Host-directed therapies are gaining considerable impetus because of the 
emergence of drug-resistant strains of pathogens due to antibiotic therapy. 
Therefore, there is an urgent need to exploit alternative and novel strategies 
directed at host molecules to successfully restrict infections. The C-type 
lectin receptor CLEC4E and Toll-like receptor TLR4 expressed by host cells are 
among the first line of defense in encountering pathogens. Therefore, we 
exploited signaling of macrophages through CLEC4E in association with TLR4 
agonists (C4.T4) to control the growth of Mycobacterium tuberculosis (Mtb). We 
observed significant improvement in host immunity and reduced bacterial load in 
the lungs of Mtb-infected mice and guinea pigs treated with C4.T4 agonists. 
Further, intracellular killing of Mtb was achieved with a 10-fold lower dose of 
isoniazid or rifampicin in conjunction with C4.T4 than the drugs alone. C4.T4 
activated MYD88, PtdIns3K, STAT1 and RELA/NFKB, increased lysosome biogenesis, 
decreased Il10 and Il4 gene expression and enhanced macroautophagy/autophagy. 
Macrophages from autophagy-deficient (atg5 knockout or Becn1 knockdown) mice 
showed elevated survival of Mtb. The present findings also unveiled the novel 
role of CLEC4E in inducing autophagy through MYD88, which is required for 
control of Mtb growth. This study suggests a unique immunotherapeutic approach 
involving CLEC4E in conjunction with TLR4 to restrict the survival of Mtb 
through autophagy.
ABBREVIATIONS: 3MA: 3 methyladenine; AO: acridine orange; Atg5: autophagy 
related 5; AVOs: acidic vesicular organelles; BECN1: beclin 1, autophagy 
related; BMDMs: bone marrow derived macrophages; bw: body weight; C4.T4: 
agonists of CLEC4E (C4/TDB) and TLR4 (T4/ultra-pure-LPS); CFU: colony forming 
unit; CLEC4E/Mincle: C-type lectin domain family 4, member e; CLR: c-type lectin 
receptor; INH: isoniazid; LAMP1: lysosomal-associated membrane protein 1; 
MφC4.T4: Mtb-infected C4.T4 stimulated macrophages; MAP1LC3/LC3: 
microtubule-associated protein 1 light chain 3; MDC: monodansylcadaverine; MTOR: 
mechanistic target of rapamycin kinase; MYD88: myeloid differentiation primary 
response 88; NFKB: nuclear factor of kappa light polypeptide gene enhance in B 
cells; NLR: NOD (nucleotide-binding oligomerization domain)-like receptors; PFA: 
paraformaldehyde; PPD: purified protein derivative; PtdIns3K: class III 
phosphatidylinositol 3-kinase; RELA: v-rel reticuloendotheliosis viral oncogene 
homolog A (avian); RIF: rifampicin; RLR: retinoic acid-inducible gene-I-like 
receptors; TDB: trehalose-6,6´-dibehenate; TLR4: toll-like receptor 4; 
Ultra-pure-LPS: ultra-pure lipopolysaccharide-EK; V-ATPase: vacuolar-type H+ 
ATPase.