Impairment of hemolytic complement activation by both classical and alternative pathways in serum from patients with kwashiorkor

Nutrition and Infectious Diseases in Developing Countries and Problems of Acquired Immunodeficiency Syndrome

Infectious diseases are the major causes of death and morbidity in underdeveloped countries, particularly in children. Increasing evidence suggests that malnutrition—both Protein-Energy type Malnutrition (PEM) and essential micronutrient (vitamins, trace minerals, essential amino acids, polyunsaturated fatty acids) type—is the underlying reason for increased susceptibility to infections. On the other hand, certain infectious diseases also cause malnutrition, which results in a vicious cycle. Before its viral origin was known, acquired immunodeficiency syndrome (AIDS) had been termed the thin disease because cachexia was AIDS' main clinical manifestation.

The relationship between infection and malnutrition is well documented in the literature. Our experience supports this. Preventive and therapeutic measures are suggested.

Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE)

An increasing recognition has emerged of the complexities of the global health agenda—specifically, the collision of infections and noncommunicable diseases and the dual burden of over- and undernutrition. Of particular practical concern are both 1) the need for a better understanding of the bidirectional relations between nutritional status and the development and function of the immune and inflammatory response and 2) the specific impact of the inflammatory response on the selection, use, and interpretation of nutrient biomarkers. The goal of the Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE) is to provide guidance for those users represented by the global food and nutrition enterprise. These include researchers (bench and clinical), clinicians providing care/treatment, those developing and evaluating programs/interventions at scale, and those responsible for generating evidence-based policy. The INSPIRE process included convening 5 thematic working groups (WGs) charged with developing summary reports around the following issues: 1) basic overview of the interactions between nutrition, immune function, and the inflammatory response; 2) examination of the evidence regarding the impact of nutrition on immune function and inflammation; 3) evaluation of the impact of inflammation and clinical conditions (acute and chronic) on nutrition; 4) examination of existing and potential new approaches to account for the impact of inflammation on biomarker interpretation and use; and 5) the presentation of new approaches to the study of these relations. Each WG was tasked with synthesizing a summary of the evidence for each of these topics and delineating the remaining gaps in our knowledge. This review consists of a summary of the INSPIRE workshop and the WG deliberations.

The immune system in children with malnutrition--a systematic review

Background

Malnourished children have increased risk of dying, with most deaths caused by infectious diseases. One mechanism behind this may be impaired immune function. However, this immune deficiency of malnutrition has not previously been systematically reviewed.

Objectives

To review the scientific literature about immune function in children with malnutrition.

Methods

A systematic literature search was done in PubMed, and additional articles identified in reference lists and by correspondence with experts in the field. The inclusion criteria were studies investigating immune parameters in children aged 1–60 months, in relation to malnutrition, defined as wasting, underweight, stunting, or oedematous malnutrition.

Results

The literature search yielded 3402 articles, of which 245 met the inclusion criteria. Most were published between 1970 and 1990, and only 33 after 2003. Malnutrition is associated with impaired gut-barrier function, reduced exocrine secretion of protective substances, and low levels of plasma complement. Lymphatic tissue, particularly the thymus, undergoes atrophy, and delayed-type hypersensitivity responses are reduced. Levels of antibodies produced after vaccination are reduced in severely malnourished children, but intact in moderate malnutrition. Cytokine patterns are skewed towards a Th2-response. Other immune parameters seem intact or elevated: leukocyte and lymphocyte counts are unaffected, and levels of immunoglobulins, particularly immunoglobulin A, are high. The acute phase response appears intact, and sometimes present in the absence of clinical infection. Limitations to the studies include their observational and often cross-sectional design and frequent confounding by infections in the children studied.

Conclusion

The immunological alterations associated with malnutrition in children may contribute to increased mortality. However, the underlying mechanisms are still inadequately understood, as well as why different types of malnutrition are associated with different immunological alterations. Better designed prospective studies are needed, based on current understanding of immunology and with state-of-the-art methods.

Extraglomerular C3 deposition and metabolic impacts in patients with IgA nephropathy

BACKGROUND

The aim of the present study was to explore the significance of extraglomerular (Bowman's capsule and/or arteriole) C3 (ex-C3) deposits in IgA nephropathy (IgAN).

METHODS

One hundred and seventy patients with IgAN were divided into two groups: Group A (n=79), patients who did not have ex-C3 deposits, and Group B (n=91), patients who had ex-C3 deposits.

RESULTS

At the time of renal biopsy, Group B was characterized by a marked increase in diastolic blood pressure, total cholesterol, triglyceride and low-density lipoprotein-cholesterol compared with those of Group A. After 4 years, the estimated glomerular filtration rate (eGFR) in Group B was significantly worse than that of Group A. Upon examination by electron microscopy, the arteriolar dense deposits in Group B were found to occur in significantly higher amounts than in Group A. One hundred and thirty-four patients underwent a 3-year follow-up study after intervention and were re-divided by therapeutic factors as follows: 'conventional therapy', treatment with anti-hypertensive drugs and/or anti-platelet drugs, and 'aggressive therapy', additional treatment with either tonsillectomy or corticosteroid. Patients treated with conventional therapy in Group B had significantly higher body mass index and levels of C3 and CH50 compared with other Groups. Aggressive therapy was significantly effective in urinary protein reduction in both Group A and Group B. Except for the patients who received aggressive therapy in Group A, the levels of the eGFR gradually declined.

CONCLUSIONS

It appears that IgAN patients who have ex-C3 deposits have worse clinical outcomes.

Metabolic impact on serum levels of complement component 3 in Japanese patients

The aim of this study was to explore the association between the serum concentration of complement component 3 (C3) and a variety of metabolic parameters. The study involved 125 patients in our outpatient clinic. Anthropometric and clinical laboratory data were collected and statistical associations between the serum concentration of C3 and other parameters were evaluated in a cross-sectional as well as a prospective manner. A group of male patients with metabolic syndrome (Mets, n=35) were characterized by marked increase in serum concentrations of C3, body mass index (BMI), waist circumference, hemoglobin (Hb) A1c, insulin resistance (HOMA-IR), triglyceride, uric acid, urinary protein, and Hb. In a one-way analysis of variance of all subjects, the serum concentration of C3 was significantly elevated as the number of items of complying with the Mets diagnostic criteria increased. In 60 of 125 patients who did not have diabetes and were given anti-lipogenetic medication, the serum concentration of C3 showed significant positive associations with serum levels of CH50, insulin, HOMA-IR, total cholesterol, hematocrit, LDL-c, C4, Hb, triglyceride, BMI, and albumin. In a prospective follow-up evaluation (n=35), there was a significant positive association between DeltaC3 (the second concentration of serum C3 minus the first concentration of serum C3)and DeltaHOMA-IR (the second concentration of HOMA-IR minus the first concentration of HOMA-IR). In conclusion, in Japanese patients, there is evidence implicating C3 concentration as a marker of Mets coinciding with insulin resistance.

Complement in the pathophysiology and diagnosis of human diseases

Complement is a humoral effector system composed of 21 plasma proteins that was identified initially because of its cytolytic effects. In addition to cytolysis, complement has a number of different functions related to inflammatory and other host defense processes. The description of the reaction mechanism includes: (1) activation of the classical pathway through recognition of IgG and IgM antibodies by C1q, (2) activation of the alternative pathway which is usually achieved without participation of immunoglobulins, (3) generation of proteolytic enzymes composed of heteropolymers that cleave certain precursor proteins, (4) formation of the membrane attack complex (MAC), and (5) participation of control mechanisms. Methodologies for studying protein concentration and functional activities of complement components include not only the classical hemolytic techniques but also the extremely sensitive new radioimmunoassays and enzyme immunoassays for measuring the products of complement activation that are generated in vivo. Examples of genetically controlled complement deficiencies have been published for most complement components. The symptomatology of some of these patients serves to emphasize the protective role of complement. Acquired deficiencies are significant not only as laboratory aids in diagnosis and to evaluate the course of certain diseases, but also to indicate possible pathogenic disease mechanisms. Recently, it has been recognized that the complement proteins with genes located in the HLA region are polymorphic. Certain variants of proteins C2, C4, and factor B occur with higher frequencies in certain diseases than in the general population, which appears to be of great practical importance in laboratory medicine.