Impairment of the hematological response and interleukin-1β production in protein-energy malnourished mice after endotoxemia with lipopolysaccharide

What Came First: Malnutrition or Severe Disease?

A 20-year-old female with depression presented to the emergency department with chronic weight loss, weakness, fatigue, hair loss, rash, palpitations, and 2 weeks of cough. Initial history revealed that she had disordered eating habits with dietary restriction, experienced a 50-pound unintentional weight loss over 2 years despite reported adherence to nutritional supplementation, and had a normal gastrointestinal workup. On examination, she was markedly cachectic with a BMI of 10.3kg/m2 and hypotensive (84/69 mmHg). Her cardiovascular examination revealed a regular rate and rhythm without a murmur. Her breath sounds were diminished in the upper lobes bilaterally. A skin examination showed diffuse hair loss, skin breakdown, and peeling with a tender, erythematous, papular rash over the bilateral ankles, and nonpitting edema. A chest radiograph showed a right upper lobe opacity and lucent lesions in the left proximal humerus. A focused assessment with sonography for trauma examination showed a large pericardial effusion. Chest computed tomography revealed a right upper lobe opacity with an associated cavitation. Though she began improving with rifampin, isoniazid, pyrazinamide, ethambutol, levofloxacin, azithromycin, and nutritional rehabilitation, her clinical course was complicated by an acute worsening nearly 1 month into her hospitalization with persistent high fevers, worsening cough, development of a murmur, and worsening consolidation on chest computed tomography. Adolescent Medicine, Infectious Diseases, Gastroenterology, and Allergy and Immunology were consulted to guide the diagnostic evaluation and management of this patient's complex clinical course.

The relationship between the degree of malnutrition and changes in selected parameters of the immune response in critically ill patients

Patients treated in intensive care units (ICUs) are at high risk of malnutrition and the resulting homeostasis, metabolic, histological and immunological disorders, especially leading to organ failure and increased susceptibility to infection. In 163 patients with malnutrition [mild in 33 (19.6%), moderate in 69 (42.9%), severe in 61 (37.4%)] treated in the ICU, changes in the concentration of selected proteins [interleukin (IL)-1Ra, tumor necrosis factor α (TNF-α), soluble tumour necrosis factor receptor-1 (sTNFR1), IL-6, IL-10, sTLR4, MyD88, A20, HSP70, HMGB1] were examined. In the whole group of malnourished patients, median values of sTNFR1, TNF-α, IL-6, TLR4, IL-1Ra were significantly increased, while the levels of MyD88 and A20 proteins were significantly reduced (in comparison to the well-nourished healthy group). Only the sTNFR1 protein showed a significant difference between mild, moderate and severe malnutrition, and increased concentrations as the severity of malnutrition increased (the correlation study found that as the degree of malnutrition increased, the sTNFR1 concentrations increased; p = 0.0000, R = 0.5442). It was observed that death was significantly more frequent in the group of patients who on the first day of hospitalization in the ICU scored 5 or more points on the NRS 2002 scale (p = 0.0004). In the patients who died significantly higher concentrations of sTNFR1, IL-6, IL-10, HSP70 were observed in comparison to the patients who survived. The present results are encouraging and indicate the desirability of undertaking multicentre clinical trials including monitoring of sTNFR1 in assessing the severity of malnutrition and immune disorders in the first hours after admission to the ICU, because it can be assumed that without early diagnosis of innate immunity disorders any attempts at their modulation may be ineffective.

Animal Models of Undernutrition and Enteropathy as Tools for Assessment of Nutritional Intervention

: Undernutrition is a major public health problem leading to 1 in 5 of all deaths in children under 5 years. Undernutrition leads to growth stunting and/or wasting and is often associated with environmental enteric dysfunction (EED). EED mechanisms leading to growth failure include intestinal hyperpermeability, villus blunting, malabsorption and gut inflammation. As non-invasive methods for investigating gut function in undernourished children are limited, pre-clinical models are relevant to elucidating the pathophysiological processes involved in undernutrition and EED, and to identifying novel therapeutic strategies. In many published models, undernutrition was induced using protein or micronutrient deficient diets, but these experimental models were not associated with EED. Enteropathy models mainly used gastrointestinal injury triggers. These models are presented in this review. We found only a few studies investigating the combination of undernutrition and enteropathy. This highlights the need for further developments to establish an experimental model reproducing the impact of undernutrition and enteropathy on growth, intestinal hyperpermeability and inflammation, that could be suitable for preclinical evaluation of innovative therapeutic intervention.

New Insights into the Pathogenesis and Treatment of Malnutrition

The volume of research into the pathogenesis and treatment of malnutrition has increased markedly over the past ten years, providing mechanistic insights that can be leveraged into more effective treatment options. These discoveries have been driven by several landmark studies employing metabolomics, metagenomics, and new preclinical models. This review highlights some of the most important recent findings, focusing in particular on the emerging roles of prenatal and perinatal factors, protein deficiency, impaired gut barrier function, immune deficiency, and the intestinal microbiome.

Impact of Childhood Malnutrition on Host Defense and Infection

The global impact of childhood malnutrition is staggering. The synergism between malnutrition and infection contributes substantially to childhood morbidity and mortality. Anthropometric indicators of malnutrition are associated with the increased risk and severity of infections caused by many pathogens, including viruses, bacteria, protozoa, and helminths. Since childhood malnutrition commonly involves the inadequate intake of protein and calories, with superimposed micronutrient deficiencies, the causal factors involved in impaired host defense are usually not defined. This review focuses on literature related to impaired host defense and the risk of infection in primary childhood malnutrition. Particular attention is given to longitudinal and prospective cohort human studies and studies of experimental animal models that address causal, mechanistic relationships between malnutrition and host defense. Protein and micronutrient deficiencies impact the hematopoietic and lymphoid organs and compromise both innate and adaptive immune functions. Malnutrition-related changes in intestinal microbiota contribute to growth faltering and dysregulated inflammation and immune function. Although substantial progress has been made in understanding the malnutrition-infection synergism, critical gaps in our understanding remain. We highlight the need for mechanistic studies that can lead to targeted interventions to improve host defense and reduce the morbidity and mortality of infectious diseases in this vulnerable population.

The influence of protein malnutrition on biological and immunomodulatory aspects of bone marrow mesenchymal stem cells

Tissues that require a great supply of nutrients and possess high metabolic demands, such as lympho-hemopoietics tissues, are the first to be affected by protein malnutrition (PM). Thus, PM directly affects hemopoiesis and the production and function of immune cells. Consequently, malnourished individuals are more susceptible to infections. Mesenchymal stem cells (MSCs) have immunomodulatory properties and are important in the formation of lympho-hemopoietic stroma. Since an adequate supply of nutrients is essential to sustain stroma formation, which is mainly constituted of MSCs and differentiated cells originated from them, this study investigated whether PM would influence some biological and immunomodulatory aspects of MSCs. Two-month-old Balb/c mice were divided into control and malnourished groups receiving normoproteic or hypoproteic diets, respectively (12% and 2% of protein) for 28 days. MSCs obtained from control (MSCct) and malnourished (MSCmaln) animals were characterized. In addition, the proliferation rate and cell cycle protein expression were determined, but no differences in these parameters were observed. In order to evaluate whether PM affects the immunomodulatory properties of MSCs, the expression of NFκB and STAT-3, and the production of IL-1α, IL-1β, IL-6, IL-10, TGF-β and TNF-α by MSCs were assessed. MSCmaln expressed lower levels of NF-κB and the production of IL-1β, IL-6 and TGF-β was significantly influenced by PM. Furthermore, MSCct and MSCmaln culture supernatants affected lymphocyte and macrophage proliferation. However, MSCmaln did not reduce the production of IFN-γ nor stimulate the production of IL-10 in lymphocytes in the same manner as observed in MSCct. Overall, this study implied that PM modifies immunosuppressive properties of MSCs.

Protein malnutrition alters spleen cell proliferation and IL-2 and IL-10 production by affecting the STAT-1 and STAT-3 balance

Protein malnutrition (PM) is an important public health problem that affects resistance to infection by impairing a number of physiological processes. PM induces structural changes in the lymphoid organs that affect the roles of the immune and inflammatory responses in a crucial way. The activation of different transcription factors, including signal transducer and activator of transcription (STAT) family members, leads to the production of different cytokines, which are mediators essential to mounting adequate immune and inflammatory responses. In this study, malnourished animals presented anemia, leukopenia, and a severe reduction in spleen cellularity, with reduced numbers of most cell populations, as well as increased percentages of CD3(+) and CD4(+) cells. The proliferation rates were reduced, and cells were increasingly observed in the G0/G1 cell cycle phase; further, IL-2 production was reduced, while IL-10 production was increased. In spleen cells from malnourished animals, STAT-3 protein expression was increased, with a concomitant reduction in STAT-1 expression. Knowing that STAT-1 and STAT-3 are key transcription factors in both immunity and inflammatory pathways, these results infer, at least in part, a mechanistic pathway that affects the manner or intensity of the immune response in malnourished individuals, increasing susceptibility to infection.

Protein malnutrition impairs the immune response and influences the severity of infection in a hamster model of chronic visceral leishmaniasis

Leishmaniasis remains one of the world's most devastating neglected tropical diseases. It mainly affects developing countries, where it often co-exists with chronic malnutrition, one of the main risk factors for developing the disease. Few studies have been published, however, on the relationship between leishmaniasis progression and malnutrition. The present paper reports the influence of protein malnutrition on the immune response and visceral disease development in adult hamsters infected with Leishmania infantum fed either standard or low protein diets. The low protein diet induced severe malnutrition in these animals, and upon infection with L. infantum 33% had severe visceral leishmaniasis compared to only 8% of animals fed the standard diet. The infected, malnourished animals showed notable leukocyte depletion, mild specific antibody responses, impairment of lymphoproliferation, presence of parasites in blood (16.67% of the hamsters) and significant increase of the splenic parasite burden. Animals fed standard diet suffered agranulocytosis and monocytopenia, but showed stronger specific immune responses and had lower parasite loads than their malnourished counterparts. The present results show that protein malnutrition promotes visceral leishmaniasis and provide clues regarding the mechanisms underlying the impairment of the immune system.