative stress factors. Lungs tissues from slaughterhouses/ morbid calves were collected to observe histopathological changes. The results of present study indicated that level of SAA and Hp remarkably increased (P < 0.05) in M. bovis infected calves in comparison to healthy calves. The oxidative stress markers indicated that nitric oxide and MDA levels in the infected calves increased significantly (P < 0.05), while infected claves had considerably lower levels of superoxide dismutase, catalase and glutathione. These findings indicate that oxidative stress play role to increase the level of APPs, while monitoring of APPs levels may serve as a valuable addition to the clinical evaluation of naturally infected calves with M. bovis. The hematological parameters were decreased significantly (P < 0.05). Altogether, this study suggests that Hp and SAA are proposed as promising biomarkers for detecting naturally occurring M. bovis infection in calves.

Diet-Induced Early Inflammatory Response of Visceral Adipose Tissue in Healthy Male Wistar Rats.

The prolonged consumption of a high-fat diet (HFD) leads to abnormal growth of the visceral adipose tissue (VAT), increased macrophage infiltration, and altered secretion of biologically active molecules. This is considered as a precondition for the development of obesity, inflammation, and obesity-related disorders. Therefore, we studied HFD-induced changes in the tissue levels of the inflammatory markers C-reactive protein, serum amyloid-A, and interleukin-4 in healthy male Wistar rats. The animals were first divided at random into two groups subjected to either a standard or a high-fat diet. The initial effect of the diet was evaluated after fourteen weeks. In order to study the diet duration effect, the standard diet was given to twelve animals from the HFD group, while the remaining continued with the HFD for an additional four weeks. Our results showed that the HFD barely affected body mass index, conicity, relative fat mass, and Lee indices, whereas it provoked adipocyte hypertrophy and gradually increased the levels of both the pro- and anti-inflammatory markers. The switch from the high-fat to the standard diet resulted in the comparatively fast restoration of the baseline levels of the studied molecules. Although, the prolonged consumption of an HFD causes adipocyte hypertrophy in healthy male animals, the inflammatory process in VAT is well-coordinated, time-dependent, and reversible.

Prognostic potential of copper, zinc, copper/zinc ratio, cobalamin, and serum amyloid A in cats with panleukopenia.

BACKGROUND: Copper (Cu), zinc (Zn), and the copper/zinc ratio (Cu/Zn), which have been studied in gastrointestinal disorders of humans, may facilitate disease prognosis. OBJECTIVE: Evaluate the predictive potential of Cu, Zn, cobalamin, and serum amyloid A (SAA) as prognostic indicators in cats with feline panleukopenia (FPV) on admission. ANIMALS: Client-owned cats diagnosed with FPV and controls. METHODS: Serum Cu and Zn concentrations were assessed using the spectrophotometric method and serum concentrations of SAA and cobalamin were measured by chemiluminescent immunoassay. RESULTS: On admission, survivor cats with FPV had significantly higher serum Cu and SAA concentrations and Cu/Zn ratios and significantly lower serum Zn and cobalamin concentrations than controls. Furthermore, non-survivor cats with FPV had significantly higher serum Cu and SAA concentrations and Cu/Zn ratios and significantly lower cobalamin concentrations than survivors and controls. Prognostic thresholds were calculated, with positive predictive value (PPV) for survival of 90% for Cu (≥120.3 µg/dL), 90% for Cu/Zn (≥1.34), 90% for cobalamin (≤430.4 pg/mL), and 90% for SAA (≥0.85 mg/L). CONCLUSIONS AND CLINICAL IMPORTANCE: Cu (0.93 area under curve [AUC]), Cu/Zn (0.95 AUC), cobalamin (0.98 AUC), and SAA (0.98 AUC) were excellent biomarkers for predicting prognosis in cats with FPV. Their effectiveness, as assessed by sensitivity (100%), specificity (80%), AUC (0.98), and PPV (90%) from receiver operating characteristic analysis, emphasizes the performance of cobalamin and SAA.

Usefulness of serum amyloid A for the diagnosis of pyelonephritis in cats: A prospective evaluation.

BACKGROUND: The diagnosis of pyelonephritis in cats is challenging and development of a noninvasive and accurate biomarker is needed. HYPOTHESES: Serum amyloid A (SAA) is increased in cats with pyelonephritis, but not in cats with other urinary tract diseases. ANIMALS: A cohort of 125 cats (149 observations). METHODS: This was a prospective study. Group 1 included cats with a diagnosis of pyelonephritis either confirmed by bacterial culture of pelvic urine (Group 1a) or presumed (1b). Group 2 included cats for which pyelonephritis was ruled out (with certainty: Group 2a or judged unlikely: Group 2b). SAA concentration was compared between groups, and accuracy of SAA for the diagnosis of pyelonephritis was calculated using a Receiver Operating Characteristic (ROC) curve analysis. RESULTS: Median SAA concentration was significantly higher in Group 1a (86.8 mg/L [73.3; 161.5]; n = 8) than in Group 2a (4 mg/L [1.8; 5.6], n = 19; P < .001) and in Group 2b (5.4 mg/L [3.1; 9.7], n = 113; P < .001). It was also significantly higher in Group 1b (98.8 mg/L [83.1; 147.3]; n = 9) than in Group 2b (P < .001) and Group 2a (P < .001). Optimal diagnostic cut-off for SAA concentration was 51.3 mg/L. yielding a sensitivity of 88% (95% confidence interval: [64%; 99%]) and a specificity of 94% (95% confidence interval: [88%; 97%]). CONCLUSIONS AND CLINICAL IMPORTANCE: Measurement of SAA could be used to rule out pyelonephritis in the case of low suspicion of the disease. Increased SAA concentration is suggestive of pyelonephritis despite a lack of specificity.

Antisense oligonucleotide targeting hepatic Serum Amyloid A limits the progression of angiotensin II-induced abdominal aortic aneurysm formation.

BACKGROUND AND AIMS: Obesity increases the risk for abdominal aortic aneurysms (AAA) in humans and enhances angiotensin II (AngII)-induced AAA formation in C57BL/6 mice. We reported that deficiency of Serum Amyloid A (SAA) significantly reduces AngII-induced inflammation and AAA in both hyperlipidemic apoE-deficient and obese C57BL/6 mice. The aim of this study is to investigate whether SAA plays a role in the progression of early AAA in obese C57BL/6 mice. METHODS: Male C57BL/6J mice were fed a high-fat diet (60% kcal as fat) throughout the study. After 4 months of diet, the mice were infused with AngII until the end of the study. Mice with at least a 25% increase in the luminal diameter of the abdominal aorta after 4 weeks of AngII infusion were stratified into 2 groups. The first group received a control antisense oligonucleotide (Ctr ASO), and the second group received ASO that suppresses SAA (SAA-ASO) until the end of the study. RESULTS: Plasma SAA levels were significantly reduced by the SAA ASO treatment. While mice that received the control ASO had continued aortic dilation throughout the AngII infusion periods, the mice that received SAA-ASO had a significant reduction in the progression of aortic dilation, which was associated with significant reductions in matrix metalloprotease activities, decreased macrophage infiltration and decreased elastin breaks in the abdominal aortas. CONCLUSIONS: We demonstrate for the first time that suppression of SAA protects obese C57BL/6 mice from the progression of AngII-induced AAA. Suppression of SAA may be a therapeutic approach to limit AAA progression.

CHRONIC CRITICAL ILLNESS-INDUCED MUSCLE ATROPHY: INSIGHTS FROM A TRAUMA MOUSE MODEL AND POTENTIAL MECHANISM MEDIATED VIA SERUM AMYLOID A.

ABSTRACT: Background: Chronic critical illness (CCI), which was characterized by persistent inflammation, immunosuppression, and catabolism syndrome (PICS), often leads to muscle atrophy. Serum amyloid A (SAA), a protein upregulated in critical illness myopathy, may play a crucial role in these processes. However, the effects of SAA on muscle atrophy in PICS require further investigation. This study aims to develop a mouse model of PICS combined with bone trauma to investigate the mechanisms underlying muscle weakness, with a focus on SAA. Methods: Mice were used to examine the effects of PICS after bone trauma on immune response, muscle atrophy, and bone healing. The mice were divided into two groups: a bone trauma group and a bone trauma with cecal ligation and puncture group. Tibia fracture surgery was performed on all mice, and PICS was induced through cecal ligation and puncture surgery in the PICS group. Various assessments were conducted, including weight change analysis, cytokine analysis, hematological analysis, grip strength analysis, histochemical staining, and immunofluorescence staining for SAA. In vitro experiments using C2C12 cells (myoblasts) were also conducted to investigate the role of SAA in muscle atrophy. The effects of inhibiting receptor for advanced glycation endproducts (RAGE) or JAK2 on SAA-induced muscle atrophy were examined. Bioinformatic analysis was conducted using a dataset from the GEO database to identify differentially expressed genes and construct a coexpression network. Results: Bioinformatic analysis confirmed that SAA was significantly upregulated in muscle tissue of patients with intensive care unit-induced muscle atrophy. The PICS animal models exhibited significant weight loss, spleen enlargement, elevated levels of proinflammatory cytokines, and altered hematological profiles. Evaluation of muscle atrophy in the animal models demonstrated decreased muscle mass, grip strength loss, decreased diameter of muscle fibers, and significantly increased expression of SAA. In vitro experiment demonstrated that SAA decreased myotube formation, reduced myotube diameter, and increased the expression of muscle atrophy-related genes. Furthermore, SAA expression was associated with activation of the FOXO signaling pathway, and inhibition of RAGE or JAK2/STAT3-FOXO signaling partially reversed SAA-induced muscle atrophy. Conclusions: This study successfully develops a mouse model that mimics PICS in CCI patients with bone trauma. Serum amyloid A plays a crucial role in muscle atrophy through the JAK2/STAT3-FOXO signaling pathway, and targeting RAGE or JAK2 may hold therapeutic potential in mitigating SAA-induced muscle atrophy.

Morphological findings in different subtypes of hepatic amyloid.

The classic findings have been well described for light-chain amyloid involving the liver. In addition to light chain, however, many additional proteins are now known to be amyloidogenic and can involve the liver. A total of 58 surgical pathology specimens with amyloid deposits were analyzed for patterns of amyloid deposition, including amyloid from light chain lambda (N = 17), light chain kappa (N = 15), transthyretin (N = 15), serum amyloid A (N = 4), apolipoprotein A1 (N = 4), fibrinogen alpha (N = 2), LECT2 (N = 1). Amyloid deposits predominately targeted the liver vasculature, including the walls of the hepatic arteries, portal veins, and sinusoids. While there was overlap, light chain amyloid predominately involved the sinusoids, while transthyretin amyloid predominately targeted the hepatic arteries, especially the larger ones in the hilum and larger portal tracts. Serum amyloid A formed nodular deposits that started in the portal vasculature but then extended into the portal tract stroma, leading to large, bulbous, portal-based amyloid deposits. Apolipoprotein A amyloid also formed large portal-based nodules. Fibrinogen was mild and subtle on H&E and predominately affected portal veins. Amyloid deposits in hilar nerves were prominent with amyloid light chain, transthyretin, and apolipoprotein A1. In conclusion, the histology of hepatic amyloid is diverse and shows several distinct clusters of findings that can aide in recognition in surgical pathology specimens.

Serum amyloid A expression in liver promotes synovial macrophage activation and chronic arthritis via NFAT5.

Nuclear factor of activated T-cells 5 (NFAT5), an osmo-sensitive transcription factor, can be activated by isotonic stimuli, such as infection. It remains unclear, however, whether NFAT5 is required for damage-associated molecular pattern-triggered (DAMP-triggered) inflammation and immunity. Here, we found that several DAMPs increased NFAT5 expression in macrophages. In particular, serum amyloid A (SAA), primarily generated by the liver, substantially upregulated NFAT5 expression and activity through TLR2/4-JNK signalling pathway. Moreover, the SAA-TLR2/4-NFAT5 axis promoted migration and chemotaxis of macrophages in an IL-6- and chemokine ligand 2-dependent (CCL2-dependent) manner in vitro. Intraarticular injection of SAA markedly accelerated macrophage infiltration and arthritis progression in mice. By contrast, genetic ablation of NFAT5 or TLR2/4 rescued the pathology induced by SAA, confirming the SAA-TLR2/4-NFAT5 axis in vivo. Myeloid-specific depletion of NFAT5 also attenuated SAA-accelerated arthritis. Of note, inflammatory arthritis in mice strikingly induced SAA overexpression in the liver. Conversely, forced overexpression of the SAA gene in the liver accelerated joint damage, indicating that the liver contributes to bolstering chronic inflammation at remote sites by secreting SAA. Collectively, this study underscores the importance of the SAA-TLR2/4-NFAT5 axis in innate immunity, suggesting that acute phase reactant SAA mediates mutual interactions between liver and joints and ultimately aggravates chronic arthritis by enhancing macrophage activation.

Predicting genetic risk factors for AA amyloidosis in Algerian patients with familial Mediterranean fever.

Renal amyloid-associated (AA) amyloidosis is a harmful complication of familial Mediterranean fever (FMF). Its occurrence involves polymorphisms and mutations in the Serum Amyloid A1 (SAA1) and Mediterranean Fever (MEFV) genes, respectively. In Algeria, the association between SAA1 variants and FMF-related amyloidosis was not investigated, hence the aim of this case-control study. It included 60 healthy controls and 60 unrelated FMF patients (39 with amyloidosis, and 21 without amyloidosis). All were genotyped for the SAA1 alleles (SAA1.1, SAA1.5, and SAA1.3), and a subset of them for the - 13 C/T polymorphism by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Comparisons between genotype and allele frequencies were performed using Chi-square and Fisher tests. The SAA1.1/1.1 genotype was predominant in amyloid FMF patients, compared to non-amyloid FMF patients (p = 0.001) and controls (p < 0.0001). SAA1.1/1.5 was higher in non-amyloid patients (p = 0.0069) and in controls (p = 0.0082) than in patients with amyloidosis. Bivariate logistic regression revealed an increased risk of AA amyloidosis with three genotypes, SAA1.1/1.1 [odds ratio 7.589 (OR); 95% confidence interval (CI): 2.130-27.041] (p = 0.0018), SAA1.1/1.3 [OR 5.700; 95% CI: 1.435-22.644] (p = 0.0134), and M694I/M694I [OR 4.6; 95% CI: 1.400-15.117] (p = 0.0119). The SAA1.1/1.5 genotype [OR 0.152; 95% CI: 0.040-0.587] (p = 0.0062) was protective against amyloidosis. In all groups, the - 13 C/C genotype predominated, and was not related to renal complication [OR 0.88; 95% CI: 0.07-10.43] (p = 0.915). In conclusion, in contrast to the - 13 C/T polymorphism, the SAA1.1/1.1, SAA1.1/1.3 and M694I/M694I genotypes may increase the risk of developing renal AA amyloidosis in the Algerian population.

Elevated expression of interleukin-6 (IL-6) and serum amyloid A (SAA) in the skin and the serum of recessive dystrophic epidermolysis bullosa: Skin as a possible source of IL-6 through Toll-like receptor ligands and SAA.

The effect of persistent skin inflammation on extracutaneous organs and blood is not well studied. Patients with recessive dystrophic epidermolysis bullosa (RDEB), a severe form of the inherited blistering skin disorder, have widespread and persistent skin ulcers, and they develop various complications including anaemia, hyperglobulinaemia, hypoalbuminaemia and secondary amyloidosis. These complications are associated with the bioactivities of IL-6, and the development of secondary amyloidosis requires the persistent elevation of serum amyloid A (SAA) level. We found that patients with RDEB had significantly higher serum levels of IL-6 and SAA compared to healthy volunteers and patients with psoriasis or atopic dermatitis. Both IL-6 and SAA were highly expressed in epidermal keratinocytes and dermal fibroblasts of the skin ulcer lesions. Keratinocytes and fibroblasts surrounding the ulcer lesions are continuously exposed to Toll-like receptor (TLR) ligands, pathogen-associated and damage-associated molecular pattern molecules. In vitro, TLR ligands induced IL-6 expression via NF-κB in normal human epidermal keratinocytes (NHEKs) and dermal fibroblasts (NHDFs). SAA further induced the expression of IL-6 via TLR1/2 and NF-κB in NHEKs and NHDFs. The limitation of this study is that NHEKs and NHDFs were not derived from RDEB patients. These observations suggest that TLR-mediated persistent skin inflammation might increase the risk of IL-6-related systemic complications, including RDEB.

Low SAA4 gene expression is associated with advanced HCC stage and a poor prognosis.

At present, although there are tumor markers for hepatocellular carcinoma (HCC), markers with better predictive efficiency are needed. SAA4 gene expression in liver tumor and paracancerous tissues was analyzed using The Cancer Genome Atlas database. The differentially expressed genes (DEGs) were analyzed and visualized by heatmap and volcano plot. Survival analysis was performed based on SAA4 expression. SAA4 expression was compared in patients grouped based on clinicopathological features, and gene set enrichment analysis (GSEA) was conducted. Immunohistochemical staining was used to verify the SAA4 protein staining intensity from The Human Protein Atlas database and our center's samples. The diagnostic value of SAA4 for HCC was evaluated by receiver operating characteristic curves. SAA4 was expressed at low levels in HCC tissues, and low SAA4 expression was associated with a poor prognosis in HCC. In addition, SAA4 expression decreased with HCC progression. There were 188 upregulated DEGs and 1551 downregulated DEGs between the high and low SAA4 expression groups. Complement and coagulation cascades, fatty acid metabolism, and ECM receptor interaction were significantly enriched in the GSEA. SAA4 had good predictive efficacy for HCC and even early HCC and was superior to AFP. In general, low SAA4 expression was associated with advanced HCC stage and a poor prognosis. In addition, SAA4 may be helpful for the diagnosis of early HCC and may become a novel tumor marker with good predictive power for HCC.

Serum amyloid A promotes glycolysis of neutrophils during PD-1 blockade resistance in hepatocellular carcinoma.

The response to programmed death-1 (PD-1) blockade varies in hepatocellular carcinoma (HCC). We utilize a panel of 16 serum factors to show that a circulating level of serum amyloid A (SAA) > 20.0 mg/L has the highest accuracy in predicting anti-PD-1 resistance in HCC. Further experiments show a correlation between peritumoral SAA expression and circulating SAA levels in patients with progressive disease after PD-1 inhibition. In vitro experiments demonstrate that SAA induces neutrophils to express PD-L1 through glycolytic activation via an LDHA/STAT3 pathway and to release oncostatin M, thereby attenuating cytotoxic T cell function. In vivo, genetic or pharmacological inhibition of STAT3 or SAA eliminates neutrophil-mediated immunosuppression and enhances antitumor efficacy of anti-PD-1 treatment. This study indicates that SAA may be a critical inflammatory cytokine implicated in anti-PD-1 resistance in HCC. Targeting SAA-induced PD-L1+ neutrophils through STAT3 or SAA inhibition may present a potential approach for overcoming anti-PD1 resistance.