Combined Neprilysin and RAS Inhibition in Cardiovascular Diseases: A Review of Clinical Studies.

The aim of this comprehensive review article is to emphasize on the possible exploration of a new therapeutic approach in the management of heart failure (HF) and other cardiovascular diseases: the renin-angiotensin-aldosterone system-neprilysin combination inhibitors, also called angiotensin receptor neprilysin inhibitor, valsartan/sacubitril (LCZ696). Sacubitril is an inhibitor of neutral endopeptidase (NEP) which degrades vasoactive peptides such as atrial natriuretic peptide and brain natriuretic peptide. Valsartan is an angiotensin receptor blocker which is usually used in hypertension. Although HF has been a global health burden, for decades there has been lack of novel therapeutic options as many trials failed due to potential side effects. With the published results of the landmark trial Prospective comparison of ARNI with ACEI to Determine the Impact on Global Mortality and morbidity in HF (PARADIGM-HF), a new direction in the treatment of HF is anticipated. This trial showed that LCZ696 was able to reduce the primary composite end point of cardiovascular death or HF hospitalization, and similar reduction was observed for cardiovascular death. This review article also highlights the results of 4 published trials of LCZ696 in both HTN and HF. After the results of PARADIGM-HF trial, the major challenge will be outcome in regular clinical practice, as subjects in the trial were mostly stable New York Heart Association class II patients with no comorbidities. In addition, many trials are simultaneously in progress regarding the use of LCZ696 in patients with diabetes, renal failure, and hepatic impairment. To conclude, sacubitril/valsartan significantly improved morbidity and mortality in patients with chronic HF, but it will need meticulous attention when used in real outpatient practice.

CD40 signaling to the rescue: A CD8 exhaustion perspective in chronic infectious diseases.

Chronic infectious diseases such as HIV, HBV, and HCV, among others, cause severe morbidity and mortality globally. Progressive decline in CD8 functionality, survival, and proliferative potential-a phenomenon referred to as CD8 exhaustion-is believed to be responsible for poor pathogen control in chronic infectious diseases. While the role of negative inhibitory receptors such as PD-1 in augmenting CD8 exhaustion has been extensively studied, the role of positive costimulatory receptors remains poorly understood. In this review, we discuss how one such costimulatory pathway, CD40-CD40L, regulates CD8 dysfunction and rescue. While the significance of this pathway has been extensively investigated in models of autoimmunity, acute infectious diseases, and tumor models, the role played by CD40-CD40L in regulating CD8 exhaustion in chronic infectious diseases is just beginning to be understood. Considering that monotherapy with blocking antibodies targeting inhibitory PD-1-PD-L1 pathway is only partially effective at ameliorating CD8 exhaustion and that humanized CD40 agonist antibodies are currently available, a better understanding of the role of the CD40-CD40L pathway in chronic infectious diseases will pave the way for the development of more robust immunotherapeutic and prophylactic vaccination strategies.

Control of Toxoplasma reactivation by rescue of dysfunctional CD8+ T-cell response via PD-1-PDL-1 blockade.

In this study, we document that Toxoplasma gondii differentiation and reactivation are mediated by systemic CD8 T-cell dysfunction during chronic infection. We demonstrate that CD8(+) T-cell exhaustion occurs despite control of parasitemia during early-chronic toxoplasmosis. During later phases, these cells become exhausted, leading to parasite reactivation and mortality. Concomitant with increased CD8(+) T-cell apoptosis and decreased effector response, this dysfunction is characterized by a graded elevation in expression of inhibitory receptor PD-1 on these cells in both lymphoid and nonlymphoid tissue. Blockade of the PD-1-PDL-1 pathway reinvigorates this suboptimal CD8(+) T-cell response, resulting in control of parasite reactivation and prevention of mortality in chronically infected animals. To the best of our knowledge, this report is unique in showing that exposure to a persistent pathogen despite initial control of parasitemia can lead to CD8(+) T-cell dysfunction and parasite reactivation.

Donor CD8+ T cells prevent Toxoplasma gondii de-encystation but fail to rescue the exhausted endogenous CD8+ T cell population.

Functional exhaustion of CD8(+) T cells due to increased expression of inhibitory molecule PD-1 (Programmed Death-1) causes reactivation of latent disease during later phases of chronic toxoplasmosis. Onset of disease recrudescence results in decreased parasite cyst burden concomitant with parasites undergoing stage conversion from a primarily encysted, quiescent bradyzoite to a fast-replicating, highly motile tachyzoite. Thus, reduced cyst burden is one of the early hallmarks of disease recrudescence. This was further validated by depleting gamma interferon (IFN-γ), a cytokine known to control latent toxoplasmosis, in chronically infected prerecrudescent mice. Since CD8(+) T cells (an important source of IFN-γ) lose their functionality during the later phases of chronic toxoplasmosis, we next examined if adoptive transfer of functional CD8(+) T cells from acutely infected donors to the chronically infected prerecrudescent hosts could impede parasite de-encystation and rescue exhausted CD8(+) T cells. While the transfer of immune CD8(+) T cells temporarily restricted the breakdown of cysts, the exhausted endogenous CD8(+) T cell population was not rescued. Over time, the donor population got deleted, resulting in parasite de-encystation and host mortality. Considering that donor CD8(+) T cells fail to become long-lived, one of the cardinal features of memory CD8(+) T cells, it bears the implication that memory CD8 differentiation is impaired during chronic toxoplasmosis. Moreover, our data strongly suggest that while adoptive immunotherapy can prevent parasite de-encystation transiently, reduced antigen burden in the chronic phase by itself is insufficient for rescue of exhausted CD8(+) T cells. The conclusions of this study have profound ramifications in designing immunotherapeutics against chronic toxoplasmosis.

Cutting edge: CD40-CD40 ligand pathway plays a critical CD8-intrinsic and -extrinsic role during rescue of exhausted CD8 T cells.

CD8 exhaustion mediated by an inhibitory programmed death-1-programmed death ligand-1 (PD-L1) pathway occurs in several chronic infections, including toxoplasmosis. Although blockade of the programmed death-1-PD-L1 pathway revives this response, the role of costimulatory receptors involved in this rescue has not been ascertained in any model of CD8 exhaustion. This report demonstrates that one such costimulatory pathway, CD40-CD40L, plays a critical role during rescue of exhausted CD8 T cells. Blockade of this pathway abrogates the ameliorative effects of anti-PD-L1 treatment on CD8 T cells. Additionally, we demonstrate in an infectious disease model that CD8-intrinsic CD40 signaling is important for optimal CD8 polyfunctionality, proliferation, T-bet upregulation, and IL-21 signaling, albeit in the context of CD8 rescue. The critical role of CD40 during the rescue of exhausted CD8 T cells may provide a rational basis for designing novel therapeutic vaccination approaches.

PD-1-mediated attrition of polyfunctional memory CD8+ T cells in chronic toxoplasma infection.

We reported earlier that during chronic toxoplasmosis CD8(+) T cells become functionally exhausted with concomitant PD-1 upregulation, leading to eventual host mortality. However, how immune exhaustion specifically mediates attrition of CD8 polyfunctionality, a hallmark of potent T-cell response, during persistent infections has not been addressed. In this study, we demonstrate that PD-1 is preferentially expressed on polyfunctional memory CD8(+) T cells, which renders them susceptible to apoptosis. In vitro blockade of the PD-1-PD-L1 pathway dramatically reduces apoptosis of polyfunctional and interferon γ(+)/granzyme B(-) memory but not effector CD8(+) T cells. In summary, the present report underscores the critical role of the PD-1-PD-L1 pathway in mediating attrition of this important CD8(+) T-cell subset and addresses the mechanistic basis of how αPD-L1 therapy reinvigorates polyfunctional CD8 response during chronic infections. The conclusions of this study can have profound immunotherapeutic implications in combating recrudescent toxoplasmosis as well other chronic infections.

Enhanced antitumor immunity by a novel small molecule HPK1 inhibitor.

BACKGROUND: Hematopoietic progenitor kinase 1 (HPK1 or MAP4K1) has been demonstrated as a negative intracellular immune checkpoint in mediating antitumor immunity in studies with HPK1 knockout and kinase dead mice. Pharmacological inhibition of HPK1 is desirable to investigate the role of HPK1 in human immune cells with therapeutic implications. However, a significant challenge remains to identify a small molecule inhibitor of HPK1 with sufficient potency, selectivity, and other drug-like properties suitable for proof-of-concept studies. In this report, we identified a novel, potent, and selective HPK1 small molecule kinase inhibitor, compound K (CompK). A series of studies were conducted to investigate the mechanism of action of CompK, aiming to understand its potential application in cancer immunotherapy. METHODS: Human primary T cells and dendritic cells (DCs) were investigated with CompK treatment under conditions relevant to tumor microenvironment (TME). Syngeneic tumor models were used to assess the in vivo pharmacology of CompK followed by human tumor interrogation ex vivo. RESULTS: CompK treatment demonstrated markedly enhanced human T-cell immune responses under immunosuppressive conditions relevant to the TME and an increased avidity of the T-cell receptor (TCR) to recognize viral and tumor-associated antigens (TAAs) in significant synergy with anti-PD1. Animal model studies, including 1956 sarcoma and MC38 syngeneic models, revealed improved immune responses and superb antitumor efficacy in combination of CompK with anti-PD-1. An elevated immune response induced by CompK was observed with fresh tumor samples from multiple patients with colorectal carcinoma, suggesting a mechanistic translation from mouse model to human disease. CONCLUSION: CompK treatment significantly improved human T-cell functions, with enhanced TCR avidity to recognize TAAs and tumor cytolytic activity by CD8+ T cells. Additional benefits include DC maturation and priming facilitation in tumor draining lymph node. CompK represents a novel pharmacological agent to address cancer treatment resistance.

Advanced myeloma masquerading as chronic shoulder pain in a 48-year-old man: a diagnostic dilemma.

Although solitary plasmacytomas may occasionally present as collar bone swellings or fractures, multiple myeloma involving clavicle is extremely rare. Ten to forty per cent of multiple myeloma cases are asymptomatic and are incidental diagnoses. Our case report describes an entirely benign presentation like chronic shoulder pain masquerading advanced myeloma, thereby posing a significant diagnostic dilemma. We present a 48-year-old man who presented with chronic bilateral shoulder pain with no history of trauma and was eventually diagnosed with advanced multiple myeloma and pathologic fracture of the right clavicle. It is, therefore, evident that a low threshold for suspicion can lead to early diagnosis and initiation of treatment and better survival.

Acute bilateral pulmonary embolism in a 21-year-old: is May-Thurner syndrome in our differential?

May-Thurner syndrome (MTS) is a clinical condition where the left common iliac vein gets compressed by the overlying right common iliac artery anterior to the fifth lumbar vertebra and the sacral promontory. It results in vessel wall injury and predisposition to thrombosis. We present a case of a 21-year-old African-American man with no significant past medical history who came to the emergency department with left lower limb swelling associated with shortness of breath, and was eventually diagnosed to have extensive left lower extremity deep vein thrombosis (DVT) along with acute bilateral extensive pulmonary embolism (PE) as a consequence to MTS. MTS should be considered in the differential when young patients present with unprovoked or recurrent left-sided DVT. Diagnosis of this anatomical variant is critical as it may need long-term anticoagulation and consideration of pharmaco-mechanical intervention such as mechanical thrombectomy and venoplasty with or without stenting.

Rare complication of milk-alkali ingestion: severe pancreatitis and acute kidney injury in a chronic hypocalcaemic patient with DiGeorge's syndrome.

Injudicious use of over-the-counter calcium supplements has resulted in increased incidences of hypercalcaemia and related complications. We present a case of acute pancreatitis in a chronic hypocalcaemic patient of DiGeorge's syndrome. The patient came into the ED with sepsis syndrome, right upper quadrant and epigastric pain and no obvious source of infection. Lab results and imaging were indicative of acute pancreatitis. There was severe renal dysfunction. The patient needed haemodialysis and had a prolonged stay in intensive care. The medical history was negative for biliary duct pathology or alcohol use. The patient had vomiting and diarrhoea in the nursing home for about a week, but she continued to receive her regular medications that included the calcium supplements and thiazide diuretics. It is likely that a complex interplay between calcium supplementation, dehydration and thiazide diuretics resulted in the development of acute pancreatitis and severe renal dysfunction in a chronic hypocalcaemic patient.

A near-fatal case of intussusception and ischaemic perforation of stomach in first-trimester pregnancy: eight years after laparoscopic Roux-en-Y gastric bypass.

The increasing demand and popularity of bariatric surgery are not only due to the ever-increasing obesity epidemic but to tackle obesity-related comorbidities like diabetes and hypertension. However, bariatric surgery is not free of complications. One rare complication is intussusception, jejuno-jejunal intussusception being the most common. Intussusception has been defined both in pregnant and in non-pregnant women as well as men. We describe the case of a 40-year-old woman in the first trimester of pregnancy came to the hospital with worsening abdominal pain, was found to have intussusception of small bowel involving the jejunum, along with ischaemic perforation and necrosis of the fundus of the stomach. Postsurgery, the patient had a complete recovery and eventually, she successfully delivered an intact, viable fetus.

RVX 208: A novel BET protein inhibitor, role as an inducer of apo A-I/HDL and beyond.

Low-density cholesterol (LDL) has been the prime target of currently available lipid-lowering therapies although current research is expanding the focus beyond LDL lowering and has included high-density cholesterol (HDL) also as the target. Bromo and extra-terminal (BET) proteins are implicated in the regulation of transcription of several regulatory genes and regulation of proinflammatory pathways. As atherosclerosis is an inflammatory pathway and studies showed that BET inhibition has a role in inhibiting inflammation, the concept of BET inhibition came in the field of atherosclerosis. RVX 208 is a novel, orally active, BET protein inhibitor and the only BET inhibitor currently available in the field of atherosclerosis. RVX 208 acts primarily by increasing apo A-I (apolipoprotein A-I) and HDL levels. RVX 208 has a novel action of increasing larger, more cardio-protective HDL particles. Post hoc analysis of Phase II trials also showed that RVX 208 reduced major adverse cardiovascular events (MACE) in treated patients, over and above that of apo A-I/HDL increasing action. This MACE reducing actions of RVX 208 were largely due to its novel anti-inflammatory actions. Currently, a phase III trial, BETonMACE, is recruiting patients to look for the effects of RVX 208 in patients with increased risk of atherosclerotic cardiovascular disease. So BET inhibitors act in multiple ways to inhibit and modulate atherosclerosis and would be an emerging and potential option in the management of multifactorial disease like coronary artery disease by inhibiting a single substrate. But we need long-term phase III trial data's to look for effects on real-world patients.

Zika and pregnancy: A comprehensive review.

Zika virus (ZIKV) infection is a well-nurtured topic for healthcare personnel nowadays. Central nervous system involvement including microcephaly and ocular involvements has already been reported in neonates of affected pregnant ladies. In this article, we have discussed these effects on the newborns of ZIKV-infected mothers. The proposed pathogenesis, modes of transmission of this infection from mothers to the fetuses, diagnosis of the cases and precaution for the pregnant ladies have also been discussed. We have gathered the recently available data on the risk of ZIKV for expectant mothers from PubMed, https://www.gov.uk/guidance/zika-virus as well as from centers for disease control and prevention websites.

Blimp-1-mediated CD4 T cell exhaustion causes CD8 T cell dysfunction during chronic toxoplasmosis.

CD8, but not CD4, T cells are considered critical for control of chronic toxoplasmosis. Although CD8 exhaustion has been previously reported in Toxoplasma encephalitis (TE)-susceptible model, our current work demonstrates that CD4 not only become exhausted during chronic toxoplasmosis but this dysfunction is more pronounced than CD8 T cells. Exhausted CD4 population expressed elevated levels of multiple inhibitory receptors concomitant with the reduced functionality and up-regulation of Blimp-1, a transcription factor. Our data demonstrates for the first time that Blimp-1 is a critical regulator for CD4 T cell exhaustion especially in the CD4 central memory cell subset. Using a tamoxifen-dependent conditional Blimp-1 knockout mixed bone marrow chimera as well as an adoptive transfer approach, we show that CD4 T cell-intrinsic deletion of Blimp-1 reversed CD8 T cell dysfunction and resulted in improved pathogen control. To the best of our knowledge, this is a novel finding, which demonstrates the role of Blimp-1 as a critical regulator of CD4 dysfunction and links it to the CD8 T cell dysfunctionality observed in infected mice. The critical role of CD4-intrinsic Blimp-1 expression in mediating CD4 and CD8 T cell exhaustion may provide a rational basis for designing novel therapeutic approaches.

Intrinsic TGF-ß signaling promotes age-dependent CD8+ T cell polyfunctionality attrition.

Advanced age is associated with immune system deficits that result in an increased susceptibility to infectious diseases; however, specific mediators of age-dependent immune dysfunction have not been fully elucidated. Here we demonstrated that aged mice exhibit poor effector CD8+ T cell polyfunctionality, primarily due to CD8+ T cell-extrinsic deficits, and that reduced CD8+ T cell polyfunctionality correlates with increased susceptibility to pathogenic diseases. In aged animals challenged with the parasite Encephalitozoon cuniculi, effector CD8+ T cell survival and polyfunctionality were suppressed by highly elevated TGF-ß1. Furthermore, TGF-ß depletion reduced effector CD8+ T cell apoptosis in both young and aged mice and enhanced effector CD8+ T cell polyfunctionality in aged mice. Surprisingly, intrinsic blockade of TGF-ß signaling in CD8+ T cells was sufficient to rescue polyfunctionality in aged animals. Together, these data demonstrate that low levels of TGF-ß1 promote apoptosis of CD8+ effector T cells and high TGF-ß1 levels associated with age result in both CD8+ T cell apoptosis and an altered transcriptional profile, which correlates with loss of polyfunctionality. Furthermore, elevated TGF-ß levels are observed in the elderly human population and in aged Drosophila, suggesting that TGF-ß represents an evolutionarily conserved negative regulator of the immune response in aging organisms.

Psychiatric disorders in toxoplasma seropositive patients--the CD8 connection.

Although the highest numbers of studies linking an infectious agent with schizophrenia has involved the parasite Toxoplasma gondii, the mechanistic underpinnings of this correlation has remained unaddressed. Incidentally, CD8 T cells, which play a pivotal role in mediating long-term immunity to Toxoplasma, are downregulated in schizophrenia patients. Recent studies have demonstrated that CD8 response is also impaired during chronic toxoplasmosis in murine models. In light of these new findings, in this article, we discuss the potential role of CD8 T cells in causing altered mental status in Toxoplasma seropositive schizophrenia patients.

IL-7 and IL-15 do not synergize during CD8 T cell recall response against an obligate intracellular parasite.

Long-term protection against Toxoplasma gondii is dependent on robust CD8(+) T cell immunity. In the absence of this response, the host is unable to maintain chronicity, which results in recrudescence of infection and possible death. Factors needed for the persistence of protective CD8(+) T cells against the parasite need to be evaluated. Previous studies from our laboratory have reported that synergism between γ chain cytokines like IL-7 and IL-15 is critical for the generation of CD8(+) T cell response needed for protection during acute infection. In this study we report that the situation is different during the recall response where CD8(+) T cell response is almost entirely dependent on IL-15, with IL-7 at best playing a minor role. In the absence of IL-15, CD8(+) T cells fail to respond optimally to parasitic re-challenge and hosts are unable to control their replication, which leads to their death. Thus T. gondii infection may represent a unique situation where CD8(+) T cell response during secondary challenge is primarily dependent on IL-15 with other γ chain cytokines having nominal effect. These findings provide important information regarding factors involved in the generation of protective immunity against T. gondii with strong implications in developing immunotherapeutic agents against the pathogen.

T cell exhaustion in protozoan disease.

Protozoan parasites cause severe morbidity and mortality in humans worldwide, especially in developing countries where access to chemotherapeutic agents is limited. Although parasites initially evoke a robust immune response, subsequent immunity fails to clear infection, ultimately leading to the chronic stage. This enigmatic situation was initially addressed in chronic viral models, where T cells lose their function, a phenomenon referred to as 'exhaustion'. However, recent studies demonstrate that this paradigm can be extended to protozoan diseases as well, although with notable differences. These studies have revealed that T cell responses generated against Toxoplasma gondii, Plasmodium sp., and Leishmania sp. can become dysfunctional. This review discusses T cell exhaustion in parasitic infection, mechanisms of development, and a possible role in disease outcome.

CD8 T Cells and Toxoplasma gondii: A New Paradigm.

CD8 T cells are essential for control of Toxoplasma gondii infection. Once activated they undergo differentiation into short-lived effector and memory precursor effector cells. As effector cells, CD8 T cells exert immune pressure on the parasite via production of inflammatory cytokines and through their cytolytic activity. Once immune control has been established, the parasite encysts and develops into chronic infection regulated by the memory CD8 T-cell population. Several signals are needed for this process to be initiated and for development of fully differentiated memory CD8 T cells. With newly developed tools including CD8 T-cell tetramers and TCR transgenic mice, dissecting the biology behind T. gondii-specific CD8 T-cell responses can now be more effectively addressed. In this paper, we discuss what is known about the signals required for effective T. gondii-specific CD8 T-cell development, their differentiation, and effector function.