Reference distributions for alpha2-macroglobulin: a comparison of a large cohort to the world's literature

High alpha-2-macroglobulin levels are a risk factor for cardiovascular disease events: A Moli-sani cohort study

BACKGROUND

α2-macroglobulin (α2M) is a versatile endopeptidase inhibitor that plays a role in cell growth, inflammation and coagulation. α2M is an inhibitor of key coagulation enzyme thrombin. Hypercoagulability due to an excess of thrombin production can cause thrombotic events. Therefore, we investigated the association of α2M levels and cardiovascular events in a subset of the general Italian population.

METHODS

We determined α2M levels in the baseline samples of a prospective cohort (n = 19,688; age: 55 ± 12 years; 47.8 % men) of the Moli-sani study and investigated the association with the cardiovascular events (n = 432, 2.2 %) in the median follow-up period of 4.3 years. Hazard ratios (HR) with 95 % confidence intervals (CI) were calculated by multivariable Cox regression and adjusted for a large panel of confounding factors.

RESULTS

α2M levels above the 90th percentile were significantly associated with cardiovascular disease (CVD) events after full adjustment for age, sex, current smoking, BMI, oral contraceptive use, cardiovascular diseases, hypertension, hypercholesterolemia, diabetes and history of cancer (HR: 1.36; CI: 1.06-1.74). Moreover, high α2M was associated with coronary heart disease (CHD; HR: 1.47; CI: 1.12-1.91), but not stroke. Stratification for CVD at baseline showed that high α2M levels are associated with CHD events in subjects without CVD at baseline (HR: 1.40; CI: 1.00-1.95) and subjects with CVD at baseline (HR: 1.58; CI: 1.02-2.44).

CONCLUSION

We show in a prospective cohort that high levels of α2M could be a risk factor for cardiovascular events, especially coronary heart disease events.

Clinical Interest of Serum Alpha-2 Macroglobulin, Apolipoprotein A1, and Haptoglobin in Patients with Non-Alcoholic Fatty Liver Disease, with and without Type 2 Diabetes, before or during COVID-19

In patients with non-alcoholic fatty liver disease (NAFLD) with or without type 2 diabetes mellitus (T2DM), alpha-2 macroglobulin (A2M), apolipoprotein A1 (ApoA1), and haptoglobin are associated with the risk of liver fibrosis, inflammation (NASH), and COVID-19. We assessed if these associations were worsened by T2DM after adjustment by age, sex, obesity, and COVID-19. Three datasets were used: the “Control Population”, which enabled standardization of protein serum levels according to age and sex (N = 27,382); the “NAFLD-Biopsy” cohort for associations with liver features (N = 926); and the USA “NAFLD-Serum” cohort for protein kinetics before and during COVID-19 (N = 421,021). The impact of T2DM was assessed by comparing regression curves adjusted by age, sex, and obesity for the liver features in “NAFLD-Biopsy”, and before and during COVID-19 pandemic peaks in “NAFLD-Serum”. Patients with NAFLD without T2DM, compared with the values of controls, had increased A2M, decreased ApoA1, and increased haptoglobin serum levels. In patients with both NAFLD and T2DM, these significant mean differences were magnified, and even more during the COVID-19 pandemic in comparison with the year 2019 (all p < 0.001), with a maximum ApoA1 decrease of 0.21 g/L in women, and a maximum haptoglobin increase of 0.17 g/L in men. In conclusion, T2DM is associated with abnormal levels of A2M, ApoA1, and haptoglobin independently of NAFLD, age, sex, obesity, and COVID-19.

Bone tissue: Rebuilding and inflammation

In this review the author summarizes the knowledge related to structural elements of bone tissue. The process of bone reorganisation and knowledge about the special feature of bone metabolism in human are also discussed. It is noted that due to the reorganisation, there is a complete renewal of bone tissue in every 10 years, and this renewal lasts throughout the life. However, there are life periods when osteoclast activity is low, e.g. in childhood and the second decade of life when the gain of bone mass may be as much as 40% of the final bone mass. Overactivity of osteoclasts occurs at age 60 years in men and somewhat earlier in women. Reorganization of bone tissue is an elementary requirement for the physiological functions (locomotion, hemopoiesis, immune functions). The RANK-RANKL-osteoprotegerin axis plays an important role in the regulation of bone metabolism. Bone mass is dependent on osteocytes; osteoblasts are building up while osteoclasts are reabsorbing bone tissue. In this process transcription factors, hormone-like substances and a large number of cytokines are involved. In addition, the inflammatory process within the bone tissue as well as the defending, reparative inflammation and specific immune response are of great importance in bone reorganisation. This is particularly valid for α2-macroglobulin and transforming growth factor, although the exact role in bone reorganization has not been fully explored. It can be concluded that the elements, which participate in bone reorganization and in defending inflammatory and specific immunological processes, are essentially identical. Therefore, the existence of an osteo-immunological complex system has been emerged. Orv. Hetil., 2014, 155(40), 1575–1583.

Reference distributions for apolipoproteins AI and B and B/AI ratios: comparison of a large cohort to the world's literature

Limiting the clinical utility of apolipoproteins AI (apo AI) and B (apo B) and the apo B/AI ratios until the last decade has been the lack of satisfactory methods for quantifying serum levels and credible reference materials. Great technological strides have been made in the last few years. The remaining barrier to more relevant and cost-effective use of serum protein data for diagnosis and prognosis has been the availability of widely recognized reliable reference intervals from birth to old age for both males and females. A total of 82 publications reporting reference intervals have been identified that meet most of the same inclusion criteria used in our prior six studies. These have been analyzed statistically and compared to similar studies, i.e., sufficient number, listed subject criteria, method, and reference material, in general terms. Published smaller studies with constrained age ranges, agree on average with our large series of life-long reference intervals that range from less than one year to over 80 years. This study was performed to assess the degree of agreement between smaller reference interval studies to our large population analysis. This meta-analysis provides support and reassurance that many of the smaller reference intervals published previously fall within reasonable limits of out large population.

Apheresis for idiopathic sudden hearing loss: Reviewing the evidence

Plasmapheresis has been used for various conditions for a number of years. Recently, its application for idiopathic sudden hearing loss (ISHL) has met with increasing interest. ISHL affects about 10-20 per 100,000 persons per year, impairing not only their hearing but also their ability to interact socially and their quality of life. ISHL is thought to be a sequela of an underlying microvascular disorder caused by a local hyperviscosity syndrome in the cochlear vessels. Plasmapheresis can effectively lower plasma and whole blood viscosity, improve erythrocyte elasticity, and reduce aggregability. Thus, it may be effectively employed in the treatment of ISHL. This article will briefly outline the background against which apheresis procedures are used in the treatment of ISHL and review studies done to date. Furthermore, a broader basis for the use of apheretic applications in the treatment of ISHL will be suggested, correlating age-adjusted ISHL incidence and age-adjusted levels of macromolecular plasma proteins such as fibrinogen. In conclusion, plasmapheresis is a promising new treatment for ISHL but more basic data on ISHL, and on apheresis applications for ISHL, are needed to safely assess treatment outcomes and possible future applications.

Human kallikrein 4: quantitative study in tissues and evidence for its secretion into biological fluids

BACKGROUND

Human kallikrein 4 (hK4) is a proteolytic enzyme belonging to the tissue kallikrein family of serine proteases. Previous tissue expression studies have demonstrated highest KLK4 mRNA expression in prostatic tissue, but there has been only limited evidence for the presence of hK4 protein in prostate and other tissues and in corresponding biological secretions.

METHODS

To investigate the concentrations of hK4 in tissues and biological fluids, we developed a new hK4-specific sandwich-type immunoassay using a monoclonal antibody as the capture reagent.

RESULTS

The assay has a detection limit of 0.02 microg/L and <0.1% cross-reactivity toward any of the other 14 human kallikreins. Twelve of 40 tissue extracts prepared from various human tissues contained detectable hK4 concentrations (0.68-7143 ng/g of total protein), with healthy prostate tissue containing the highest amount of hK4. Examination of 16 malignant and 18 benign prostate tissues revealed no significant differences in hK4 protein content, and the tissues contained a wide range of values (benign, <0.02 to 801 ng/g; malignant, <0.02 to 824 ng/g). Among the biological fluids tested, seminal plasma and urine contained widely varying amounts of hK4; concentrations in 54 urine samples were <0.02 to 2.6 microg/L, whereas concentrations in 58 seminal plasma samples were 0.2-202 microg/L. Affinity purification of hK4 from seminal plasma and subsequent mass spectrometry demonstrated the secreted nature of hK4 in seminal plasma.

CONCLUSIONS

hK4 is found primarily in prostate tissue and is secreted in seminal plasma. Its value as a novel prostatic biomarker needs to be defined further.

Reference distributions for alpha2-macroglobulin: a practical, simple and clinically relevant approach in a large cohort

In this 11th article in a series, reference values of serum levels alpha(2)-macroglobulin alpha(2)M) are examined. The study is based on a cohort of 40,420 Caucasian individuals from northern New England that were tested in our laboratory between 1994 and 2000. Measurements were standardized against Certified Reference Material (CRM 470)/Reference Preparation for Proteins in Human Serum (RPPHS) and the results analyzed using a previously described statistical approach. Individuals with unequivocal laboratory evidence of inflammation (C-reactive protein >10 mg/L) were excluded in one leg of the study and included in the other, confirming that alpha(2)M does not respond to acute phase drive in man. Nephrotic syndrome, diabetes mellitus, and chronic liver disease have significant effect on levels of alpha(2)M. Dramatic changes occur during life with males higher from birth to age 12, females thereafter have higher values until the ninth decade. When values were expressed as multiples of the age- and gender-specific median levels, the resulting distributions fitted a log-Gaussian distribution well over a broad range. When patient data are normalized in this manner, the distribution parameters can be used to assign a centile corresponding to an individual's measurement thus simplifying interpretation.