Enrique Hernández-Jiménez

Human Monocytes Undergo Functional Re-programming during Sepsis Mediated by Hypoxia-Inducible Factor-1α

Sepsis is characterized by a dysregulated inflammatory response to infection. Despite studies in mice, the cellular and molecular basis of human sepsis remains unclear and effective therapies are lacking. Blood monocytes serve as the first line of host defense and are equipped to recognize and respond to infection by triggering an immune-inflammatory response. However, the response of these cells in human sepsis and their contribution to sepsis pathogenesis is poorly understood. To investigate this, we performed a transcriptomic, functional, and mechanistic analysis of blood monocytes from patients during sepsis and after recovery. Our results revealed the functional plasticity of monocytes during human sepsis, wherein they transited from a pro-inflammatory to an immunosuppressive phenotype, while enhancing protective functions like phagocytosis, anti-microbial activity, and tissue remodeling. Mechanistically, hypoxia inducible factor-1α (HIF1α) mediated this functional re-programming of monocytes, revealing a potential mechanism for their therapeutic targeting to regulate human sepsis.

Inherited BCL10 deficiency impairs hematopoietic and nonhematopoietic immunity

Heterotrimers composed of B cell CLL/lymphoma 10 (BCL10), mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1), and caspase recruitment domain-containing (CARD) family adaptors play a role in NF-κB activation and have been shown to be involved in both the innate and the adaptive arms of immunity in murine models. Moreover, individuals with inherited defects of MALT1, CARD9, and CARD11 present with immunological and clinical phenotypes. Here, we characterized a case of autosomal-recessive, complete BCL10 deficiency in a child with a broad immunodeficiency, including defects of both hematopoietic and nonhematopoietic immunity. The patient died at 3 years of age and was homozygous for a loss-of-expression, loss-of-function BCL10 mutation. The effect of BCL10 deficiency was dependent on the signaling pathway, and, for some pathways, the cell type affected. Despite the noted similarities to BCL10 deficiency in mice, including a deficient adaptive immune response, human BCL10 deficiency in this patient resulted in a number of specific features within cell populations. Treatment of the patients myeloid cells with a variety of pathogen-associated molecular pattern molecules (PAMPs) elicited a normal response; however, NF-κB-mediated fibroblast functions were dramatically impaired. The results of this study indicate that inherited BCL10 deficiency should be considered in patients with combined immunodeficiency with B cell, T cell, and fibroblast defects.

Mitochondrial DAMPs Induce Endotoxin Tolerance in Human Monocytes: An Observation in Patients with Myocardial Infarction

Monocyte exposure to mitochondrial Danger Associated Molecular Patterns (DAMPs), including mitochondrial DNA (mtDNA), induces a transient state in which these cells are refractory to further endotoxin stimulation. In this context, IRAK-M up-regulation and impaired p65 activity were observed. This phenomenon, termed endotoxin tolerance (ET), is characterized by decreased production of cytokines in response to the pro-inflammatory stimulus. We also show that monocytes isolated from patients with myocardial infarction (MI) exhibited high levels of circulating mtDNA, which correlated with ET status. Moreover, a significant incidence of infection was observed in those patients with a strong tolerant phenotype. The present data extend our current understanding of the implications of endotoxin tolerance. Furthermore, our data suggest that the levels of mitochondrial antigens in plasma, such as plasma mtDNA, should be useful as a marker of increased risk of susceptibility to nosocomial infections in MI and in other pathologies involving tissue damage.

p21 mediates macrophage reprogramming through regulation of p50-p50 NF-κB and IFN-β.

M1 and M2 macrophage phenotypes, which mediate proinflammatory and antiinflammatory functions, respectively, represent the extremes of immunoregulatory plasticity in the macrophage population. This plasticity can also result in intermediate macrophage states that support a balance between these opposing functions. In sepsis, M1 macrophages can compensate for hyperinflammation by acquiring an M2-like immunosuppressed status that increases the risk of secondary infection and death. The M1 to M2 macrophage reprogramming that develops during LPS tolerance resembles the pathological antiinflammatory response to sepsis. Here, we determined that p21 regulates macrophage reprogramming by shifting the balance between active p65-p50 and inhibitory p50-p50 NF-κB pathways. p21 deficiency reduced the DNA-binding affinity of the p50-p50 homodimer in LPS-primed and -rechallenged macrophages, impairing their ability to attenuate IFN-β production and acquire an M2-like hyporesponsive status. High p21 levels in sepsis patients correlated with low IFN-β expression, and p21 knockdown in human monocytes corroborated its role in IFN-β regulation. The data demonstrate that p21 adjusts the equilibrium between p65-p50 and p50-p50 NF-κB pathways to mediate macrophage plasticity in LPS tolerance. Identifying p21-related pathways involved in monocyte reprogramming may lead to potential targets for sepsis treatment.

Arabinoxylan rice bran (MGN-3/Biobran) enhances natural killer cell–mediated cytotoxicity against neuroblastoma in vitro and in vivo

BACKGROUND AIMS Natural killer cell (NK) cytotoxic activity plays a major role in natural immunologic defences against malignancies. NK cells are emerging as a tool for adoptive cancer immunotherapies. Arabinoxylan rice bran (MGN-3/Biobran) has been described as a biological response modifier that can enhance the cytotoxic activity of NK cells. This study evaluated the effect of MGN-3/Biobran on NK cell activation, expansion and cytotoxicity against neuroblastoma cells. METHODS NK cells were enriched with magnetic beads and stimulated with MGN-3/Biobran. NK cell activation was evaluated via analysis of their phenotype, and their expansion capability was tracked. The in vitro cytotoxic ability of the activated NK cells was tested against K562, Jurkat, A673, NB1691, A-204, RD and RH-30 cell lines and the in vivo cytotoxic ability against the NB1691 cell line. RESULTS MGN-3/Biobran stimulation of NK cells induced a higher expression of the activation-associated receptors CD25 and CD69 than in unstimulated cells (P < 0.05). The expression of NKG2D, DNAM, NCRs and TLRs remained unchanged. Overnight MGN-3/Biobran stimulation increased NK cell cytotoxic activity against all cell lines tested in vitro and decelerated neuroblastoma growth in vivo. The mechanism is not mediated by lipopolysaccharide contamination in MGN-3/Biobran. Furthermore, the addition of MGN-3/Biobran promoted NK cell expansion and decreased T cells in vitro. CONCLUSIONS Our data show that MGN-3/Biobran upregulates NK cell activation markers, stimulates NK cell cytotoxic activity against neuroblastoma in vitro and in vivo and selectively augments the expansion of NK cells. These results may be useful for future NK cell therapeutic strategies of the treatment of neuroblastoma.

Chronic Lymphocytic Leukemia: A Paradigm of Innate Immune Cross-Tolerance

Infections are a significant cause of morbidity and mortality in patients with chronic lymphocytic leukemia (CLL). The pathogenesis of infections is multifactorial and includes hypogammaglobulinemia, conventional therapy with alkylating drugs, and recently, purine analogs and mAb-associated T cells. Patients without these risk factors also suffer from infections, although the mechanism remains unknown. In a cohort of 70 patients with CLL, we demonstrated that their monocytes were locked into a refractory state and were unable to mount a classic inflammatory response to pathogens. In addition, they exhibited the primary features of endotoxin tolerance, including low cytokine production, high phagocytic activity, and impaired Ag presentation. The involvement of miR-146a in this phenomenon was suspected. We found miR-146a target genes, such as IRAK1 and TRAF6, were manifestly downregulated. Our study provides a new explanation for infections in patients with CLL and describes a cross-tolerance between endotoxins and tumors.

NFκB2/p100 Is a Key Factor for Endotoxin Tolerance in Human Monocytes: A Demonstration Using Primary Human Monocytes from Patients with Sepsis

Endotoxin tolerance (ET) is a state of reduced responsiveness to endotoxin stimulation after a primary bacterial insult. This phenomenon has been described in several pathologies, including sepsis, in which an endotoxin challenge results in reduced cytokine production. In this study, we show that the NFκ L chain enhancer of activated B cells 2 (NFκB2)/p100 was overexpressed and accumulated in a well-established in vitro human monocyte model of ET. The p100 accumulation in these cells inversely correlated with the inflammatory response after LPS stimulation. Knocking down NFκB2/p100 using small interfering RNA in human monocytes further indicated that p100 expression is a crucial factor in the progression of ET. The monocytes derived from patients with sepsis had high levels of p100, and a downregulation of NFκB2/p100 in these septic monocytes reversed their ET status.

Adipose-derived mesenchymal stem cell administration does not improve corneal graft survival outcome.

The effect of local and systemic injections of mesenchymal stem cells derived from adipose tissue (AD-MSC) into rabbit models of corneal allograft rejection with either normal-risk or high-risk vascularized corneal beds was investigated. The models we present in this study are more similar to human corneal transplants than previously reported murine models. Our aim was to prevent transplant rejection and increase the length of graft survival. In the normal-risk transplant model, in contrast to our expectations, the injection of AD-MSC into the graft junction during surgery resulted in the induction of increased signs of inflammation such as corneal edema with increased thickness, and a higher level of infiltration of leukocytes. This process led to a lower survival of the graft compared with the sham-treated corneal transplants. In the high-risk transplant model, in which immune ocular privilege was undermined by the induction of neovascularization prior to graft surgery, we found the use of systemic rabbit AD-MSCs prior to surgery, during surgery, and at various time points after surgery resulted in a shorter survival of the graft compared with the non-treated corneal grafts. Based on our results, local or systemic treatment with AD-MSCs to prevent corneal rejection in rabbit corneal models at normal or high risk of rejection does not increase survival but rather can increase inflammation and neovascularization and break the innate ocular immune privilege. This result can be partially explained by the immunomarkers, lack of immunosuppressive ability and immunophenotypical secretion molecules characterization of AD-MSC used in this study. Parameters including the risk of rejection, the inflammatory/vascularization environment, the cell source, the time of injection, the immunosuppression, the number of cells, and the mode of delivery must be established before translating the possible benefits of the use of MSCs in corneal transplants to clinical practice.

Differential Induction of Apoptosis, Interferon Signaling, and Phagocytosis in Macrophages Infected with a Panel of Attenuated and Nonattenuated Poxviruses

ABSTRACT Due to the essential role macrophages play in antiviral immunity, it is important to understand the intracellular and molecular processes that occur in macrophages following infection with various strains of vaccinia virus, particularly those used as vaccine vectors. Similarities as well as differences were found in macrophages infected with different poxvirus strains, particularly at the level of virus-induced apoptosis and the expression of immunomodulatory genes, as determined by microarray analyses. Interestingly, the attenuated modified vaccinia Ankara virus (MVA) was particularly efficient in triggering apoptosis and beta interferon (IFN-β) secretion and in inducing changes in the expression of genes associated with increased activation of innate immunity, setting it apart from the other five vaccinia virus strains tested. Taken together, these results increase our understanding of how these viruses interact with human macrophages, at the cellular and molecular levels, and suggest mechanisms that may underlie their utility as recombinant vaccine vectors. IMPORTANCE Our studies clearly demonstrate that there are substantial biological differences in the patterns of cellular gene expression between macrophages infected with different poxvirus strains and that these changes are due specifically to infection with the distinct viruses. For example, a clear induction in IFN-β mRNA was observed after infection with MVA but not with other poxviruses. Importantly, antiviral bioassays confirmed that MVA-infected macrophages secreted a high level of biologically active type I IFN. Similarly, the phagocytic capacity of macrophages was also specifically increased after infection with MVA. Although the main scope of this study was not to test the vaccine potential of MVA as there are several groups in the field working extensively on this aspect, the characteristics/phenotypes we observed at the in vitro level clearly highlight the inherent advantages that MVA possesses in comparison to other poxvirus strains.

Response to "In vivo attenuation and genetic evolution of a ST247-SCCmecI MRSA clone after 13 years of pathogenic bronchopulmonary colonization in a patient with cystic fibrosis: implications of the innate immune response".

to ‘‘In vivo attenuation and genetic evolution of a ST247SCCmecI MRSA clone after 13 years of pathogenic bronchopulmonary colonization in a patient with cystic fibrosis: implications of the innate immune response’’ E López-Collazo, T Jurado, J de Dios Caballero, M Pérez-Vázquez, A Vindel, E Hernández-Jiménez, J Tamames, C Cubillos-Zapata, M Manrique, R Tobes, L Máiz, R Cantón, F Baquero and R del Campo