Dietary Modifications of Nitrogen Intake Decreases Inflammation and Promotes Rejuvenation of Spleen in Aged Mice

Abstract

The spleen is a lymphoid organ with multiple functions including blood filtration and immune activity.Aging changes the spleen's anatomy for both immune and stromal cells and can lead to immunesenescence, contributing to the increased rates of mortality and morbidity commonly observed in the elderly. Much evidence indicates that the combination of food quantity and quality can influence chronic inflammatory states in the spleen. Quantitative amino-acids (AA) adequacy is pivotal to maintain cell integrity in mammals. Aged mice feed with balanced essential-AA (EAA) formulation improved mitochondrial biogenesis and morphological and molecular changes in many organs, as well as increased lifespan. Here, we evaluated the inflammatory state of the spleen in aged male mice (fifteen months old) chronically fed for twelve months with a particular EAA-rich diet compared to a standard laboratory diet. This study found that chronic consumption of an EAA-rich diet decreased inflammation and modulated reticular and mitochondrial chaperones, mitochondrial function and cells survival, maintaining the correct architecture of the spleen. These changes could also be beneficial for immune system integrity, providing a possible theoretical-speculative basis for the role of EAA improving the quality of life of the elderly by probably slowing immune-senescence.

Influence of Diets with Varying Essential/Nonessential Amino Acid Ratios on Mouse Lifespan

“…We also observed that the EAA-100% diet reduced Hpg level, but not NLR ratio, more than StD. This confirms that EAA have anti-inflammatory activity as observed previously [11,40].…”

“…We also observed that the EAA-100% diet reduced inflammation, as suggested by the lower Hpg level found in animals on this diet, even when compared to StD. This is in agreement with the anti-inflammatory activity of EAA observed in previous experimental [11,40] and clinical settings [1,54,55]. Those effects on inflammation modulation could represent one of the mechanisms underpinning the longer lifespan reached by these animals.…”

Qualitative Nitrogen Malnutrition Damages Gut and Alters Microbiome in Adult Mice. A Preliminary Histopathological Study

“…A possible limitation of this study is the exclusive application of IHC to support our results. However, as applied in a previous spleen study [ 2 , 87 ], this choice was dictated by the fact that the gut also contains heterogeneous cell population (enterocytes, goblet cells, Paneth’s cells, myocytes, etc.). Consequently, histopathological changes and especially the exact location of markers is possible alone with IHC and HC.…”

“…The other AAs can be synthesized in an autonomous way by the body, and therefore are defined non-essential (NEAAs). To best survive, all organisms must maintain a full complement of the AAs, best if with excess of EAAs [ 1 , 2 , 3 ].…”

Nutritional Supplementation and Exercise – Essential Allies in the Treatment of Chronic Heart Failure: The Metabolic and Molecular Bases.

“…Unfortunately, we should note that no dietary proteins have an EAA/NEAA ratio > 0.9, whereas, conversely most proteins have a <0.7 ratio at best. Interestingly, experimental data show that special EAA mixtures with an EAA/NEAA ratio >1 increases lifespan (23) and albumin (24), and also reduces inflammation in healthy mice (25,26). This would suggest that NEAA are not indispensable for cell life and that they are synthesized according to metabolic needs if adequate amounts of EAA are provided.…”